National Primary Drinking Water Regulations: Stage 2
Disinfectants and Disinfection Byproducts Rule
[Federal Register: January 4, 2006 (Volume 71, Number 2)]
[Rules and Regulations]
[Page 387-493]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr04ja06-14]
[[Page 388]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 9, 141, and 142
[EPA-HQ-OW-2002-0043; FRL-8012-1]
RIN 2040-AD38
National Primary Drinking Water Regulations: Stage 2
Disinfectants and Disinfection Byproducts Rule
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The Environmental Protection Agency (EPA) is promulgating
today's final rule, the Stage 2 Disinfectants and Disinfection
Byproducts Rule (DBPR), to provide for increased protection against the
potential risks for cancer and reproductive and developmental health
effects associated with disinfection byproducts (DBPs). The final Stage
2 DBPR contains maximum contaminant level goals for chloroform,
monochloroacetic acid and trichloroacetic acid; National Primary
Drinking Water Regulations, which consist of maximum contaminant levels
(MCLs) and monitoring, reporting, and public notification requirements
for total trihalomethanes (TTHM) and haloacetic acids (HAA5); and
revisions to the reduced monitoring requirements for bromate. This
document also specifies the best available technologies for the final
MCLs. EPA is also approving additional analytical methods for the
determination of disinfectants and DBPs in drinking water. EPA believes
the Stage 2 DBPR will reduce the potential risks of cancer and
reproductive and developmental health effects associated with DBPs by
reducing peak and average levels of DBPs in drinking water supplies.
The Stage 2 DBPR applies to public water systems (PWSs) that are
community water systems (CWSs) or nontransient noncommunity water
systems (NTNCWs) that add a primary or residual disinfectant other than
ultraviolet light or deliver water that has been treated with a primary
or residual disinfectant other than ultraviolet light.
This rule also makes minor corrections to drinking water
regulations, specifically the Public Notification tables. New endnotes
were added to these tables in recent rulemakings; however, the
corresponding footnote numbering in the tables was not changed. In
addition, this rule makes a minor correction to the Stage 1
Disinfectants and Disinfection Byproducts Rule by replacing a sentence
that was inadvertently removed.
DATES: This final rule is effective on March 6, 2006. For judicial
review purposes, this final rule is promulgated as January 4, 2006. The
incorporation by reference of certain publications listed in the rule
is approved by the Director of the Federal Register as of March 6, 2006.
ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-OW-2002-0043. All documents in the docket are listed on the
http://www.regulations.gov 
Web site.
Although listed in the index, some information is not publicly
available, e.g., CBI or other information whose disclosure is
restricted by statute. Certain other material, such as copyrighted
material, is not placed on the Internet and will be publicly available
only in hard copy form.
Publicly available docket materials are available either
electronically through http://www.regulations.gov or in hard copy
at the Water Docket, EPA/DC, EPA West, Room B102, 1301 Constitution Ave.,
NW., Washington, DC. The Public Reading Room is open from 10 a.m. to 4
p.m., Monday through Friday, excluding legal holidays. The telephone
number for the Public Reading Room is (202) 566-1744, and the telephone
number for the Water Docket is (202) 566-2426.
FOR FURTHER INFORMATION CONTACT: For technical inquiries, contact Tom
Grubbs, Standards and Risk Management Division, Office of Ground Water
and Drinking Water (MC 4607M), Environmental Protection Agency, 1200
Pennsylvania Ave., NW., Washington, DC 20460; telephone number: (202)
564-5262; fax number: (202) 564-3767; e-mail address:
grubbs.thomas@epa.gov. For general information, contact the Safe
Drinking Water Hotline, Telephone (800) 426-4791. The Safe Drinking
Water Hotline is open Monday through Friday, excluding legal holidays,
from 10 a.m. to 4 p.m. Eastern Time.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Apply to Me?
Entities potentially regulated by the Stage 2 DBPR are community
and nontransient noncommunity water systems that add a primary or
residual disinfectant other than ultraviolet light or deliver water
that has been treated with a primary or residual disinfectant other
than ultraviolet light. Regulated categories and entities are
identified in the following chart.
------------------------------------------------------------------------
Examples
of
Category regulated
entities
------------------------------------------------------------------------
Industry..................................................... Community
and
nontransi
ent
noncommun
ity water
systems
that use
a primary
or
residual
disinfect
ant other
than
ultraviol
et light
or
deliver
water
that has
been
treated
with a
primary
or
residual
disinfect
ant other
than
ultraviol
et light.
State, Local, Tribal, or Federal Governments................. Community
and
nontransi
ent
noncommun
ity water
systems
that use
a primary
or
residual
disinfect
ant other
than
ultraviol
et light
or
deliver
water
that has
been
treated
with a
primary
or
residual
disinfect
ant other
than
ultraviol
et light.
------------------------------------------------------------------------
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in the table could also be regulated. To determine whether
your facility is regulated by this action, you should carefully examine
the definition of ``public water system'' in Sec. 141.2 and the
section entitled ``coverage'' (Sec. 141.3) in Title 40 of the Code of
Federal Regulations and applicability criteria in Sec. 141.600 and
141.620 of today's proposal. If you have questions regarding the
applicability of this action to a particular entity, contact the person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.
B. How Can I Get Copies of This Document and Other Related Information?
See the ADDRESSES section for information on how to receive a copy
of this document and related information.
Regional contacts:
I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room 203,
Boston, MA 02203, (617) 565-3616.
II. Michael Lowy, Water Supply Section, 290 Broadway, 24th Floor, New
[[Page 389]]
York, NY 10007-1866, (212) 637-3830.
III. Jason Gambatese, Drinking Water Section (3WM41), 1650 Arch Street,
Philadelphia, PA 19103-2029, (215) 814-5759.
IV. Robert Burns, Drinking Water Section, 61 Forsyth Street SW.,
Atlanta, GA 30303, (404) 562-9456.
V. Miguel Del Toral, Water Supply Section, 77 W. Jackson Blvd.,
Chicago, IL 60604, (312) 886-5253.
VI. Blake L. Atkins, Drinking Water Section, 1445 Ross Avenue, Dallas,
TX 75202, (214) 665-2297.
VII. Douglas J. Brune, Drinking Water Management Branch, 901 North 5th
Street, Kansas City, KS 66101, (800) 233-0425.
VIII. Bob Clement, Public Water Supply Section (8P2-W-MS), 999 18th
Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653.
IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San
Francisco, CA 94105, (415) 972-3569.
X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136),
Seattle, WA 98101, (206) 553-1890.
Abbreviations Used in This Document
ASDWA Association of State Drinking Water Administrators
ASTM American Society for Testing and Materials
AWWA American Water Works Association
AwwaRF American Water Works Association Research Foundation
BAT Best available technology
BCAA Bromochloroacetic acid
BDCM Bromodichloromethane
CDBG Community Development Block Grant
CWS Community water system
DBAA Dibromoacetic acid
DBCM Dibromochloromethane
DBP Disinfection byproduct
DBPR Disinfectants and Disinfection Byproducts Rule
DCAA Dichloroacetic acid
EA Economic analysis
EC Enhanced coagulation
EDA Ethylenediamine
EPA United States Environmental Protection Agency
ESWTR Enhanced Surface Water Treatment Rule
FACA Federal Advisory Committee Act
GAC Granular activated carbon
GC/ECD Gas chromatography using electron capture detection
GWR Ground Water Rule
GWUDI Ground water under the direct influence of surface water
HAA5 Haloacetic acids (five) (sum of monochloroacetic acid,
dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and
dibromoacetic acid)
HAN Haloacetonitriles (trichloroacetonitrile, dichloroacetonitrile,
bromochloroacetonitrile, and dibromoacetonitrile)
IC Ion chromatograph
IC/ICP-MS Ion chromatograph coupled to an inductively coupled plasma
mass spectrometer
IDSE Initial distribution system evaluation
ILSI International Life Sciences Institute
IESWTR Interim Enhanced Surface Water Treatment Rule
IPCS International Programme on Chemical Safety
IRIS Integrated Risk Information System (EPA)
LOAEL Lowest observed adverse effect level
LRAA Locational running annual average
LT1ESTWR Long Term 1 Enhanced Surface Water Treatment Rule
LT2ESTWR Long Term 2 Enhanced Surface Water Treatment Rule
MBAA Monobromoacetic acid
MCAA Monochloroacetic acid
MCL Maximum contaminant level
MCLG Maximum contaminant level goal
M-DBP Microbial and disinfection byproducts mg/L Milligram per liter
MRL Minimum reporting level
MRDL Maximum residual disinfectant level
MRDLG Maximum residual disinfectant level goal
NDMA N-nitrosodimethylamine
NDWAC National Drinking Water Advisory Council
NF Nanofiltration
NOAEL No Observed Adverse Effect Level
NODA Notice of data availability
NPDWR National primary drinking water regulation
NRWA National Rural Water Association
NTNCWS Nontransient noncommunity water system
NTP National Toxicology Program
NTTAA National Technology Transfer and Advancement Act
OMB Office of Management and Budget
PAR Population attributable risk
PE Performance evaluation
PWS Public water system
RAA Running annual average
RFA Regulatory Flexibility Act
RfD Reference dose
RSC Relative source contribution
RUS Rural Utility Service
SAB Science Advisory Board
SBAR Small Business Advisory Review
SBREFA Small Business Regulatory Enforcement Fairness Act
SDWA Safe Drinking Water Act, or the ``Act,'' as amended in 1996
SER Small Entity Representative
SGA Small for gestational age
SUVA Specific ultraviolet absorbance
SWAT Surface Water Analytical Tool
SWTR Surface Water Treatment Rule
TC Total coliforms
TCAA Trichloroacetic acid
TCR Total Coliform Rule
THM Trihalomethane
TOC Total organic carbon
TTHM Total trihalomethanes (sum of four THMs: chloroform,
bromodichloromethane, dibromochloromethane, and bromoform)
TWG Technical work group
UMRA Unfunded Mandates Reform Act
UV 254 Ultraviolet absorption at 254 nm
VSL Value of Statistical Life
WTP Willingness To Pay
Table of Contents
I. General Information
A. Does This Action Apply to Me?
B. How Can I Get Copies of This Document and Other Related Information?
II. Summary of the Final Rule
A. Why is EPA Promulgating the Stage 2 DBPR?
B. What Does the Stage 2 DBPR Require?
1. Initial Distribution System Evaluation
2. Compliance and monitoring requirements
3. Operational Evaluation Levels
4. Consecutive systems
C. Correction of Sec. 141.132
III. Background
A. Statutory Requirements and Legal Authority
B. What is the Regulatory History of the Stage 2 DBPR and How
Were Stakeholders Involved?
1. Total Trihalomethanes Rule
2. Stage 1 Disinfectants and Disinfection Byproducts Rule
3. Stakeholder involvement
a. Federal Advisory Committee process
b. Other outreach processes
C. Public Health Concerns to be Addressed
1. What are DBPs?
2. DBP Health Effects
a. Cancer health effects
i. Epidemiology
ii. Toxicology
b. Reproductive and developmental health effects
i. Epidemiology
ii. Toxicology
c. Conclusions
D. DBP Occurrence and DBP Control
1. Occurrence
2. Treatment
E. Conclusions for Regulatory Action
IV. Explanation of Today's Action
A. MCLGs
[[Page 390]]
1. Chloroform MCLG
a. Today's rule
b. Background and analysis
c. Summary of major comments
2. HAA MCLGs: TCAA and MCAA
a. Today's rule
b. Background and analysis
c. Summary of major comments
B. Consecutive Systems
1. Today's Rule
2. Background and analysis
3. Summary of major comments
C. LRAA MCLs for TTHM and HAA5
1. Today's rule
2. Background and analysis
3. Summary of major comments
D. BAT for TTHM and HAA5
1. Today's rule
2. Background and analysis
3. Summary of major comments
E. Compliance Schedules
1. Today's rule
2. Background and analysis
3. Summary of major comments
F. Initial Distribution System Evaluation (IDSE)
1. Today's rule
a. Applicability
b. Data collection
i. Standard monitoring
ii. System specific study
iii. 40/30 certification
c. Implementation
2. Background and analysis
a. Standard monitoring
b. Very small system waivers
c. 40/30 certifications
d. System specific studies
e. Distribution System Schematics
3. Summary of major comments
G. Monitoring Requirements and Compliance Determination for TTHM
and HAA5 MCLs
1. Today's Rule
a. IDSE Monitoring
b. Routine Stage 2 Compliance Monitoring
i. Reduced monitoring
ii. Compliance determination
2. Background and Analysis
3. Summary of Major Comments
H. Operational Evaluation Requirements initiated by TTHM and
HAA5 Levels
1. Today's rule
2. Background and analysis
3. Summary of major comments
I. MCL, BAT, and Monitoring for Bromate
1. Today's rule
2. Background and analysis
a. Bromate MCL
b. Criterion for reduced bromate monitoring
3. Summary of major comments
J. Public Notice Requirements
1. Today's rule
2. Background and analysis
3. Summary of major comments
K. Variances and Exemptions
1. Today's Rule
2. Background and Analysis
a. Variances
b. Affordable Treatment Technologies for Small Systems
c. Exemptions
3. Summary of major comments
L. Requirements for Systems to Use Qualified Operators
M. System Reporting and Recordkeeping Requirements
1. Today's rule
2. Summary of major comments
N. Approval of Additional Analytical Methods
1. Today's Rule
2. Background and Analysis
O. Laboratory Certification and Approval
1. PE acceptance criteria
a. Today's rule
b. Background and analysis
c. Summary of major comments
2. Minimum reporting limits
a. Today's rule
b. Background and analysis
c. Summary of major comments
P. Other regulatory changes
V. State Implementation
A. Today's rule
1. State Primacy Requirements for Implementation Flexibility
2. State recordkeeping requirements
3. State reporting requirements
4. Interim primacy
5. IDSE implementation
B. Background and Analysis
C. Summary of Major Comments
VI. Economic Analysis
A. Regulatory Alternatives Considered
B. Analyses that Support Today's Final Rule
1. Predicting water quality and treatment changes
2. Estimating benefits
3. Estimating costs
4. Comparing regulatory alternatives
C. Benefits of the Stage 2 DBPR
1. Nonquantified benefits
2. Quantified benefits
3. Timing of benefits accrual
D. Costs of the Stage 2 DBPR
1. Total annualized present value costs
2. PWS costs
a. IDSE costs
b. PWS treatment costs
c. Monitoring costs
3. State/Primacy agency costs
4. Non-quantified costs
E. Household Costs of the Stage 2 DBPR
F. Incremental Costs and Benefits of the Stage 2 DBPR
G. Benefits From the Reduction of Co-occurring Contaminants
H. Potential Risks From Other Contaminants
1. Emerging DBPs
2. N-nitrosamines
3. Other DBPs
I. Effects of the Contaminant on the General Population and
Groups within the General Population that are Identified as Likely
To Be at Greater Risk of Adverse Health Effects
J. Uncertainties in the Risk, Benefit, and Cost Estimates for
the Stage 2 DBPR
K. Benefit/Cost Determination for the Stage 2 DBPR
L. Summary of Major Comments
1. Interpretation of health effects studies
2. Derivation of benefits
3. Use of SWAT
5. Unanticipated risk issues
6. Valuation of cancer cases avoided
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children from
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions to Address
Environmental Justice in Minority Populations or Low-Income Populations
K. Consultations with the Science Advisory Board, National
Drinking Water Advisory Council, and the Secretary of Health and
Human Services
L. Plain Language
M. Analysis of the Likely Effect of Compliance With the Stage 2
DBPR on the Technical, Managerial, and Financial Capacity of Public
Water Systems
N. Congressional Review Act
VIII. References
II. Summary of the Final Rule
A. Why is EPA Promulgating the Stage 2 DBPR?
The Environmental Protection Agency is finalizing the Stage 2
Disinfectants and Disinfection Byproduct Rule (DBPR) to reduce
potential cancer risks and address concerns with potential reproductive
and developmental risks from DBPs. The Agency is committed to ensuring
that all public water systems provide clean and safe drinking water.
Disinfectants are an essential element of drinking water treatment
because of the barrier they provide against harmful waterborne
microbial pathogens. However, disinfectants react with naturally
occurring organic and inorganic matter in source water and distribution
systems to form disinfection byproducts (DBPs) that may pose health
risks. The Stage 2 DBPR is designed to reduce the level of exposure
from DBPs without undermining the control of microbial pathogens. The
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) is being
finalized and implemented simultaneously with the Stage 2 DBPR to
ensure that drinking water is microbiologically safe at the limits set
for DBPs.
Congress required EPA to promulgate the Stage 2 DBPR as part of the
1996 Safe Drinking Water Act (SDWA) Amendments (section 1412(b)(2)(C)).
The Stage 2 DBPR augments the Stage 1 DBPR that was finalized in 1998
(63 FR 69390, December 16, 1998) (USEPA
[[Page 391]]
1998a). The goal of the Stage 2 DBPR is to target the highest risk
systems for changes beyond those required for Stage 1 DBPR. Today's
rule reflects consensus recommendations from the Stage 2 Microbial/
Disinfection Byproducts (M-DBP) Federal Advisory Committee (the
Advisory Committee) as well as public comments.
New information on health effects, occurrence, and treatment has
become available since the Stage 1 DBPR that supports the need for the
Stage 2 DBPR. EPA has completed a more extensive analysis of health
effects, particularly reproductive and developmental endpoints,
associated with DBPs since the Stage 1 DBPR. Some recent studies on
both human epidemiology and animal toxicology have shown possible
associations between chlorinated drinking water and reproductive and
developmental endpoints such as spontaneous abortion, stillbirth,
neural tube and other birth defects, intrauterine growth retardation,
and low birth weight. While results of these studies have been mixed,
EPA believes they support a potential hazard concern. New epidemiology
and toxicology studies evaluating bladder, colon, and rectal cancers
have increased the weight of evidence linking these health effects to
DBP exposure. The large number of people (more than 260 million
Americans) exposed to DBPs and the potential cancer, reproductive, and
developmental risks have played a significant role in EPA's decision to
move forward with regulatory changes that target lowering DBP exposures
beyond the requirements of the Stage 1 DBPR.
While the Stage 1 DBPR is predicted to provide a major reduction in
DBP exposure, national survey data suggest that some customers may
receive drinking water with elevated, or peak, DBP concentrations even
when their distribution system is in compliance with the Stage 1 DBPR.
Some of these peak concentrations are substantially greater than the
Stage 1 DBPR maximum contaminant levels (MCLs) and some customers
receive these elevated levels of DBPs on a consistent basis. The new
survey results also show that Stage 1 DBPR monitoring sites may not be
representative of higher DBP concentrations that occur in distribution
systems. In addition, new studies indicate that cost-effective
technologies including ultraviolet light (UV) and granular activated
carbon (GAC) may be very effective at lowering DBP levels. EPA's
analysis of this new occurrence and treatment information indicates
that significant public health benefits may be achieved through
further, cost-effective reductions of DBPs in distribution systems.
The Stage 2 DBPR presents a risk-targeting approach to reduce risks
from DBPs. The new requirements provide for more consistent, equitable
protection from DBPs across the entire distribution system and the
reduction of DBP peaks. New risk-targeting provisions require systems
to first identify their risk level; then, only those systems with the
greatest risk will need to make operational or treatment changes. The
Stage 2 DBPR, in conjunction with the LT2ESWTR, will help public water
systems deliver safer water to Americans with the benefits of
disinfection to control pathogens and with fewer risks from DBPs.
B. What Does the Stage 2 DBPR Require?
The risk-targeting components of the Stage 2 DBPR focus the
greatest amount of change where the greatest amount of risk may exist.
Therefore, the provisions of the Stage 2 DBPR focus first on
identifying the higher risks through the Initial Distribution System
Evaluation (IDSE). The rule then addresses reducing exposure and
lowering DBP peaks in distribution systems by using a new method to
determine MCL compliance (locational running annual average (LRAA)),
defining operational evaluation levels, and regulating consecutive
systems. This section briefly describes the requirements of this final
rule. More detailed information on the regulatory requirements for this
rule can be found in Section IV.
1. Initial Distribution System Evaluation
The first provision, designed to identify higher risk systems, is
the Initial Distribution System Evaluation (IDSE). The purpose of the
IDSE is to identify Stage 2 DBPR compliance monitoring sites that
represent each system's highest levels of DBPs. Because Stage 2 DBPR
compliance will be determined at these new monitoring sites, only those
systems that identify elevated concentrations of TTHM and HAA5 will
need to make treatment or process changes to bring the system into
compliance with the Stage 2 DBPR. By identifying compliance monitoring
sites with the highest concentrations of TTHM and HAA5 in each system's
distribution system, the IDSE will offer increased assurance that MCLs
are being met across the distribution system and that customers are
receiving more equitable public health protection. Both treatment
changes and awareness of TTHM and HAA5 levels resulting from the IDSE
will allow systems to better control for distribution system peaks.
The IDSE is designed to offer flexibility to public water systems.
The IDSE requires TTHM and HAA5 monitoring for one year on a regular
schedule that is determined by source water type and system size.
Alternatively, systems have the option of performing a site-specific
study based on historical data, water distribution system models, or
other data; and waivers are available under certain circumstances. The
IDSE requirements are discussed in Sections IV.E, IV.F., and IV.G of
this preamble and in subpart U of the rule language.
2. Compliance and Monitoring Requirements
As in Stage 1, the Stage 2 DBPR focuses on monitoring for and
reducing concentrations of two classes of DBPs: total trihalomethanes
(TTHM) and haloacetic acids (HAA5). These two groups of DBPs act as
indicators for the various byproducts that are present in water
disinfected with chlorine or chloramine. This means that concentrations
of TTHM and HAA5 are monitored for compliance, but their presence in
drinking water is representative of many other chlorination DBPs that
may also occur in the water; thus, a reduction in TTHM and HAA5
generally indicates an overall reduction of DBPs.
The second provision of the Stage 2 DBPR is designed to address
spatial variations in DBP exposure through a new compliance calculation
(referred to as locational running annual average) for TTHM and HAA5
MCLs. The MCL values remain the same as in the Stage 1. The Stage 1
DBPR running annual average (RAA) calculation allowed some locations
within a distribution system to have higher DBP annual averages than
others as long as the system-wide average was below the MCL. The Stage
2 DBPR bases compliance on a locational running annual average (LRAA)
calculation, where the annual average at each sampling location in the
distribution system will be used to determine compliance with the MCLs
of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5, respectively. The LRAA
will reduce exposures to high DBP concentrations by ensuring that each
monitoring site is in compliance with the MCLs as an annual average,
while providing all customers drinking water that more consistently
meets the MCLs. A more detailed discussion of Stage 2 DBPR MCL
requirements can be found in Sections IV.C, IV.E, and IV.G of this preamble
and in Sec. 141.64(b)(2) and (3) and subpart V of the rule language.
The number of compliance monitoring sites is based on the
[[Page 392]]
population served and the source water type. EPA believes that
population-based monitoring provides better risk-targeting and is
easier to implement. Section IV.G describes population-based monitoring
and how it affects systems complying with this rule.
The Stage 2 DBPR includes new MCLGs for chloroform,
monochloroacetic acid, and trichloroacetic acid, but these new MCLGs do
not affect the MCLs for TTHM or HAA5.
3. Operational Evaluation Levels
The IDSE and LRAA calculation will lead to lower DBP concentrations
overall and reduce short term exposures to high DBP concentrations in
certain areas, but this strengthened approach to regulating DBPs will
still allow individual DBP samples above the MCL even when systems are
in compliance with the Stage 2 DBPR. Today's rule requires systems that
exceed operational evaluation levels (referred to as significant
excursions in the proposed rule) to evaluate system operational
practices and identify opportunities to reduce DBP concentrations in
the distribution system. This provision will curtail peaks by providing
systems with a proactive approach to remain in compliance. Operational
evaluation requirements are discussed in greater detail in Section IV.H.
4. Consecutive Systems
The Stage 2 DBPR also contains provisions for regulating
consecutive systems, defined in the Stage 2 DBPR as public water
systems that buy or otherwise receive some or all of their finished
water from another public water system. Uniform regulation of
consecutive systems provided by the Stage 2 DBPR will ensure that
consecutive systems deliver drinking water that meets applicable DBP
standards, thereby providing better, more equitable public health
protection. More information on regulation of consecutive systems can
be found in Sections IV.B, IV.E, and IV.G.
C. Correction of Sec. 141.132
Section 553 of the Administrative Procedure Act, 5 U.S.C.
553(b)(B), provides that, when an agency for good cause finds that
notice and public procedure are impracticable, unnecessary, or contrary
to the public interest, the agency may issue a rule without providing
prior notice and an opportunity for public comment. In addition to
promulgating the Stage 2 regulations, this rule also makes a minor
correction to the National Primary Drinking Water Regulations,
specifically the Stage 1 Disinfection Byproducts Rule. This rule
corrects a technical error made in the January 16, 2001, Federal
Register Notice (66 FR 3769) (see page 3770). This rule restores the
following sentence that was inadvertently removed from Sec. 141.132
(b)(1)(iii), ``Systems on a reduced monitoring schedule may remain on
that reduced schedule as long as the average of all samples taken in
the year (for systems which must monitor quarterly) or the result of
the sample (for systems which must monitor no more frequently than
annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5,
respectively.'' This text had been part of the original regulation when
it was codified in the CFR on December 16, 1998. However, as a result
of a subsequent amendment to that regulatory text, the text discussed
today was removed. EPA recognized the error only after publication of
the new amendment, and is now correcting the error. EPA is merely
restoring to the CFR language that EPA had promulgated on December 16,
1998. EPA is not creating any new rights or obligations by this
technical correction. Thus, additional notice and public comment is not
necessary. EPA finds that this constitutes ``good cause'' under 5
U.S.C. 553(b)(B).
III. Background
A combination of factors influenced the development of the Stage 2
DBPR. These include the initial 1992-1994 Microbial and Disinfection
Byproduct (M-DBP) stakeholder deliberations and EPA's Stage 1 DBPR
proposal (USEPA 1994); the 1996 Safe Drinking Water Act (SDWA)
Amendments; the 1996 Information Collection Rule; the 1998 Stage 1
DBPR; new data, research, and analysis on disinfection byproduct (DBP)
occurrence, treatment, and health effects since the Stage 1 DBPR; and
the Stage 2 DBPR Microbial and Disinfection Byproducts Federal Advisory
Committee. The following sections provide summary background
information on these subjects. For additional information, see the
proposed Stage 2 DBPR and supporting technical material where cited (68
FR 49548, August 18, 2003) (USEPA 2003a).
A. Statutory Requirements and Legal Authority
The SDWA, as amended in 1996, authorizes EPA to promulgate a
national primary drinking water regulation (NPDWR) and publish a
maximum contaminant level goal (MCLG) for any contaminant the
Administrator determines ``may have an adverse effect on the health of
persons,'' is ``known to occur or there is a substantial likelihood
that the contaminant will occur in public water systems with a
frequency and at levels of public health concern,'' and for which ``in
the sole judgement of the Administrator, regulation of such contaminant
presents a meaningful opportunity for health risk reduction for persons
served by public water systems'' (SDWA section 1412(b)(1)(A)). MCLGs
are non-enforceable health goals set at a level at which ``no known or
anticipated adverse effects on the health of persons occur and which
allows an adequate margin of safety.'' These health goals are published
at the same time as the NPDWR (SDWA sections 1412(b)(4) and 1412(a)(3)).
SDWA also requires each NPDWR for which an MCLG is established to
specify an MCL that is as close to the MCLG as is feasible (sections
1412(b)(4) and 1401(1)(C)). The Agency may also consider additional
health risks from other contaminants and establish an MCL ``at a level
other than the feasible level, if the technology, treatment techniques,
and other means used to determine the feasible level would result in an
increase in the health risk from drinking water by--(i) increasing the
concentration of other contaminants in drinking water; or (ii)
interfering with the efficacy of drinking water treatment techniques or
processes that are used to comply with other national primary drinking
water regulations'' (section 1412(b)(5)(A)). When establishing an MCL
or treatment technique under this authority, ``the level or levels or
treatment techniques shall minimize the overall risk of adverse health
effects by balancing the risk from the contaminant and the risk from
other contaminants the concentrations of which may be affected by the
use of a treatment technique or process that would be employed to
attain the maximum contaminant level or levels'' (section
1412(b)(5)(B)). In today's rule, the Agency is establishing MCLGs and
MCLs for certain DBPs, as described in Section IV.
Finally, section 1412(b)(2)(C) of the Act requires EPA to
promulgate a Stage 2 DBPR. Consistent with statutory provisions for
risk balancing (section 1412(b)(5)(B)), EPA is finalizing the LT2ESWTR
concurrently with the Stage 2 DBPR to ensure simultaneous protection
from microbial and DBP risks.
B. What is the Regulatory History of the Stage 2 DBPR and How Were
Stakeholders Involved?
This section first summarizes the existing regulations aimed at
controlling
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levels of DBPs in drinking water. The Stage 2 DBPR establishes
regulatory requirements beyond these rules that target high risk
systems and provide for more equitable protection from DBPs across the
entire distribution system. Next, this section summarizes the extensive
stakeholder involvement in the development of the Stage 2 DBPR.
1. Total Trihalomethanes Rule
The first rule to regulate DBPs was promulgated on November 29,
1979. The Total Trihalomethanes Rule (44 FR 68624, November 29, 1979)
(USEPA 1979) set an MCL of 0.10 mg/L for total trihalomethanes (TTHM).
Compliance was based on the running annual average (RAA) of quarterly
averages of all samples collected throughout the distribution system.
This TTHM standard applied only to community water systems using
surface water and/or ground water that served at least 10,000 people
and added a disinfectant to the drinking water during any part of the
treatment process.
2. Stage 1 Disinfectants and Disinfection Byproducts Rule
The Stage 1 DBPR, finalized in 1998 (USEPA 1998a), applies to all
community and nontransient noncommunity water systems that add a
chemical disinfectant to water. The rule established maximum residual
disinfectant level goals (MRDLGs) and enforceable maximum residual
disinfectant level (MRDL) standards for three chemical disinfectants--
chlorine, chloramine, and chlorine dioxide; maximum contaminant level
goals (MCLGs) for three trihalomethanes (THMs), two haloacetic acids
(HAAs), bromate, and chlorite; and enforceable maximum contaminant
level (MCL) standards for TTHM, five haloacetic acids (HAA5), bromate
(calculated as running annual averages (RAAs)), and chlorite (based on
daily and monthly sampling). The Stage 1 DBPR uses TTHM and HAA5 as
indicators of the various DBPs that are present in disinfected water.
Under the Stage 1 DBPR, water systems that use surface water or ground
water under the direct influence of surface water and use conventional
filtration treatment are required to remove specified percentages of
organic materials, measured as total organic carbon (TOC), that may
react with disinfectants to form DBPs. Removal is achieved through
enhanced coagulation or enhanced softening, unless a system meets one
or more alternative compliance criteria.
The Stage 1 DBPR was one of the first rules to be promulgated under
the 1996 SDWA Amendments (USEPA 1998a). EPA finalized the Interim
Enhanced Surface Water Treatment Rule (63 FR 69477, December 16, 1998)
(USEPA 1998b) at the same time as the Stage 1 DBPR to ensure
simultaneous compliance and address risk tradeoff issues. Both rules
were products of extensive Federal Advisory Committee deliberations and
final consensus recommendations in 1997.
3. Stakeholder Involvement
a. Federal Advisory Committee process. EPA reconvened the M-DBP
Advisory Committee in March 1999 to develop recommendations on issues
pertaining to the Stage 2 DBPR and LT2ESWTR. The Stage 2 M-DBP Advisory
Committee consisted of 21 organizational members representing EPA,
State and local public health and regulatory agencies, local elected
officials, Native American Tribes, large and small drinking water
suppliers, chemical and equipment manufacturers, environmental groups,
and other stakeholders. Technical support for the Advisory Committee's
discussions was provided by a technical working group established by
the Advisory Committee. The Advisory Committee held ten meetings from
September 1999 to July 2000, which were open to the public, with an
opportunity for public comment at each meeting.
The Advisory Committee carefully considered extensive new data on
the occurrence and health effects of DBPs, as well as costs and
potential impacts on public water systems. In addition, they considered
risk tradeoffs associated with treatment changes. Based upon this
detailed technical evaluation, the committee concluded that a targeted
protective public health approach should be taken to address exposure
to DBPs beyond the requirements of the Stage 1 DBPR. While there had
been substantial research to date, the Advisory Committee also
concluded that significant uncertainty remained regarding the risk
associated with DBPs in drinking water. After reaching these
conclusions, the Advisory Committee developed an Agreement in Principle
(65 FR 83015, December 29, 2000) (USEPA 2000a) that laid out their
consensus recommendations on how to further control DBPs in public
water systems, which are reflected in today's final rule.
In the Agreement in Principle, the Advisory Committee recommended
maintaining the MCLs for TTHM and HAA5 at 0.080 mg/L and 0.060 mg/L,
respectively, but changing the compliance calculation in two phases to
facilitate systems moving from the running annual average (RAA)
calculation to a locational running annual average (LRAA) calculation.
In the first phase, systems would continue to comply with the Stage 1
DBPR MCLs as RAAs and, at the same time, comply with MCLs of 0.120 mg/L
for TTHM and 0.100 mg/L for HAA5 calculated as LRAAs. RAA calculations
average all samples collected within a distribution system over a one-
year period, but LRAA calculations average all samples taken at each
individual sampling location in a distribution system during a one-year
period. Systems would also carry out an Initial Distribution System
Evaluation (IDSE) to select compliance monitoring sites that reflect
higher TTHM and HAA5 levels occurring in the distribution system. The
second phase of compliance would require MCLs of 0.080 mg/L for TTHM
and 0.060 mg/L for HAA5, calculated as LRAAs at individual monitoring
sites identified through the IDSE. The first phase has been dropped in
the final rule, as discussed in section IV.C.
The Agreement in Principle also provided recommendations for
simultaneous compliance with the LT2ESWTR so that the reduction of DBPs
does not compromise microbial protection. The complete text of the
Agreement in Principle (USEPA 2000a) can be found online at
http://www.regulations.gov.
b. Other outreach processes. EPA worked with stakeholders to
develop the Stage 2 DBPR through various outreach activities other than
the M-DBP Federal Advisory Committee process. The Agency consulted with
State, local, and Tribal governments; the National Drinking Water
Advisory Committee (NDWAC); the Science Advisory Board (SAB); and Small
Entity Representatives (SERs) and small system operators (as part of an
Agency outreach initiative under the Regulatory Flexibility Act).
Section VII includes a complete description of the many stakeholder
activities which contributed to the development of the Stage 2 DBPR.
Additionally, EPA posted a pre-proposal draft of the Stage 2 DBPR
preamble and regulatory language on an EPA Internet site on October 17,
2001. This public review period allowed readers to comment on the Stage
2 DBPR's consistency with the Agreement in Principle of the Stage 2 M-
DBP Advisory Committee. EPA received important suggestions on this pre-
proposal draft from 14 commenters, which included public water systems,
State governments, laboratories, and other stakeholders.
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C. Public Health Concerns to be Addressed
EPA is promulgating the Stage 2 rule to reduce the potential risks
of cancer and reproductive and developmental health effects from DBPs.
In addition, the provisions of the Stage 2 DBPR provide for more
equitable public health protection. Sections C and D describe the
general basis for this public health concern through reviewing
information in the following areas: the health effects associated with
DBPs, DBP occurrence, and the control of DBPs.
1. What Are DBPs?
Chlorine has been widely used to kill disease-causing microbes in
drinking water. The addition of chlorine in PWSs across the U.S. to
kill microbial pathogens in the water supply has been cited as one of
the greatest public health advances of the twentieth century (Okun
2003). For example, during the decade 1880-1890, American cities
experienced an average mortality rate of 58 per 100,000 from typhoid,
which was commonly transmitted through contaminated water. By 1938,
this rate had fallen to 0.67 deaths per 100,000, largely due to
improved treatment of drinking water (Blake 1956).
During the disinfection process, organic and inorganic material in
source waters can combine with chlorine and certain other chemical
disinfectants to form DBPs. More than 260 million people in the U.S.
are exposed to disinfected water and DBPs (USEPA 2005a). Although
chlorine is the most commonly applied disinfectant, other
disinfectants, including ozone, chlorine dioxide, chloramine, and
ultraviolet radiation, are in use. In combination with these, all
surface water systems must also use either chlorine or chloramine to
maintain a disinfectant residual in their distribution system. The kind
of disinfectant used can produce different types and levels of
disinfectant byproducts in the drinking water.
Many factors affect the amount and kinds of DBPs in drinking water.
Areas in the distribution system that have had longer contact time with
chemical disinfectants tend to have higher levels of DBPs, such as
sites farther from the treatment plant, dead ends in the system, and
small diameter pipes. The makeup and source of the water also affect
DBP formation. Different types of organic and inorganic material will
form different types and levels of DBPs. Other factors, such as water
temperature, season, pH, and location within the water purification
process where disinfectants are added, can affect DBP formation within
and between water systems.
THMs and HAAs are widely occurring classes of DBPs formed during
disinfection with chlorine and chloramine. The four THMs (TTHM) and
five HAAs (HAA5) measured and regulated in the Stage 2 DBPR act as
indicators for DBP occurrence. There are other known DBPs in addition
to a variety of unidentified DBPs present in disinfected water. THMs
and HAAs typically occur at higher levels than other known and
unidentified DBPs (McGuire et al. 2002; Weinberg et al. 2002). The
presence of TTHM and HAA5 is representative of the occurrence of many
other chlorination DBPs; thus, a reduction in the TTHM and HAA5
generally indicates an overall reduction of DBPs.
2. DBP Health Effects
Since the mid 1980's, epidemiological studies have supported a
potential association between bladder cancer and chlorinated water and
possibly also with colon and rectal cancers. In addition, more recent
health studies have reported potential associations between chlorinated
drinking water and reproductive and developmental health effects.
Based on a collective evaluation of both the human epidemiology and
animal toxicology data on cancer and reproductive and developmental
health effects discussed below and in consideration of the large number
of people exposed to chlorinated byproducts in drinking water (more
than 260 million), EPA concludes that (1) new cancer data since Stage 1
strengthen the evidence of a potential association of chlorinated water
with bladder cancer and suggests an association for colon and rectal
cancers, (2) current reproductive and developmental health effects data
do not support a conclusion at this time as to whether exposure to
chlorinated drinking water or disinfection byproducts causes adverse
developmental or reproductive health effects, but do support a
potential health concern, and (3) the combined health data indicate a
need for public health protection beyond that provided by the Stage 1 DBPR.
This section summarizes the key information in the areas of cancer,
reproductive, and developmental health studies that EPA used to arrive
at these conclusions. Throughout this writeup, EPA uses `weight of
evidence,' `causality,' and `hazard' as follows:
? A `weight of evidence' evaluation is a collective
evaluation of all pertinent information. Judgement about the weight of
evidence involves considerations of the quality and adequacy of data
and consistency of responses. These factors are not scored mechanically
by adding pluses and minuses; they are judged in combination.
? Criteria for determining `causality' include consistency,
strength, and specificity of association, a temporal relationship, a
biological gradient (dose-response relationship), biological
plausibility, coherence with multiple lines of evidence, evidence from
human populations, and information on agent's structural analogues
(USEPA 2005i). Additional considerations for individual study findings
include reliable exposure data, statistical power and significance, and
freedom from bias and confounding.
? The term `hazard' describes not a definitive conclusion,
but the possibility that a health effect may be attributed to a certain
exposure, in this case chlorinated water. Analyses done for the Stage 2
DBPR follow the 1999 EPA Proposed Guidelines for Carcinogenic Risk
Assessment (USEPA 1999a). In March 2005, EPA updated and finalized the
Cancer Guidelines and a Supplementary Children's Guidance, which
include new considerations on mode of action for cancer risk
determination and additional potential risks due to early childhood
exposure (USEPA 2005i; USEPA 2005j). Conducting the cancer evaluation
using the 2005 Cancer Guidelines would not result in any change from
the existing analysis. With the exception of chloroform, no mode of
action has been established for other specific regulated DBPs. Although
some of the DBPs have given mixed mutagenicity and genotoxicity
results, having a positive mutagenicity study does not necessarily mean
that a chemical has a mutagenic mode of action. The extra factor of
safety for children's health protection does not apply because the new
Supplementary Children's Guidance requires application of the
children's factor only when a mutagenic mode of action has been identified.
a. Cancer health effects. The following section briefly discusses
cancer epidemiology and toxicology information EPA analyzed and some
conclusions of these studies and reports. Further discussion of these
studies and EPA's conclusions can be found in the proposed Stage 2 DBPR
(USEPA 2003a) and the Economic Analysis for the Final Stage 2
Disinfectants and Disinfection Byproducts Rule (Economic Analysis (EA))
(USEPA 2005a).
Human epidemiology studies and animal toxicology studies have
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examined associations between chlorinated drinking water or DBPs and
cancer. While EPA cannot conclude there is a causal link between
exposure to chlorinated surface water and cancer, EPA believes that the
available research indicates a potential association between bladder
cancer and exposure to chlorinated drinking water or DBPs. EPA also
believes the available research suggests a possible association between
rectal and colon cancers and exposure to chlorinated drinking water or
DBPs. This is based on EPA's evaluation of all available cancer
studies. The next two sections focus on studies published since the
Stage 1 DBPR. Conclusions are based on the research as a whole.
i. Epidemiology. A number of epidemiological studies have been
conducted to investigate the relationship between exposure to
chlorinated drinking water and various cancers. These studies
contribute to the overall evidence on potential human health hazards
from exposure to chlorinated drinking water.
Epidemiology studies provide useful health effects information
because they reflect human exposure to a drinking water DBP mixture
through multiple routes of intake such as ingestion, inhalation and
dermal absorption. The greatest difficulty with conducting cancer
epidemiology studies is the length of time between exposure and effect.
Higher quality studies have adequately controlled for confounding and
have limited the potential for exposure misclassification, for example,
using DBP levels in drinking water as the exposure metric as opposed to
type of source water. Study design considerations for interpreting
cancer epidemiology data include sufficient follow-up time to detect
disease occurrence, adequate sample size, valid ascertainment of cause
of the cancer, and reduction of potential selection bias in case-
control and cohort studies (by having comparable cases and controls and
by limiting loss to follow-up). Epidemiology studies provide extremely
useful information on human exposure to chlorinated water, which
complement single chemical, high dose animal data.
In the Stage 1 DBPR, EPA concluded that the epidemiological
evidence suggested a potential increased risk for bladder cancer. Some
key studies EPA considered for Stage 1 include Cantor et al. (1998),
Doyle et al. (1997), Freedman et al. (1997), King and Marrett (1996),
McGeehin et al. (1993), Cantor et al. (1987), and Cantor et al. (1985).
Several studies published since the Stage 1 DBPR continue to support an
association between increased risk of bladder cancer and exposure to
chlorinated surface water (Chevrier et al. 2004; Koivusalo et al. 1998;
Yang et al. 1998). One study found no effects on a biomarker of
genotoxicity in urinary bladder cells from TTHM exposure (Ranmuthugala
et al. 2003). Epidemiological reviews and meta-analyses generally
support the possibility of an association between chlorinated water or
THMs and bladder cancer (Villanueva et al. 2004; Villanueva et al.
2003; Villanueva et al. 2001; Mills et al. 1998). The World Health
Organization (WHO 2000) found data inconclusive or insufficient to
determine causality between chlorinated water and any health endpoint,
although they concluded that the evidence is better for bladder cancer
than for other cancers.
In the Stage 1 DBPR, EPA concluded that early studies suggested a
small possible increase in rectal and colon cancers from exposure to
chlorinated surface waters. The database of studies on colon and rectal
cancers continues to support a possible association, but evidence
remains mixed. For colon cancer, one newer study supports the evidence
of an association (King et al. 2000a) while others showed inconsistent
findings (Hildesheim et al. 1998; Yang et al. 1998). Rectal cancer
studies are also mixed. Hildesheim et al. (1998) and Yang et al. (1998)
support an association with rectal cancer while King et al. (2000a) did
not. A review of colon and rectal cancer concluded evidence was
inconclusive but that there was a stronger association for rectal
cancer and chlorination DBPs than for colon cancer (Mills et al. 1998).
The WHO (2000) review reported that studies showed weak to moderate
associations with colon and rectal cancers and chlorinated surface
water or THMs but that evidence is inadequate to evaluate these
associations.
Recent studies on kidney, brain, and lung cancers and DBP exposure
support a possible association (kidney: Yang et al. 1998, Koivusalo et
al. 1998; brain: Cantor et al. 1999; lung: Yang et al. 1998). However,
so few studies have examined these endpoints that definitive
conclusions cannot be made. Studies on leukemia found little or no
association with DBPs (Infante-Rivard et al. 2002; Infante-Rivard et
al. 2001). A recent study did not find an association between
pancreatic cancer and DBPs (Do et al. 2005). A study researching
multiple cancer endpoints found an association between THM exposure and
all cancers when grouped together (Vinceti et al. 2004). More details
on the cancer epidemiology studies since the Stage 1 DBPR are outlined
in Table II.D-1.
Table II.D-1.--Summary of Cancer Epidemiology Studies Reviewed for Stage 2 DBPR
----------------------------------------------------------------------------------------------------------------
Exposure(s) Outcome(s)
Study type studied measured Findings
----------------------------------------------------------------------------------------------------------------
Author(s)
Do et al. 2005................. Case-control Estimated Pancreatic cancer No association was
study in Canada, chlorinated found between
1994-1997. DBPs, pancreatic cancer and
chloroform, BDCM exposure to
concentrations. chlorinated DBPs,
chloroform, or BDCM.
Chevrier et al. 2004........... Case-control Compared THM Bladder cancer... A statistically
study in France, levels, duration significant decreased
1985-1987. of exposure, and risk of bladder
3 types of water cancer was found as
treatment duration of exposure
(ozonation, to ozonated water
chlorination, increased. This was
ozonation/ evident with and
chlorination). without adjustment
for other exposure
measures. A small
association was
detected for
increased bladder
cancer risk and
duration of exposure
to chlorinated
surface water and
with the estimated
THM content of the
water, achieving
statistical
significance only
when adjusted for
duration of ozonated
water exposures.
Effect modification
by gender was noted
in the adjusted
analyses.
[[Page 396]]
Vinceti et al. 2004............ Retrospective Standardized 15 cancers Mortality ratio from
cohort study in mortality ratios including colon, all cancers showed a
Italy, 1987-1999. from all causes rectum, and statistically
vs. cancer for bladder. significant small
consumers increase for males
drinking water consuming drinking
with high THMs. water with high THMs.
For females, an
increased mortality
ratio for all cancers
was seen but was not
statistically
significant. Stomach
cancer in men was the
only individual
cancer in which a
statistically
significant excess in
mortality was
detected for
consumption of
drinking water with
high THMs.
Ranmuthugala et al. 2003....... Cohort study in 3 Estimated dose of Frequency of Relative risk
Australian TTHM, micronuclei in estimates for DNA
communities, chloroform, and urinary bladder damage to bladder
1997. bromoform from epithelial cells. cells for THM dose
routinely- metrics were near
collected THM 1.0. The study
measurements and provides no evidence
fluid intake that THMs are
diary. associated with DNA
damage to bladder
epithelial cells, and
dose-response
patterns were not
detected.
Infante-Rivard et al. 2002..... Population-based Estimated Acute Data are suggestive,
case-control prenatal and lymphoblastic but imprecise,
study in Quebec, postnatal leukemia. linking DNA variants
1980-1993. exposure to THMs with risk of acute
and lymphoblastic
polymorphisms in leukemia associated
two genes. with drinking water
DBPs. The number of
genotyped subjects
for GSTT1 and CYP2E1
genes was too small
to be conclusive.
Infante-Rivard et al. 2001..... Population-based Compared water Acute No increased risk for
case-control chlorination lymphoblastic lymphoblastic
study in Quebec, (never, leukemia. leukemia was observed
1980-1993. sometimes, for prenatal exposure
always) and at average levels of
exposure to TTHMs, metals or
TTHMs, metals, nitrates. However, a
and nitrates. non-statistically
significant, small
increased risk was
seen for postnatal
cumulative exposure
to TTHMs and
chloroform (both at
above the 95th
exposure percentile
of the distribution
for cases and
controls), for zinc,
cadmium, and arsenic,
but not other metals
or nitrates.
King et al. 2000a.............. Population-based Compared source Colon and rectal Colon cancer risk was
case-control of drinking cancer. statistically
study in water and associated with
southern chlorination cumulative long term
Ontario, 1992- status. exposure to THMs,
1994. Estimated TTHM chlorinated surface
levels, duration water, and tap water
of exposure, and consumption metrics
tap water among males only.
consumption. Exposure-response
relationships were
evident for exposure
measures combining
duration and THM
levels. Associations
between the exposure
measures and rectal
cancer were not
observed for either
gender.
Cantor et al. 1999............. Population-based Compared level Brain cancer..... Among males, a
case-control and duration of statistically
study in Iowa, THM exposure significant increased
1984-1987. (cumulative and risk of brain cancer
average), source was detected for
of water, duration of
chlorination, chlorinated versus
and water non-chlorinated
consumption. source water,
especially among high-
level consumers of
tap water. An
increased risk of
brain cancer for high
water intake level
was found in men. No
associations were
found for women for
any of the exposure
metrics examined.
Cantor et al. 1998............. Population-based Compared level Bladder cancer... A statistically
case-control and duration of significant positive
study in Iowa, THM exposure association between
1986-1989. (cumulative and risk of bladder
average), source cancer and exposure
of water, to chlorinated
chlorination, groundwater or
and water surface water
consumption. reported for men and
for smokers, but no
association found for
male/female non-
smokers, or for women
overall. Limited
evidence was found
for an association
between tapwater
consumption and
bladder cancer risk.
Suggestive evidence
existed for exposure-
response effects of
chlorinated water and
lifetime THM measures
on bladder cancer
risk.
Hildesheim et al. 1998......... Population-based Compared level Colon and rectal Increased risks of
case-control and duration of cancer. rectal cancer was
study in Iowa, THM exposure associated with
1986-1989. (cumulative and duration of exposure
average), source to chlorinated
of water, surface water and any
chlorination, chlorinated water,
and water with evidence of an
consumption. exposure-response
relationship. Risk of
rectal cancer is
statistically
significant increased
with >60 years
lifetime exposure to
THMs in drinking
water, and risk
increased for
individuals with low
dietary fiber intake.
Risks were similar
for men and women and
no effects were
observed for tapwater
measures. No
associations were
detected for water
exposure measures and
risk of colon cancer.
Koivusalo et al. 1998.......... Population-based Estimated Bladder and Drinking water
case-control residential kidney cancer. mutagenicity was
study in duration of associated with a
Finland, 1991- exposure and small, statistically
1992. level of significant, exposure-
drinking water related excess risk
mutagenicity. for kidney and
bladder cancers among
men; weaker
associations were
detected for
mutagenic water and
bladder or kidney
cancer among women.
The effect of
mutagenicity on
bladder cancer was
modified by smoking
status, with an
increased risk among
non-smokers.
[[Page 397]]
Yang et al. 1998............... Cross-sectional Examined Cancer of rectum, Residence in
study in Taiwan, residence in lung, bladder, chlorinating
1982-1991. chlorinated kidney, colon, municipalities (vs.
(mainly surface and 11 others. non-chlorinating) was
water sources) statistically
relative to non- significantly
chlorinated associated with the
(mainly private following types of
well) water. cancer in both males
and females: rectal,
lung, bladder, and
kidney cancer. Liver
cancer and all
cancers were also
statistically
significantly
elevated in
chlorinated towns for
males only. Mortality
rates for cancers of
the esophagus,
stomach, colon,
pancreas, prostate,
brain, breast, cervix
uteri and uterus, and
ovary were comparable
for chlorinated and
non-chlorinated
residence.
Doyle et al. 1997.............. Prospective Examined Colon, rectum, Statistically
cohort study in chloroform bladder, and 8 significant increased
Iowa, 1987-1993. levels and other cancers in risk of colon cancer,
source of women. breast cancer and all
drinking water. cancers combined was
observed for women
exposed to chloroform
in drinking water,
with evidence of
exposure-response
effects. No
associations were
detected between
chloroform and
bladder, rectum,
kidney, upper
digestive organs,
lung, ovary,
endometrium, or
breast cancers, or
for melanomas or non-
Hodgkin's lymphoma.
Surface water
exposure (compared to
ground water users)
was also a
significant predictor
of colon and breast
cancer risk.
Freedman et al. 1997........... Population-based Estimated Bladder cancer... There was a weak
case-control duration of association between
study in exposure to bladder cancer risk
Maryland, 1975- chlorinated and duration of
1992. water. Compared exposure to municipal
exposure to water for male
chlorinated cigarette smokers, as
municipal water well as an exposure-
(yes/no). response
relationship. No
association was seen
for those with no
history of smoking,
suggesting that
smoking may modify a
possible effect of
chlorinated surface
water on the risk of
bladder cancer.
King and Marrett 1996.......... Case-control Compared source Bladder cancer... Statistically
study in of drinking significant
Ontario, Canada, water and associations were
1992-1994. chlorination detected for bladder
status. cancer and
Estimated TTHM chlorinated surface
levels, duration water, duration or
of exposure, and concentration of THM
tap water levels and tap water
consumption. consumption metrics.
Population
attributable risks
were estimated at 14
to 16 percent. An
exposure-response
relationship was
observed for
estimated duration of
high THM exposures
and risk of bladder
cancer.
McGeehin et al. 1993........... Population-based Compared source Bladder cancer... Statistically
case-control of drinking significant
study in water, water associations were
Colorado, 1990- treatment, and detected for bladder
1991. tap water versus cancer and duration
bottled water. of exposure to
Estimated chlorinated surface
duration of water. The risk was
exposure to similar for males and
TTHMs and levels females and among
of TTHMs, nonsmokers and
nitrates, and smokers. The
residual attributable risk was
chlorine. estimated at 14.9
percent. High tap
water intake was
associated with risk
of bladder cancer in
a exposure-response
fashion. No
associations were
detected between
bladder cancer and
levels of TTHMs,
nitrates, and
residual chlorine.
Cantor et al. 1987 (and Cantor Population-based Compared source Bladder cancer... Bladder cancer was
et al. 1985). case-control of drinking statistically
study in 10 water. Estimated associated with
areas of the total beverage duration of exposure
U.S., 1977-1978. and tap water to chlorinated
consumption and surface water for
duration of women and nonsmokers
exposure. of both sexes. The
largest risks were
seen when both
exposure duration and
level of tap water
ingestion were
combined. No
association was seen
for total beverage
consumption.
Reviews/Meta-analyses
Villanueva et al. 2004......... Review and meta- Individual-based Bladder cancer... The meta-analysis
analysis of 6 exposure suggests that risk of
case-control estimates to bladder cancer in men
studies. THMs and water increases with long-
consumption over term exposure to
a 40-year period. TTHMs. An exposure-
response pattern was
observed among men
exposed to TTHMs,
with statistically
significant risk seen
at exposures higher
than 50 ug/L. No
association between
TTHMs and bladder
cancer was seen for
women.
Villanueva et al. 2003 (and Review and meta- Compared source Bladder cancer... The meta-analysis
Goebell et al. 2004). analysis of 6 of water and findings showed a
case-control estimated moderate excess risk
studies and 2 duration of of bladder cancer
cohort studies. exposure to attributable to long-
chlorinated term consumption of
drinking water. chlorinated drinking
water for both
genders, particularly
in men. Statistically
significance seen
with men and combined
both sexes. The risk
was higher when
exposure exceeded 40
years.
[[Page 398]]
Villanueva et al. 2001......... Qualitative Compared exposure Cancer of Review found that
review of 31 to TTHM levels, bladder, colon, although results for
cancer studies. mutagenic rectum, and 5 cancer studies varied
drinking water, other cancers.. and were not always
water statistically
consumption, significant, evidence
source water, for bladder cancer is
types of strongest, and all 10
disinfection of the bladder cancer
(chlorination studies showed
and increased cancer
chloramination), risks with ingestion
and residence of chlorinated water.
times. The authors felt
associations with
chlorinated water and
cancer of the colon,
rectum, pancreas,
esophagus, brain, and
other cancers were
inconsistent.
WHO 2000....................... Qualitative Various exposures Various cancers.. Studies reviewed
reviews of to THMs.. reported weak to
various studies moderate increased
in Finland, relative risks of
U.S., and Canada. bladder, colon,
rectal, pancreatic,
breast, brain or lung
cancer associated
with long-term
exposure to
chlorinated drinking
water. The authors
felt evidence is
inconclusive for an
association between
colon cancer and long-
term exposure to
THMs; that evidence
is insufficient to
evaluate a causal
relationship between
THMs and rectal,
bladder, and other
cancers. They found
no association
between THMs and
increased risk of
cardiovascular
disease.
Mills et al. 1998.............. Qualitative Examined TTHM Cancer of colon, Review suggests
review of 22 levels and water rectum, and possible increases in
studies. consumption. bladder. risks of bladder
Compared source cancer with exposure
of water and 2 to chlorinated
types of water drinking water. The
treatment authors felt evidence
(chlorination for increased risk of
and colon and rectal
chloramination). cancers is
inconclusive, though
evidence is stronger
for rectal cancer.
----------------------------------------------------------------------------------------------------------------
Overall, bladder cancer data provide the strongest basis for
quantifying cancer risks from DBPs. EPA has chosen this endpoint to
estimate the primary benefits of the Stage 2 DBPR (see Section VI).
ii. Toxicology. Cancer toxicology studies provide additional
support that chlorinated water is associated with cancer. In general,
EPA uses long term toxicology studies that show a dose response to
derive MCLGs and cancer potency factors. Short term studies are used
for hazard identification and to design long term studies. Much of the
available cancer toxicology information was available for the Stage 1
DBPR, but there have also been a number of new cancer toxicology and
mode of action studies completed since the Stage 1 DBPR was finalized
in December 1998.
In support of this rule, EPA has developed health criteria
documents which summarize the available toxicology data for brominated
THMs (USEPA 2005b), brominated HAAs (USEPA 2005c), MX (USEPA 2000b),
MCAA (USEPA 2005d), and TCAA (USEPA 2005e). The 2003 IRIS assessment of
DCAA (USEPA 2003b) and an addendum (USEPA 2005k) also provides analysis
released after Stage 1. It summarizes information on exposure from
drinking water and develops a slope factor for DCAA. IRIS also has
toxicological reviews for chloroform (USEPA 2001a), chlorine dioxide
and chlorite (USEPA 2000c), and bromate (USEPA 2001b), and is currently
reassessing TCAA.
Slope factors and risk concentrations for BDCM, bromoform, DBCM and
DCAA have been developed and are listed in Table II.D-2. For BDCM,
bromoform, and DBCM, table values are derived from the brominated THM
criteria document (USEPA 2005b), which uses IRIS numbers that have been
updated using the 1999 EPA Proposed Guidelines for Carcinogenic Risk
Assessment (USEPA 1999a). For DCAA, the values are derived directly
from IRIS.
Table II.D-2.--Quantification of Cancer Risk
----------------------------------------------------------------------------------------------------------------
LED 10a ED 10a
-----------------------------------------------------------------------
Disinfection byproduct 10 -6 Risk 10 -6 Risk
Slope factor concentration Slope factor concentration
(mg/kg/day)-1 (mg/L) (mg/kg/day) -1 (mg/L)
----------------------------------------------------------------------------------------------------------------
Bromodichloromethane.................... 0.034 0.001 0.022 0.002
Bromoform............................... 0.0045 0.008 0.0034 0.01
Dibromochloromethane.................... 0.04 0.0009 0.017 0.002
Dichloroacetic Acid..................... 0.048 0.0007 0.015 b 0.0023 b
----------------------------------------------------------------------------------------------------------------
a LED10 is the lower 95% confidence bound on the (effective dose) ED10 value. ED10 is the estimated dose
producing effects in 10% of animals.
b The ED10 risk factors for DCAA have been changed from those given in the comparable table in the proposed
Stage 2 DBPR to correct for transcriptional errors.
More research on DBPs is underway at EPA and other research
institutions. Summaries of on-going studies may be found on EPA's DRINK
Web site (http://www.epa.gov/safewater/drink/intro.html). Two-year
bioassays by the National Toxicology Program (NTP) released in abstract
form have recently been completed on BDCM and chlorate. The draft
abstract on BDCM reported no evidence of carcinogenicity when BDCM was
administered via drinking
[[Page 399]]
water (NTP 2005a). Another recent study, a modified two-year bioassay
on BDCM in the drinking water, reported little evidence of
carcinogenicity (George et al. 2002). In a previous NTP study, tumors
were observed, including an increased incidence of kidney, liver, and
colon tumors, when BDCM was administered at higher doses by gavage in
corn oil (NTP 1987). EPA will examine new information on BDCM as it
becomes available. In the chlorate draft abstract, NTP found some
evidence that it may be a carcinogen (NTP 2004). Chlorate is a
byproduct of hypochlorite and chlorine dioxide systems. A long-term,
two-year bioassay NTP study on DBA is also complete but has not yet
undergone peer review (NTP 2005b).
b. Reproductive and developmental health effects. Both human
epidemiology studies and animal toxicology studies have examined
associations between chlorinated drinking water or DBPs and
reproductive and developmental health effects. Based on an evaluation
of the available science, EPA believes the data suggest that exposure
to DBPs is a potential reproductive and developmental health hazard.
The following section briefly discusses the reproductive and
developmental epidemiology and toxicology information available to EPA.
Further discussion of these studies and EPA's conclusions can be found
in the proposed Stage 2 DBPR (USEPA 2003a) and the Economic Analysis
(USEPA 2005a).
i. Epidemiology. As discussed previously, epidemiology studies have
the strength of relating human exposure to DBP mixtures through
multiple intake routes. Although the critical exposure window for
reproductive and developmental effects is much smaller than that for
cancer (generally weeks versus years), exposure assessment is also a
main limitation of reproductive and developmental epidemiology studies.
Exposure assessment uncertainties arise from limited data on DBP
concentrations and maternal water usage and source over the course of
the pregnancy. However, classification errors typically push the true
risk estimate towards the null value (Vineis 2004). According to Bove
et al. (2002), ``Difficulties in assessing exposure may result in
exposure misclassification biases that would most likely produce
substantial underestimates of risk as well as distorted or attenuated
exposure-response trends.'' Studies of rare outcomes (e.g., individual
birth defects) often have limited statistical power because of the
small number of cases being examined. This limits the ability to detect
statistically significant associations for small to moderate relative
risk estimates. Small sample sizes also result in imprecision around
risk estimates reflected by wide confidence intervals. In addition to
the limitations of individual studies, evaluating reproductive and
developmental epidemiology studies collectively is difficult because of
the methodological differences between studies and the wide variety of
endpoints examined. These factors may contribute to inconsistencies in
the scientific body of literature as noted below.
More recent studies tend to be of higher quality because of
improved exposure assessments and other methodological advancements.
For example, studies that use THM levels to estimate exposure tend to
be higher quality than studies that define exposure by source or
treatment. These factors were taken into account by EPA when comparing
and making conclusions on the reproductive and developmental
epidemiology literature. What follows is a summary of available
epidemiology literature on reproductive and developmental endpoints
such as spontaneous abortion, stillbirth, neural tube and other birth
defects, low birth weight, and intrauterine growth retardation.
Information is grouped, where appropriate, into three categories on
fetal growth, viability, and malformations, and reviews are described
separately afterward. Table II.D-3 provides a more detailed description
of each study or review.
Fetal growth. Many studies looked for an association between fetal
growth (mainly small for gestational age, low birth weight, and pre-
term delivery) and chlorinated water or DBPs. The results from the
collection of studies as a whole are inconsistent. A number of studies
support the possibility that exposure to chlorinated water or DBPs are
associated with adverse fetal growth effects (Infante-Rivard 2004;
Wright et al. 2004; Wright et al. 2003; K[auml]ll[eacute]n and Robert
2000; Gallagher et al. 1998; Kanitz et al. 1996; Bove et al. 1995;
Kramer et al. 1992). Other studies showed mixed results (Porter et al.
2005; Savitz et al. 2005; Yang 2004) or did not provide evidence of an
association (Toledano et al. 2005; Jaakkola et al. 2001; Dodds et al.
1999; Savitz et al. 1995) between DBP exposure and fetal growth. EPA
notes that recent, higher quality studies provide some evidence of an
increased risk of small for gestational age and low birth weight.
Fetal viability. While the database of epidemiology studies for
fetal loss endpoints (spontaneous abortion or stillbirth) remains
inconsistent as a whole, there is suggestive evidence of an association
between fetal loss and chlorinated water or DBP exposure. Various
studies support the possibility that exposure to chlorinated water or
DBPs is associated with decreased fetal viability (Toledano et al.
2005; Dodds et al. 2004; King et al. 2000b; Dodds et al. 1999; Waller
et al. 1998; Aschengrau et al. 1993; Aschengrau et al. 1989). Other
studies did not support an association (Bove et al. 1995) or reported
inconclusive results (Savitz et al. 2005; Swan et al. 1998; Savitz et
al. 1995) between fetal viability and exposure to THMs or tapwater. A
recent study by King et al. (2005) found little evidence of an
association between stillbirths and haloacetic acids after controlling
for trihalomethane exposures, though non-statistically significant
increases in stillbirths were seen across various exposure levels.
Fetal malformations. A number of epidemiology studies have examined
the relationship between fetal malformations (such as neural tube, oral
cleft, cardiac, or urinary defects, and chromosomal abnormalities) and
chlorinated water or DBPs. It is difficult to assess fetal
malformations in aggregate due to inconsistent findings and disparate
endpoints being examined in the available studies. Some studies support
the possibility that exposure to chlorinated water or DBPs is
associated with various fetal malformations (Cedergren et al. 2002;
Hwang et al. 2002; Dodds and King 2001; Klotz and Pyrch 1999; Bove et
al. 1995; Aschengrau et al. 1993). Other studies found little evidence
(Shaw et al. 2003; K[auml]ll[eacute]n and Robert 2000; Dodds et al.
1999; Shaw et al. 1991) or inconclusive results (Magnus et al. 1999)
between chlorinated water or DBP exposure and fetal malformations.
Birth defects most consistently identified as being associated with
DBPs include neural tube defects and urinary tract malformations.
Other endpoints have also been examined in recent epidemiology
studies. One study suggests an association between DBPs and decreased
menstrual cycle length (Windham et al. 2003), which, if corroborated,
could be linked to the biological basis of other reproductive endpoints
observed. No association between THM exposure and semen quality was
found (Fenster et al. 2003). More work is needed in both areas to
support these results.
Reviews. An early review supported an association between measures
of fetal viability and tap water (Swan et al.
[[Page 400]]
1992). Three other reviews found data inadequate to support an
association between reproductive and developmental health effects and
THM exposure (Reif et al. 1996; Craun 1998; WHO 2000). Mills et al.
(1998) examined data on and found support for an association between
fetal viability and malformations and THMs. Another review presented to
the Stage 2 MDBP FACA found some evidence for an association with fetal
viability and some fetal malformations and exposure to DBPs but
reported that the evidence was inconsistent for these endpoints as well
as for fetal growth (Reif et al. 2000). Reif et al. (2000) concluded
that the weight of evidence from epidemiology studies suggests that
``DBPs are likely to be reproductive toxicants in humans under
appropriate exposure conditions,'' but from a risk assessment
perspective, data are primarily at the hazard identification stage.
Nieuwenhuijsen et al. (2000) found some evidence for an association
between fetal growth and THM exposure and concluded evidence for
associations with other fetal endpoints is weak but gaining weight. A
qualitative review by Villanueva et al. (2001) found evidence generally
supports a possible association between reproductive effects and
drinking chlorinated water. Graves et al. (2001) supports a possible
association for fetal growth but not fetal viability or malformations.
More recently, Bove et al. (2002) examined and supported an association
between small for gestational age, neural tube defects and spontaneous
abortion endpoints and DBPs. Following a meta-analysis on five
malformation studies, Hwang and Jaakkola (2003) concluded that there
was evidence which supported associations between DBPs and risk of
birth defects, especially neural tube defects and urinary tract defects.
Table II.D-3.--Summary of Reproductive/Developmental Epidemiology Studies
----------------------------------------------------------------------------------------------------------------
Exposure(s) Outcome(s)
Author(s) Study type studied measured Findings
----------------------------------------------------------------------------------------------------------------
Porter et al. 2005............. Cross-sectional Estimated THM and Intrauterine No consistent
study in HAA exposure growth association or dose-
Maryland, 1998- during pregnancy. retardation. response relationship
2002. was found between
exposure to either
TTHM or HAA5 and
intrauterine growth
retardation. Results
suggest an increased
risk of intrauterine
growth retardation
associated with TTHM
and HAA5 exposure in
the third trimester,
although only HAA5
results were
statistically
significant.
Savitz et al. 2005............. Population-based Estimated TTHM, Early and late No association with
prospective HAA9, and TOC pregnancy loss, pregnancy loss was
cohort study in exposures during preterm birth, seen when looking at
three pregnancy. small for high exposure of TTHM
communities Indices examined gestational age, compared to low
around the U.S., included and term birth exposure of TTHM.
2000-2004. concentration, weight. When examining
ingested amount, individual THMs, a
exposure from statistically
showering and significant
bathing, and an association was found
integration of between
all exposures bromodichloromethane
combined. (BDCM) and pregnancy
loss. A similar, non-
statistically
significant
association was seen
between
dibromochloromethane
(DBCM) and pregnancy
loss. Some increased
risk was seen for
losses at greater
than 12 weeks'
gestation for TTHM,
BDCM, and TOX (total
organic halide), but
most results
generally did not
provide support for
an association.
Preterm birth showed
a small inverse
relationship with DBP
exposure (i.e. higher
exposures showed less
preterm births), but
this association was
weak. TTHM exposure
of 80 ug/L was
associated with twice
the risk for small
for gestational age
during the third
trimester and was
statistically
significant.
Toledano et al. 2005........... Large cross- Linked mother's Stillbirth, low A significant
sectional study residence at birth weight. association between
in England, 1992- time of delivery TTHM and risk of
1998. to modeled stillbirth, low birth
estimates of weight, and very low
TTHM levels in birth weight was
water zones. observed in one of
the three regions.
When all three
regions were
combined, small, but
non-significant,
excess risks were
found between all
three outcomes and
TTHM and chloroform.
No associations were
observed between
reproductive risks
and BDCM or total
brominated THMs.
Dodds et al. 2004 (and King et Population-based Estimated THM and Stillbirth....... A statistically
al. 2005). case-control HAA exposure at significant
study in Nova residence during association was
Scotia and pregnancy. observed between
Eastern Ontario, Linked water stillbirths and
1999-2001. consumption and exposure to total
showering/ THM, BDCM, and
bathing to THM chloroform.
exposure. Associations were
also detected for
metrics, which
incorporated water
consumption,
showering and bathing
habits. Elevated
relative risks were
observed for
intermediate
exposures for total
HAA and DCAA
measures; TCAA and
brominated HAA
exposures showed no
association. No
statistically
significant
associations or dose-
response
relationships between
any HAAs and
stillbirth were
detected after
controlling for THM
exposure.
[[Page 401]]
Infante-Rivard 2004............ Case-control Estimated THM Intrauterine No associations were
study of levels and water growth found between
newborns in consumption retardation. exposure to THMs and
Montreal, 1998- during intrauterine growth
2000. pregnancy. retardation. However,
Exposure from a significant effect
showering and was observed between
presence of two THM exposure and
genetic intrauterine growth
polymorphisms. retardation for
newborns with the
CYP2E1 gene variant.
Findings suggest that
exposure to THMs at
the highest levels
can affect fetal
growth but only in
genetically
susceptible newborns.
Wright et al. 2004............. Large cross- Estimated Birth weight, Statistically
sectional study: maternal third- small for significant
Massachusetts, trimester gestational age, reductions in mean
1995-1998. exposures to preterm birth weight were
TTHMs, delivery, observed for BDCM,
chloroform, gestational age. chloroform, and
BDCM, total mutagenic activity.
HAAs, DCA, TCA, An exposure-response
MX and relationship was
mutagenicity in found between THM
drinking water. exposure and
reductions in mean
birth weight and risk
of small for
gestational age.
There was no
association between
preterm delivery and
elevated levels of
HAAs, MX, or
mutagenicity. A
reduced risk of
preterm delivery was
observed with high
THM exposures.
Gestational age was
associated with
exposure to THMs and
mutagenicity.
Yang et al. 2004 (and Yang et Large cross- Compared maternal Low birth weight, Residence in area
al. 2000). sectional consumption of preterm delivery. supplied with
studies in chlorinated chlorinated drinking
Taiwan, 1994- drinking water water showed a
1996. (yes/no). statistically
significant
association with
preterm delivery. No
association was seen
between chlorinated
drinking water and
low birth weight.
Fenster et al. 2003............ Small prospective Examined TTHM Sperm motility, No association between
study in levels within sperm morphology. TTHM level and sperm
California, 1990- the 90 days mobility or
1991. preceding semen morphology. BDCM was
collection. inversely associated
with linearity of
sperm motion. There
was some suggestion
that water
consumption and other
ingestion metrics may
be associated with
different indicators
of semen quality.
Shaw et al. 2003............... 2 case-control Estimated THM Neural tube No associations or
maternal levels for defects, oral exposure-response
interview mothers' clefts, selected relation were
studies: CA, residences from heart defects. observed between
1987-1991. before malformations and
conception TTHMs in either
through early study.
pregnancy.
Windham et al. 2003............ Prospective Estimated Menstrual cycle, Findings suggest that
study: CA, 1990- exposure to THMs follicular phase THM exposure may
1991. through length (in days). affect ovarian
showering and function. All
ingestion over brominated THM
average of 5.6 compounds were
menstrual cycles associated with
per woman. significantly shorter
menstrual cycles with
the strongest finding
for
chlorodibromomethane.
There was little
association between
TTHM exposure and
luteal phase length,
menses length, or
cycle variability.
Wright et al. 2003............. Cross-sectional Estimated TTHM Birth weight, Statistically
study: exposure in small for significant
Massachusetts, women during gestational age, associations between
1990. pregnancy preterm 2nd trimester and
(average for delivery, pregnancy average
pregnancy and gestational age. TTHM exposure and
during each small for gestational
trimester). age and fetal birth
weight were detected.
Small, statistically
significant increases
in gestational
duration/age were
observed at increased
TTHM levels, but
there was little
evidence of an
association between
TTHM and preterm
delivery or low birth
weight.
Cedergren et al. 2002.......... Retrospective Examined maternal Cardiac defects.. Exposure to chlorine
case-control periconceptional dioxide in drinking
study: Sweden, DBP levels and water showed
1982-1997. used GIS to statistical
assign water significance for
supplies. cardiac defects. THM
concentrations of 10
ug/L and higher were
significantly
associated with
cardiac defects. No
excess risk for
cardiac defect and
nitrate were seen.
Hwang et al. 2002.............. Large cross- Compared exposure Birth defects Risk of any birth
sectional study to chlorination (neural tube defect, cardiac,
in Norway, 1993- (yes/no) and defects, respiratory system,
1998. water color cardiac, and urinary tract
levels for respiratory defects were
mother's system, oral significantly
residence during cleft, urinary associated with water
pregnancy. tract). chlorination.
Exposure to
chlorinated drinking
water was
statistically
significantly
associated with risk
of ventricular septal
defects, and an
exposure-response
pattern was seen. No
other specific
defects were
associated with the
exposures that were
examined.
[[Page 402]]
Dodds and King 2001............ Population-based Estimated THM, Neural tube Exposure to BDCM was
retrospective chloroform, and defects, associated with
cohort in Nova bromodichloromet cardiovascular increased risk of
Scotia, 1988- hane (BDCM) defects, cleft neural tube defects,
1995. exposure. defects, cardiovascular
chromosomal anomalies. Chloroform
abnormalities. was not associated
with neural tube
defects, but was
associated with
chromosomal
abnormalities. No
association between
THM and cleft defects
were detected.
Jaakkola et al. 2001........... Large cross- Compared Low birth weight, No evidence found for
sectional study chlorination small for association between
in Norway, 1993- (yes/no) and gestational age, prenatal exposure to
1995. water color preterm delivery. chlorinated drinking
(high/low) for water and low birth
mother during weight or small for
pregnancy. gestational age. A
reduced risk of
preterm delivery was
noted for exposure to
chlorinated water
with high color
content.
K[auml]ll[eacute]n and Robert Large cross- Linked prenatal Gestational A statistically
2000. sectional cohort exposure to duration, birth significant
study in Sweden, drinking water weight, difference was found
1985-1994. disinfected with intrauterine for short gestational
various methods growth, duration and low
(no chlorine, mortality, birth weight among
chlorine dioxide congenital infants whose mother
only, sodium malformations, resided in areas
hypochlorite and other birth using sodium
only). outcomes. hypochlorite, but not
for chlorine dioxide.
Sodium hypochlorite
was also associated
with other indices of
fetal development but
not with congenital
defects. No other
effects were observed
for intrauterine
growth, childhood
cancer, infant
mortality, low Apgar
score, neonatal
jaundice, or neonatal
hypothyroidism in
relation to either
disinfection method.
Dodds et al. 1999 (and King et Population-based Estimated TTHM Low birth weight, A statistically
al. 2000b). retrospective level for women preterm birth, significant increased
cohort study in during pregnancy. small for risk for stillbirths
Nova Scotia, gestational age, and high total THMs
1988-1995. stillbirth, and specific THMs
chromosomal during pregnancy was
abnormalities, detected, with higher
neural tube risks observed among
defects, cleft asphyxia-related
defects, major stillbirths.
cardiac defects. Bromodichloromethane
had the strongest
association and
exhibited an exposure-
response pattern.
There was limited
evidence of an
association between
THM level and other
reproductive
outcomes. No
congenital anomalies
were associated with
THM exposure, except
for a non-
statistically
significant
association with
chromosomal
abnormalities.
Klotz and Pyrch 1999 (and Klotz Population-based Estimated Neural tube A significant
and Pyrch 1998). case-control exposure of defects. association was seen
study in New pregnant mothers between exposure to
Jersey, 1993- to TTHMs and THMs and neural tube
1994. HAAs, and defects. No
compared source associations were
of water. observed for neural
tube defects and
haloacetic acids or
haloacetonitriles.
Magnus et al. 1999............. Large cross- Compared Birth defects Statistically
sectional study chlorination (neural tube significant
in Norway, 1993- (yes/no) and defects, major associations were
1995. water color cardiac, seen between urinary
(high/low) at respiratory, tract defects and
mothers' urinary, oral chlorination and high
residences at cleft). water color (high
time of birth. content of organic
compounds). No
associations were
detected for other
outcomes or all birth
defects combined. A
non-statistically
significant, overall
excess risk of birth
defects was seen
within municipalities
with chlorination and
high water color
compared to
municipalities with
no chlorination and
low color.
Gallagher et al. 1998.......... Retrospective Estimated THM Low birth weight, Weak, non-
cohort study of levels in term low statistically
newborns in drinking water birthweight, and significant
Colorado, 1990- during third preterm delivery. association with low
1993. trimester of birth weight and TTHM
pregnancy. exposure during the
third trimester.
Large statistically
significant increase
for term low
birthweight at
highest THM exposure
levels. No
association between
preterm delivery and
THM exposure.
Swan et al. 1998............... Prospective study Compared Spontaneous Pregnant women who
in California, consumption of abortion. drank cold tap water
1990-1991. cold tap water compared to those who
to bottled water consumed no cold tap
during early water showed a
pregnancy. significant finding
for spontaneous
abortion at one of
three sites.
[[Page 403]]
Waller et al. 1998 (and Waller Prospective Estimated TTHM Spontaneous Statistically
et al. 2001). cohort in levels during abortion. significant increased
California, 1989- first trimester risk between high
1991. of pregnancy via intake of TTHMs and
ingestion and spontaneous abortion
showering. compared to low
intake. BDCM
statistically
associated with
increased spontaneous
abortion; other THMs
not. Reanalysis of
exposure yielded less
exposure
misclassification and
relative risks
similar in magnitude
to earlier study. An
exposure-response
relationship was seen
between spontaneous
abortion and
ingestion exposure to
TTHMs.
Kanitz et al. 1996............. Cross-sectional Compared 3 types Low birth weight, Smaller body length
study in Italy, of water body length, and small cranial
1988-1989. treatment cranial circumference showed
(chlorine circumference, statistical
dioxide, sodium preterm significant
hypochlorite, delivery, and association with
and chlorine other effects. maternal exposure to
dioxide/sodium chlorinated drinking
hypochlorite). water. Neonatal
jaundice linked
statistically to
prenatal exposure to
drinking water
treated with chlorine
dioxide. Length of
pregnancy, type of
delivery, and
birthweight showed no
association.
Bove et al. 1995 (and Bove et Large cohort Examined maternal Low birth weight, Weak, statistically
al. 1992a & 1992b). cross-sectional exposure to TTHM fetal deaths, significant increased
study in New and various small for risk found for higher
Jersey, 1985- other gestational age, TTHM levels with
1988. contaminants. birth defects small for gestational
(neural tube age, neural tube
defects, oral defects, central
cleft, central nervous system
nervous system, defects, oral cleft
major cardiac). defects, and major
cardiac defects. Some
association with
higher TTHM exposure
and low birth weight.
No effect seen for
preterm birth, very
low birth weight, or
fetal deaths.
Savitz et al. 1995............. Population-based Examined TTHM Spontaneous There was a
case-control concentration at abortion, statistically
study: North residences and preterm significant increased
Carolina, 1988- water delivery, low miscarriage risk with
1991. consumption birth weight. high THM
(during first concentration, but
and third THM intake (based on
trimesters). concentration times
consumption level)
was not related to
pregnancy outcome. No
associations were
seen for preterm
delivery or low birth
weight. Water source
was not related to
pregnancy outcome
either, with the
exception of a non-
significant,
increased risk of
spontaneous abortion
for bottled water
users. There was a
non-statistically
significant pattern
of reduced risk with
increased consumption
of water for all
three outcomes.
Aschengrau et al. 1993......... Case-control Source of water Neonatal death, There was a non-
study in and 2 types of stillbirth, significant,
Massachusetts, water treatment congenital increased association
1977-1980. (chlorination, anomalies. between frequency of
chloramination). stillbirths and
maternal exposure to
chlorinated versus
chloraminated surface
water. An increased
risk of urinary track
and respiratory track
defects and
chlorinated water was
detected. Neonatal
death and other major
malformations showed
no association. No
increased risk seen
for any adverse
pregnancy outcomes
for surface water
versus ground and
mixed water use.
Kramer et al. 1992............. Population-based Examined Low birth weight, Statistically
case-control chloroform, prematurity, significant increased
study in Iowa, DCBM, DBCM, and intrauterine risk for intrauterine
1989-1990. bromoform levels growth growth retardation
and compared retardation. effects from
type of water chloroform exposure
source (surface, were observed. Non-
shallow well, significant increased
deep well). risks were observed
for low birth weight
and chloroform and
for intrauterine
growth retardation
and DCBM. No
intrauterine growth
retardation or low
birth weight effects
were seen for the
other THMs, and no
effects on
prematurity were
observed for any of
the THMs.
Shaw et al. 1991 (and Shaw et Small case- Estimated Congenital Following reanalysis,
al. 1990). control study: chlorinated tap cardiac no association
Santa Clara water anomalies. between cardiac
County, CA, 1981- consumption, anomalies and TTHM
1983. mean maternal level were observed.
TTHM level,
showering/
bathing exposure
at residence
during first
trimester.
Aschengrau et al. 1989......... Case-control Source of water Spontaneous A statistically
study in and exposure to abortion. significantly
Massachusetts, metals and other association was
1976-1978. contaminants. detected between
surface water source
and frequency of
spontaneous abortion.
[[Page 404]]
Reviews/Meta-analyses
Hwang and Jakkola 2003......... Review and meta- Compared DBP Birth defects The meta-analysis
analysis of 5 levels, source (respiratory supports an
studies. of water, system, urinary association between
chlorine system, neural exposure to
residual, color tube defects, chlorination by-
(high/low), and cardiac, oral products and the risk
2 types of cleft). of any birth defect,
disinfection: particularly the risk
chlorination and of neural tube
chloramination. defects and urinary
system defects.
Bove et al. 2002............... Qualitative Examined THM Birth defects, Review found the
review of 14 levels. Compared small for studies of THMs and
studies. drinking water gestational age, adverse birth
source and type low birth outcomes provide
of water weight, preterm moderate evidence for
treatment. delivery, associations with
spontaneous small for gestational
abortion, fetal age, neural tube
death. defects, and
spontaneous
abortions. Authors
felt risks may have
been underestimated
and exposure-response
relationships
distorted due to
exposure
misclassification.
Graves et al. 2001............. Review of Examined water Low birth weight, Weight of evidence
toxicological consumption, preterm suggested positive
and duration of delivery, small association with DBP
epidemiological exposure, THM for gestational exposure for growth
studies using a levels, HAA age, retardation such as
weight of levels, and intrauterine small for gestational
evidence other growth age or intrauterine
approach. contaminants. retardation, growth retardation
Compared source specific birth and urinary tract
of water, water defects, defects. Review found
treatment, water neonatal death, no support for DBP
color (high/ decreased exposure and low
low), etc. fertility, fetal birth weight, preterm
resorption, and delivery, some
other effects. specific birth
defects, and neonatal
death, and
inconsistent findings
for all birth
defects, all central
nervous system
defects, neural tube
defects, spontaneous
abortion, and
stillbirth.
Villanueva et al. 2001......... Qualitative Compared exposure Spontaneous Review found positive
review of 14 to TTHM levels, abortion, low associations between
reproductive and mutagenic birth weight, increased spontaneous
developmental drinking water, small for abortion, low birth
health effect water gestational age, weight, small for
studies. consumption, neural tube gestational age, and
source water, defects, other neural tube defects
types of reproductive and and drinking
disinfection developmental chlorinated water in
(chlorination outcomes. most studies,
and although not always
chloramination), with statistical
and residence significance.
times.
Nieuwenhuijsen et al. 2000..... Qualitative Examined levels Low birth weight, The review supports
review of of various DBPs, preterm some evidence of
numerous water delivery, association between
toxicological consumption, and spontaneous THMs and low birth
and duration of abortions, weight, but
epidemiological exposure. stillbirth, inconclusive. Review
studies. Compared water birth defects, found no evidence of
color, water etc. association between
treatment, THMs and preterm
source of water, delivery, and that
etc. associations for
other outcomes
(spontaneous
abortions,
stillbirth, and birth
defects) were weak
but gaining weight.
Reif et al. 2000............... Qualitative Compared source Birth weight, low Weight of evidence
reviews of of water supply birth weight, suggested DBPs are
numerous and methods of intrauterine reproductive
epidemiological disinfection. growth toxicants in humans
studies. Estimated TTHM retardation, under appropriate
levels. small for exposure conditions.
gestational age, The review reports
preterm deliver, findings between
somatic TTHMs and effects on
parameters, fetal growth, fetal
neonatal viability, and
jaundice, congenital anomalies
spontaneous as inconsistent.
abortion, Reviewers felt data
stillbirth, are at the stage of
developmental hazard identification
anomalies. and did not suggest a
dose-response pattern
of increasing risk
with increasing TTHM
concentration.
WHO 2000....................... Qualitative Various exposures Various Review found some
reviews of to THMs. reproductive and support for an
various studies developmental association between
in Finland, effects. increased risks of
U.S., and Canada. neural tube defects
and miscarriage and
THM exposure. Other
associations have
been observed, but
the authors believed
insufficient data
exist to assess any
of these
associations.
Craun, ed. 1998................ Qualitative Examined THM Stillbirth, Associations between
review of 10 levels and water neonatal death, DBPs and various
studies, focus consumption, and spontaneous reproductive effects
on California compared source abortion, low were seen in some
cohort study. of water and birth weight, epidemiological
water treatment preterm studies, but the
(chlorine, delivery, authors felt these
chloramines, intrauterine results do not
chlorine growth provide convincing
dioxide). retardation, evidence for a causal
neonatal relationship between
jaundice, birth DBPs and reproductive
defects. effects.
[[Page 405]]
Mills et al. 1998.............. Qualitative Examined TTHM Various Review found studies
review of 22 levels and water reproductive and suggest possible
studies. consumption. developmental increases in adverse
Compared source effects. reproductive and
of water and 2 developmental
types of water effects, such as
treatment increased spontaneous
(chlorination abortion rates, small
and for gestational age,
chloramination). and fetal anomalies,
but that insufficient
evidence exists to
establish a causal
relationship.
Reif et al. 1996............... Review of 3 case- Examined THM Birth defects Studies reviewed
control studies levels at (central nervous suggest that exposure
and 1 cross- residences, dose system, neural to DBPs may increase
sectional study. consumption, tube defects, intrauterine growth
chloroform. cardiac, oral retardation, neural
Compared source cleft, tube defects, major
of waters and 2 respiratory, heart defects, and
types of water urinary tract), oral cleft defects.
treatment spontaneous Review found
(chlorination abortion, low epidemiologic
and birth weight, evidence supporting
chloramination). growth associations between
retardation, exposure to DBPs and
preterm adverse pregnancy
delivery, outcomes to be sparse
intrauterine and to provide an
growth inadequate basis to
retardation, identify DBPs as a
stillbirth, reproductive or
neonatal death. developmental hazard.
Swan et al. 1992............... Qualitative Compared maternal Spontaneous Four of the studies
review of 5 consumption of abortion. reviewed suggest that
studies in Santa residence tap women drinking
Clara County, CA water to bottled bottled water during
(Deane et al. water. the first trimester
1992, Wrensch et of pregnancy may have
al. 1992, Hertz- reduced risk of
Picciotto et al. spontaneous abortion
1992, Windham et relative to drinking
al. 1992, tap water. No
Fenster et al. association seen in
1992). the fifth study.
Review concluded that
if findings are
causal and not due to
chance or bias, data
suggest a 10-50%
increase in
spontaneous abortion
risk for pregnant
women drinking tap
water over bottled
water.
----------------------------------------------------------------------------------------------------------------
ii. Toxicology. To date, the majority of reproductive and
developmental toxicology studies have been short term and higher dose.
Many of these studies are summarized in a review by Tyl (2000). A
summary of this review and of additional studies is provided in the
proposed Stage 2 DBPR (USEPA 2003a). Individual DBP supporting
documents evaluate and assess additional studies as well (USEPA 2000b;
USEPA 2000c; USEPA 2001a; USEPA 2001b; USEPA 2003b; USEPA 2005b; USEPA
2005c; USEPA 2005d; USEPA 2005e; USEPA 2005k). A number of recent
studies have been published that include in vivo and in vitro assays to
address mechanism of action. Overall, reproductive and developmental
toxicology studies indicate a possible reproductive/developmental
health hazard although they are preliminary in nature for the majority
of DBPs, and the dose-response characteristics of most DBPs have not
been quantified. Some of the reproductive effects of DCAA were
quantified as part of the RfD development process, and impacts of DCAA
on testicular structure are one of the critical effects in the study
that is the basis of the RfD (USEPA 2003b).
A few long term, lower dose studies have been completed. Christian
et al. (2002a and 2002b) looked for an association between BDCM and
DBAA and reproductive and developmental endpoints. The authors
identified a NOAEL and LOAEL of 50 ppm and 150 ppm, respectively, based
on delayed sexual maturation for BDCM and a NOAEL and LOAEL of 50 ppm
and 250 ppm based on abnormal spermatogenesis for DBAA. The authors
concluded that similar effects in humans would only be seen at levels
many orders of magnitude higher than that of current drinking water
levels. As discussed in more detail in the proposal, EPA believes that
because of key methodological differences indicated as being important
in other studies (Bielmeier et al. 2001; Bielmeier et al. 2004; Kaydos
et al. 2004; Klinefelter et al. 2001; Klinefelter et al. 2004),
definitive conclusions regarding BDCM and DBAA cannot be drawn. Other
multi-generation research underway includes a study on BCAA, but this
research is not yet published.
Biological plausibility for the effects observed in reproductive
and developmental epidemiological studies has been demonstrated through
various toxicological studies on some individual DBPs (e.g., Bielmeier
et al. 2001; Bielmeier et al. 2004; Narotsky et al. 1992; Chen et al.
2003; Chen et al. 2004). Some of these studies were conducted at high
doses, but similarity of effects observed between toxicology studies
and epidemiology studies strengthens the weight of evidence for a
possible association between adverse reproductive and developmental
health effects and exposure to chlorinated surface water.
c. Conclusions. EPA's weight of evidence evaluation of the best
available science on carcinogenicity and reproductive and developmental
effects, in conjunction with the widespread exposure to DBPs, supports
the incremental regulatory changes in today's rule that target lowering
DBPs and providing equitable public health protection.
EPA believes that the cancer epidemiology and toxicology literature
provide important information that contributes to the weight of
evidence for potential health risks from exposure to chlorinated
drinking water. At this time, the cancer epidemiology studies support a
potential association between exposure to chlorinated drinking water
and cancer, but evidence is insufficient to establish a causal
relationship. The epidemiological evidence for an association between
DBP exposure and colon and rectal cancers is not as consistent as it is
for bladder cancer, although similarity of effects reported in animal
toxicity and human epidemiology studies strengthens the evidence for an
association with colon and rectal cancers. EPA believes that the
overall cancer epidemiology and toxicology data support the decision to
[[Page 406]]
pursue additional DBP control measures as reflected in the Stage 2 DBPR.
Based on the weight of evidence evaluation of the reproductive and
developmental epidemiology data, EPA concludes that a causal link
between adverse reproductive or developmental health effects and
exposure to chlorinated drinking water or DBPs has not been
established, but that there is a potential association. Despite
inconsistent findings across studies, some recent studies continue to
suggest associations between DBP exposure and various adverse
reproductive and developmental effects. In addition, data from a number
of toxicology studies, although the majority of them were conducted
using high doses, demonstrate biological plausibility for some of the
effects observed in epidemiology studies. EPA concludes that no dose-
response relationship or causal link has been established between
exposure to chlorinated drinking water or disinfection byproducts and
adverse developmental or reproductive health effects. EPA's evaluation
of the best available studies, particularly epidemiology studies is
that they do not support a conclusion at this time as to whether
exposure to chlorinated drinking water or disinfection byproducts
causes adverse developmental and reproductive health effects, but do
provide an indication of a potential health concern that warrants
incremental regulatory action beyond the Stage 1 DBPR.
D. DBP Occurrence and DBP Control
New information on the occurrence of DBPs in distribution systems
raises issues about the protection provided by the Stage 1 DBPR. This
section presents new occurrence and treatment information used to
identify key issues and to support the development of the Stage 2 DBPR.
For a more detailed discussion see the proposed Stage 2 DBPR (USEPA
2003a). For additional information on occurrence of regulated and
nonregulated DBPs, see the Occurrence Assessment for the Final Stage 2
Disinfectants and Disinfection Byproducts Rule (USEPA 2005f).
1. Occurrence
EPA, along with the M-DBP Advisory Committee, collected, developed,
and evaluated new information that became available after the Stage 1
DBPR was published. The Information Collection Rule (ICR) (USEPA 1996)
provided new field data on DBP exposure for large water systems and new
study data on the effectiveness of several DBP control technologies.
The unprecedented amount of information collected under the ICR was
supplemented by a survey conducted by the National Rural Water
Association, data provided by various States, the Water Utility
Database (which contains data collected by the American Water Works
Association), and ICR Supplemental Surveys for small and medium water
systems.
After analyzing the DBP occurrence data, EPA and the Advisory
Committee reached three significant conclusions that in part led the
Advisory Committee to recommend further control of DBPs in public water
systems. First, the data from the Information Collection Rule showed
that the RAA compliance calculation under the Stage 1 DBPR allows
elevated TTHM or HAA5 levels to regularly occur at some locations in
the distribution system while the overall average of TTHM or HAA5
levels at all DBP monitoring locations is below the MCLs of the Stage 1
DBPR. Customers served at those sampling locations with DBP levels that
are regularly above 0.080 mg/L TTHM and 0.060 mg/L HAA5 experience
higher exposure compared to customers served at locations where these
levels are consistently met.
Second, the new data demonstrated that DBP levels in single samples
can be substantially above 0.080 mg/L TTHM and 0.060 mg/L HAA5. Some
customers receive drinking water with concentrations of TTHM and HAA5
up to 75% above 0.080 mg/L and 0.060 mg/L, respectively, even when
their water system is in compliance with the Stage 1 DBPR. Some studies
support an association between acute exposure to DBPs and potential
adverse reproductive and developmental health effects (see Section
III.C for more detail).
Third, the data from the Information Collection Rule revealed that
the highest TTHM and HAA5 levels can occur at any monitoring site in
the distribution system. In fact, the highest concentrations did not
occur at the maximum residence time locations in more than 50% of all
ICR samples. The fact that the locations with the highest DBP levels
vary in different public water systems indicates that the Stage 1 DBPR
monitoring may not accurately represent the high DBP concentrations
that actually exist in distribution systems, and that additional
monitoring is needed to identify distribution system locations with
elevated DBP levels.
These data showed that efforts beyond the Stage 1 DBPR are needed
to provide more equitable protection from DBP exposure across the
entire distribution system. The incremental regulatory changes made
under the Stage 2 DBPR meet this need by reevaluating the locations of
DBP monitoring sites and addressing high DBP concentrations that occur
at particular locations or in single samples within systems in compliance.
2. Treatment
The analysis of the new treatment study data confirmed that certain
technologies are effective at reducing DBP concentrations. Bench- and
pilot-scale studies for granular activated carbon (GAC) and membrane
technologies required by the Information Collection Rule provided
information on the effectiveness of the two technologies. Other studies
found UV light to be highly effective for inactivating Cryptosporidium
and Giardia at low doses without promoting the formation of DBPs
(Malley et al. 1996; Zheng et al. 1999). This new treatment information
adds to the treatment options available to utilities for controlling
DBPs beyond the requirements of the Stage 1 DBPR.
E. Conclusions for Regulatory Action
After extensive analysis of available data and rule options
considered by the Advisory Committee and review of public comments on
the proposed Stage 2 DBPR (USEPA, 2003a), EPA is finalizing a Stage 2
DBPR control strategy consistent with the key elements of the Agreement
in Principle signed in September 2000 by the participants in the Stage
2 M-DBP Advisory Committee. EPA believes that exposure to chlorinated
drinking water may be associated with cancer, reproductive, and
developmental health risks. EPA determined that the risk-targeting
measures recommended in the Agreement in Principle will require only
those systems with the greatest risk to make treatment and operational
changes and will maintain simultaneous protection from potential health
concerns from DBPs and microbial contaminants. EPA has carefully
evaluated and expanded upon the recommendations of the Advisory
Committee and public comments to develop today's rule. EPA also made
simplifications where possible to minimize complications for public
water systems as they transition to compliance with the Stage 2 DBPR
while expanding public health protection. The requirements of the Stage
2 DBPR are described in detail in Section IV of this preamble.
IV. Explanation of Today's Action
A. MCLGs
MCLGs are set at concentration levels at which no known or
anticipated adverse health effects occur, allowing for an adequate
margin of safety.
[[Page 407]]
Establishment of an MCLG for each specific contaminant is based on the
available evidence of carcinogenicity or noncancer adverse health
effects from drinking water exposure using EPA's guidelines for risk
assessment. MCLGs are developed to ensure they are protective of the
entire population.
Today's rule provides MCLGs for chloroform and two haloacetic
acids, monochloroacetic acid (MCAA) and trichloroacetic acid (TCAA).
1. Chloroform MCLG
a. Today's rule. The final MCLG for chloroform is 0.07 mg/L. The
MCLG was calculated using toxicological evidence that the carcinogenic
effects of chloroform are due to sustained tissue toxicity. EPA is not
changing the other THM MCLGs finalized in the Stage 1 DBPR.
b. Background and analysis. The MCLG for chloroform is unchanged
from the proposal. The MCLG is calculated using a reference dose (RfD)
of 0.01 mg/kg/day and an adult tap water consumption of 2 L per day for
a 70 kg adult. A relative source contribution (RSC) of 20% was used in
accordance with Office of Water's current approach for deriving RSC
through consideration of data that indicate that other routes and
sources of exposure may potentially contribute substantially to the
overall exposure to chloroform. See the proposed Stage 2 DBPR (USEPA
2003a) for a detailed discussion of the chloroform MCLG.
[GRAPHIC]
[TIFF OMITTED]
TR04JA06.003
Based on an analysis of the available scientific data on
chloroform, EPA believes that the chloroform dose-response is nonlinear
and that chloroform is likely to be carcinogenic only under high
exposure conditions (USEPA 2001a). This assessment is supported by the
principles of the 1999 EPA Proposed Guidelines for Carcinogen Risk
Assessment (USEPA 1999a) and reconfirmed by the 2005 final Cancer
Guidelines (USEPA 2005i). The science in support of a nonlinear
approach for estimating the carcinogenicity of chloroform was affirmed
by the Chloroform Risk Assessment Review Subcommittee of the EPA SAB
Executive Committee (USEPA 2000d). Since the nonzero MCLG is based on a
mode of action consideration specific to chloroform, it does not affect
the MCLGs of other trihalomethanes.
c. Summary of major comments. EPA received many comments in support
of the proposed MCLG calculation for chloroform, although some
commenters disagreed with a non-zero MCLG.
At this time, based on an analysis of all the available scientific
data on chloroform, EPA concludes that chloroform is likely to be
carcinogenic to humans only under high exposure conditions that lead to
cytotoxicity and regenerative hyperplasia and that chloroform is not
likely to be carcinogenic to humans under conditions that do not cause
cytotoxicity and cell regeneration (USEPA 2001a). Therefore, the dose-
response is nonlinear, and the MCLG is set at 0.07 mg/L. This
conclusion has been reviewed by the SAB (USEPA 2000d), who agree that
nonlinear approach is most appropriate for the risk assessment of
chloroform; it also remains consistent with the principles of the 1999
EPA Proposed Guidelines for Carcinogenic Risk Assessment (USEPA 1999a)
and the final Cancer Guidelines ( USEPA 2005i), which allow for
nonlinear extrapolation.
EPA also received some comments requesting a combined MCLG for THMs
or HAAs. This is not appropriate because these different chemicals have
different health effects.
2. HAA MCLGs: TCAA and MCAA
a. Today's rule. Today's rule finalizes the proposed Stage 2 MCLG
for TCAA of 0.02 mg/L (USEPA 2003a) and sets an MCLG for MCAA of 0.07
mg/L. EPA is not changing the other HAA MCLGs finalized in the Stage 1
DBPR (USEPA 1998a).
b. Background and analysis. The Stage 1 DBPR included an MCLG for
TCAA of 0.03 mg/L and did not include an MCLG for MCAA (USEPA 1998a).
Based on toxicological data published after the Stage 1 DBPR, EPA
proposed new MCLGs for TCAA and MCAA of 0.02 mg/L and 0.03 mg/L,
respectively, in the Stage 2 proposal (USEPA 2003a). The proposed TCAA
MCLG and its supporting analysis is being finalized unchanged in
today's final rule. The MCLG calculation for MCAA is revised in this
final rule, based on a new reference dose, as discussed later. See the
proposed Stage 2 DBPR (USEPA 2003a) for a detailed discussion of the
calculation of the MCLGs.
TCAA. The MCLG for TCAA was calculated based on the RfD of 0.03 mg/
kg/day using a 70 kg adult body weight, a 2 L/day drinking water
intake, and a relative source contribution of 20%. An additional
tenfold risk management factor has been applied to account for the
possible carcinogenicity of TCAA. This approach is consistent with EPA
policy. TCAA induces liver tumors in mice (Ferreira-Gonzalez et al.
1995; Pereira 1996; Pereira and Phelps 1996; Tao et al. 1996;
Latendresse and Pereira 1997; Pereira et al. 1997) but not in rats
(DeAngelo et al. 1997). Much of the recent data on the carcinogenicity
of TCAA have focused on examining the carcinogenic mode(s) of action.
However, at this time, neither the bioassay nor the mechanistic data
are sufficient to support the development of a slope factor from which
to quantify the cancer risk.
[GRAPHIC]
[TIFF OMITTED]
TR04JA06.000
The chronic bioassay for TCAA by DeAngelo et al. (1997) was
selected as the critical study for the development of the RfD. In this
chronic drinking water study, a dose-response was noted for several
endpoints and both a LOAEL and NOAEL were determined. The data are
consistent with the findings in both the Pereira (1996) chronic
drinking water study and the Mather et al. (1990) subchronic drinking
water study. The RfD of 0.03 mg/kg/day is based on the NOAEL of 32.5
mg/kg/day for liver histopathological changes in rats (DeAngelo et al.
1997). A composite uncertainty factor of 1000 was applied in the RfD
determination. A default uncertainty factor of 10 was applied to
[[Page 408]]
the RfD to account for extrapolation from an animal study because data
to quantify rat-to-human differences in toxicokinetics or
toxicodynamics are not available. The default uncertainty factor of 10
was used to account for human variability in the absence of data on
differences in human susceptibility. Although subchronic and chronic
studies of TCAA have been reported for multiple species, many studies
have focused on liver lesions and a full evaluation of a wide range of
potential target organs has not been conducted in two different
species. In addition, there has been no multi-generation study of
reproductive toxicity and the data from teratology studies in rats
provide LOAEL values but no NOAEL for developmental toxicity. Thus, an
additional uncertainty factor of 10 was used to account for database
insufficiencies.
The MCLG calculation also includes a relative source contribution
(RSC) of 20%. The RSC was derived consistent with Office of Water's
current approach for deriving RSC. In addition to disinfected water,
foods are expected to contribute to daily exposure to TCAA (Raymer et
al. 2001, 2004; Reimann et al. 1996). Some of the TCAA in foods comes
from cleaning and cooking foods in chlorinated water. Additional TCAA
is found in some foods because of the widespread use of chlorine as a
sanitizing agent in the food industry (USFDA 1994). EPA was not able to
identify any dietary surveys or duplicate diet studies of TCAA in the
diet. TCAA also has been identified in rain water, suggesting some
presence in the atmosphere (Reimann et al. 1996); however, due to the
low volatility (0.5--0.7 mm Hg at 25 [deg]C) of TCAA, exposure from
ambient air is expected to be minimal. Dermal exposure to disinfected
water is also unlikely to be significant. A study by Xu et al. (2002)
reports that dermal exposure from bathing and showering is only 0.01%
of that from oral exposure. In addition, the solvents
trichloroethylene, tetrachlorethylene, 1,1,1-trichloroethane (often
found in ambient air and drinking water), and the disinfection
byproduct chloral hydrate all contribute to the body's TCAA load since
each of these compounds is metabolized to TCAA (ATSDR 2004; ATSDR
1997a; ATSDR 1997b; USEPA 2000e). Due to the limitations primarily in
the dietary data and a clear indication of exposure from other sources,
EPA applied a relative source contribution of 20%.
MCAA. The MCLG for MCAA uses the following calculations: An RfD of
0.01 mg/kg/day, a 70 kg adult consuming 2 L/day of tap water, and a
relative source contribution of 20%.
The RfD included in the proposal was based on a chronic drinking
water study in rats conducted by DeAngelo et al. (1997). In the
assessment presented for the proposed rule, the LOAEL from this study
was identified as 3.5 mg/kg/day based on increased absolute and
relative spleen weight in the absence of histopathologic changes. After
reviewing comments and further analysis of the data, EPA concludes that
it is more appropriate to identify this change as a NOAEL. Increased
spleen weights in the absence of histopathological effects are not
necessarily adverse. In addition, spleen weights were decreased, rather
than increased in the mid- and high-dose groups in the DeAngelo et al.
(1997) study and were accompanied by a significant decrease in body
weight, decreased relative and absolute liver weights, decreased
absolute kidney weight, and an increase in relative testes weight.
Accordingly, the mid-dose in this same study (26.1 mg/kg/day) has been
categorized as the LOAEL with the lower 3.5 mg/kg/day dose as a NOAEL.
Based on a NOAEL of 3.5 mg/kg/day (DeAngelo et al. 1997), the
revised RfD was calculated as shown below, with a composite uncertainty
factor of 300. EPA used a default uncertainty factor of 10 to account
for extrapolation from an animal study, since no data on rat-to-human
differences in toxicokinetics or toxicodynamics were identified. A
default uncertainty factor of 10 was used to account for human
variability in the absence of data on the variability in the
toxicokinetics of MCAA in humans or in human susceptibility to MCAA. An
additional uncertainty factor of three was used to account for database
insufficiencies. Although there is no multi-generation reproduction
study, the available studies of reproductive and developmental
processes suggest that developmental toxicity is unlikely to be the
most sensitive endpoint. This led to the following calculation of the
Reference Dose (RfD) and MCLG for MCAA:
[GRAPHIC]
[TIFF OMITTED]
TR04JA06.001
Where:
3.5 mg/kg/day = NOAEL for decreased body weight plus decreased liver,
kidney and spleen weights in rats exposed to MCA for 104 weeks in
drinking water (DeAngelo et al. 1997).
300 = composite uncertainty factor chosen to account for inter species
extrapolation, inter-individual variability in humans, and deficiencies
in the database.
[GRAPHIC]
[TIFF OMITTED]
TR04JA06.002
The RSC for MCAA was selected using comparable data to that
discussed for TCAA. MCAA, like TCAA, has been found in foods and is
taken up by foods during cooking (15% in chicken to 62% in pinto beans)
and cleaning (2.5% for lettuce) with water containing 500 ppb MCAA
(Reimann et al.1996; Raymer et al. 2001, 2004). Rinsing of cooked foods
did not increase the MCAA content of foods to the same extent as was
observed for TCAA (Raymer et al. 2004). MCAA was found to be completely
stable in water boiled for 60 minutes and is likely to be found in the
diet due to the use of chlorinated water in food preparation and the
use of chlorine as a sanitizing agent by the food industry (USFDA
1994). As with TCAA, inhalation and dermal exposures are unlikely to be
significant. Dermal exposure from bathing and showering was estimated
to contribute only 0.03% of that from oral exposure (Xu et al. 2002).
As with TCAA, due to the limitations in dietary data and a clear
indication of exposure from other
[[Page 409]]
sources, EPA applied a relative source contribution of 20%.
c. Summary of major comments. EPA received few comments on MCAA and
TCAA. The majority of comments about the MCLGs for TCAA and MCAA were
general MCLG questions, including RSC derivation. Some commenters
questioned why MCAA, TCAA, and chloroform were calculated using an RSC
of 20%. In particular, some commenters compared these calculations to
that for DBCM in the Stage 1 DBPR, which uses 80%. Each of the MCLGs
set for chloroform, TCAA, and MCAA under this rule is calculated using
the best available science and EPA Office of Water's current approach
for deriving the RSC. EPA chose an RSC of 20%, not 80%, because of
clear indications of exposure from other sources; data limitations
preclude the derivation of a specific RSC.
The RSC for DBCM was 80% in the Stage 1 DBPR. The DBCM MCLG is not
part of today's rulemaking. Any possible future revision to the DBCM
MCLG as a result of an RSC change would not affect the MCL for TTHM
finalized in today's rule.
In response to comments received on the RfD for MCAA, EPA has
reviewed the critical study regarding the appropriateness of an
increase in spleen weight in the absence of histopathology as a LOAEL.
EPA has determined that the dose associated with this endpoint is more
appropriately categorized as a NOAEL rather than a LOAEL and has
revised the RfD and MCLG for MCAA.
B. Consecutive Systems
Today's rule includes provisions for consecutive systems, which are
public water systems that receive some or all of their finished water
from another water system (a wholesale system). Consecutive systems
face particular challenges in providing water that meets regulatory
standards for DBPs and other contaminants whose concentration can
increase in the distribution system. Moreover, previous regulation of
DBP levels in consecutive systems varies widely among States. In
consideration of these factors, EPA is finalizing monitoring,
compliance schedule, and other requirements specifically for
consecutive systems. These requirements are intended to facilitate
compliance by consecutive systems with MCLs for TTHM and HAA5 under the
Stage 2 DBPR and help to ensure that consumers in consecutive systems
receive equivalent public health protection.
1. Today's Rule
As public water systems, consecutive systems must provide water
that meets the MCLs for TTHM and HAA5 under the Stage 2 DBPR, use
specified analytical methods, and carry out associated monitoring,
reporting, recordkeeping, public notification, and other requirements.
The following discusses a series of definitions needed for addressing
consecutive system requirements in today's rule. Later sections of this
preamble provide further details on how rule requirements (e.g.,
schedule and monitoring) apply to consecutive systems.
A consecutive system is a public water system that receives some or
all of its finished water from one or more wholesale systems.
Finished water is water that has been introduced into the
distribution system of a public water system and is intended for
distribution and consumption without further treatment, except as
necessary to maintain water quality in the distribution system (e.g.,
booster disinfection, addition of corrosion control chemicals).
A wholesale system is a public water system that treats source
water as necessary to produce finished water and then delivers finished
water to another public water system. Delivery may be through a direct
connection or through the distribution system of one or more
consecutive systems.
The combined distribution system is defined as the interconnected
distribution system consisting of the distribution systems of wholesale
systems and of the consecutive systems that receive finished water from
those wholesale system(s).
EPA is allowing States some flexibility in defining what systems
are a part of a combined distribution system. This provision determines
effective dates for requirements in today's rule; see Section IV.E
(Compliance Schedules) for further discussion. EPA has consulted with
States and deferred to their expertise regarding the nature of the
connection in making combined distribution system determinations. In
the absence of input from the State, EPA will determine that combined
distribution systems include all interconnected systems for the purpose
of determining compliance schedules for implementation of this rule.
2. Background and Analysis
The practice of public water systems buying and selling water to
each other has been commonplace for many years. Reasons include saving
money on pumping, treatment, equipment, and personnel; assuring an
adequate supply during peak demand periods; acquiring emergency
supplies; selling surplus supplies; and delivering a better product to
consumers. EPA estimates that there are more than 10,000 consecutive
systems nationally.
Consecutive systems face particular challenges in providing water
that meets regulatory standards for contaminants that can increase in
the distribution system. Examples of such contaminants include
coliforms, which can grow if favorable conditions exist, and some DBPs,
including THMs and HAAs, which can increase when a disinfectant and DBP
precursors continue to react in the distribution system.
EPA included requirements specifically for consecutive systems
because States have taken widely varying approaches to regulating DBPs
in consecutive systems in previous rules. For example, some States have
not regulated DBP levels in consecutive systems that deliver
disinfected water but do not add a disinfectant. Other States have
determined compliance with DBP standards based on the combined
distribution system that includes both the wholesaler and consecutive
systems. In this case, sites in consecutive systems are treated as
monitoring sites within the combined distribution system. Neither of
these approaches provide the same level of public health protection as
non-consecutive systems receive under the Stage 1 DBPR. Once fully
implemented, today's rule will ensure similar protection for consumers
in consecutive systems.
In developing its recommendations, the Stage 2 M-DBP Advisory
Committee recognized two principles related to consecutive systems: (1)
consumers in consecutive systems should be just as well protected as
customers of all systems, and (2) monitoring provisions should be
tailored to meet the first principle. Accordingly, the Advisory
Committee recommended that all wholesale and consecutive systems comply
with provisions of the Stage 2 DBPR on the same schedule required of
the wholesale or consecutive system serving the largest population in
the combined distribution system. In addition, the Advisory Committee
recommended that EPA solicit comments on issues related to consecutive
systems that the Advisory Committee had not fully explored (USEPA
2000a). EPA agreed with these recommendations and they are reflected in
today's rule.
[[Page 410]]
3. Summary of Major Comments
Commenters generally supported the proposed definitions. However,
commenters did express some concerns, especially with including a time
period of water delivery that defined whether a system was a
consecutive system (proposed to trigger plant-based monitoring
requirements) or wholesale system (proposed to allow determination that
a combined distribution system existed). EPA has dropped this
requirement from the final rule; population-based monitoring
requirements in the final rule do not need to define how long a plant
must operate in order to be considered a plant, and EPA has provided
some flexibility for States to determine which systems comprise a
combined distribution system (without presenting a time criterion).
Other commenters expressed concern that the proposed definition of
consecutive system was inconsistent with use of the term prior to the
rulemaking. EPA acknowledges that the Agency has not previously
formally defined the term, but believes that the definition in today's
rule best considers all commenters' concerns, while also providing for
accountability and public health protection in as simple a manner as is
possible given the many consecutive system scenarios that currently exist.
Several States requested flexibility to determine which systems
comprised a combined distribution system under this rule; EPA has
included that flexibility for situations in which systems have only a
marginal association (such as an infrequently used emergency
connection) with other systems in the combined distribution system. To
prepare for the IDSE and subsequent Stage 2 implementation, EPA has
worked with States in identifying all systems that are part of each
combined distribution system.
Finally, several commenters requested that the wholesale system
definition replace ``public water system'' with ``water system'' so
that wholesale systems serving fewer than 25 people would not be
considered public water systems. EPA did not change the definition in
today's rule; EPA considers any water system to be a public water
system (PWS) if it serves 25 or more people either directly (retail) or
indirectly (by providing finished water to a consecutive system) or
through a combination of retail and consecutive system customers. If a
PWS receives water from an unregulated entity, that PWS must meet all
compliance requirements (including monitoring and treatment techniques)
that any other public water system that uses source water of unknown
quality must meet.
C. LRAA MCLs for TTHM and HAA5
1. Today's Rule
This rule requires the use of locational running annual averages
(LRAAs) to determine compliance with the Stage 2 MCLs of 0.080 mg/L
TTHM and 0.060 mg/L HAA5. All systems, including consecutive systems,
must comply with the MCLs for TTHM and HAA5 using sampling sites
identified under the Initial Distribution System Evaluation (IDSE) or
using existing Stage 1 DBPR compliance monitoring locations (as
discussed in Section IV.F). EPA has dropped the proposed phased
approach for LRAA implementation (Stage 2A and Stage 2B) by removing
Stage 2A and redesignating Stage 2B as Stage 2.
Details of monitoring requirements and compliance schedules are
discussed in preamble Sections IV.G and IV.E, respectively, and may be
found in subpart V of today's rule.
2. Background and Analysis
The MCLs for TTHM and HAA5 are the same as those proposed, 0.080
mg/L TTHM and 0.060 mg/L HAA5 as an LRAA. See the proposed rule (68 FR
49584, August 18, 2003) (USEPA 2003a) for a more detailed discussion of
the analysis supporting the MCLs. The primary objective of the LRAA is
to reduce exposure to high DBP levels. For an LRAA, an annual average
must be computed at each monitoring location. The RAA compliance basis
of the 1979 TTHM rule and the Stage 1 DBPR allows a system-wide annual
average under which high DBP concentrations in one or more locations
are averaged with, and dampened by, lower concentrations elsewhere in
the distribution system. Figure IV.C-1 illustrates the difference in
calculating compliance with the MCLs for TTHM between a Stage 1 DBPR
RAA, and the Stage 2 DBPR LRAA.
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EPA and the Stage 2 M-DBP Advisory Committee considered an array of
alternative MCL strategies. The Advisory Committee discussions
primarily focused on the relative magnitude of exposure reduction
versus the expected impact on the water industry and its customers.
Strategies considered included across the board requirements, such as
significantly decreasing the MCLs (e.g., 40/30) or single hit MCLs
(e.g., all samples must be below 80/60); and risk targeting
requirements. In the process of evaluating alternatives, EPA and the
Advisory Committee reviewed vast quantities of data and many analyses
that addressed health effects, DBP occurrence, predicted reductions in
DBP levels, predicted technology changes,
[[Page 412]]
and capital, annual, and household costs. The Advisory Committee
recommended and EPA proposed the risk targeting approach of 80/60 as an
LRAA preceded by an IDSE. Today's rule finalizes these requirements.
EPA has chosen compliance based on an LRAA due to concerns about
levels of DBPs above the MCL in some portions of the distribution
system. The LRAA standard will eliminate system-wide averaging of
monitoring results from different monitoring locations. The individuals
served in areas of the distribution system with above average DBP
occurrence levels masked by averaging under an RAA are not receiving
the same level of health protection. Although an LRAA standard still
allows averaging at a single location over an annual period, EPA
concluded that changing the basis of compliance from an RAA to an LRAA
will result in decreased exposure to higher DBP levels (see Section VI
for predictions of DBP reductions under the LRAA MCLs). This conclusion
is based on three considerations:
(1) There is considerable evidence that under the current RAA MCL
compliance monitoring requirements, a small but significant proportion
of monitoring locations experience high DBP levels at least some of the
time. Of systems that collected data under the Information Collection
Rule that met the Stage 1 DBPR RAA MCLs, 14 percent had TTHM single
sample concentrations greater than the Stage 1 MCL, and 21 percent had
HAA5 single sample concentrations above the MCL. Although most TTHM and
HAA5 samples were below 100 [mu]g/L, some ranged up to 140 [mu]g/L and
130 [mu]g/L, respectively.
(2) In some situations, the populations served by certain portions
of the distribution system consistently receive water that exceeds
0.080 mg/L for TTHM or 0.060 mg/L for HAA5 (both as LRAAs) even though
the system is in compliance with Stage 1 MCLs). Of Information
Collection Rule systems meeting the Stage 1 DBPR MCLs as RAAs, five
percent had monitoring locations that exceeded 0.080 mg/L TTHM and
three percent exceeded 0.060 mg/L HAA5 as an annual average (i.e., as
LRAAs) by up to 25% (calculated as indicated in Figure IV.C-1).
Customers served at these locations consistently received water with
TTHM and/or HAA5 concentrations higher than the system-wide average and
higher than the MCL.
(3) Compliance based on an LRAA will remove the opportunity for
systems to average out samples from high and low quality water sources.
Some systems are able to comply with an RAA MCL even if they have a
plant with a poor quality water source (that thus produces high
concentrations of DBPs) because they have another plant that has a
better quality water source (and thus lower concentrations of DBPs).
Individuals served by the plant with the poor quality source will usually
have higher DBP exposure than individuals served by the other plant.
In part, both the TTHM and HAA5 classes are regulated because they
occur at high levels and represent chlorination byproducts that are
produced from source waters with a wide range of water quality. The
combination of TTHM and HAA5 represent a wide variety of compounds
resulting from bromine substitution and chlorine substitution reactions
(e.g., bromoform has three bromines, TCAA has three chlorines, BDCM has
one bromine and two chlorines). EPA believes that the TTHM and HAA5
classes serve as an indicator for unidentified and unregulated DBPs.
EPA believes that controlling the occurrence levels of TTHM and HAA5
will help control the overall levels of chlorination DBPs.
3. Summary of Major Comments
Commenters supported the proposed, risk-targeted MCL strategy over
the alternative MCL strategies that were considered by the Advisory
Committee as the preferred regulatory strategy. Commenters concurred
with EPA's analysis that such an approach will reduce peak and average
DBP levels. Commenters supported the Stage 2 long-term MCLs of 0.080
mg/L TTHM and 0.060 mg/L HAA5 as LRAAs.
EPA received many comments on today's MCLs specific to consecutive
systems. While commenters supported consecutive system compliance with
the Stage 2 DBPR in order to provide comparable levels of public health
protection, they noted that it would be difficult for many consecutive
systems to meet Stage 2 requirements because they have not had to meet
the full scope of DBP requirements under previous rules. EPA has
developed a training and outreach program to assist these systems and
encourages States, wholesale systems, and professional associations to
also provide assistance.
Some commenters expressed concern about holding consecutive systems
responsible for water quality over which they have no control. Several
commenters were concerned about the establishment of contracts between
wholesale and consecutive systems, including concern about a strain on
their relationship, wholesale system reluctance to commit to keep DBPs
at a level suggested by the consecutive systems, and the time and money
it could take to work out differences. Although setting up a contract
is a prudent business action, commenters noted that small consecutive
water systems have few resources to sue for damages should the
wholesaler provide water exceeding the MCL.
The purpose of DBPRs is to protect public health from exposure to
high DBP levels. Not requiring violations when distributed water
exceeds MCLs undermines the intent of the rule. While EPA recognizes
consecutive systems do not have full control over the water they
receive, agreements between wholesale and consecutive systems may
specify water quality and actions required of the wholesaler if those
water quality standards are not met.
Finally, commenters recommended that the Stage 2A provisions in the
proposed rule be removed. These provisions (compliance with locational
running annual average MCLs of 0.120 mg/L for TTHM and 0.100 mg/L for
HAA5) required systems to comply with the Stage 1 MCLs (as running
annual averages) and the Stage 2A MCLs (as LRAAs) concurrently until
systems were required to comply with Stage 2B MCLs. Commenters noted
that having two separate MCLs for an individual system to comply with
at the same time was confusing to the system and its customers. In
addition, State resources needed for compliance determinations and data
management for this short-term requirement would be resource-intensive.
Finally, resources spent to comply with Stage 2A would be better spent
in complying with Stage 2B, especially given that some of the changes
for Stage 2A compliance might not provide any benefit for Stage 2B.
Since EPA agrees with commenters' concerns, the Stage 2A requirements
have been removed from the final rule.
D. BAT for TTHM and HAA5
1. Today's Rule
Today, EPA is identifying the best available technology (BAT) for
the TTHM and HAA5 LRAA MCLs (0.080 mg/L and 0.060 mg/L respectively)
for systems that treat their own source water as one of the three
following technologies:
(1) GAC10 (granular activated carbon filter beds with an empty-bed
contact time of 10 minutes based on average daily flow and a carbon
reactivation frequency of every 120 days)
(2) GAC20 (granular activated carbon filter beds with an empty-bed
contact time of 20 minutes based on average
[[Page 413]]
daily flow and a carbon reactivation frequency of every 240 days)
(3) Nanofiltration (NF) using a membrane with a molecular weight
cutoff of 1000 Daltons or less.
EPA is specifying a different BAT for consecutive systems than for
systems that treat their own source water to meet the TTHM and HAA5
LRAA MCLs. The consecutive system BAT is chloramination with management
of hydraulic flow and storage to minimize residence time in the
distribution system for systems that serve at least 10,000 people and
management of hydraulic flow and storage to minimize residence time in
the distribution system for systems that serve fewer than 10,000 people.
2. Background and Analysis
The BATs are the same as was proposed, except that consecutive
systems serving fewer than 10,000 people do not have chloramination as
part of the consecutive system BAT. See the proposal (68 FR 49588,
August 18, 2003) (USEPA 2003a) for more detail on the analysis
supporting these requirements. The Safe Drinking Water Act directs EPA
to specify BAT for use in achieving compliance with the MCL. Systems
unable to meet the MCL after application of BAT can get a variance (see
Section IV.K for a discussion of variances). Systems are not required
to use BAT in order to comply with the MCL. PWSs may use any State-
approved technologies as long as they meet all drinking water standards.
EPA examined BAT options first by analyzing data from the
Information Collection Rule treatment studies designed to evaluate the
ability of GAC and NF to remove DBP precursors. Based on the treatment
study results, GAC is effective for controlling DBP formation for
waters with influent TOC concentrations below approximately 6 mg/L
(based on the Information Collection Rule and NRWA data, over 90
percent of plants have average influent TOC levels below 6 mg/L (USEPA
2003c)). Of the plants that conducted an Information Collection Rule
GAC treatment study, approximately 70 percent of the surface water
plants studied could meet the 0.080 mg/L TTHM and 0.060 mg/L HAA5 MCLs,
with a 20 percent safety factor (i.e., 0.064 mg/L and 0.048 mg/L,
respectively) using GAC with 10 minutes of empty bed contact time and a
120 day reactivation frequency, and 78 percent of the plants could meet
the MCLs with a 20 percent safety factor using GAC with 20 minutes of
empty bed contact time and a 240 day reactivation frequency. Because
the treatment studies were conducted at plants with much poorer water
quality than the national average, EPA believes that much higher
percentages of plants nationwide could meet the MCLs with the proposed
GAC BATs.
Among plants using GAC, larger systems would likely realize an
economic benefit from on-site reactivation, which could allow them to
use smaller, 10-minute empty bed contact time contactors with more
frequent reactivation (i.e., 120 days or less). Most small systems
would not find it economically advantageous to install on-site carbon
reactivation facilities, and thus would opt for larger, 20-minute empty
bed contact time contactors, with less frequent carbon replacement
(i.e., 240 days or less).
The Information Collection Rule treatment study results also
demonstrated that nanofiltration was the better DBP control technology
for ground water sources with high TOC concentrations (i.e., above
approximately 6 mg/L). The results of the membrane treatment studies
showed that all ground water plants could meet the 0.080 mg/L TTHM and
0.060 mg/L HAA5 MCLs, with a 20% safety factor (i.e., 0.064 mg/L and
0.048 mg/L, respectively) at the system average distribution system
residence time using nanofiltration. Nanofiltration would be less
expensive than GAC for high TOC ground waters, which generally require
minimal pretreatment prior to the membrane process. Also,
nanofiltration is an accepted technology for treatment of high TOC
ground waters in Florida and parts of the Southwest, areas of the
country with elevated TOC levels in ground waters.
The second method that EPA used to examine alternatives for BAT was
the Surface Water Analytical Tool model that was developed to compare
alternative regulatory strategies as part of the Stage 1 and Stage 2 M-
DBP Advisory Committee deliberations. EPA modeled a number of BAT
options. In the model, GAC10 was defined as granular activated carbon
with an empty bed contact time of 10 minutes and a reactivation or
replacement interval of 90 days or longer. GAC20 was defined as
granular activated carbon with an empty bed contact time of 20 minutes
and a reactivation or replacement interval of 90 days or longer.
The compliance percentages forecasted by the SWAT model are
indicated in Table IV.D-1. EPA estimates that more than 97 percent of
large systems will be able to achieve the Stage 2 MCLs with the GAC
BAT, regardless of post-disinfection choice (Seidel Memo, 2001).
Because the source water quality (e.g., DBP precursor levels) in medium
and small systems is expected to be comparable to or better than that
for the large system (USEPA 2005f), EPA believes it is conservative to
assume that at least 90 percent of medium and small systems will be
able to achieve the Stage 2 MCLs if they were to apply one of the
proposed GAC BATs. EPA assumes that small systems may adopt GAC20 in a
replacement mode (with replacement every 240 days) over GAC10 because
it may not be economically feasible for some small systems to install
and operate an on-site GAC reactivation facility. Moreover, some small
systems may find nanofiltration cheaper than the GAC20 in a replacement
mode if their specific geographic locations cause a relatively high
cost for routine GAC shipment.
Table IV.D-1.--SWAT Model Predictions of Percent of Large Plants in Compliance With TTHM and HAA5 Stage 2 MCLs After Application of Specified Treatment
Technologies
--------------------------------------------------------------------------------------------------------------------------------------------------------
Compliance with 0.080 mg/L TTHM and 0.060 mg/L Compliance with 0.064 mg/L TTHM and 0.048 mg/L
HAA5 LRAAs HAA5 LRAAs (MCLs with 20% Safety factor)
-----------------------------------------------------------------------------------------------
Technology Residual disinfectant Residual disinfectant
-------------------------------- All systems -------------------------------- All systems
Chlorine Chloramine (percent) Chlorine Chloramine (percent)
(percent) (percent) (percent) (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Enhanced Coagulation (EC)............................... 73.5 76.9 74.8 57.2 65.4 60.4
EC (no pre-disinfection)................................ 73.4 88.0 78.4 44.1 62.7 50.5
EC & GAC10.............................................. 100 97.1 99.1 100 95.7 98.6
[[Page 414]]
EC & GAC20.............................................. 100 100 100 100 100 100
EC & All Chloramines.................................... NA 83.9 NA NA 73.6 NA
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Enhanced coagulation/softening is required under the Stage 1 DBPR for conventional plants.
Source: Seidel (2001).
The BAT requirements for large consecutive systems are the same as
proposed, but the requirements have changed for small consecutive
systems. EPA believes that the best compliance strategy for consecutive
systems is to collaborate with wholesalers on the water quality they
need. For consecutive systems that are having difficulty meeting the
MCLs, EPA is specifying a BAT of chloramination with management of
hydraulic flow and storage to minimize residence time in the
distribution system for systems serving at least 10,000 and management
of hydraulic flow and storage to minimize residence time in the
distribution system for systems serving fewer than 10,000. EPA believes
that small consecutive systems can use this BAT to comply with the
Stage 2 DBPR, but if they cannot, then they can apply to the State for
a variance.
Chloramination has been used for residual disinfection for many
years to minimize the formation of chlorination DBPs, including TTHM
and HAA5 (USEPA 2003d). EPA estimates that over 50 percent of large
subpart H systems serving at least 10,000 use chloramination for Stage
1. The BAT provision to manage hydraulic flow and minimize residence
time in the distribution system is to facilitate the maintenance of the
chloramine residual and minimize the likelihood for nitrification. EPA
has not included chloramination for consecutive systems as part of the
BAT for systems serving fewer than 10,000 due to concerns about their
ability to properly control the process, given that many have no
treatment capability or expertise and the Agency's concern about such
systems having operational difficulties such as distribution system
nitrification.
EPA believes that the BATs for nonconsecutive systems are not
appropriate for consecutive systems because their efficacy in
controlling DBPs is based on precursor removal. Consecutive systems
face the unique challenge of receiving waters in which DBPs are already
present if the wholesale system has used a residual disinfectant, which
the BATs for non-consecutive systems do not effectively remove. GAC is
not cost-effective for removing DBPs. Nanofiltration is only moderately
effective at removing THMs or HAAs if membranes with a very low
molecular weight cutoff (and very high cost of operation are employed).
Therefore, GAC and nanofiltration are not appropriate BATs for
consecutive systems.
3. Summary of Major Comments
Commenters concurred with EPA's identification of BATs for non-
consecutive systems but expressed concern about the BAT for consecutive
systems. Many commenters agreed that Stage 2 compliance for consecutive
systems would usually best be achieved by improved treatment by the
wholesale system. However, they noted that the proposed BAT may not be
practical for compliance if water delivered to the consecutive system
is at or near DBP MCLs. In addition, chloramination requires operator
supervision and adjustment and many consecutive systems that buy water
may be reluctant to operate chemical feed systems. Therefore, EPA
included chloramines as part of the BAT in today's rule only for
systems serving at least 10,000 because of the operator attention it
requires and concerns with safety and nitrification. While some
commenters believed that having a BAT for consecutive systems
contradicts the premise of the Stage 1 DBPR that DBPs are best
controlled through TOC removal and optimizing disinfection processes,
the SDWA requires EPA to identify a BAT for all systems required to
meet an MCL. No commenter recommended an alternative BAT. EPA still
believes that precursor removal remains a highly effective strategy to
reduce DBPs. Thus, EPA encourages States to work with wholesale systems
and consecutive systems to identify strategies to ensure compliance,
especially those systems with DBP levels close to the MCL.
E. Compliance Schedules
1. Today's Rule
This section specifies compliance dates for the IDSE and MCL
compliance requirements in today's rule. As described elsewhere in
Section IV of this preamble, today's rule requires PWSs to carry out
the following activities:
? Conduct initial distribution system evaluations (IDSEs) on
a required schedule. Systems may comply by using any of four approaches
for which they qualify (standard monitoring, system specific study, 40/
30 certification, or very small system waiver).
? Determine Stage 2 monitoring locations based on the IDSE.
? Comply with Stage 2 MCLs on a required schedule.
Compliance dates for these activities vary by PWS size. Table IV.E-
1 and Figure IV.E-1 specify IDSE and Stage 2 compliance dates.
Consecutive systems of any size must comply with the requirements of
the Stage 2 DBPR on the same schedule as required for the largest
system in the combined distribution system.
[[Page 415]]
Table IV.E-1.--IDSE and Stage 2 Compliance Dates
--------------------------------------------------------------------------------------------------------------------------------------------------------
Compliance dates by PWS size (retail population served) \1\
--------------------------------------------------------------------------------------------------------------------
Requirement CWSs and NTNCWSs
serving at least CWSs and NTNCWSs CWSs and NTNCWSs CWSs serving < 10,000 NTNCWSs serving
100,000 serving 50,000-99,999 serving 10,000-49,999 < 10,000
--------------------------------------------------------------------------------------------------------------------------------------------------------
Submit IDSE monitoring plan OR..... October 1, 2006....... April 1, 2007......... October 1, 2007...... April 1, 2008........ Not applicable.
Submit IDSE system specific study
plan OR.
Submit 40/30 certification OR......
Receive very small system waiver
from State.
Complete standard monitoring or September 30, 2008.... March 31, 2009........ September 30, 2009... March 31, 2010....... Not applicable.
system specific study.
Submit IDSE Report................. January 1, 2009....... July 1, 2009.......... January 1, 2010...... July 1, 2010......... Not applicable.
Begin subpart V (Stage 2) April 1, 2012......... October 1, 2012....... October 1, 2013...... October 1, 2013
compliance monitoring \2\. (October 1, 2014 if
Crypto- sporidium
monitoring is
required under
Subpart W)..
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Wholesale and consecutive systems that are part of a combined distribution system must comply based on the schedule required of the largest system
in the combined distribution system.
\2\ States may grant up to an additional 2 years for systems making capital improvements.
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2. Background and Analysis
The compliance schedule in today's final rule stems from the risk-
targeted approach of the rule, wherein PWSs conduct initial monitoring
to determine locations and concentrations of high DBPs. A primary
objective of this schedule is to ensure that PWSs identify locations
with high DBP concentrations and provide appropriate additional
treatment in a timely manner for high risk areas, while not requiring
low risk systems to add additional treatment. The compliance schedule
balances the objective of early risk-targeted monitoring with adequate
time for PWSs and the State or primacy agency to assure full
implementation and compliance. EPA is establishing concurrent
compliance schedules under the Stage 2 DBPR for all systems (both
wholesale systems and consecutive systems) in a particular combined
distribution system because this will assure comparable risk-based
targeting information being available at the same time for all PWSs
that are part of a combined distribution system and thereby allow for
more cost-effective compliance with TTHM and HAA5 MCLs.
SDWA section 1412(b)(10) states that a drinking water regulation
shall take effect 3 years from the promulgation date unless the
Administrator determines that an earlier date is practicable. Today's
rule requires PWSs to begin monitoring prior to 3 years from the
promulgation date. Based on EPA's assessment and recommendations of the
Advisory Committee, as described in this section, EPA has determined
that these monitoring start dates are practicable and appropriate.
Systems must submit their IDSE plans (monitoring plans for standard
monitoring, study plans for system specific studies) to the primacy
agency for review and approval. The State or primacy agency will then
have 12 months to review, and, as necessary, consult with the system. A
number of PWSs will then conduct one year of distribution system
monitoring for TTHM and HAA5 at locations other than those currently
used for Stage 1 DBPR compliance monitoring. At the conclusion of this
monitoring, these PWSs have three months to evaluate analysis and
monitoring results and submit Stage 2 compliance monitoring locations
and schedules to the State or primacy agency. Where required, PWSs must
provide the necessary level of treatment to comply with the Stage 2
MCLs within three years of the completion of State or primacy agency
review of the IDSE report, though States may allow an additional two
years for PWSs making capital improvements.
EPA has modified the proposed compliance schedule to stagger
monitoring start dates for PWSs serving 10,000 to 99,999 people and to
allow more time for development and review of IDSE monitoring plans
prior to the start of monitoring. The following discussion addresses
these changes from the proposal.
The proposed rule required all PWSs serving at least 10,000 people
(plus smaller systems that are part of a combined distribution system
with a PWS that serves at least 10,000 people) to complete IDSE
monitoring and submit IDSE reports (including recommended Stage 2
compliance monitoring locations) two years after rule promulgation,
followed by one year for review of IDSE reports, after which systems
had three years to come into compliance with Stage 2B MCLs.
Under today's final rule, PWSs serving at least 100,000 people
(plus smaller systems that are part of the combined distribution
system) will meet the same Stage 2 compliance deadlines as proposed.
However, the timing of the IDSE has been changed to allow for a more
even workload and a greater opportunity for primacy agency involvement
(e.g., through monitoring plan review and approval). The IDSE plan
submission dates for PWSs serving 50,000 to 99,999 people (plus smaller
systems that are part of the combined distribution system) will be 12
months after the effective date; for PWSs serving 10,000 to 49,999
(plus smaller systems that are part of the combined distribution
system), the IDSE plan submission dates will be 18 months after the
effective date. The Stage 2 compliance schedule for systems serving
fewer than 10,000 people remains the same as proposed. Stage 2 MCL
compliance dates are modified accordingly.
This staggering of IDSE start dates for PWSs serving 10,000 to
99,999 people is advantageous in several respects:
? Provides PWSs greater assurance that IDSEs are properly
conducted by requiring IDSE plan review prior to conducting the IDSE.
? Provides additional time to develop budgets and establish
contracts with laboratories.
? Spreads out the workload for technical assistance and
guidance. The staggered schedule will allow States and EPA to provide
more support to individual PWSs as needed.
? Provides time for DBP analytical laboratories to build
capacity as needed to accommodate the sample analysis needs of PWSs and
extends and smooths the demand for laboratory services.
? Maintains simultaneous rule compliance with the LT2ESWTR
as recommended by the Stage 2 M-DBP Advisory Committee and as mandated
by the 1996 SDWA Amendments, which require that EPA ``minimize the
overall risk of adverse health effects by balancing the risk from the
contaminant and the risk from other contaminants the concentrations of
which may be affected by the use of a treatment technique or process
that would be employed to attain the maximum contaminant level'' (Sec.
1412(b)(5)(B)(i)).
The Advisory Committee recommended the Initial Distribution System
Evaluation, as discussed in Section IV.F, and EPA is finalizing an IDSE
schedule generally consistent with the Advisory Committee timeframe
recommendation, but modified to stagger the schedule for systems
serving more than 10,000 but less than 100,000, and to address public
comments on the IDSE requirements.
For all systems, the IDSE schedule has been revised to allow
systems to submit and States or primacy agencies to review (and revise,
if necessary) systems' recommendations for IDSE and Stage 2 monitoring
locations, while still allowing systems three years after completion of
the State or primacy agency review of Stage 2 compliance monitoring
locations to make necessary treatment and operational changes to comply
with Stage 2 MCLs.
Figure IV.E-2 illustrates compliance schedules for examples of
three combined distribution systems, with the schedule dictated by the
retail population served by the largest system.
Figure IV.E-2.--Schedule Examples.
------------------------------------------------------------------------
-------------------------------------------------------------------------
--Wholesale system (pop. 64,000) with three consecutive systems (pops.
21,000; 15,000; 5,000):
--IDSE monitoring plan due for all systems April 1, 2007 since
wholesale system serves 50,000-99,999
--Stage 2 compliance beginning October 1, 2012 for all systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
21,000; 5,000; 5,000):
[[Page 418]]
--IDSE monitoring plan due for all systems October 1, 2007 since the
largest system in combined distribution system serves 10,000-49,999
--Stage 2 compliance beginning October 1, 2013 for all systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
8,000; 5,000; 5,000):
--IDSE monitoring plan due for all systems April 1, 2008 since no
individual system in combined distribution system exceeds 10,000
(even though total population exceeds 10,000)
--Stage 2 compliance beginning October 1, 2013 if no Cryptosporidium
monitoring under the LT2ESWTR is required or beginning October 1,
2014 if Cryptosporidium monitoring under the LT2ESWTR is required
------------------------------------------------------------------------
This schedule requires wholesale systems and consecutive systems
that are part of a combined distribution system with at least one
system with an earlier compliance deadline to conduct their IDSE
simultaneously so that the wholesale system will be aware of compliance
challenges facing the consecutive systems and will be able to implement
treatment plant, capital, and operational improvements as necessary to
ensure compliance of both the wholesale and consecutive systems. The
Advisory Committee and EPA both recognized that DBPs, once formed, are
difficult to remove and are generally best addressed by treatment plant
improvements, typically through precursor removal or use of alternative
disinfectants. For a wholesale system to make the best decisions
concerning the treatment steps necessary to meet TTHM and HAA5 LRAAs
under the Stage 2 DBPR, both in its own distribution system and in the
distribution systems of consecutive systems it serves, the wholesale
system must know the DBP levels throughout the combined distribution
system. Without this information, the wholesale system may design
treatment changes that allow the wholesale system to achieve
compliance, but leave the consecutive system out of compliance.
In summary, the compliance schedule for today's rule maintains the
earliest compliance dates recommended by the Advisory Committee for
PWSs serving at least 100,000 people (plus smaller systems that are
part of the combined distribution system). These PWSs serve the
majority of people. The schedule also maintains the latest compliance
dates the Advisory Committee recommended, which apply to PWSs serving
fewer than 10,000 people. EPA has staggered compliance schedules for
PWSs between these two size categories in order to facilitate
implementation of the rule. This staggered schedule is consistent with
the schedule required under the LT2ESWTR promulgated elsewhere in
today's Federal Register.
3. Summary of Major Comments
EPA received significant public comment on the compliance schedule
in the August 18, 2003 proposal. Major issues raised by commenters
include providing more time for PWSs to prepare for monitoring, giving
States or primacy agencies more time to oversee monitoring, and
establishing consistent schedules for consecutive PWSs. A summary of
these comments and EPA's responses follows.
Standard monitoring plan and system specific study plan
preparation. Many commenters were concerned about the proposed
requirement to develop and execute an IDSE monitoring plan without any
primacy agency review. PWSs specifically expressed concern about the
financial commitment without prior State approval and noted that some
PWSs would need more than the time allowed under the proposed rule to
develop and implement an IDSE monitoring plan, especially without an
opportunity for State or primacy agency review and approval. Smaller
PWSs may require substantial time and planning to budget for IDSE
expenses, especially for systems that have not previously complied with
DBP MCLs.
EPA recognizes these concerns and today's final rule provides time
for PWSs to submit IDSE plans (monitoring plans, study plans, or 40/30
certifications) for State or primacy agency review and more time before
having to begin monitoring. Specifically, PWSs serving 50,000 to 99,999
people and those serving 10,000 to 49,999 people must submit IDSE plans
about 12 months and 18 months after the effective date, respectively,
and complete standard monitoring or a system specific study within two
years after submitting their IDSE plan. This is significantly more time
than was specified under the proposal, where these systems would have
had to conduct their IDSE and submit their IDSE report 24 months after
the effective date. PWSs serving at least 100,000 people must submit
IDSE plans about six months after the effective date and complete
standard monitoring or a system specific study about 30 months after
the effective date, which also provides more time than was specified
under the proposal. PWSs serving fewer than 10,000 people, not
associated with a larger system in their combined distribution system,
do not begin monitoring until more than 36 months after the effective date.
EPA believes that the final compliance schedule allows PWSs
sufficient time to develop IDSE plans with these compliance dates. The
schedule also allows 12 months for State or primacy agency review of
IDSE plans, which allows additional time for review and for
coordination with systems and provides more time to address
deficiencies in IDSE plans. This is especially important for smaller
PWSs, which are likely to need the most assistance from States. By
staggering monitoring start dates, today's rule also eases
implementation by reducing the number of PWSs that will submit plans at
any one time, when the most assistance from regulatory agencies will be
required.
In summary, today's schedule has been modified so that systems are
required to submit IDSE plans for primacy agency review and approval
prior to conducting their IDSE. Systems can consider that their plan
has been approved if they have not heard back from the State by the end
of the State review period. Systems are also required to conduct the
approved monitoring and submit their IDSE report (including the
system's recommended Stage 2 compliance monitoring) for State or
primacy agency review on a schedule that allows for systems to still
have a minimum of full three years to comply with Stage 2 following
State or primacy agency review of the system's Stage 2 recommended
monitoring. As with the review of plans, systems can consider that
their IDSE report has been approved if they have not heard back from
the State by the end of the State review period.
State/primacy agency oversight. EPA is preparing to support
implementation of IDSE requirements that must be completed prior to
States achieving primacy. Several States have expressed concern about
EPA providing guidance and reviewing reports from systems that the
State has permitted, inspected, and worked with for a long time. These
States believe that their familiarity with
[[Page 419]]
the systems enables them to make the best decisions to implement the
rule and protect public health and that the rule requirement should be
delayed until States receive primacy. Commenters were concerned that
some States will not participate in early implementation activities and
indicated that States would prefer monitoring to begin 24 months after
rule promulgation. Commenters also noted that States need sufficient
time to become familiar with the rule, train their staff, prepare
primacy packages, and train PWSs.
EPA agrees that State familiarity is an important component of the
review and approval process, looks forward to working closely with the
State drinking water program representatives during IDSE
implementation, and welcomes proactive State involvement. However, the
Agency believes that delaying implementation of risk-based IDSE
targeting activities until States receive primacy is an unacceptable
delay in public health protection and also inconsistent with the
Advisory Committee's recommendations. EPA remains committed to working
with States to the greatest extent feasible to implement today's rule,
consistent with the schedule promulgated today. For States unable to
actively participate in IDSE implementation, however, EPA believes it
has an obligation to provide support and guidance to PWSs who are
covered and independently responsible for complying with the IDSE
requirements of today's rule and is prepared to oversee implementation.
Moreover, EPA believes that the staggered compliance schedule in
today's final rule will enhance States' ability to help implement the rule.
Consecutive systems. Most commenters supported consecutive systems
being on the same IDSE schedule as wholesale systems, recognizing the
benefits of treatment plant capital and operational improvements by the
wholesale system as the preferred method of DBP compliance, with the
timely collection of DBP data throughout the combined distribution
system a key component. Several commenters preferred that consecutive
systems have a later Stage 2 compliance date to allow for evaluation of
whether wholesale system treatment changes are adequate to ensure
compliance and to consider changes to water delivery specifications.
EPA disagrees with those commenters recommending a different Stage
2 compliance date and thus has maintained the approach in the proposal,
which keeps all systems that are part of a combined distribution system
(the interconnected distribution system consisting of the distribution
systems of wholesale systems and of the consecutive systems that
receive finished water) on the same Stage 2 compliance schedule.
Extending the Stage 2 compliance dates would unnecessarily delay the
public health protection afforded by this rule. Consecutive systems
must be able to evaluate whether wholesale system changes are
sufficient to ensure compliance and, if they are not, to make cost-
effective changes to ensure compliance where wholesale system efforts
address some, but not all, of the concerns with compliance. Public
health protection through compliance with Stage 2 MCLs will occur on
the schedule of the largest system for all systems in the combined
distribution system (regardless of size). If a consecutive system must
make capital improvements to comply with this rule, the State may use
its existing authority to grant up to an additional 24 months to that
system. In addition, implementation and data tracking will be
simplified because all systems in a combined distribution system will
be on the same IDSE and Stage 2 compliance schedule. EPA believes that
this is a better approach from both a public health standpoint and an
implementation standpoint.
EPA agrees with many commenters that a high level of coordination
among wholesaler, consecutive system, and States will be necessary to
ensure compliance. The schedule in today's rule provides more time for
planning, reviewing, and conducting the IDSE than the schedule in the
proposed rule, which will allow more time for necessary coordination,
including small consecutive systems that need help in negotiations with
their wholesale system. EPA will work with ASDWA and States to develop
guidance to facilitate wholesale/consecutive system cooperation. This
additional time and the staggered schedule discussed in this section
also lessens the laboratory burden associated with IDSE monitoring.
The staggered schedule also helps address commenter concerns about
evaluating combined distribution systems. Other commenters' concerns
about time needed for developing contracts between systems and for
planning, funding, and implementing treatment changes are addressed by
not requiring Stage 2 compliance until at least six years following
rule promulgation.
F. Initial Distribution System Evaluation (IDSE)
1. Today's Rule
Today's rule establishes requirements for systems to perform an
Initial Distribution System Evaluation (IDSE). The IDSE is intended to
identify sample locations for Stage 2 compliance monitoring that
represent distribution system sites with high DBP concentrations.
Systems will develop an IDSE plan, collect data on DBP levels
throughout their distribution system, evaluate these data to determine
which sampling locations are most representative of high DBP levels,
and compile this information into a report for submission to the State
or primacy agency. Systems must complete one IDSE to meet the
requirements of today's rule.
a. Applicability. This requirement applies to all community water
systems, and to large nontransient noncommunity water systems (those
serving at least 10,000 people) that use a primary or residual
disinfectant other than ultraviolet light, or that deliver water that
has been treated with a primary or residual disinfectant other than
ultraviolet light. Systems serving fewer than 500 people are covered by
the very small system waiver provisions of today's rule and are not
required to complete an IDSE if they have TTHM and HAA5 data collected
under Subpart L. Consecutive systems are subject to the IDSE
requirements of today's rule. Consecutive systems must comply with IDSE
requirements on the same schedule as the system serving the largest
population in the combined distribution system, as described in section
IV.E.
b. Data collection. For those systems not receiving a very small
system waiver, there are three possible approaches by which a system
can meet the IDSE requirement.
i. Standard monitoring. Standard monitoring requires one year of
DBP monitoring throughout the distribution system on a specified
schedule. Prior to commencing standard monitoring, systems must prepare
a monitoring plan and submit it to the primacy agency for review. The
frequency and number of samples required under standard monitoring is
determined by source water type and system size. The number of samples
does not depend on the number of plants per system. Section IV.G
provides a detailed discussion of the specific population-based
monitoring requirements for IDSE standard monitoring. Although standard
monitoring results are not to be used for determining compliance with MCLs,
[[Page 420]]
systems are required to include individual sample results for the IDSE
results when determining the range of TTHM and HAA5 levels to be
reported in their Consumer Confidence Report (see section IV.J).
ii. System specific study. Under this approach, systems may choose
to perform a system specific study based on earlier monitoring studies
or distribution system hydraulic models in lieu of standard monitoring.
Prior to commencing a system specific study, systems must prepare a
study plan and submit it to the primacy agency for approval. The two
options for system specific studies are: (1) TTHM and HAA5 monitoring
data that encompass a wide range of sample sites representative of the
entire distribution system, including those judged to represent high
TTHM and HAA5 concentrations, and (2) extended period simulation
hydraulic models that simulate water age in the distribution system, in
conjunction with one round of TTHM and HAA5 sampling.
iii. 40/30 certification. Under this approach, systems must certify
to their State or primacy agency that every individual compliance
sample taken under subpart L during the period specified in Table IV.F-
2 were less than or equal to 0.040 mg/L for TTHM and less than or equal
to 0.030 mg/L for HAA5, and that there were no TTHM or HAA5 monitoring
violations during the same period. The State or primacy agency may
require systems to submit compliance monitoring results, distribution
system schematics, or recommend subpart V compliance monitoring
locations as part of the certification. This certification must be kept
on file and submitted to the State or primacy agency for review.
Systems that qualify for reduced monitoring for the Stage 1 DBPR during
the two years prior to the start of the IDSE may use results of reduced
Stage 1 DBPR monitoring to prepare the 40/30 certification. The
requirements for the 40/30 certification are listed in Table IV.F-1.
Table IV.F-1.--40/30 Certification Requirements
------------------------------------------------------------------------
------------------------------------------------------------------------
40/30 Certification Requirements.. ? A certification that every
individual compliance sample taken
under subpart L during the period
specified in Table IV.F-2 were less
than or equal to 0.040 mg/L for
TTHM and less than or equal to
0.030 mg/L for HAA5, and that there
were no TTHM or HAA5 monitoring
violations during the same period.
? Compliance monitoring
results, distribution system
schematics, and/or recommended
subpart V compliance monitoring
locations as required by the State
or primacy agency.
------------------------------------------------------------------------
Table IV.F-2.--40/30 Eligibility Dates
------------------------------------------------------------------------
Then your eligibility for 40/30
certification is based on eight
consecutive calendar quarters
If your 40/30 Certification Is Due of subpart L compliance
monitoring results beginning no
earlier than\1\
------------------------------------------------------------------------
(1) October 1, 2006.................... January 2004.
(2) April 1, 2007...................... January 2004.
(3) October 1, 2007.................... January 2005.
(4) April 1, 2008...................... January 2005.
------------------------------------------------------------------------
\1\ Unless you are on reduced monitoring under subpart L and were not
required to monitor during the specified period. If you did not
monitor during the specified period, you must base your eligibility on
compliance samples taken during the 12 months preceding the specified
period.
c. Implementation. All systems subject to the IDSE requirement
under this final rule (except those covered by the very small system
waiver) must prepare and submit an IDSE plan (monitoring plan for
standard monitoring, study plan for system specific study) or 40/30
certification to the State or primacy agency. IDSE plans and 40/30
certifications must be submitted according to the schedule described in
section IV.E and IV.M. The requirements for the IDSE plan depend on the
IDSE approach that the system selects and are listed in Tables IV.F-1
and IV.F-3.
TABLE IV.F-3.--IDSE Monitoring Plan Requirements
------------------------------------------------------------------------
IDSE data collection alternative IDSE plan requirements
------------------------------------------------------------------------
Standard Monitoring............... ? Schematic of the
distribution system (including
distribution system entry points
and their sources, and storage
facilities), with notes indicating
locations and dates of all
projected standard monitoring, and
all projected subpart L compliance
monitoring.
? Justification for all
standard monitoring locations
selected and a summary of data
relied on to select those
locations.
? Population served and
system type (subpart H or ground
water).
System Specific Study:
Hydraulic Model................... Hydraulic models must meet the
following criteria:
? Extended period simulation
hydraulic model.
? Simulate 24 hour variation
in demand and show a consistently
repeating 24 hour pattern of
residence time.
? Represent 75% of pipe
volume; 50% of pipe length; all
pressure zones; all 12-inch
diameter and larger pipes; all 8-
inch and larger pipes that connect
pressure zones, influence zones
from different sources, storage
facilities, major demand areas,
pumps, and control valves, or are
known or expected to be significant
conveyors of water; all pipes 6
inches and larger that connect
remote areas of a distribution
system to the main portion of the
system; all storage facilities with
standard operations represented in
the model; all active pump stations
with controls represented in the
model; and all active control
valves.
[[Page 421]]
? The model must be
calibrated, or have calibration
plans, for the current
configuration of the distribution
system during the period of high
TTHM formation potential. All
storage facilities must be
evaluated as part of the
calibration process.
? All required calibration
must be completed no later than 12
months after plan submission.
Submission must include:
? Tabular or spreadsheet data
demonstrating percent of total pipe
volume and pipe length represented
in the model, broken out by pipe
diameter, and all required model
elements.
? A description of all
calibration activities undertaken,
and if calibration is complete, a
graph of predicted tank levels
versus measured tank levels for the
storage facility with the highest
residence time in each pressure
zone, and a time series graph of
the residence time at the longest
residence time storage facility in
the distribution system showing the
predictions for the entire
simulation period (i.e., from time
zero until the time it takes for
the model to reach a consistently
repeating pattern of residence time).
? Model output showing
preliminary 24 hour average
residence time predictions
throughout the distribution system.
? Timing and number of
samples planned for at least one
round of TTHM and HAA5 monitoring
at a number of locations no less
than would be required for the
system under standard monitoring in
Sec. 141.601 during the
historical month of high TTHM.
These samples must be taken at
locations other than existing
subpart L compliance monitoring
locations.
? Description of how all
requirements will be completed no
later than 12 months after
submission of the system specific
study plan.
? Schematic of the
distribution system (including
distribution system entry points
and their sources, and storage
facilities), with notes indicating
the locations and dates of all
completed system specific study
monitoring (if calibration is
complete) and all subpart L
compliance monitoring.
? Population served and system type
(subpart H or ground water).
? If the model submitted does
not fully meet the requirements,
the system must correct the
deficiencies and respond to State
inquiries on a schedule the State
approves, or conduct standard
monitoring.
System Specific Study:
Existing Monitoring Results....... Existing monitoring results must
meet the following criteria:
? TTHM and HAA5 results must
be based on samples collected and
analyzed in accordance with Sec.
141.131. Samples must be collected
within five years of the study plan
submission date.
? The sampling locations and
frequency must meet the
requirements identified in Table
IV.F-4. Each location must be
sampled once during the peak
historical month for TTHM levels or
HAA5 levels or the month of warmest
water temperature for every 12
months of data submitted for that
location. Monitoring results must
include all subpart L compliance
monitoring results plus additional
monitoring results as necessary to
meet minimum sample requirements.
Submission must include:
? Previously collected
monitoring results
? Certification that the
reported monitoring results include
all compliance and non-compliance
results generated during the time
period beginning with the first
reported result and ending with the
most recent subpart L results.
? Certification that the
samples were representative of the
entire distribution system and that
treatment and distribution system
have not changed significantly
since the samples were collected.
? Schematic of the
distribution system (including
distribution system entry points
and their sources, and storage
facilities), with notes indicating
the locations and dates of all
completed or planned system
specific study monitoring.
? Population served and
system type (subpart H or ground
water).
? If a system submits
previously collected data that
fully meet the number of samples
required for IDSE monitoring in
Table IV.F-4 and some of the data
are rejected due to not meeting the
additional requirements, the system
must either conduct additional
monitoring to replace rejected data
on a schedule the State approves,
or conduct standard monitoring.
------------------------------------------------------------------------
Table IV.F-4.--SSS Existing Monitoring Data Sample Requirements.
----------------------------------------------------------------------------------------------------------------
Number of Number of samples
System type Population size monitoring -------------------------------
category locations TTHM HAA5
----------------------------------------------------------------------------------------------------------------
Subpart H:
< 500 3 3 3
500-3,300 3 9 9
3,301-9,999 6 36 36
10,000-49,999 12 72 72
50,000-249,999 24 144 144
250,000-999,999 36 216 216
[[Page 422]]
1,000,000-4,999,999 48 288 288
>= 5,000,000 60 360 360
Ground Water: < 500 3 3 3
500-9,999 3 9 9
10,000-99,999 12 48 48
100,000-499,999 18 72 72
>= 500,000 24 96 96
----------------------------------------------------------------------------------------------------------------
The State or primacy agency will approve the IDSE plan or 40/30
certification, or request modifications. If the State or primacy agency
has not taken action by the date specified in section IV.E or has not
notified the system that review is not yet complete, systems may
consider their submissions to be approved. Systems must implement the
IDSE option described in the IDSE plan approved by the State or primacy
agency according to the schedule described in section IV.E.
All systems completing standard monitoring or a system specific
study must submit a report to the State or primacy agency according to
the schedule described in section IV.E. Systems that have completed
their system specific study at the time of monitoring plan submission
may submit a combined monitoring plan and report on the required
schedule for IDSE plan submissions. The requirements for the IDSE
report are listed in Table IV.F-5. Some of these reporting requirements
have changed from the proposal to reduce reporting and paperwork burden
on systems.
TABLE IV.F-5.--IDSE Report Requirements
------------------------------------------------------------------------
IDSE data collection alternative IDSE report requirements
------------------------------------------------------------------------
Standard Monitoring............... ? All subpart L compliance
monitoring and standard monitoring
TTHM and HAA5 analytical results in
a tabular format acceptable to the
State.
? If changed from the
monitoring plan, a schematic of the
distribution system, population
served, and system type.
? An explanation of any
deviations from the approved
monitoring plan.
? Recommendations and
justifications for subpart V
compliance monitoring locations and
timing.
System Specific Study............. ? All subpart L compliance
monitoring and all system specific
study monitoring TTHM and HAA5
analytical results conducted during
the period of the system specific
study in a tabular or spreadsheet
form acceptable to the State.
? If changed from the study
plan, a schematic of the
distribution system, population
served, and system type.
? If using the modeling
provision, include final
information for required plan
submissions and a 24-hour time
series graph of residence time for
each subpart V compliance
monitoring location selected.
? An explanation of any
deviations from the original study
plan.
? All analytical and modeling
results used to select subpart V
compliance monitoring locations
that show that the system specific
study characterized TTHM and HAA5
levels throughout the entire
distribution system.
? Recommendations and
justifications for subpart V
compliance monitoring locations and
timing.
------------------------------------------------------------------------
All systems must prepare Stage 2 compliance monitoring
recommendations. All IDSE reports must include recommendations for
Stage 2 compliance monitoring locations and sampling schedule. Systems
submitting a 40/30 certification must include their Stage 2 compliance
monitoring recommendations in their Stage 2 (Subpart V) monitoring plan
unless the State requests Subpart V site recommendations as part of the
40/30 certification. The number of sampling locations and the criteria
for their selection are described in Sec. 141.605 of today's final
rule, and in section IV.G. Generally, a system must recommend locations
with the highest LRAAs unless it provides a rationale (such as ensuring
geographical coverage of the distribution system instead of clustering
all sites in a particular section of the distribution system) for
selecting other locations. In evaluating possible Stage 2 compliance
monitoring locations, systems must consider both Stage 1 DBPR
compliance data and IDSE data.
The State or primacy agency will approve the IDSE report or request
modifications. If the State or primacy agency has not taken action by
the date specified in section IV.E or has not notified the system that
review is not yet complete, systems may consider their submission to be
approved and prepare to begin Stage 2 compliance monitoring.
EPA has developed the Initial Distribution System Evaluation
Guidance Manual for the Final Stage 2 Disinfectants and Disinfection
Byproducts Rule (USEPA 2006) to assist systems with implementing each
of these requirements. This guidance may be requested from EPA's Safe
Drinking
[[Page 423]]
Water Hotline, which may be contacted as described under FOR FURTHER
INFORMATION CONTACT in the beginning of this notice. This guidance
manual is also available on the EPA Web site at
http://www.epa.gov/safewater/stage2/index.html.
2. Background and Analysis
In the Stage 2 DBPR proposal (USEPA, 2003a), EPA proposed
requirements for systems to complete an IDSE. The Agency based its
proposal upon the Stage 2 M-DBP Advisory Committee recommendations in
the Agreement in Principle. The Advisory Committee believed and EPA
concurs that maintaining Stage 1 DBPR monitoring sites for the Stage 2
DBPR would not accomplish the risk-targeting objective of minimizing
high DBP levels and providing consistent and equitable protection
across the distribution system. Most of these requirements have not
changed from the proposed rule.
The data collection requirements of the IDSE are designed to find
both high TTHM and high HAA5 sites (see section IV.G for IDSE
monitoring requirements). High TTHM and HAA5 concentrations often occur
at different locations in the distribution system. The Stage 1 DBPR
monitoring sites identified as the maximum location are selected
according to residence time. HAAs can degrade in the distribution
system in the absence of sufficient disinfectant residual (Baribeau et
al. 2000). Consequently, residence time is not an ideal criterion for
identifying high HAA5 sites. In addition, maximum residence time
locations that are associated with high TTHM levels may not be constant
due to daily or seasonal changes in demand. The analysis of maximum
residence time completed for the selection of Stage 1 monitoring sites
may not have been capable of detecting these variations. The
Information Collection Rule data show that over 60 percent of the
highest HAA5 LRAAs and 50 percent of the highest TTHM LRAAs were found
at sampling locations in the distribution system other than the maximum
residence time compliance monitoring location (USEPA 2003a). Therefore,
the method and assumptions used to select the Information Collection
Rule monitoring sites and the Stage 1 DBPR compliance monitoring sites
may not reliably capture high DBP levels for Stage 2 DBPR compliance
monitoring sites.
a. Standard monitoring. The Advisory Committee recommended that
systems sample throughout the distribution system at twice the number
of locations as required under Stage 1 and, using these results in
addition to Stage 1 compliance data, identify high DBP locations.
Monitoring at additional sites increases the chance of finding sites
with high DBP levels and targets both DBPs that degrade and DBPs that
form as residence time increases in the distribution system. EPA
believes that the required number of standard monitoring locations plus
Stage 1 monitoring results will provide an adequate characterization of
DBP levels throughout the distribution system at a reasonable cost. By
revising Stage 2 compliance monitoring plans to target locations with
high DBPs, systems will be required to take steps to address high DBP
levels at locations that might otherwise have gone undetected.
The Advisory Committee recommended that an IDSE be performed by all
community water systems, unless the system had sufficiently low DBP
levels or is a very small system with a simple distribution system. EPA
believes that large nontransient noncommunity water systems (NTNCWS)
(those serving at least 10,000 people) also have distribution systems
that require further evaluation to determine the locations most
representative of high DBP levels and proposed that they be required to
conduct an IDSE. Therefore, large NTNCWS and all community water
systems are required to comply with IDSE requirements under today's
final rule, unless they submit a 40/30 certification or they are
covered by the very small system waiver provisions.
b. Very small system waivers. Systems serving fewer than 500 people
that have taken samples under the Stage 1 DBPR will receive a very
small system waiver. EPA proposed and the Advisory Committee
recommended a very small system waiver following a State determination
that the existing Stage 1 compliance monitoring location adequately
characterizes both high TTHM and high HAA5 for the distribution system
because many very small systems have small or simple distribution
systems. The final rule grants the very small system waiver to all
systems serving fewer than 500 that have Stage 1 DBPR data. This
provision was changed from the proposal to reflect that most very small
systems that sample under the Stage 1 DBPR have sampling locations that
are representative of both high TTHM and high HAA5 because most very
small systems have small and simple distribution systems. In addition,
many very small systems are ground water systems that typically have
stable DBP levels that tend to be lower than surface water DBP levels.
NRWA survey data show that free chlorine residual in very small systems
(serving < 500) at both average residence time and maximum residence
time locations are lower than levels at both of those locations in
larger systems, and the change in residual concentration between those
two locations is smaller in very small systems compared to larger sized
systems. The magnitude of the reduction in residual concentration gives
an indication of how much disinfectant has reacted to form DBPs,
including TTHM and HAA5. The smaller reduction in disinfectant
concentration between average residence time and maximum residence time
in very small systems compared to larger systems indicates that DBP
formation potential is probably lower in very small systems compared to
larger systems, and the likelihood for significant DBP variation within
the distribution system of very small systems is low if the
distribution system is small and not complex. However, there may be
some small systems with extended or complex distribution systems that
should be studied further to determine new sampling locations. For this
reason, States or primacy agencies can require any particular very
small system to conduct an IDSE. Very small systems subject to the
Stage 2 DBPR that do not have a Stage 1 compliance monitoring location
may monitor in accordance with the Stage 1 DBPR provisions to be
eligible for this waiver.
c. 40/30 certifications. Systems that certify to their State or
primacy agency that all compliance samples taken during eight
consecutive calendar quarters prior to the start of the IDSE were
< =0.040 mg/L TTHM and < =0.030 mg/L HAA5 are not required to collect
additional DBP monitoring data under the IDSE requirements as long as
the system has no TTHM or HAA5 monitoring violations. These criteria
were developed because both EPA and the AdvisoryCommittee determined
that these systems most likely would not have DBP levels that exceed
the MCLs. Systems must have qualifying TTHM and HAA5 data for eight
consecutive calendar quarters according to the schedule in Table IV.F-2
to be eligible for this option. Systems on reduced monitoring that did
not monitor during the specified time period may use data from the
prior year to meet the 40/30 certification criteria. Systems that have
not previously conducted Stage 1 DBPR compliance monitoring may begin
such monitoring to collect the data necessary to qualify for 40/30
certification. The certification and data supporting it must be
available to the public upon request.
[[Page 424]]
The qualifying time period for the 40/30 certification has changed
from the proposed rule.
Under the proposed rule, the rule language identified a specific
two year window with start and end dates. In today's final rule, the
qualifying time period has been changed to ``eight consecutive calendar
quarters of subpart L compliance monitoring results beginning no
earlier than * * *'' (see Table IV.F-2). This change was made so that
systems that have made a treatment change within the two years prior to
rule promulgation and have collected initial data that meet the 40/30
criteria might have the opportunity to collect eight consecutive
quarters of qualifying data and apply for a 40/30 certification. This
schedule change also allows systems that have not previously monitored
under Stage 1 an opportunity to qualify for a 40/30 certification.
Under the proposed Stage 2 DBPR, systems that missed the deadline
for submitting a 40/30 certification would be required to conduct
either standard monitoring or a system specific study even if the
system otherwise qualified for the 40/30 certification. Under today's
final rule, systems that do not make any submission by the IDSE plan
submission deadline will still receive a violation, but may submit a
late 40/30 certification if their data meet the requirements. This
change was made so that systems and primacy agencies do not spend time
preparing and reviewing standard monitoring plans and IDSE reports for
systems with a low likelihood of finding high TTHM and HAA5 levels.
The reporting requirements for this provision have been reduced
from the requirements in the proposed rulemaking. In the proposal,
systems qualifying for the 40/30 certification were required to submit
all qualifying data and provide recommendations for Stage 2 compliance
monitoring locations. The final rule requires systems to submit a
certification that their data meet all the requirements of the 40/30
certification and to include their Stage 2 compliance monitoring
recommendations in their Stage 2 monitoring plan. These changes were
made to reduce the reporting burden on systems that qualify for the 40/
30 certification and to maintain consistency with monitoring plan
requirements under the Stage 1 DBPR. This approach also gives systems
more time to select appropriate monitoring sites for Stage 2 compliance
monitoring. The State or primacy agency may request systems to submit
the data, a distribution system schematic, and/or recommendations for
Stage 2 compliance monitoring as part of the 40/30 certification. This
provision was included to facilitate primacy agency review of 40/30
certifications; the additional information is only required if
requested by the primacy agency.
d. System specific studies. Advisory Committee members recognized
that some systems have detailed knowledge of their distribution systems
by way of ongoing hydraulic modeling and/or existing widespread
monitoring plans (beyond that required for compliance monitoring) that
would provide equivalent or superior monitoring site selection
information compared to standard monitoring. Therefore, the Advisory
Committee recommended that such systems be allowed to determine new
monitoring sites using system-specific data such as hydraulic model
results or existing monitoring data; this provision remains in the
final rule. In the proposed rule, the only specification for SSSs was
to identify monitoring sites that would be equivalent or superior to
those identified under Standard Monitoring. The final rule includes
more specific requirements on how these studies should be completed.
The requirements in the final rule were developed to be consistent with
the proposal, yet more specific to help systems better understand
expectations under this provision and lessen the chances of a study
plan not being approved.
The new modeling requirements were developed to reflect that
hydraulic models can identify representative high TTHM monitoring
locations by predicting hydraulic residence time in the distribution
system. Water age has been found to correlate with TTHM formation in
the distribution system. Consequently, for this system specific study
approach, hydraulic residence time predicted by the model is used as a
surrogate for TTHM formation to locate appropriate Stage 2 compliance
monitoring locations. To predict hydraulic residence time in the
distribution system, the model must represent most of the distribution
system and must have been calibrated recently and appropriately to
reflect water age in the distribution system. Requirements to reflect
this are in today's rule. All storage facilities must be evaluated for
the calibration, and systems using this option must submit a graph of
predicted tank levels versus measured tank levels for the storage
facility with the highest residence time in each pressure zone. These
calibration requirements are focused on storage facilities because they
are the largest controlling factor for water age in the distribution
system. The calibration requirements reflect the fact that the purpose
of the model is to predict water age. ICR data show that HAA5 data do
not necessarily correlate well with water age (USEPA 2003a). Because
the purpose of the IDSE is to locate representative high locations for
both TTHM and HAA5, one round of monitoring must be completed at
potential Stage 2 compliance monitoring locations to determine
appropriate HAA5 monitoring locations during the historical high month
of TTHM concentrations. The number of locations must be no less than
would be required under standard monitoring.
Preliminary average residence time data are required as a part of
the study plan for systems to demonstrate that their distribution
system hydraulic model is able to produce results for water age
throughout the distribution system, even though calibration may not be
complete. Systems also need to describe their plans to complete the
modeling requirements within 12 months of submitting the study plan.
These last two requirements were developed so that States can be
assured that systems have the technical capacity to complete their
modeling requirements by the IDSE report deadline. If systems cannot
demonstrate that they are in a position to complete the modeling
requirements according to the required schedule, they will be required
to complete standard monitoring.
All new modeling requirements were added to help systems
demonstrate how their model will fulfill the purpose and requirements
of the IDSE and to assist primacy agencies with approval
determinations. The associated reporting requirements were developed to
balance the needs of systems to demonstrate that they have fulfilled
the requirements and the needs of primacy agency reviewers to be able
to understand the work completed by the system.
EPA has specified new requirements for systems complete an SSS
using existing monitoring data to help systems understand the extent of
historical data that would meet the requirements of the IDSE. The
number of required sample locations and samples are consistent with
sampling requirements under standard monitoring and the recommendations
made by the Advisory Committee. The Advisory Committee recommended that
systems complete an IDSE sample at twice the number of sites required
by the Stage 1 DBPR in addition to Stage 1 DBPR sampling. Because the
number of required Stage 1 DBPR monitoring locations varies within each
population category under
[[Page 425]]
the Stage 1 plant-based monitoring approach (since systems have
different numbers of plants), EPA used the number of required Standard
Monitoring locations plus the number of Stage 2 compliance monitoring
locations to develop minimum requirements for the use of existing
monitoring data for the SSS. The number of required locations and
samples are shown in Table IV.F-4. Systems will use their Stage 1
monitoring results plus additional non-compliance or operational
samples to fulfill these requirements. Small systems with many plants
may have been collecting a disproportionate number of samples under the
Stage 1 DBPR compared to the population based monitoring requirements
presented in today's rule and may have sufficient historical data to
characterize the entire distribution system. These requirements allow
those systems to submit an SSS based on existing Stage 1 monitoring
results, and they also accommodate systems that have been completing
additional monitoring throughout the distribution system.
The requirement to sample during the historical month of high TTHM,
high HAA5, or warmest water temperature during each year for which data
were collected was added to maintain consistency with the standard
monitoring requirements where each location must be sampled one time
during the peak historical month. Samples that qualify for this SSS
must have been collected within five years of the study plan submission
date and must reflect the current configuration of treatment and the
distribution system. Five years was selected as a cut off for eligible
data so that all data submitted would be reasonably representative of
current source water conditions and DBP formation within the
distribution system. Data that are older may not reflect current DBP
formation potential in the distribution system. Five years prior to the
submission of the study plan also correlates with the signing of the
Agreement in Principle where the Advisory Committee made the
recommendation for this provision. Systems interested in using this
provision would have started eligible monitoring after the agreement
was signed.
Systems that submit existing monitoring data must submit all Stage
1 sample results from the beginning of the SSS to the time when the SSS
plan is submitted. The purpose of this requirement is to demonstrate
that there have been no significant changes in source water quality
since the first samples were collected, especially if all existing
monitoring results were taken during the earliest eligible dates.
Again, these clarifications were made so that systems could better
understand the extent of data necessary for a monitoring plan to be
deemed acceptable and be confident that efforts to complete an SSS
would be found acceptable to the State or primacy agency.
e. Distribution System Schematics. EPA has considered security
concerns that may result from the requirement for systems to submit a
distribution system schematic as part of their IDSE plan. EPA believes
that the final rule strikes an appropriate balance between security
concerns and the need for States and primacy agencies to be able to
review IDSE plans. EPA has developed guidance for systems on how to
submit a distribution system schematic that does not include sensitive
information.
3. Summary of Major Comments
The Agency received significant comments on the following issues
related to the proposed IDSE requirements: Waiver limitations, and
State or primacy agency review of IDSE plans.
In the proposed rule, EPA requested comment on what the appropriate
criteria should be for States or primacy agencies to grant very small
system waivers. Commenters responded with a wide range of suggestions
including support for the proposal as written, different population
cut-offs, State or primacy agency discretion on what system size should
qualify for the waiver, and alternative waiver criteria such as pipe
length or number of booster stations. There was no consensus among the
commenters on what changes should be made to the proposal for the very
small system waiver requirements. EPA did not change the population
cutoff for the very small system waiver because analysis of NRWA survey
data also showed that systems serving fewer than 500 had different
residence times and lower free chlorine residual concentrations
compared to other population categories, indicating that larger systems
have different DBP formation characteristics compared to very small
systems. Some of the suggested changes for very small system waiver
criteria may require data that are not readily available to systems
(such as pipe length in service) and for which there were no specific
criteria proposed or recommended by the commenters. Implementation of
subjective very small system waiver criteria would result in reduced
public health protection from the rule by allowing higher DBP levels to
go undetected.
In addition to addressing the very small system waivers, commenters
suggested that different criteria should be used for the 40/30
certification, such as higher minimum DBP levels, cut-offs of 40/30 as
LRAAs or RAAs rather than single sample maximums, or State or primacy
agency discretion on which systems should qualify for 40/30
certification. There was no consensus among the commenters on what
changes should be made to the proposal for the 40/30 certification
requirements. EPA did not change the requirements for the 40/30
certification eligibility because the recommended alternatives were not
technically superior to the requirements of the proposed rule.
Implementation of 40/30 criteria using an LRAA or RAA would result in
reduced public health protection from the rule by allowing higher DBP
levels to go undetected. EPA did change the eligibility dates and
reporting requirements for the 40/30 certification to reduce the burden
on the system. Under today's final rule, States or primacy agencies can
request TTHM and HAA5 data as desired for a more in-depth review of a
system's qualifications.
Many commenters expressed concern over the implementation schedule
for the IDSE. Commenters were especially concerned that IDSE plans
would be developed and implemented prior to State primacy, and once
States receive primacy, they might not support the IDSE plan and would
reject the results of the completed IDSE. To address this issue,
commenters requested the opportunity for States to review the IDSE
plans prior to systems completing their IDSEs. In today's rule EPA has
modified the compliance schedule for the Stage 2 DBPR so that systems
have the opportunity to complete their IDSE plan and have it reviewed
by the primacy agency prior to completing the IDSE to address the
concern that States or primacy agencies may reject the results of the
completed IDSE. The changes to the compliance schedule are discussed
further in section IV.E.
G. Monitoring Requirements and Compliance Determination for TTHM and
HAA5 MCLs
EPA is finalizing monitoring requirements under a population-based
approach described in this section. EPA believes the population-based
approach will provide more representative high DBP concentrations
throughout distribution systems than would plant-based monitoring, is
equitable, and will simplify implementation for both States and
systems. For these reasons, EPA believes this approach is more
appropriate than the proposed plant-
[[Page 426]]
based monitoring. Detailed discussion of the two approaches is
presented in the preamble of the proposed rule (USEPA 2003a) and EA for
today's rule (USEPA 2005a).
1. Today's Rule
Today's rule establishes TTHM and HAA5 monitoring requirements for
all systems based on a population-based monitoring approach instead of
a plant-based approach. Under the population-based approach, monitoring
requirements are based solely on the retail population served and the
type of source water used and not influenced by the number of treatment
plants or entry points in the distribution system as in previous rules
(i.e., TTHM Rule (USEPA 1979) and Stage 1 DBPR (USEPA 1998a)).
a. IDSE Monitoring. All systems conducting IDSE standard monitoring
must collect samples during the peak historical month for DBP levels or
water temperature; this will determine their monitoring schedule. Table
IV.G-1 contains the IDSE monitoring frequencies and locations for all
source water and size category systems. Section IV.F identifies other
approaches by which systems can meet IDSE requirements.
Table IV.G-1.--IDSE Monitoring Frequencies and Locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distribution system monitoring locations \1\
----------------------------------------------------------------
Source water type Population size Monitoring periods and Total per Average
category frequency of sampling monitoring Near entry residence High TTHM High HAA5
period points time locations locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H
< 500 consecutive one (during peak 2 1 ........... 1
systems. historical month) \2\.
< 500 non-consecutive ....................... 2 ........... ........... 1 1
systems.
--------------------------------------
500-3,300 non- four (every 90 days)... 2 1 ........... 1 ...........
consecutive systems.
500-3,300 consecutive ....................... 2 ........... ........... 1 1
systems.
--------------------------------------
3,301-9,999............ ....................... 4 ........... 1 2 1
10,000-49,999.......... six (every 60 days).... 8 1 2 3 2
50,000-249,999......... ....................... 16 3 4 5 4
250,000-999,999........ ....................... 24 4 6 8 6
1,000,000-4,999,999.... ....................... 32 6 8 10 8
>=5,000,000............ ....................... 40 8 10 12 10
======================================
Ground Water
< 500 consecutive one (during peak 2 1 ........... 1 ...........
systems. historical month) \2\.
--------------------------------------
< 500 non-consecutive ....................... 2 ........... ........... 1 1
systems.
500-9,999.............. four (every 90 days)... 2 ........... ........... 1 1
10,000-99,999.......... ....................... 6 1 1 2 2
100,000-499,999........ ....................... 8 1 1 3 3
>=500,000.............. ....................... 12 2 2 4 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
\2\ The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.
b. Routine Stage 2 Compliance Monitoring. For all systems
conducting either standard monitoring or a system specific study,
initial Stage 2 compliance monitoring locations are based on the
system's IDSE results, together with an analysis of a system's Stage 1
DBPR compliance monitoring results. Systems receiving 40/30
certification or a very small system waiver, and nontransient
noncommunity water systems serving < 10,000 not required to conduct an
IDSE, base Stage 2 initial compliance monitoring locations on the
system's Stage 1 DBPR compliance monitoring results. Some of these
systems may also need an evaluation of distribution system
characteristics to identify additional monitoring locations, if
required by the transition from plant-based monitoring to population-
based monitoring.
Systems recommend Stage 2 monitoring locations generally by
arraying results of IDSE standard monitoring (or system specific study
results) and Stage 1 compliance monitoring by monitoring location (from
highest to lowest LRAA for both TTHM and HAA5). Using the protocol in
Sec. 141.605(c) of today's rule, systems then select the required
number of locations. Larger systems include existing Stage 1 monitoring
locations in order to be able to have historical continuity for
evaluating how changes in operations or treatment affect DBP levels.
Systems may also recommend locations with lower levels of DBPs that
would not be picked up by the protocol if they provide a rationale for
the recommendation. Examples of rationales include ensuring better
distribution system or population coverage (not having all locations in
the same area) or maintaining existing locations with DBP levels that
are nearly as high as those that would otherwise be selected. The State
or primacy agency will review these recommendations as part of the
review of the IDSE report submitted by systems that conducted standard
monitoring or a system specific study.
Table IV.G-2 contains the routine Stage 2 TTHM and HAA5 compliance
[[Page 427]]
monitoring requirements for all systems (both non-consecutive and
consecutive systems), as well as the protocol for Stage 2 compliance
monitoring location selection in the IDSE report. Systems that do not
have to submit an IDSE report (those receiving a 40/30 certification or
very small system waiver and nontransient noncommunity water systems
serving < 10,000) must conduct Stage 2 compliance monitoring as
indicated in the ``Total per monitoring period'' column at current
Stage 1 compliance monitoring locations, unless the State or primacy
agency specifically directs otherwise. All systems are then required to
maintain and follow a Stage 2 compliance monitoring plan.
Table IV.G-2. Routine Compliance Monitoring Frequencies and Locations
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distribution system monitoring location
---------------------------------------------------
Existing
Source water type Population size category Monitoring frequency\1\ Total per Highest Highest Subpart L
monitoring TTHM HAA5 compliance
period\2\ locations locations locations
---------------------------------------------------------------------------------------------------------------------------------------------
Subpart H:
< 500.................... per year................ 2 1 1 ...........
500-3,300............... per quarter............. 2 1 1 ...........
3,301-9,999............. per quarter............. 2 1 1 ...........
10,000-49,999........... per quarter............. 4 2 1 1
50,000-249,999.......... per quarter............. 8 3 3 2
250,000-999,999......... per quarter............. 12 5 4 3
1,000,000-4,999,999..... per quarter............. 16 6 6 4
>= 5,000,000............ per quarter............. 20 8 7 5
Ground water:
< 500.................... per year................ 2 1 1 ...........
500-9,999............... per year................ 2 1 1 ...........
10,000-99,999........... per quarter............. 4 2 1 1
100,000-499,999......... per quarter............. 6 3 2 1
>= 500,000.............. per quarter............. 8 3 3 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must monitor during month of highest DBP concentrations.
\2\ Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for subpart H systems serving 500-
3,300. Systems on annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of a dual
sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring
period is needed if highest TTHM and HAA5 concentrations occur at the same location, and month, if monitored annually).
Today's rule provides States the flexibility to specify alternative
Stage 2 compliance monitoring requirements (but not alternative IDSE
monitoring requirements) for multiple consecutive systems in a combined
distribution system. As a minimum under such an approach, each
consecutive system must collect at least one sample among the total
number of samples required for the combined distribution system and
will base compliance on samples collected within its distribution
system. The consecutive system is responsible for ensuring that
required monitoring is completed and the system is in compliance. It
also must document its monitoring strategy as part of its subpart V
monitoring plan.
Consecutive systems not already conducting disinfectant residual
monitoring under the Stage 1 DBPR must comply with the monitoring
requirements and MRDLs for chlorine and chloramines. States may use the
provisions of Sec. 141.134(c) to modify reporting requirements. For
example, the State may require that only the consecutive system
distribution system point-of-entry disinfectant concentration be
reported to demonstrate MRDL compliance, although monitoring
requirements may not be reduced.
i. Reduced monitoring. Systems can qualify for reduced monitoring,
as specified in Table IV.G-3, if the LRAA at each location is < =0.040
mg/L for TTHM and < =0.030 mg/L for HAA5 based on at least one year of
monitoring at routine compliance monitoring locations. Systems may
remain on reduced monitoring as long as the TTHM LRAA is < =0.040 mg/L
and the HAA5 LRAA is < =0.030 mg/L at each monitoring location for
systems with quarterly reduced monitoring. If the LRAA at any location
exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or if the
source water annual average TOC level, before any treatment, exceeds
4.0 mg/L at any of the system's treatment plants treating surface water
or ground water under the direct influence of surface water, the system
must resume routine monitoring. For systems with annual or less
frequent reduced monitoring, systems may remain on reduced monitoring
as long as each TTHM sample is < =0.060 mg/L and each HAA5 sample is
< =0.045 mg/L. If the annual (or less frequent) sample at any location
exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the
source water annual average TOC level, before any treatment, exceeds
4.0 mg/L at any treatment plant treating surface water or ground water
under the direct influence of surface water, the system must resume
routine monitoring.
Table IV.G-3.--Reduced Monitoring Frequency
----------------------------------------------------------------------------------------------------------------
Distribution system
Source water type Population size Monitoring frequency 1 monitoring location per
category monitoring period
----------------------------------------------------------------------------------------------------------------
Subpart H:
< 500.................. ...................... Monitoring may not be
reduced.
[[Page 428]]
500-3,300............. per year.............. 1 TTHM and 1 HAA5 sample:
one at the location and
during the quarter with
the highest TTHM single
measurement, one at the
location and during the
quarter with the highest
HAA5 single measurement; 1
dual sample set per year
if the highest TTHM and
HAA5 measurements occurred
at the same location and
quarter.
3,301-9,999........... per year.............. 2 dual sample sets: one at
the location and during
the quarter with the
highest TTHM single
measurement, one at the
location and during the
quarter with the highest
HAA5 single measurement.
10,000-49,999......... per quarter........... 2 dual sample sets at the
locations with the highest
TTHM and highest HAA5
LRAAs.
50,000-249,999........ per quarter........... 4 dual sample sets--at the
locations with the two
highest TTHM and two
highest HAA5 LRAAs.
250,000-999,999....... per quarter........... 6 dual sample sets--at the
locations with the three
highest TTHM and three
highest HAA5 LRAAs
1,000,000-4,999,999... per quarter........... 8 dual sample sets--at the
locations with the four
highest TTHM and four
highest HAA5 LRAAs.
>=5,000,000........... per quarter........... 10 dual sample sets--at the
locations with the five
highest TTHM and five
highest HAA5 LRAAs.
Ground Water:
< 500.................. every third year...... 1 TTHM and 1 HAA5 sample:
one at the location and
during the quarter with
the highest TTHM single
measurement, one at the
location and during the
quarter with the highest
HAA5 single measurement; 1
dual sample set per year
if the highest TTHM and
HAA5 measurements occurred
at the same location and
quarter.
500-9,999............. per year.............. 1 TTHM and 1 HAA5 sample:
one at the location and
during the quarter with
the highest TTHM single
measurement, one at the
location and during the
quarter with the highest
HAA5 single measurement; 1
dual sample set per year
if the highest TTHM and
HAA5 measurements occurred
at the same location and
quarter.
10,000-99,999......... per year.............. 2 dual sample sets: one at
the location and during
the quarter with the
highest TTHM single
measurement, one at the
location and during the
quarter with the highest
HAA5 single measurement.
100,000-499,999....... per quarter........... 2 dual sample sets; at the
locations with the highest
TTHM and highest HAA5
LRAAs.
>=500,000............. per quarter........... 4 dual sample sets at the
locations with the two
highest TTHM and two
highest HAA5 LRAAs.
----------------------------------------------------------------------------------------------------------------
1 Systems on quarterly monitoring must take dual sample sets every 90 days.
ii. Compliance determination. A PWS is in compliance when the
annual sample or LRAA of quarterly samples is less than or equal to the
MCLs. If an annual sample exceeds the MCL, the system must conduct
increased (quarterly) monitoring but is not immediately in violation of
the MCL. The system is out of compliance if the LRAA of the quarterly
samples for the past four quarters exceeds the MCL.
Monitoring and MCL violations are assigned to the PWS where the
violation occurred. Several examples are as follows:
? If monitoring results in a consecutive system indicate an
MCL violation, the consecutive system is in violation because it has
the legal responsibility for complying with the MCL under State/EPA
regulations. The consecutive system may set up a contract with its
wholesale system that details water quality delivery specifications.
? If a consecutive system has hired its wholesale system
under contract to monitor in the consecutive system and the wholesale
system fails to monitor, the consecutive system is in violation because
it has the legal responsibility for monitoring under State/EPA regulations.
? If a wholesale system has a violation and provides that
water to a consecutive system, the wholesale system is in violation.
Whether the consecutive system is in violation will depend on the
situation. The consecutive system will also be in violation unless it
conducted monitoring that showed that the violation was not present in
the consecutive system.
2. Background and Analysis
EPA proposed the plant-based approach for all systems that produce
some or all of their finished water and the population-based monitoring
approach for systems purchasing all of their finished water year-round.
As part of the proposal, EPA presented a monitoring cost analysis for
applying this approach to all systems in the Economic Analysis to
better understand the impacts of using the population-based approach.
The plant-based approach was adopted from the 1979 TTHM rule and
the Stage 1 DBPR and was derived from the generally valid assumption
that, as systems increase in size, they tend to have more plants and
increased complexity. During the development of the Stage 2 proposal,
EPA identified a number of issues associated with the use of the plant-
based monitoring approach. These included: (1) Plant-based monitoring
is not as effective as population-based monitoring in targeting
locations with the highest risk; (2) a plant-based approach can result
in disproportionate monitoring requirements for systems serving the
same number of people (due to widely varying numbers of plants per
system); (3) it cannot be adequately applied to plants or consecutive
system entry points that are operated seasonally or intermittently if
an LRAA is used for compliance due to complex implementation and a need
for repeated transactions between the State and
[[Page 429]]
system to determine whether and how compliance monitoring requirements
may need to be changed; (4) State determinations of monitoring
requirements for consecutive systems would be complicated, especially
in large combined distribution systems with many connections between
systems; and (5) systems with multiple disinfecting wells would have to
conduct evaluation of common aquifers in order to avoid taking
unnecessary samples for compliance (if they did not conduct such
evaluations under Stage 1). EPA requested comment on two approaches to
address these issues: (1) keep the plant-based monitoring approach and
add new provisions to address specific concerns; and (2) base
monitoring requirements on source water type and population served, in
lieu of plant-based monitoring.
The final rule's requirements of population-based monitoring for
all systems are based on improved public health protection,
flexibility, and simplified implementation. For determining monitoring
requirements, EPA's objective was to maintain monitoring loads
consistent with Stage 1 and similar to monitoring loads proposed for
Stage 2 under a plant-based approach, using a population-based approach
to facilitate implementation, better target high DBP levels, and
protect human health. This leads to a more cost-effective
characterization of where high levels occur. For the proposed rule, EPA
used 1995 CWSS data to derive the number of plants per system for
calculating the number of proposed monitoring sites per system. During
the comment period, 2000 CWSS data became available. Compared to the
1995 CWSS, the 2000 CWSS contained questions more relevant for
determining the number of plants in each system. Based on 2000 CWSS
data, EPA has modified the number of monitoring sites per system for
several categories (particularly for the larger subpart H systems) to
align the median population-based monitoring requirements with the median
monitoring requirements under plant-based monitoring, as was proposed.
EPA also believes that more samples are necessary to characterize
larger systems (as defined by population) than for smaller systems.
This progressive approach is included in Table IV.G-4. As system size
increases, the number of samples increases to better reflect the
hydraulic complexity of these systems. While the national monitoring
burden under the population-based approach is slightly less than under
a plant-based approach, some larger systems with few plants relative to
system population will take more samples per system than they had under
plant-based monitoring. However, EPA believes that many of these large
systems with few plants have traditionally been undermonitored (as
noted in the proposal). Systems with more plants will see a reduction
in monitoring (e.g., small ground water systems with multiple wells).
While population-based monitoring requirements for ground water
systems in today's rule remain the same as those in the proposed rule,
the final rule consolidates ten population categories for subpart H
systems into eight categories for ease of implementation. As indicated
in Table IV.G-4, EPA has gone from four to three population size
categories for smaller subpart H systems (serving fewer than 10,000
people) and the ranges have been modified to be consistent with those
for other existing rules (such as the Lead and Copper Rule). This
change will reduce implementation transactional costs. For medium and
large subpart H systems (serving at least 10,000 people), EPA has gone
from seven categories in the proposal to five categories in final rule.
The population groups are sized so that the ratio of maximum population
to minimum population for each of the categories is consistent. EPA
believes that this will allow most systems to remain in one population
size category and maintain the same monitoring requirements within a
reasonable range of population variation over time. In addition, it
assures that systems within a size category will not have disparate
monitoring burdens as could occur if there were too few categories.
Overall, EPA believes that the population-based monitoring approach
allows systems to have more flexibility to designate their monitoring
sites within the distribution system to better target high DBP levels
and is more equitable.
To derive the number of monitoring sites for IDSE standard
monitoring, EPA doubled the number of routine compliance monitoring
sites per system for each size category. This is consistent with the
advice and recommendations of the M-DBP Advisory Committee for the
IDSE. EPA has developed the Initial Distribution System Evaluation
Guidance Manual for the Final Stage 2 Disinfectants and Disinfection
Byproducts Rule (USEPA 2006) to assist systems in choosing IDSE
monitoring locations, including criteria for selecting monitoring.
Table IV.G-4.--Comparison of Monitoring Locations per System for Stage 2 Routine Compliance Monitoring with Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
Plant-based Number of plants per Calculated number of
approach* system (Based on 2000 sites per system for
Ratio of ------------- CWSS data) plant-based approach Number of
maximum Number of ---------------------------------------------------- monitoring
Population category population sampling Based on Based on sites per
to minimum periods per # median mean # system for
population year Sites per Median Mean # plants pop-based
plant plants per per system approach
system
........... A B C D E=B*C F=B*D G
-------------------------------------------------
< 500............................................ ........... 1 **1 1 1.21 1 1.2 **1
500-3,300....................................... 6.6 4 **1 1 1.22 1 1.2 **1
3,301-9,999..................................... 3 4 2 1 1.56 2 3.1 2
10,000-49,999................................... 5 4 4 1 1.37 4 5.5 4
50,000-249,999.................................. 5 4 4 1 1.83 4 7.3 8
250,000-< 1 million.............................. 4 4 4 2 2.53 8 10.1 12
1 million-< 5 million............................ 5 4 4 4 3.62 16 14.5 16
>=5 million..................................... ........... 4 4 4 4.33 16 17.3 20
--------------------------------------------------------------------------------------------------------------------------------------------------------
* As in the proposal.
** System is required to take individual TTHM and HAA5 samples at the locations with the highest TTHM and HAA5 concentrations, respectively, if highest
TTHM and HAA5 concentrations do not occur at the same location.
[[Page 430]]
Note: To determine the number of routine compliance monitoring sites per population category, EPA took these steps: (1) Maintaining about the same
sampling loads in the nation as required under the plant-based approach, but basing on population rather than number of plants to better target high
DBP levels in distribution systems and facilitate implementation; (2) The number of monitoring sites per plant under the plant-based approach (Column
B) were multiplied by the number of plants per system (Columns C and D) to calculate the number of monitoring sites per system under the plant-based
approach (Columns E and F in terms of median and mean, respectively); and (3) The number of monitoring sites per system under the population-based
approach were derived with adjustments to keep categories consistent and to maintain an even incremental trend as the population size category
increases (Column G).
3. Summary of Major Comments
EPA received significant support for applying the population-based
approach to all systems. EPA also received comments concerning the
specific requirements in a population-based approach.
Excessive Sampling Requirements. Several commenters believed that
the proposed sampling requirements were excessive (especially in the
larger population categories for subpart H systems) and that some
individual systems would be required to sample more under the
population-based approach than the plant-based approach. EPA recognizes
that a small fraction of systems in some categories will have to take
more samples under the population-based approach than the plant-based
approach because their number of plants is substantially less than the
national median or mean. However, the number of samples required under
the Stage 1 DBPR for these systems may not have been sufficient to
determine the concentrations of DBPs throughout the distribution system
of these systems. On the other hand, systems with many plants may have
taken excessive samples under the Stage 1 DBPR that were not necessary
to appropriately determine DBP levels throughout the distribution
system. Consequently, the total number of samples taken nationally will
be comparable to the Stage 1 DBPR, but will better target DBP risks in
individual distribution systems.
Consecutive systems. Some commenters noted that a consecutive
system may need to take more samples than its associated wholesale
system. Under today's rule, all systems, including consecutive systems,
must monitor based on retail population served. Thus, large consecutive
systems will take more samples than a smaller wholesale system. The
population-based monitoring approach will allow the samples to better
represent the DBP concentrations consumed by the population associated
with the sampling locations and to understand the DBP concentrations
reaching consumers. There is also a provision that allows States to
specify alternative monitoring requirements for a consecutive system in
a combined distribution system (40 CFR 142.16(m)(3)). This special
primacy condition allows the State to establish monitoring requirements
that account for complicated distribution system relationships, such as
where neighboring systems buy from and sell to each other regularly
throughout the year. In this case, water may pass through multiple
consecutive systems before it reaches a user. Another example would be
a large group of interconnected systems that have a complicated
combined distribution system. This approach also allows the combined
distribution system to concentrate IDSE and Stage 2 monitoring sites in
the system with the highest known DBP concentrations, while assigning
fewer sample sites to systems with low DBP concentrations.
Population Size Categories. Some commenters recommended fewer
population categories for subpart H systems (those using surface water
or ground water under the direct influence of surface water as a
source) than proposed while others recommended more. Today's rule has
fewer categories than proposed. However, EPA believes that further
reduction of the number of population size categories will not reflect
the fact that the number of plants and complexity of distribution
systems (and DBP exposure) tend to increase as the population served
increases. As a result, the population served by a large system in one
particular category would receive much less protection from the DBP
risks than a smaller system in the same size category. On the other
hand, too many categories with smaller population ranges would result
in frequent category and requirement shifts as population fluctuates.
Much greater implementation effort would be needed for those systems
without much benefit in DBP exposure knowledge.
Population Definition. Some commenters supported use of the
population of a combined distribution system (i.e., the wholesale and
consecutive systems should be considered a single system for monitoring
purposes) while others preferred use of the retail population for each
individual system (i.e., wholesale systems and consecutive systems are
considered separately). Today's final rule uses the retail population
for each individual system. EPA chose this approach for today's rule
because of the complexity involved in making implementation decisions
for consecutive systems. Using the retail population to determine
requirements eases the complexity by specifying minimum system-level
requirements; simplicity is essential for meeting the implementation
schedule in today's rule. If monitoring requirements were determined by
the combined distribution system population, many implementation
problems would occur. Some of these problems would have the potential
to impact public health protection. For example, States or primacy
agencies would have to decide how to allocate IDSE distribution system
samples (where and how much to monitor in individual PWSs) in a
complicated combined distribution system with many systems, multiple
sources, multiple treatment plants, and varying water demand and with
limited understanding of DBP levels throughout the combined
distribution system. This would have to happen shortly after rule
promulgation in order to meet the schedule. For example, some
consecutive systems buy water seasonally (in times of high water
demand) or buy from more than one wholesale system (with the volume
purchased based on many factors). The State or primacy agency would
find it difficult to properly assign a limited number of IDSE
monitoring locations (especially since there are States where many
consecutive systems have no DBP data) to adequately reflect DBP levels
in such a system, as well as throughout the combined distribution system.
EPA believes that assigning compliance monitoring requirements
appropriately throughout the combined distribution system requires a
case-by-case determination based on factors such as amount and
percentage of finished water provided; whether finished water is
provided seasonally, intermittently, or full-time; and improved DBP
occurrence information. Since the IDSE will provide improved DBP
occurrence information throughout the combined distribution system,
States may consider modifications to Stage 2 compliance monitoring
requirements for consecutive systems on a case-by-case basis as allowed
by Sec. 141.29 or under the special primacy condition at Sec.
142.16(m)(3) by taking all these factors into consideration. In making
these case-by-case determinations, the State will be able to use its
system-specific knowledge, along with the IDSE results, to develop an
appropriate monitoring plan for each
[[Page 431]]
system within the combined distribution system.
Changes to monitoring plans. Commenters requested more specific
language regarding how IDSE and Stage 2 monitoring plans should be
updated as a result of treatment or population changes in the
distribution system. Changes to IDSE plans should not be necessary
since the State or primacy agency will have reviewed those plans
shortly before the system must conduct the IDSE and the reviewed plan
should identify such issues. EPA provided a process in the Stage 2 DBPR
proposal for updating monitoring plans for systems that have
significant changes to treatment or in the distribution system after
they complete their IDSE. This process remains in today's rule, with an
added requirement that systems must consult with the State or primacy
agency to determine whether the changes are necessary and appropriate
prior to implementing changes to their Stage 2 monitoring plan.
In addition, the State or primacy agency may require a system to
revise its IDSE plan, IDSE report, or Stage 2 monitoring plan at any
time. This change was made so that systems could receive system-
specific guidance from the State or primacy agency on the appropriate
revisions to the Stage 2 monitoring plan. Regulatory language regarding
changes that might occur is not appropriate because any modifications
would be system-specific and a national requirement is not capable of
addressing these system-specific issues.
H. Operational Evaluation Requirements Initiated by TTHM and HAA5 Levels
A system that is in full compliance with the Stage 2 DBPR LRAA MCL
may still have individual DBP measurements that exceed the Stage 2 DBPR
MCLs, since compliance is based on individual DBP measurements at a
location averaged over a four-quarter period. EPA and the Advisory
Committee were concerned about these higher levels of DBPs. This
concern was clearly reflected in the Agreement in Principle, which
states, ``. . . significant excursions of DBP levels will sometimes
occur, even when systems are in full compliance with the enforceable
MCL. . .''.
Today's final rule addresses this concern by requiring systems to
conduct operational evaluations that are initiated by operational
evaluation levels identified in Stage 2 DBPR compliance monitoring and
to submit an operational evaluation report to the State.
1. Today's Rule
Today's rule defines the Stage 2 DBP operational evaluation levels
that require systems to conduct operational evaluations. The Stage 2
DBP operational evaluation levels are identified using the system's
Stage 2 DBPR compliance monitoring results. The operational evaluation
levels for each monitoring location are determined by the sum of the
two previous quarters' TTHM results plus twice the current quarter's
TTHM result, at that location, divided by 4 to determine an average and
the sum of the two previous quarters' HAA5 results plus twice the
current quarter's HAA5 result, at that location, divided by 4 to
determine an average. If the average TTHM exceeds 0.080 mg/L at any
monitoring location or the average HAA5 exceeds 0.060 mg/L at any
monitoring location, the system must conduct an operational evaluation
and submit a written report of the operational evaluation to the State.
Operational evaluation levels (calculated at each monitoring location)
IF (Q1 + Q2 + 2Q3)/4> MCL, then
the system must conduct an operational evaluation
where:
Q3 = current quarter measurement
Q2 = previoius quarter measurement
Q1 = quarter before previous quarter measurement
MCL = Stage 2 MCL for TTHM (0.080 mg/l) or Stage 2 MCL for HAA5
(0.060 mg/L)
The operational evaluation includes an examination of system
treatment and distribution operational practices, including changes in
sources or source water quality, storage tank operations, and excess
storage capacity, that may contribute to high TTHM and HAA5 formation.
Systems must also identify what steps could be considered to minimize
future operational evaluation level exceedences. In cases where the
system can identify the cause of DBP levels that resulted in the
operational evaluation, based on factors such as water quality data,
plant performance data, and distribution system configuration the
system may request and the State may allow limiting the evaluation to
the identified cause. The State must issue a written determination
approving limiting the scope of the operational evaluation. The system
must submit their operational evaluation report to the State for review
within 90 days after being notified of the analytical result that
initiates the operational evaluation. Requesting approval to limit the
scope of the operational evaluation does not extend the schedule (90
days after notification of the analytical result) for submitting the
operational evaluation report.
2. Background and Analysis
The Stage 2 DBPR proposal outlined three components of the
requirements for significant excursions (definition, system evaluation
and excursion report). In response to public comments, the term
``significant excursion'' has been replaced by the term ``operational
evaluation level'' in today's rule. The evaluation and report
components remain the same as those outlined in the proposed rule for
significant excursions. However, the scope of the evaluation and report
components of the operational evaluation has also been modified from
the proposed significant excursion evaluation components based on
public comments.
In the Stage 2 DBPR proposal, States were to define criteria to
identify significant excursions rather than using criteria defined by
EPA. Concurrent with the Stage 2 DBPR proposal, EPA issued draft
guidance (USEPA 2003e) for systems and States that described how to
determine whether a significant excursion has occurred, using several
different options. The rule proposal specifically requested public
comment on the definition of a significant excursion, whether it should
be defined by the State or nationally, and the scope of the evaluation.
After reviewing comments on the Stage 2 DBPR proposal, EPA
determined that DBP levels initiating an operational evaluation should
be defined in the regulation to ensure national consistency. Systems
were concerned with the evaluation requirements being initiated based
on criteria that might not be consistent nationally. Also, many States
believed the requirement for States to define criteria to initiate an
evaluation would be difficult for States to implement.
Under today's rule, EPA is defining operational evaluation levels
with an algorithm based on Stage 2 DBPR compliance monitoring results.
These operational evaluation levels will act as an early warning for a
possible MCL violation in the following quarter. This early warning is
accomplished because the operational evaluation requirement is
initiated when the system assumes that the current quarter's result is
repeated and this will result in an MCL violation. This early
identification allows the system to act to prevent the violation.
Today's rule also modifies the scope of an operational evaluation.
EPA has concluded that the source of DBP levels
[[Page 432]]
that would initiate an operational evaluation can potentially be linked
to a number of factors that extend beyond distribution system
operations. Therefore, EPA believes that evaluations must include a
consideration of treatment plant and other system operations rather
than limiting the operational evaluation to only the distribution
system, as proposed. Because the source of the problem could be
associated with operations in any of these system components (or more
than one), an evaluation that provides systems with valuable
information to evaluate possible modifications to current operational
practices (e.g. water age management, source blending) or in planning
system modifications or improvements (e.g. disinfection practices, tank
modifications, distribution looping) will reduce DBP levels initiating
an operational evaluation. EPA also believes that State review of
operational evaluation reports is valuable for both States and systems
in their interactions, particularly when systems may be in discussions
with or requesting approvals from the State for system improvements.
Timely reviews of operational evaluation reports will be valuable for
States in reviewing other compliance submittals and will be
particularly valuable in reviewing and approving any proposed source,
treatment or distribution system modifications for a water system.
Under today's rule, systems must submit a written report of the
operational evaluation to the State no later than 90 days after being
notified of the DBP analytical result initiating an operational
evaluation. The written operational evaluation report must also be made
available to the public upon request.
3. Summary of Major Comments
EPA received comments both in favor of and opposed to the proposed
evaluation requirements. While some commenters felt that the evaluation
requirements should not be a part of the Stage 2 DBPR until there was
more information regarding potential health effects correlated to
specific DBP levels, other commenters felt that the existing health
effects data were sufficient to warrant strengthening the proposed
requirements for an evaluation. Today's final rule requirements are
consistent with the Agreement in Principle recommendations.
Some commenters noted that health effects research on DBPs is
insufficient to identify a level at which health effects occur and were
concerned that the proposed significant excursion requirements placed
an emphasis on DBP levels that might not be warranted rather than on
system operational issues and compliance with Stage 2 DBPR MCLs.
Basis. The proposed requirements for significant excursion
evaluations were not based upon health effects, but rather were
intended to be an indicator of operational performance. To address
commenter's concerns and to emphasize what EPA believes should initiate
a comprehensive evaluation of system operations that may result in
elevated DBP levels and provide a proactive procedure to address
compliance with Stage 2 DBP LRAA MCLs , EPA has replaced the term
``significant excursion'' used in the Stage 2 DBPR proposal with the
term ``operational evaluation level'' in today's rule.
Definition of the operational evaluation levels. The majority of
commenters stated that EPA should define the DBP levels initiating an
operational evaluation (``significant excursion'' in the proposal) in
the regulation to ensure national consistency rather than requiring
States to develop their own criteria (as was proposed). Commenters
suggested several definitions, including a single numerical limit and
calculations comparing previous quarterly DBP results to the current
quarter's result. Commenters that recommended a single numerical limit
felt that such an approach was justified by the available health
effects information, while other commenters felt available heath
effects information did not support a single numerical limit.
Commenters recommended that any definition be easy to understand and
implement.
EPA agrees with commenter preference for national criteria to
initiate an operational evaluation. The DBP levels initiating an
operational evaluation in today's rule consider routine operational
variations in distribution systems, are simple for water systems to
calculate, and minimize the implementation burden on States. They also
provide an early warning to help identify possible future MCL
violations and allow the system to take proactive steps to remain in
compliance. EPA emphasizes, as it did in the proposal and elsewhere in
this notice, that health effects research is insufficient to identify a
level at which health effects occur, and thus today's methodology for
initiating operational evaluation is not based upon health effects, but
rather is intended as an indicator of operational performance.
Scope of an evaluation. Some commenters felt that the scope of an
evaluation initiated by locational DBP levels should be limited to the
distribution systems, as in the proposal. Others felt that the
treatment processes should be included in the evaluation, noting that
these can be significant in the formation of DBPs.
The Agency agrees with commenters that treatment processes can be a
significant factor in DBP levels initiating an operational evaluation
and that a comprehensive operational evaluation should address
treatment processes. In cases where the system can clearly identify the
cause of the DBP levels initiating an operational evaluation (based on
factors such as water quality data, plant performance data,
distribution system configuration, and previous evaluations) the State
may allow the system to limit the scope of the evaluation to the
identified cause. In other cases, it is appropriate to evaluate the
entire system, from source through treatment to distribution system
configuration and operational practices.
Timing for completion and review of the evaluation report. While
some commenters agreed that the evaluation report should be reviewed as
part of the sanitary survey process (as proposed), many commenters felt
that the time between sanitary surveys (up to five years) minimized the
value of the evaluation report in identifying both the causes of DBP
levels initiating an operational evaluation and in possible changes to
prevent recurrence. Moreover, a number of commenters felt that the
evaluation report was important enough to warrant a separate submittal
and State review rather than have the evaluation report compete with
other priorities during a sanitary survey.
The Agency agrees that completion and State review of evaluation
reports on a three or five year sanitary survey cycle, when the focus
of the evaluation is on what may happen in the next quarter, would
allow for an unreasonable period of time to pass between the event
initiating the operational evaluation and completion and State review
of the report. This would diminish the value of the evaluation report
for both systems and States, particularly when systems may be in
discussions with or requesting approval for treatment changes from
States, and as noted above, the focus of the report is on what may
occur in the next quarter. EPA believes that timely reviews of
evaluation reports by States is important, would be essential for
States in understanding system operations and reviewing other
compliance submittals, and would be extremely valuable in reviewing and
approving any proposed source, treatment or distribution system
modifications for a water system.
[[Page 433]]
Having the evaluation information on an ongoing basis rather than a
delayed basis would also allow States to prioritize their resources in
scheduling and reviewing particular water system operations and
conditions as part of any on-site system review or oversight.
Therefore, today's rule requires that systems complete the operational
evaluation and submit the evaluation report to the State within 90 days
of the occurrence.
I. MCL, BAT, and Monitoring for Bromate
1. Today's Rule
Today EPA is confirming that the MCL for bromate for systems using
ozone remains at 0.010 mg/L as an RAA for samples taken at the entrance
to the distribution system as established by the Stage 1 DBPR. Because
the MCL remains the same, EPA is not modifying the existing bromate
BAT. EPA is changing the criterion for a system using ozone to qualify
for reduced bromate monitoring from demonstrating low levels of bromide
to demonstrating low levels of bromate.
2. Background and Analysis
a. Bromate MCL. Bromate is a principal byproduct from ozonation of
bromide-containing source waters. As described in more detail in the
Stage 2 DBPR proposal (USEPA 2003a), more stringent bromate MCL has the
potential to decrease current levels of microbial protection, impair
the ability of systems to control resistant pathogens like
Cryptosporidium, and increase levels of DBPs from other disinfectants
that may be used instead of ozone. EPA considered reducing the bromate
MCL from 0.010 mg/L to 0.005 mg/L as an annual average but concluded
that many systems using ozone to inactivate microbial pathogens would
have significant difficulty maintaining bromate levels at or below
0.005 mg/L. In addition, because of the high doses required, the
ability of systems to use ozone to meet Cryptosporidium treatment
requirements under the LT2ESWTR would be diminished if the bromate MCL
was decreased from 0.010 to 0.005 mg/L; higher doses will generally
lead to greater bromate formation. After evaluation under the risk-
balancing provisions of section 1412(b)(5) of the SDWA, EPA concluded
that the existing MCL was justified. EPA will review the bromate MCL as
part of the six-year review process and determine whether the MCL
should remain at 0.010 mg/L or be reduced to a lower level. As a part
of that review, EPA will consider the increased utilization of
alternative technologies, such as UV, and whether the risk/risk concerns
reflected in today's rule, as well as in the LT2ESWTR, remain valid.
b. Criterion for reduced bromate monitoring. Because more sensitive
bromate methods are now available, EPA is requiring a new criterion for
reduced bromate monitoring. In the Stage 1 DBPR, EPA required ozone
systems to demonstrate that source water bromide levels, as a running
annual average, did not exceed 0.05 mg/L. EPA elected to use bromide as
a surrogate for bromate in determining eligibility for reduced
monitoring because the available analytical method for bromate was not
sensitive enough to quantify levels well below the bromate MCL of 0.010
mg/L.
EPA approved several new analytical methods for bromate that are
far more sensitive than the existing method as part of today's rule.
Since these methods can measure bromate to levels of 0.001 mg/L or
lower, EPA is replacing the criterion for reduced bromate monitoring
(source water bromide running annual average not to exceed 0.05 mg/L)
with a bromate running annual average not to exceed 0.0025 mg/L.
In the past, EPA has often set the criterion for reduced monitoring
eligibility at 50% of the MCL, which would be 0.005 mg/L. However, the
MCL for bromate will remain at 0.010 mg/L, representing a risk level of
2x10/b 2x10-4, 10-4 and 10-6 (higher
than EPA's usual excess cancer risk range of 10-4 to
10-6) because of risk tradeoff considerations) (USEPA 2003a).
EPA believes that the decision for reduced monitoring is separate
from these risk tradeoff considerations. Risk tradeoff considerations
influence the selection of the MCL, while reduced monitoring
requirements are designed to ensure that the MCL, once established, is
reliably and consistently achieved. Requiring a running annual average
of 0.0025 mg/L for the reduced monitoring criterion allows greater
confidence that the system is achieving the MCL and thus ensuring
public health protection.
3. Summary of Major Comments
Commenters supported both the retention of the existing bromate MCL
and the modified reduced monitoring criterion.
J. Public Notice Requirements
1. Today's Rule
Today's rule does not alter existing public notification language
for TTHM, HAA5 or TOC, which are listed under 40 CFR 141.201-141.210
(Subpart Q).
2. Background and Analysis
EPA requested comment on including language in the proposed rule
concerning potential reproductive and developmental health effects. EPA
believes this is an important issue because of the large population
exposed (58 million women of child-bearing age; USEPA 2005a) and the
number of studies that, while not conclusive, point towards a potential
risk concern. While EPA is not including information about reproductive
and developmental health effects in public notices at this time, the
Agency plans to reconsider whether to include this information in the
future. As part of this effort, EPA intends to support research to
assess communication strategies on how to best provide this information.
The responsibilities for public notification and consumer
confidence reports rest with the individual system. Under the Public
Notice Rule (Part 141 subpart Q) and Consumer Confidence Report Rule
(Part 141 subpart O), the wholesale system is responsible for notifying
the consecutive system of analytical results and violations related to
monitoring conducted by the wholesale system. Consecutive systems are
required to conduct appropriate public notification after a violation
(whether in the wholesale system or the consecutive system). In their
consumer confidence report, consecutive systems must include results of
the testing conducted by the wholesale system unless the consecutive
system conducted equivalent testing (as required in today's rule) that
indicated the consecutive system was in compliance, in which case the
consecutive system reports its own compliance monitoring results.
3. Summary of Major Comments
EPA requested and received many comments on the topic of including
public notification language regarding potential reproductive and
developmental effects. A number of comments called for including
reproductive and developmental health effects language to address the
potential health concerns that research has shown. Numerous comments
also opposed such language due to uncertainties in the underlying
science and the implications such language could have on public trust
of utilities.
EPA agrees on the importance of addressing possible reproductive
and developmental health risks. However, given the uncertainties in the
science and our lack of knowledge of how to best communicate undefined
risks, a general statement about reproductive
[[Page 434]]
and developmental health effects is premature at this time. The Agency
needs to understand how best to characterize and communicate these
risks and what to do to follow up any such communication. The public
deserves accurate, timely, relevant, and understandable communication.
The Agency will continue to follow up on this issue with additional
research, possibly including a project to work with stakeholders to
assess risk communication strategies.
Some comments also suggested leaving the choice of language up to
the water server. EPA believes that this strategy would cause undue
confusion to both the PWS and the public.
Commenters generally agreed that both wholesale and consecutive
systems that conduct monitoring be required to report their own
analytical results as part of their CCRs. One commenter requested
clarification of consecutive system public notification requirements
when there is a violation in the wholesale system but the consecutive
system data indicate that it meets DBP MCLs.
Although EPA requires consecutive systems to conduct appropriate
public notification of violations (whether in the wholesale or
consecutive system), there may be cases where the violation may only
affect an isolated portion of the distribution system. Under the public
notification rule, the State may allow systems to limit distribution of
the notice to the area that is out of compliance if the system can
demonstrate that the violation occurred in a part of the distribution
system that is ``physically or hydraulically isolated from other parts
of the distribution system.'' This provision remains in place. As for a
consecutive system whose wholesale system is in violation, the
consecutive system is not required to conduct public notification if
DBP levels in the consecutive system are in compliance.
K. Variances and Exemptions
1. Today's Rule
States may grant variances in accordance with sections 1415(a) and
1415(e) of the SDWA and EPA's regulations. States may grant exemptions
in accordance with section 1416(a) of the SDWA and EPA's regulations.
2. Background and Analysis
a. Variances. The SDWA provides for two types of variances--general
variances and small system variances. Under section 1415(a)(1)(A) of
the SDWA, a State that has primary enforcement responsibility
(primacy), or EPA as the primacy agency, may grant general variances
from MCLs to those public water systems of any size that cannot comply
with the MCLs because of characteristics of the raw water sources. The
primacy agency may grant general variances to a system on condition
that the system install the best technology, treatment techniques, or
other means that EPA finds available and based upon an evaluation
satisfactory to the State that indicates that alternative sources of
water are not reasonably available to the system. At the time this type
of variance is granted, the State must prescribe a compliance schedule
and may require the system to implement additional control measures.
Furthermore, before EPA or the State may grant a general variance, it
must find that the variance will not result in an unreasonable risk to
health (URTH) to the public served by the public water system. In
today's final rule, EPA is specifying BATs for general variances under
section 1415(a) (see section IV.D).
Section 1415(e) authorizes the primacy agency to issue variances to
small public water systems (those serving fewer than 10,000 people)
where the primacy agent determines (1) that the system cannot afford to
comply with an MCL or treatment technique and (2) that the terms of the
variances will ensure adequate protection of human health (63 FR 43833,
August 14, 1998) (USEPA 1998c). These variances may only be granted
where EPA has determined that there is no affordable compliance
technology and has identified a small system variance technology under
section 1412(b)(15) for the contaminant, system size and source water
quality in question. As discussed below, small system variances under
section 1415(e) are not available because EPA has determined that
affordable compliance technologies are available.
The 1996 Amendments to the SDWA identify three categories of small
public water systems that need to be addressed: (1) Those serving a
population of 3301-10,000; (2) those serving a population of 500-3300;
and (3) those serving a population of 25-499. The SDWA requires EPA to
make determinations of available compliance technologies for each size
category. A compliance technology is a technology that is affordable
and that achieves compliance with the MCL and/or treatment technique.
Compliance technologies can include point-of-entry or point-of-use
treatment units. Variance technologies are only specified for those
system size/source water quality combinations for which there are no
listed affordable compliance technologies.
Using its current National Affordability Criteria, EPA has
determined that multiple affordable compliance technologies are
available for each of the three system sizes (USEPA 2005a), and
therefore did not identify any variance treatment technologies. The
analysis was consistent with the current methodology used in the
document ``National-Level Affordability Criteria Under the 1996
Amendments to the Safe Drinking Water Act'' (USEPA 1998d) and the
``Variance Technology Findings for Contaminants Regulated Before 1996''
(USEPA 1998e). However, EPA is currently reevaluating its national-
level affordability criteria and has solicited recommendations from
both the NDWAC and the SAB as part of this review. EPA intends to apply
the revised criteria to the Stage 2 DBPR once they have been finalized
for the purpose of determining whether to enable States to give
variances. Thus, while the analysis of Stage 2 household costs will not
change, EPA's determination regarding the availability of affordable
compliance technologies for the different categories of small systems may.
b. Affordable Treatment Technologies for Small Systems. The
treatment trains considered and predicted to be used in EPA's
compliance forecast for systems serving under 10,000 people, are listed
in Table IV.K-1.
Table IV.K-1.--Technologies Considered and Predicted To Be Used in
Compliance Forecast for Small Systems
------------------------------------------------------------------------
SW Water Plants GW Water Plants
------------------------------------------------------------------------
? Switching to chloramines as a ? Switching to
residual disinfectant. chloramines as a residual
disinfectant
? Chlorine dioxide (not for ? UV
systems serving fewer than 100 people).
? UV............................ ? Ozone (not for systems
serving fewer than 100 people)
? Ozone (not for systems serving ? GAC20
fewer than 100 people).
? Micro-filtration/Ultra- ? Nanofiltration
filtration.
[[Page 435]]
? GAC20.........................
? GAC20 + Advanced disinfectants
? Integrated Membranes..........
------------------------------------------------------------------------
Note: Italicized technologies are those predicted to be used in the
compliance forecast.
Source: Exhibits 5.11b and 5.14b, USEPA 2005a.
The household costs for these technologies were compared against
the EPA's current national-level affordability criteria to determine
the affordable treatment technologies. The Agency's national level
affordability criteria were published in the August 6, 1998 Federal
Register (USEPA 1998d). A complete description of how this analysis was
applied to Stage 2 DBPR is given in Section 8.3 of the Economic
Analysis (USEPA 2005a).
Of the technologies listed in Table IV.K-1, integrated membranes
with chloramines, GAC20 with advanced oxidants, and ozone are above the
affordability threshold in the 0 to 500 category. No treatment
technologies are above the affordability threshold in the 500 to 3,300
category or the 3,300 to 10,000 category. As shown in the Economic
Analysis for systems serving fewer than 500 people, 14 systems are
predicted to use GAC20 with advanced disinfectants, one system is
predicted to use integrated membranes, and no systems are predicted to
use ozone to comply with the Stage 2 DBPR (USEPA 2005a). However,
several alternate technologies are affordable and likely available to
these systems. In some cases, the compliance data for these systems
under the Stage 2 DBPR will be the same as under the Stage 1 DBPR
(because many systems serving fewer than 500 people will have the same
single sampling site under both rules); these systems will have already
installed the necessary compliance technology to comply with the Stage
1 DBPR. It is also possible that less costly technologies such as those
for which percentage use caps were set in the decision tree may
actually be used to achieve compliance (e.g., chloramines, UV). Thus,
EPA believes that compliance by these systems will be affordable.
As shown in Table IV.K-2, the cost model predicts that some
households served by very small systems will experience household cost
increases greater than the available expenditure margins as a result of
adding advanced technology for the Stage 2 DBPR (USEPA 2005a). This
prediction may be overestimated because small systems may have other
compliance alternatives available to them besides adding treatment,
which were not considered in the model. For example, some of these
systems currently may be operated on a part-time basis; therefore, they
may be able to modify the current operational schedule or use excessive
capacity to avoid installing a costly technology to comply with the
Stage 2 DBPR. The system also may identify another water source that
has lower TTHM and HAA5 precursor levels. Systems that can identify
such an alternate water source may not have to treat that new source
water as intensely as their current source, resulting in lower
treatment costs. Systems may elect to connect to a neighboring water
system. While connecting to another system may not be feasible for some
remote systems, EPA estimates that more than 22 percent of all small
water systems are located within metropolitan regions (USEPA 2000f)
where distances between neighboring systems will not present a
prohibitive barrier. Low-cost alternatives to reduce total
trihalomethanes (TTHM) and haloacetic acid (HAA5) levels also include
distribution system modifications such as flushing distribution mains
more frequently, looping to prevent dead ends, and optimizing storage
to minimize retention time. More discussion of household cost increases
is presented in Section VI.E and the Economic Analysis (USEPA 2005a).
Table IV.K-2.--Distribution of Household Unit Treatment Costs for Plants Adding Treatment
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Number of
households Number of Number of Number of Total
served by households surface groundwater number of
plants 90th 95th with annual water plants with plants with
adding Mean annual Median Percentile Percentile Available cost plants with annual cost annual cost
treatment household annual annual annual expenditure increases annual cost increases increases
Systems size (population seved) (Percent of cost household household household margin ($/ greater increases greater greater
all increase cost cost cost hh/yr) than the greater than the than the
households increase increase increase available than the available available
subject to expenditure available expenditure expenditure
the Stage 2 margin expenditure margin margin
DBPR) margin
A B C D E F G H I J = H + I
---------------------------------------------------------------
0-500......................................................... 43045(3) $201.55 $299.01 $299.01 $414.74 $733 964 15 0 15
501-3,300..................................................... 205842 (4) $58.41 $29.96 $75.09 $366.53 $724 0 9 0 0
3,301-10,000.................................................. 342525 (5) $37.05 $14.59 $55.25 $200.05 $750 0 0 0 0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Household unit costs represent treatment costs only. All values in year 2003 dollars.
Source: Exhibit 8.4c, USEPA 2005a.
c. Exemptions. Under section 1416(a), EPA or a State that has
primary enforcement responsibility (primacy) may exempt a public water
system from any requirements related to an MCL or treatment technique
of an NPDWR, if it finds that (1) due to compelling factors (which may
include economic factors such as qualification of the PWS as serving a
disadvantaged community), the PWS is unable to comply with the
requirement or implement measures to develop an alternative source of
water supply; (2) the exemption will not result in an unreasonable risk
to health; and; (3) the PWS was in operation on the effective date of
the NPDWR, or for a system that was not in operation by that date, only
if no reasonable alternative source of drinking water is available to
the new system; and (4) management or restructuring changes (or both)
cannot reasonably result in compliance with the Act or improve the
quality of
[[Page 436]]
drinking water. If EPA or the State grants an exemption to a public
water system, it must at the same time prescribe a schedule for
compliance (including increments of progress or measures to develop an
alternative source of water supply) and implementation of appropriate
control measures that the State requires the system to meet while the
exemption is in effect. Under section 1416(b)(2)(A), the schedule
prescribed shall require compliance as expeditiously as practicable (to
be determined by the State), but no later than 3 years after the
effective date for the regulations established pursuant to section
1412(b)(10). For public water systems which do not serve more than a
population of 3,300 and which need financial assistance for the
necessary improvements, EPA or the State may renew an exemption for one
or more additional two-year periods, but not to exceed a total of 6
years, if the system establishes that it is taking all practicable
steps to meet the requirements above. A public water system shall not
be granted an exemption unless it can establish that either: (1) the
system cannot meet the standard without capital improvements that
cannot be completed prior to the date established pursuant to section
1412(b)(10); (2) in the case of a system that needs financial
assistance for the necessary implementation, the system has entered
into an agreement to obtain financial assistance pursuant to section
1452 or any other Federal or state program; or (3) the system has
entered into an enforceable agreement to become part of a regional
public water system.
3. Summary of Major Comments
Several commenters agreed with the proposal not to list variances
technologies for the Stage 2 DBPR. One commenter requested that EPA
modify the methodology used to assess affordability. As mentioned
earlier, EPA is currently reevaluating its national-level affordability
criteria and has solicited recommendations from both the NDWAC and the
SAB as part of this review. EPA intends to apply the revised criteria
to the Stage 2 DBPR for the purpose of determining whether to enable
States to give variances.
L. Requirements for Systems to Use Qualified Operators
EPA believes that systems that must make treatment changes to
comply with requirements to reduce microbiological risks and risks from
disinfectants and disinfection byproducts should be operated by
personnel who are qualified to recognize and respond to problems.
Subpart H systems were required to be operated by qualified operators
under the SWTR (Sec. 141.70). The Stage 1 DBPR added requirements for
all disinfected systems to be operated by qualified personnel who meet
the requirements specified by the State, which may differ based on
system size and type. The rule also requires that States maintain a
register of qualified operators (40 CFR 141.130(c)). While the Stage 2
DBPR requirements do not supercede or modify the requirement that
disinfected systems be operated by qualified operators, such personnel
play an important role in delivering drinking water that meets Stage 2
MCLs to the public. States should also review and modify, as required,
their qualification standards to take into account new technologies
(e.g., ultraviolet (UV) disinfection) and new compliance requirements
(including simultaneous compliance and consecutive system
requirements). EPA received only one comment on this topic; the
commenter supported the need for a qualified operator.
M. System Reporting and Recordkeeping Requirements
1. Today's Rule
Today's Stage 2 DBPR, consistent with the existing system reporting
and recordkeeping regulations under 40 CFR 141.134 (Stage 1 DBPR),
requires public water systems (including consecutive systems) to report
monitoring data to States within ten days after the end of the
compliance period. In addition, systems are required to submit the data
required in Sec. 141.134. These data are required to be submitted
quarterly for any monitoring conducted quarterly or more frequently,
and within ten days of the end of the monitoring period for less
frequent monitoring. As with other chemical analysis data, the system
must keep the results for 10 years.
In addition to the existing Stage 1 reporting requirements, today's
rule requires systems to perform specific IDSE-related reporting to the
primacy agency, except for systems serving fewer than 500 for which the
State or primacy agency has waived this requirement. Required reporting
includes submission of IDSE monitoring plans, 40/30 certification, and
IDSE reports. This reporting must be accomplished on the schedule
specified in the rule (see Sec. 141.600(c)) and discussed in section
IV.E of today's preamble. System submissions must include the elements
identified in subpart U and discussed further in section IV.F of
today's preamble. These elements include recommended Stage 2 compliance
monitoring sites as part of the IDSE report.
Systems must report compliance with Stage 2 TTHM and HAA5 MCLs
(0.080 mg/LTTHM and 0.060 mg/L HAA5, as LRAAs) according to the
schedules specified in Sec. Sec. 141.620 and 141.629 and discussed in
section IV.E of today's preamble. Reporting for DBP monitoring, as
described previously, will remain generally consistent with current
public water system reporting requirements (Sec. 141.31 and Sec.
141.134); systems will be required to calculate and report each LRAA
(instead of the system's RAA) and each individual monitoring result (as
required under the Stage 1 DBPR). Systems will also be required to
provide a report to the State about each operational evaluation within
90 days, as discussed in section IV.H. Reports and evaluations must be
kept for 10 years and may prove valuable in identifying trends and
recurring issues.
2. Summary of Major Comments
EPA requested comment on all system reporting and recordkeeping
requirements. Commenters generally supported EPA's proposed
requirements, but expressed concern about two specific issues. The
first issue was the data management and tracking difficulties that
States would face if EPA finalized a monitoring approach which had both
plant-based and population-based requirements, as was proposed. Since
today's rule contains only population-based monitoring requirements,
this concern is no longer an issue. See section IV.G in today's
preamble for further discussion.
The second concern related to reporting associated with the IDSE.
Commenters who supported an approach other than the IDSE for
determining Stage 2 compliance monitoring locations did not support
IDSE-related reporting. The IDSE remains a key component of the final
rule; thus, EPA has retained IDSE-related reporting. However, the
Agency has modified both the content and the timing of the reporting to
reduce the burden. See sections IV.F and IV.E, respectively, of today's
preamble for further discussion.
N. Approval of Additional Analytical Methods
1. Today's Rule
EPA is taking final action to:
(1) allow the use of 13 methods published by the Standard Methods
Committee in Standard Methods for the Examination of Water and
Wastewater,
[[Continued on page 437]]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]]
[[pp. 437-486]]
National Primary Drinking Water Regulations: Stage 2
Disinfectants and Disinfection Byproducts Rule
[[Continued from page 436]]
[[Page 437]]
20th edition, 1998 (APHA 1998) and 12 methods in Standard Methods Online.
(2) approve three methods published by American Society for Testing
and Materials International.
(3) approve EPA Method 327.0 Revision 1.1 (USEPA 2005h) for daily
monitoring of chlorine dioxide and chlorite, EPA Method 552.3 (USEPA
2003f) for haloacetic acids (five) (HAA5), EPA Methods 317.0 Revision 2
(USEPA 2001c) and 326.0 (USEPA 2002) for bromate, chlorite, and
bromide, EPA Method 321.8 (USEPA 2000g) for bromate only, and EPA
Method 415.3 Revision 1.1 (USEPA 2005l) for total organic carbon (TOC)
and specific ultraviolet absorbance (SUVA).
(4) update the citation for EPA Method 300.1 (USEPA 2000h) for
bromate, chlorite, and bromide.
(5) standardize the HAA5 sample holding times and the bromate
sample preservation procedure and holding time.
(6) add the requirement to remove inorganic carbon prior to
determining TOC or DOC, remove the specification of type of acid used
for TOC/DOC sample preservation; and require that TOC samples be
preserved at the time of collection.
(7) clarify which methods are approved for magnesium hardness
determinations (40 CFR 141.131 and 141.135).
2. Background and Analysis
The Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1
DBPR) was promulgated on December 16, 1998 (USEPA 1998a) and it
included approved analytical methods for DBPs, disinfectants, and DBP
precursors. Additional analytical methods became available subsequent
to the rule and were proposed in the Stage 2 Disinfectants and
Disinfection Byproducts Rule (Stage 2 DBPR) (USEPA 2003a). These
methods are applicable to monitoring that is required under the Stage 1
DBPR. After the Stage 2 DBPR proposal, analytical methods for
additional drinking water contaminants were proposed for approval in a
Methods Update Rule proposal (USEPA 2004). The Stage 2 DBPR and Methods
Update Rule proposals both included changes in the same sections of the
CFR. EPA decided to make all the changes to Sec. 141.131 as part of
the Stage 2 DBPR and the remainder of the methods that were proposed
with the Stage 2 DBPR will be considered as part of the Methods Update
Rule, which will be finalized at a later date. Two ASTM methods, D
1253-86(96) and D 1253-03, that were proposed in the Methods Update
Rule, are being approved for measuring chlorine residual as part of
today's action.
Minor corrections have been made in two of the methods that were
proposed in the Stage 2 DBPR. In today's rule, the Agency is approving
EPA Method 327.0 (Revision 1.1, 2005) which corrects three
typographical errors in the proposed method.
EPA is also approving EPA Method 415.3 (Revision 1.1, 2005), which
does not contain the requirement that samples for the analysis of TOC
must be received within 48 hours of sample collection.
A summary of the methods that are included in today's rule is
presented in Table IV.N-1.
Table IV.N-1. Analytical Methods Approved in Today's Rule
----------------------------------------------------------------------------------------------------------------
Standard methods Standard methods
Analyte EPA method 20th edition online Other
----------------------------------------------------------------------------------------------------------------
Sec. 141.131--Disinfection Byproducts
----------------------------------------------------------------------------------------------------------------
HAA5............................ 552.3............. 6251 B............ 6251 B-94......... ..................
Bromate......................... 317.0, Revision .................. .................. ASTM D 6581-00
2.0.
321.8.............
326.0.............
Chlorite (monthly or daily)..... 317.0, Revision .................. .................. ASTM D 6581-00
2.0.
326.0.............
Chlorite (daily)................ 327.0, Revision 4500-ClO2 E....... 4500-ClO2 E-00.... ..................
1.1.
---------------------------------
Sec. 141.131--Disinfectants
----------------------------------------------------------------------------------------------------------------
Chlorine (free, combined, total) .................. 4500-Cl D......... 4500-Cl D-00...... ASTM D 1253-86(96)
4500-Cl F......... 4500-Cl F-00...... ASTM D 1253-03
4500-Cl G......... 4500-Cl G-00......
Chlorine (total)................ .................. 4500-Cl E......... 4500-Cl E-00...... ..................
4500-Cl I......... 4500-Cl I-00......
Chlorine (free)................. .................. 4500-Cl H......... 4500-Cl H-00...... ..................
Chlorine Dioxide................ 327.0, Revision 4500-ClO2 D....... 4500-ClO2 E-00.... ..................
1.1. 4500-ClO2 E.......
---------------------------------
Sec. 141.131--Other parameters
----------------------------------------------------------------------------------------------------------------
Bromide......................... 317.0, Revision .................. .................. ASTM D 6581-00
2.0.
326.0.............
TOC/DOC......................... 415.3, Revision 5310 B............ 5310 B-00......... ..................
1.1. 5310 C............ 5310 C-00.........
5310 D............ 5310 D-00.........
UV254........................... 415.3, Revision 5910 B............ 5910 B-00......... ..................
1.1.
SUVA............................ 415.3, Revision .................. .................. ..................
1.1.
----------------------------------------------------------------------------------------------------------------
[[Page 438]]
O. Laboratory Certification and Approval
1. PE Acceptance Criteria
a. Today's rule. Today's rule maintains the requirements of
laboratory certification for laboratories performing analyses to
demonstrate compliance with MCLs and all other analyses to be conducted
by approved parties. It revises the acceptance criteria for performance
evaluation (PE) studies which laboratories must pass as part of the
certification program. The new acceptance limits are effective 60 days
after promulgation. Laboratories that were certified under the Stage 1
DBPR PE acceptance criteria will be subject to the new criteria when it
is time for them to analyze their annual DBP PE sample(s). Today's rule
also requires that TTHM and HAA5 analyses that are performed for the
IDSE or system-specific study be conducted by laboratories certified
for those analyses.
Table IV.O-1.--Performance Evaluation (PE) Acceptance Criteria
------------------------------------------------------------------------
Acceptance
limits
DBP (percent of Comments
true value)
------------------------------------------------------------------------
TTHM
Chloroform..................... < plus- Laboratory must meet
minus>20 all 4 individual THM
acceptance limits in
order to successfully
pass a PE sample for
TTHM
Bromodichloromethane........... < plus-
minus>20
Dibromochloromethane........... < plus-
minus>20
Bromoform...................... < plus-
minus>20
HAA5
Monochloroacetic Acid.......... < plus- Laboratory must meet
minus>40 the acceptance limits
for 4 out of 5 of the
HAA5 compounds in
order to successfully
pass a PE sample for
HAA5
Dichloroacetic Acid............ < plus-
minus>40
Trichloroacetic Acid........... < plus-
minus>40
Monobromoacetic Acid........... < plus-
minus>40
Dibromoacetic Acid............. < plus-
minus>40
Chlorite........................... < plus-
minus>30
Bromate............................ < plus-
minus>30
------------------------------------------------------------------------
b. Background and analysis. The Stage 1 DBPR (USEPA 1998a)
specified that in order to be certified the laboratory must pass an
annual performance evaluation (PE) sample approved by EPA or the State
using each method for which the laboratory wishes to maintain
certification. The acceptance criteria for the DBP PE samples were set
as statistical limits based on the performance of the laboratories in
each study. This was done because EPA did not have enough data to
specify fixed acceptance limits.
Subsequent to promulgation of the Stage 1 DBPR, EPA was able to
evaluate data from PE studies conducted during the Information
Collection Rule (USEPA 1996) and during the last five general Water
Supply PE studies. Based on the evaluation process as described in the
proposed Stage 2 DBPR (USEPA 2003a), EPA determined that fixed
acceptance limits could be established for the DBPs. Today's action
replaces the statistical PE acceptance limits with fixed limits
effective one year after promulgation.
c. Summary of major comments. Four commenters supported the fixed
acceptance criteria as presented in the proposed rule. One requested
that a minimum concentration be set for each DBP in the PE studies, so
that laboratories would not be required to meet tighter criteria in the
PE study than they are required to meet with the minimum reporting
level (MRL) check standard. EPA has addressed this concern by directing
the PE sample suppliers to use concentrations no less than 10 [mu]g/L
for the individual THM and HAAs, 100 [mu]g/L for chlorite, and 7 [mu]g/
L for bromate in PE studies used for certifying drinking water laboratories.
Two commenters requested that the effective date for the new PE
acceptance criteria be extended from 60 days to 180 days, because they
felt that 60 days was not enough time for laboratories to meet the new
criteria. EPA realized from those comments that the original intent of
the proposal was not clearly explained; the 60 days was to be the
deadline for when the PE providers must change the acceptance criteria
that are used when the studies are conducted. Laboratories would have
to meet the criteria when it is time for them to analyze their annual
PE samples in order to maintain certification. Depending upon when the
last PE sample was analyzed, laboratories could have up to one year to
meet the new criteria. In order to eliminate this confusion, EPA has
modified the rule language to allow laboratories one year from today's
date to meet the new PE criteria.
2. Minimum Reporting Limits
a. Today's rule. EPA is establishing regulatory minimum reporting
limits (MRLs) for compliance reporting of DBPs by Public Water Systems.
These regulatory MRLs (Table IV.O-2) also define the minimum
concentrations that must be reported as part of the Consumer Confidence
Reports (40 CFR Sec. 141.151(d)). EPA is incorporating MRLs into the
laboratory certification program for DBPs by requiring laboratories to
include a standard near the MRL concentration as part of the
calibration curve for each DBP and to verify the accuracy of the
calibration curve at the MRL concentration by analyzing an MRL check
standard with a concentration less than or equal to 110% of the MRL
with each batch of samples. The measured DBP concentration for the MRL
check standard must be ±50% of the expected value, if any
field sample in the batch has a concentration less than 5 times the
regulatory MRL.
[[Page 439]]
Table IV.O-2.--Regulatory Minimum Reporting Levels
----------------------------------------------------------------------------------------------------------------
Minimum reporting level
DBP (mg/L) \1\ Comments
----------------------------------------------------------------------------------------------------------------
TTHM \2\
Chloroform................................. 0.0010
Bromodichloromethane....................... 0.0010
Dibromochloromethane....................... 0.0010
Bromoform.................................. 0.0010
HAA5 \2\
Monochloroacetic Acid...................... 0.0020
Dichloroacetic Acid........................ 0.0010
Trichloroacetic Acid....................... 0.0010
Monobromoacetic Acid....................... 0.0010
Dibromoacetic Acid......................... 0.0010
Chlorite....................................... 0.020 Applicable to monitoring as prescribed
in Sec. 141.132(b)(2)(i)(B) and
(b)(2)(ii).
Bromate........................................ 0.0050 or 0.0010 Laboratories that use EPA Methods
317.0 Revision 2.0, 326.0 or 321.8
must meet a 0.0010 mg/L MRL for
bromate.
----------------------------------------------------------------------------------------------------------------
\1\ The calibration curve must encompass the regulatory minimum reporting level (MRL) concentration. Data may be
reported for concentrations lower than the regulatory MRL as long as the precision and accuracy criteria are
met by analyzing an MRL check standard at the lowest reporting limit chosen by the laboratory. The laboratory
must verify the accuracy of the calibration curve at the MRL concentration by analyzing an MRL check standard
with a concentration less than or equal to 110% of the MRL with each batch of samples. The measured
concentration for the MRL check standard must be ±50% of the expected value, if any field sample in
the batch has a concentration less than 5 times the regulatory MRL. Method requirements to analyze higher
concentration check standards and meet tighter acceptance criteria for them must be met in addition to the MRL
check standard requirement.
\2\ When adding the individual trihalomethane or haloacetic acid concentrations to calculate the TTHM or HAA5
concentrations, respectively, a zero is used for any analytical result that is less than the MRL concentration
for that DBP, unless otherwise specified by the State.
b. Background and analysis. EPA proposed to establish regulatory
MRLs for DBPs in order to define expectations for reporting compliance
monitoring data to the Primacy Agencies and in the Consumer Confidence
Reports. The proposed MRLs were generally based on those used during
the Information Collection Rule (USEPA 1996), because an analysis of
the quality control data set from the Information Collection Rule (Fair
et al. 2002) indicated that laboratories are able to provide
quantitative data down to those concentrations.
EPA also proposed that laboratories be required to demonstrate
ability to quantitate at the MRL concentrations by analyzing an MRL
check standard and meeting accuracy criteria on each day that
compliance samples are analyzed. Three public commenters noted that
meeting the accuracy requirement for the MRL check standard did not
contribute to the quality of the data in cases in which the
concentration of a DBP in the samples was much higher than the MRL. For
example, if chloroform concentrations are always greater than 0.040 mg/
L in a water system's samples, then verifying accurate quantitation at
0.0010 mg/L is unnecessary and may require the laboratory to dilute
samples or maintain two calibration curves in order to comply with the
requirement. EPA has taken this into consideration in today's rule and
has adjusted the requirement accordingly. EPA is maintaining the
requirement for all laboratories to analyze the MRL check standard, but
the laboratory is only required to meet the accuracy criteria (< plus-
minus>50%) if a field sample has a concentration less than five times
the regulatory MRL concentration.
EPA proposed a regulatory MRL of 0.200 mg/L for chlorite, because
data from the Information Collection Rule indicated that most samples
would contain concentrations greater than 0.200 mg/L (USEPA 2003c). EPA
also took comment on a lower MRL of 0.020 mg/L. Commenters were evenly
divided concerning which regulatory MRL concentration should be adopted
in the final rule. EPA has decided to set the chlorite regulatory MRL
at 0.020 mg/L in today's rule. This decision was based on two factors.
First, the approved analytical methods for determining compliance with
the chlorite MCL can easily support an MRL of 0.020 mg/L. More
importantly, since the proposal, EPA has learned that water systems
that have low chlorite concentrations in their water have been
obtaining data on these low concentrations from their laboratories and
have been using these data in their Consumer Confidence Reports.
Setting the MRL at 0.020 mg/L is reflective of current practices in
laboratories and current data expectations by water systems.
c. Summary of major comments. There were no major comments.
P. Other Regulatory Changes
As part of today's action, EPA has included several
``housekeeping'' actions to remove sections of Part 141 that are no
longer effective. These sections have been superceded by new
requirements elsewhere in Part 141.
Sections 141.12 (Maximum contaminant levels for total
trihalomethanes) and 141.30 (Total trihalomethanes sampling, analytical
and other requirements) were promulgated as part of the 1979 TTHM Rule.
These sections have been superceded in their entirety by Sec. 141.64
(Maximum contaminant levels for disinfection byproducts) and subpart L
(Disinfectant Residuals, Disinfection Byproducts, and Disinfection
Byproduct Precursors), respectively, as of December 31, 2003. Also,
Sec. 141.32 (Public notification) has been superceded by subpart Q
(Public Notification of Drinking Water Violations), which is now fully
in effect.
Section 553 of the Administrative Procedure Act, 5 U.S.C.
553(b)(B), provides that, when an agency for good cause finds that
notice and public procedure are impracticable, unnecessary, or contrary
to the public interest, the agency may issue a rule without providing
prior notice and an opportunity for public comment. In addition to
updating methods, this rule also makes minor corrections to the
National Primary Drinking Water Regulations, specifically the Public
Notification tables (Subpart Q, Appendices A and B). Two final drinking
water rules (66 FR 6976 and 65 FR 76708) inadvertently added new
endnotes to two existing tables using the same endnote numbers. This
rule corrects this technical drafting error by
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renumbering the endnote citations in these two tables. Thus, additional
notice and public comment is not necessary. EPA finds that this
constitutes ``good cause'' under 5 U.S.C. 553(b)(B). For the same
reasons, EPA is making this rule change effective upon publication. 5
U.S.C. 553(d)(3).
V. State Implementation
A. Today's Rule
This section describes the regulations and other procedures and
policies States must adopt to implement today's rule. States must
continue to meet all other conditions of primacy in 40 CFR Part 142. To
implement the Stage 2 DBPR, States must adopt revisions to the following:
--Sec. 141.2--Definitions
--Sec. 141.33--Record maintenance;
--Sec. 141.64--Maximum contaminant levels for disinfection byproducts;
--subpart L--Disinfectant Residuals, Disinfection Byproducts, and
Disinfection Byproduct Precursors;
--subpart O, Consumer Confidence Reports;
--subpart Q, Public Notification of Drinking Water Violations;
--new subpart U, Initial Distribution System Evaluation; and
--new subpart V, Stage 2 Disinfection Byproducts Requirements.
1. State Primacy Requirements for Implementation Flexibility
In addition to adopting basic primacy requirements specified in 40
CFR part 142, States are required to address applicable special primacy
conditions. Special primacy conditions pertain to specific regulations
where implementation of the rule involves activities beyond general
primacy provisions. The purpose of these special primacy requirements
in today's rule is to ensure State flexibility in implementing a
regulation that (1) applies to specific system configurations within
the particular State and (2) can be integrated with a State's existing
Public Water Supply Supervision Program. States must include these
rule-distinct provisions in an application for approval or revision of
their program. These primacy requirements for implementation
flexibility are discussed in this section.
To ensure that a State program includes all the elements necessary
for an effective and enforceable program under today's rule, a State
primacy application must include a description of how the State will
implement a procedure for modifying consecutive system and wholesale
system monitoring requirements on a case-by-case basis, if a State will
use the authority to modify monitoring requirements under this special
primacy condition.
2. State Recordkeeping Requirements
Today's rule requires States to keep additional records of the
following, including all supporting information and an explanation of
the technical basis for each decision:
--very small system waivers.
--IDSE monitoring plans.
--IDSE reports and 40/30 certifications, plus any modifications
required by the State.
--operational evaluations conducted by the system.
3. State Reporting Requirements
Today's rule has no new State reporting requirements.
4. Interim Primacy
States that have primacy for every existing NPDWR already in effect
may obtain interim primacy for this rule, beginning on the date that
the State submits the application for this rule to USEPA, or the
effective date of its revised regulations, whichever is later. A State
that wishes to obtain interim primacy for future NPDWRs must obtain
primacy for today's rule. As described in Section IV.F, EPA expects to
work with States to oversee the individual distribution system
evaluation process that begins shortly after rule promulgation.
5. IDSE Implementation
As discussed in section IV.E, many systems will be performing
certain IDSE activities prior to their State receiving primacy. During
that period, EPA will act as the primacy agency, but will consult and
coordinate with individual States to the extent practicable and to the
extent that States are willing and able to do so. In addition, prior to
primacy, States may be asked to assist EPA in identifying and
confirming systems that are required to comply with certain IDSE
activities. Once the State has received primacy, it will become
responsible for IDSE implementation activities.
B. Background and Analysis
SDWA establishes requirements that a State or eligible Indian Tribe
must meet to assume and maintain primary enforcement responsibility
(primacy) for its PWSs. These requirements include the following
activities: (1) Adopting drinking water regulations that are no less
stringent than Federal drinking water regulations; (2) adopting and
implementing adequate procedures for enforcement; (3) keeping records
and making reports available on activities that EPA requires by
regulation; (4) issuing variances and exemptions (if allowed by the
State), under conditions no less stringent than allowed under SDWA; and
(5) adopting and being capable of implementing an adequate plan for the
provisions of safe drinking water under emergency situations.
40 CFR part 142 sets out the specific program implementation
requirements for States to obtain primacy for the public water supply
supervision program as authorized under SDWA section 1413. In addition
to adopting basic primacy requirements specified in 40 CFR Part 142,
States may be required to adopt special primacy provisions pertaining
to specific regulations where implementation of the rule involves
activities beyond general primacy provisions. States must include these
regulation specific provisions in an application for approval of their
program revision.
The current regulations in 40 CFR 142.14 require States with
primacy to keep various records, including the following: analytical
results to determine compliance with MCLs, MRDLs, and treatment
technique requirements; PWS inventories; State approvals; enforcement
actions; and the issuance of variances and exemptions. Today's final
rule requires States to keep additional records, including all
supporting information and an explanation of the technical basis for
decisions made by the State regarding today's rule requirements. The
State may use these records to identify trends and determine whether to
limit the scope of operational evaluations. EPA currently requires in
40 CFR 142.15 that States report to EPA information such as violations,
variance and exemption status, and enforcement actions; today's rule
does not add additional reporting requirements or modify existing
requirements.
On April 28, 1998, EPA amended its State primacy regulations at 40
CFR 142.12 to incorporate the new process identified in the 1996 SDWA
Amendments for granting primary enforcement authority to States while
their applications to modify their primacy programs are under review
(63 FR 23362, April 28, 1998) (USEPA 1998f). The new process grants
interim primary enforcement authority for a new or revised regulation
during the period in which EPA is making a determination with regard to
primacy for that new or revised regulation. This interim enforcement
authority begins on the date of the primacy application submission or
the effective date of the
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new or revised State regulation, whichever is later, and ends when EPA
makes a final determination. However, this interim primacy authority is
only available to a State that has primacy (including interim primacy)
for every existing NPDWR in effect when the new regulation is
promulgated. States that have primacy for every existing NPDWR already
in effect may obtain interim primacy for this rule and a State that
wishes to obtain interim primacy for future NPDWRs must obtain primacy
for this rule.
EPA is aware that due to the complicated wholesale system-
consecutive system relationships that exist nationally, there will be
cases where the standard monitoring framework will be difficult to
implement. Therefore, States may develop, as a special primacy
condition, a program under which the State can modify monitoring
requirements for consecutive systems. These modifications must not
undermine public health protection and all systems, including
consecutive systems, must comply with the TTHM and HAA5 MCLs based on
the LRAA at each compliance monitoring location. Each consecutive
system must have at least one compliance monitoring location. However,
such a program allows the State to establish monitoring requirements
that account for complicated distribution system relationships, such as
where neighboring systems buy from and sell to each other regularly
throughout the year, water passes through multiple consecutive systems
before it reaches a user, or a large group of interconnected systems
have a complicated combined distribution system. EPA has developed a
guidance manual to address these and other consecutive system issues.
C. Summary of Major Comments
Public comment generally supported the special primacy requirements
in the August 11, 2003 proposal, and many commenters expressed
appreciation for the flexibility the special primacy requirements
provided to States.
Many commenters expressed concern about EPA as the implementer
instead of the State, given the existing relationship between the State
and system. EPA agrees that States perform an essential role in rule
implementation and intends to work with States to the greatest extent
possible, consistent with the rule schedule promulgated today. EPA
believes that pre-promulgation coordination with States, changes in the
final rule strongly supported by States (e.g., population-based
monitoring instead of plant-based monitoring), and the staggered rule
schedule will facilitate State involvement in pre-primacy implementation.
Many commenters also requested that the State have more flexibility
to grant sampling waivers and exemptions. EPA believes that it has
struck a reasonable balance among competing objectives in granting
State flexibility. State flexibility comes at a resource cost and
excessive system-by-system flexibility could overwhelm State resources.
Also, EPA believes that much of the monitoring and water quality
information a State would need to properly consider whether a waiver is
appropriate is generally not available and, if available, difficult to
evaluate.
VI. Economic Analysis
This section summarizes the Economic Analysis for the Final Stage 2
Disinfectants and Disinfection Byproducts Rule (Economic Analysis (EA))
(USEPA 2005a). The EA is an evaluation of the benefits and costs of
today's final rule and other regulatory alternatives the Agency
considered. Specifically, this evaluation addresses both quantified and
non-quantified benefits to PWS consumers, including the general
population and sensitive subpopulations. Costs are presented for PWSs,
States, and consumer households. Also included is a discussion of
potential risks from other contaminants, uncertainties in benefit and
cost estimates, and a summary of major comments on the EA for the
proposed Stage 2 DBPR.
EPA relied on data from several epidemiologic and toxicologic
studies, the Information Collection Rule (ICR), and other sources,
along with analytical models and input from technical experts, to
understand DBP risk, occurrence, and PWS treatment changes that will
result from today's rule. Benefits and costs are presented as
annualized values using social discount rates of three and seven
percent. The time frame used for benefit and cost comparisons is 25
years--approximately five years account for rule implementation and 20
years for the average useful life of treatment technologies.
EPA has prepared this EA to comply with the requirements of SDWA,
including the Health Risk Reduction and Cost Analysis required by SDWA
section 1412(b)(3)(C), and Executive Order 12866, Regulatory Planning
and Review. The full EA is available in the docket for today's rule,
which is available online as described in the ADDRESSES section. The
full document provides detailed explanations of the analyses summarized
in this section and additional analytical results.
A. Regulatory Alternatives Considered
The Stage 2 DBPR is the second in a set of rules that address
public health risks from DBPs. EPA promulgated the Stage 1 DBPR to
decrease average exposure to DBPs and mitigate associated health
risks--compliance with TTHM and HAA5 MCLs is based on averaging
concentrations across the distribution system. In developing the Stage
2 DBPR, EPA sought to identify and further reduce remaining risks from
exposure to chlorinated DBPs.
The regulatory options EPA considered for the Stage 2 DBPR are the
direct result of a consensus rulemaking process (Federal Advisory
Committee Act (FACA) process) that involved various drinking water
stakeholders (see Section III for a description of the FACA process).
The Advisory Committee considered the following key questions during
the negotiation process for the Stage 2 DBPR:
? What are the remaining health risks after implementation
of the Stage 1 DBPR?
? What are approaches to addressing these risks?
? What are the risk tradeoffs that need to be considered in
evaluating these approaches?
? How do the estimated costs of an approach compare to
reductions in peak DBP occurrences and overall DBP exposure for that
approach?
The Advisory Committee considered DBP occurrence estimates to be
important in understanding the nature of public health risks. Although
the ICR data were collected prior to promulgation of the Stage 1 DBPR,
they were collected under a similar sampling strategy. The data support
the concept that a system could be in compliance with the RAA Stage 1
DBPR MCLs of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5, respectively,
and yet have points in the distribution system with either periodically
or consistently higher DBP levels.
Based on these findings, the Advisory Committee discussed an array
of alternatives to address disproportionate risk within distribution
systems. Alternative options included lowering DBP MCLs, revising the
method for MCL compliance determination e.g., requiring individual
sampling locations to meet the MCL as an LRAA or requiring that no
samples exceed the MCL), and combinations of both. The Advisory
Committee also considered the associated technology changes and costs
for these alternatives. After narrowing down options, the Advisory Committee
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primarily focused on four types of alternative MCL scenarios. These are
the alternatives EPA evaluated in the EA, as follows:
Preferred Alternative
--MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as LRAAs
--Bromate MCL remaining at 0.010 mg/L
Alternative 1
--MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as LRAAs
--Bromate MCL of 0.005 mg/L
Alternative 2
--MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as absolute
maximums for individual measurements
--Bromate MCL remaining at 0.010 mg/L
Alternative 3
--MCLs of 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 as RAAs
--Bromate MCL remaining at 0.010 mg/L.
Figure VI.A-1 shows how compliance would be determined under each
of the TTHM/HAA5 alternatives described and the Stage 1 DBPR for a
hypothetical large surface water system. This hypothetical system has
one treatment plant and measures TTHM in the distribution system in
four locations per quarter (the calculation methodology shown would be
the same for HAA5). Ultimately, the Advisory Committee recommended the
Preferred Alternative in combination with an IDSE requirement
(discussed in Section IV.F).
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B. Analyses That Support Today's Final Rule
EPA's goals in designing the Stage 2 DBPR were to protect public
health by reducing peak DBP levels in the distribution system while
maintaining microbial protection. As described earlier, the Stage 1
DBPR reduces overall average DBP levels, but specific locations within
distribution systems can still experience relatively high DBP
concentrations. EPA believes that high DBP concentrations should be
reduced due to the potential association of DBPs with cancer, as well
as reproductive and developmental health effects.
EPA analyzed the benefits and costs of the four regulatory
alternatives presented in the previous section. Consistent with the
recommendations of the Advisory Committee, EPA is establishing the
preferred alternative to achieve the Agency's goals for the Stage 2
DBPR. The following discussion summarizes EPA's analyses that support
today's final rule. This discussion explains how EPA predicted water
quality and treatment changes, estimated benefits and costs, and
assessed the regulatory alternatives.
1. Predicting Water Quality and Treatment Changes
Water quality and treatment data from the ICR were used in
predicting treatment plant technology changes (i.e. compliance
forecasts) and reductions in DBP exposure resulting from the Stage 2
DBPR. Because ICR data were gathered prior to Stage 1 DBPR compliance
deadlines, EPA first accounted for treatment changes resulting from the
Stage 1 DBPR. Benefit and cost estimates for the Stage 2 DBPR reflect
changes following compliance with the Stage 1 DBPR.
The primary model used to predict changes in treatment and
reductions in DBP levels was the Surface Water Analytical Tool (SWAT),
which EPA developed using results from the ICR. SWAT results were
applied directly for large and medium surface water systems and were
adjusted for small surface water systems to account for differences in
source water DBP precursor levels and operational constraints in small
systems. EPA used ICR data and a Delphi poll process (a group of
drinking water experts who provided best professional judgment in a
structured format) to project technologies selected by ground water systems.
To address uncertainty in SWAT predictions, EPA also predicted
treatment changes using a second methodology, called the ``ICR Matrix
Method.'' Rather than a SWAT-predicted pre-Stage 1 baseline, the ICR
Matrix Method uses unadjusted ICR TTHM and HAA5 pre-Stage 1 data to
estimate the percent of plants changing technology to comply with the
Stage 2 DBPR. EPA gives equal weight to SWAT and ICR Matrix Method
predictions in estimating Stage 2 compliance forecasts and resultant
reductions in DBP exposure. The ICR Matrix Method is also used to
estimate reductions in the occurrence of peak TTHM and HAA5
concentrations because SWAT-predicted TTHM and HAA5 concentrations are
valid only when considering national averages, not at the plant level.
When evaluating compliance with a DBP MCL, EPA assumed that systems
would maintain DBP levels at least 20 percent below the MCL. This
safety margin represents the level at which systems typically take
action to ensure they meet a drinking water standard and reflects
industry practice. In addition, the safety margin accounts for year-to-
year fluctuations in DBP levels. To address the impact of the IDSE, EPA
also analyzed compliance using a safety margin of 25 percent based on
an analysis of spatial variability in TTHM and HAA5 occurrence. EPA
assigned equal probability to the 20 and 25 percent safety margin for
large and medium surface water systems for the final analysis because
both alternatives are considered equally plausible. EPA assumes the 20
percent operational safety margin accounts for variability in small
surface water systems and all groundwater systems.
2. Estimating Benefits
Quantified benefits estimates for the Stage 2 DBPR are based on
potential reductions in fatal and non-fatal bladder cancer cases. In
the EA, EPA included a sensitivity analysis for benefits from avoiding
colon and rectal cancers. EPA believes additional benefits from this
rule could come from reducing potential reproductive and developmental
risks. EPA has not included these potential risks in the primary
benefit analysis because of the associated uncertainty.
The major steps in deriving and characterizing potential cancer
cases avoided include the following: (1) estimate the current and
future annual cases of illness from all causes; (2) estimate how many
cases can be attributed to DBP occurrence and exposure; and (3)
estimate the reduction in future cases corresponding to anticipated
reductions in DBP occurrence and exposure due to the Stage 2 DBPR.
EPA used results from the National Cancer Institute's Surveillance,
Epidemiology, and End Results program in conjunction with data from the
2000 U.S. Census to estimate the number of new bladder cancer cases per
year (USEPA 2005a). Three approaches were then used to gauge the
percentage of cases attributable to DBP exposure (i.e., population
attributable risk (PAR)). Taken together, the three approaches provide
a reasonable estimate of the range of potential risks. EPA notes that
the existing epidemiological evidence has not conclusively established
causality between DBP exposure and any health risk endpoints, so the
lower bound of potential risks may be as low as zero.
The first approach used the range of PAR values derived from
consideration of five individual epidemiology studies. This range was
used at the basis for the Stage 1 and the proposed Stage 2 economic
analyses (i.e., 2 percent to 17 percent) (USEPA 2003a).
The second approach used results from the Villanueva et al. (2003)
meta-analysis. This study develops a combined Odds Ratio (OR) of 1.2
that reflects the ever-exposed category for both sexes from all studies
considered in the meta-analysis and yields a PAR value of approximately
16 percent.
The third approach used the Villanueva et al. (2004) pooled data
analysis to develop a dose-response relationship for OR as a function
of average TTHM exposure. Using the results from this approach, EPA
estimates a PAR value of approximately 17 percent.
EPA used the PAR values from all three approaches to estimate the
number of bladder cancer cases ultimately avoided annually as a result
of the Stage 2 DBPR. To quantify the reduction in cases, EPA assumed a
linear relationship between average DBP concentration and relative risk
of bladder cancer. Because of this, EPA considers these estimates to be
an upper bound on the annual reduction in bladder cancer cases due to
the rule.
A lag period (i.e., cessation lag) exists between when reduction in
exposure to a carcinogen occurs and when the full risk reduction
benefit of that exposure reduction is realized by exposed individuals.
No data are available that address the rate of achieving bladder cancer
benefits resulting from DBP reductions. Consequently, EPA used data
from epidemiological studies that address exposure reduction to
cigarette smoke and arsenic to generate three possible cessation lag
functions for bladder cancer and DBPs. The cessation lag functions are
used in conjunction
[[Page 445]]
with the rule implementation schedule to project the number of bladder
cancer cases avoided each year as a result of the Stage 2 DBPR.
Although EPA used three approaches for estimating PAR, for
simplicity's sake, EPA used the Villanueva et al. (2003) study to
calculate the annual benefits of the Stage 2 DBPR. The benefits
estimates derived from Villanueva et al. (2003) capture a substantial
portion of the overall range of results, reflecting the uncertainty in
both the underlying OR and PAR values, as well as the uncertainty in
DBP reductions for Stage 2.
To assign a monetary value to avoided bladder cancer cases, EPA
used the value of a statistical life (VSL) for fatal cases and used two
alternate estimates of willingness-to-pay to avoid non-fatal cases (one
based on curable lymphoma and the other based on chronic bronchitis).
EPA believes additional benefits from this rule could come from a
reduction in potential reproductive and developmental risks. See
Chapter 6 of the EA for more information on estimating benefits (USEPA
2005a).
3. Estimating Costs
Analyzing costs for systems to comply with the Stage 2 DBPR
included identifying and costing treatment process improvements that
systems will make, as well as estimating the costs to implement the
rule, conduct IDSEs, prepare monitoring plans, perform additional
routine monitoring, and evaluate significant DBP excursion events. The
cost analysis for States/Primacy Agencies included estimates of the
labor burdens for training employees on the requirements of the Stage 2
DBPR, responding to PWS reports, and record keeping.
All treatment costs are based on mean unit cost estimates for
advanced technologies and chloramines. Derivation of unit costs are
described in detail in Technologies and Costs for the Final Long Term 2
Enhanced Surface Water Treatment Rule and Final Stage 2 Disinfectants
and Disinfection Byproducts Rule (USEPA 2005g). Unit costs (capital and
O&M) for each of nine system size categories are calculated using mean
design and average daily flows values. The unit costs are then combined
with the predicted number of plants selecting each technology to
produce national treatment cost estimates.
Non-treatment costs for implementation, the IDSE, monitoring plans,
additional routine monitoring, and operational evaluations are based on
estimates of labor hours for performing these activities and on
laboratory costs.
While systems vary with respect to many of the input parameters to
the Stage 2 DBPR cost analysis (e.g., plants per system, population
served, flow per population, labor rates), EPA believes that mean
values for the various input parameters are appropriate to generate the
best estimate of national costs for the rule. Uncertainty in the
national average unit capital and O&M costs for the various
technologies has been incorporated into the cost analysis (using Monte
Carlo simulation procedures). Costs of the Stage 2 DBPR are estimated
at both mean and 90 percent confidence bound values.
EPA assumes that systems will, to the extent possible, pass cost
increases on to their customers through increases in water rates.
Consequently, EPA has also estimated annual household cost increases
for the Stage 2 DBPR. This analysis includes costs for all households
served by systems subject to the rule, costs just for those households
served by systems actually changing treatment technologies to comply
with the rule, costs for households served by small systems, and costs
for systems served by surface water and ground water sources.
4. Comparing Regulatory Alternatives
Through the analyses summarized in this section, EPA assessed the
benefits and costs of the four regulatory alternatives described
previously. Succeeding sections of this preamble present the results of
these analyses. As recommended by the Advisory Committee, EPA is
establishing the preferred regulatory alternative for today's Stage 2
DBPR. This regulation will reduce peak DBP concentrations in
distribution systems through requiring compliance determinations with
existing TTHM and HAA5 MCLs using the LRAA. Further, the IDSE will
ensure that systems identify compliance monitoring sites that reflect
high DBP levels. EPA believes that these provision are appropriate
given the association of DBPs with cancer, as well as potential
reproductive and developmental health effects.
Alternative 1 would have established the same DBP regulations as
the preferred alternative, and would have lowered the bromate MCL from
0.010 to 0.005 mg/L. The Advisory Committee did not recommend and EPA
did not establish this alternative because it could have an adverse
effect on microbial protection. The lower bromate MCL could cause many
systems to reduce or eliminate the use of ozone, which is an effective
disinfectant for a broad spectrum of microbial pathogens, including
microorganisms like Cryptosporidium that are resistant to chlorine.
Alternative 2 would have prohibited any single sample from
exceeding the TTHM or HAA5 MCL. This is significantly more stringent
than the preferred alternative and would likely require a large
fraction of surface water systems to switch from their current
treatment practices to more expensive advanced technologies. Consistent
with the Advisory Committee, EPA does not believe such a drastic shift
is warranted at this time.
Similarly, Alternative 3, which would decrease TTHM and HAA5 MCLs
to 0.040 mg/L and 0.030 mg/L, respectively, and would require a
significant portion of surface water systems to implement expensive
advanced technologies in place of their existing treatment. Further,
compliance with TTHM and HAA5 MCLs under this alternative would be
based on the RAA, which does not specifically address DBP peaks in the
distribution system as the LRAA, in conjunction with the IDSE, are
designed to do. Based on these considerations, EPA and the Advisory
Committee did not favor this alternative.
C. Benefits of the Stage 2 DBPR
The benefits analysis for the Stage 2 DBPR includes a description
of non-quantified benefits, calculations of quantified benefits, and a
discussion of when benefits will occur after today's final rule is
implemented. An overview of the methods used to determine benefits is
provided in Section VI.B. More detail can be found in the final EA. A
summary of benefits for the Stage 2 DBPR is given in this section.
1. Nonquantified Benefits
Non-quantified benefits of the Stage 2 DBPR include potential
benefits from reduced reproductive and developmental risks, reduced
risks of cancers other than bladder cancer, and improved water quality.
EPA believes that additional benefits from this rule could come from a
reduction in potential reproductive and developmental risks. However,
EPA does not believe the available evidence provides an adequate basis
for quantifying these potential risks in the primary analysis.
Both toxicology and epidemiology studies indicate that other
cancers may be associated with DBP exposure but currently there is not
enough data to include them in the primary analysis. However, EPA
believes that the association between exposure to DBPs and colon and
rectal cancer is possibly
[[Page 446]]
significant, so an analysis of benefits is presented as a sensitivity
analysis.
To the extent that the Stage 2 DBPR changes perceptions of the
health risks associated with drinking water and improves taste and
odor, it may reduce actions such as buying bottled water or installing
filtration devices. Any resulting cost savings would be a regulatory
benefit. Also, as PWSs move away from conventional treatment to more
advanced technologies, other non-health benefits are anticipated
besides better tasting and smelling water. For example, GAC lowers
nutrient availability for bacterial growth, produces a biologically
more stable finished water, and facilitates management of water quality
in the distribution system. Since GAC also removes synthetic organic
chemicals (SOCs), it provides additional protection from exposure to
chemicals associated with accidental spills or environmental runoff.
2. Quantified Benefits
EPA has quantified the benefits associated with the expected
reductions in the incidence of bladder cancer. As discussed in Section
VI.B, EPA used the PAR values from all three approaches to estimate the
number of bladder cancer cases ultimately avoided annually as a result
of the Stage 2 DBPR, shown in Figure VI.C-1.
Table VI.C-1 summarizes the estimated number of bladder cancer
cases avoided as a result of the Stage 2 DBPR, accounting for cessation
lag and the rule implementation schedule, and the monetized value of
those cases. The benefits in Table VI.C-1 were developed using the PAR
value from Villanueva et al. (2003), as described in Section VI.B.
Table VI.C-1 summarizes the benefits for the Preferred Regulatory
Alternative for the Stage 2 DBPR. Benefits estimates for the other
regulatory alternatives were derived using the same methods as for the
Preferred Regulatory Alternative and are presented in the EA.
The confidence bounds of the results in Table VI.C-1 reflect
uncertainty in PAR, uncertainty in the compliance forecast and
resulting reduction in DBP concentrations, and cessation lag.
Confidence bounds of the monetized benefits also reflect uncertainty in
valuation parameters. An estimated 26 percent of bladder cancer cases
avoided are fatal, and 74 percent are non-fatal (USEPA 1999b). The
monetized benefits therefore reflect the estimate of avoiding both
fatal and non-fatal cancers in those proportions.
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Table VI.C-1.--Summary of Quantified Benefits for the Stage 2 DBPR (Millions of $2003)
----------------------------------------------------------------------------------------------------------------
Annual average cases avoided Discount rate, WTP Annualized benefits of cases avoided
---------------------------------- for non-fatal --------------------------------------- Cessation lag
Mean 5th 95th cases Mean 5th 95th model
----------------------------------------------------------------------------------------------------------------
279 103 541 3%, Lymphoma...... $1,531 $233 $3,536 Smoking/Lung
7% Lymphoma....... 1,246 190 2,878 Cancer
3% Bronchitis..... 763 165 1,692
7% Bronchitis..... 621 135 1,376
188 61 399 3%, Lymphoma...... 1,032 157 2,384 Smoking/Bladder
7% Lymphoma....... 845 129 1,950 Cancer
3% Bronchitis..... 514 111 1,141
7% Bronchitis..... 420 91 932
333 138 610 3%, Lymphoma...... 1,852 282 4,276 Arsenic/Bladder
7% Lymphoma....... 1,545 235 3,566 Cancer
3% Bronchitis..... 922 200 2,045
7% Bronchitis..... 769 167 1,704
----------------------------------------------------------------------------------------------------------------
Notes: Values are discounted and annualized in 2003$. The 90 percent confidence interval for cases incorporates
uncertainty in PAR, reduction in average TTHM and HAA5 concentrations, and cessation lag. The 90 percent
confidence bounds for monetized benefits reflect uncertainty in monetization inputs relative to mean cases.
Based on TTHM as an indicator, benefits were calculated using the Villanueva et al. (2003) PAR. EPA recognizes
that benefits may be as low as zero since causality has not yet been established between exposure to
chlorinated water and bladder cancer. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA
1999b).
Source: Exhibit 6.1, USEPA 2005a.
3. Timing of Benefits Accrual
EPA recognizes that it is unlikely that all cancer reduction
benefits would be realized immediately upon exposure reduction. Rather,
it is expected that there will likely be some transition period as
individual risks reflective of higher past exposures at the time of
rule implementation become, over time, more reflective of the new lower
exposures. EPA developed cessation lag models for DBPs from literature
to describe the delayed benefits, in keeping with the recommendations
of the SAB (USEPA 2001d). Figure VI.C-2 illustrates the effects of the
cessation lag models. The results from the cessation lag models show
that the majority of the potential cases avoided occur within the first
fifteen years after initial reduced exposure to DBPs. For example,
fifteen years after the exposure reduction has occurred, the annual
cases avoided will be 489 for the smoking/lung cancer cessation lag
model, 329 for the smoking/bladder cancer cessation lag model, and 534
cases for the arsenic/bladder cancer cessation lag model. These
represent approximately 84%, 57%, and 92%, respectively, of the
estimated 581 annual cases ultimately avoidable by the Stage 2 DBPR.
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In addition to the delay in reaching a steady-state level of risk
reduction as a result of cessation lag, there is a delay in attaining
maximum exposure reduction across the entire affected population that
results from the Stage 2 DBPR implementation schedule. For example,
large surface water PWSs have six years from rule promulgation to meet
the new Stage 2 MCLs, with up to a two-year extension possible for
capital improvements. In general, EPA assumes that a fairly constant
increment of systems will complete installation of new treatment
technologies each year, with the last systems installing treatment by
2016. The delay in exposure reduction resulting from the rule
implementation schedule is incorporated into the benefits model by
adjusting the cases avoided for the given year and is illustrated in
Table VI.C-2.
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Table VI.C-2.--Bladder Cancer Cases Avoided (TTHM as Indicator) Each Year using Three Cessation Lag Models
----------------------------------------------------------------------------------------------------------------
Smoking/lung cancer Smoking/bladder Arsenic/bladder
cessation lag model cancer cessation lag cancer cessation lag
Year ---------------------- model model
-------------------------------------------
Total Percent Total Percent Total Percent
----------------------------------------------------------------------------------------------------------------
1............................................. 0 0 0 0 0 0
2............................................. 0 0 0 0 0 0
3............................................. 0 0 0 0 0 0
4............................................. 0 0 0 0 0 0
5............................................. 0 0 0 0 0 0
6............................................. 24 4 23 4 45 8
7............................................. 62 11 54 9 110 19
8............................................. 111 19 90 16 187 32
9............................................. 170 29 132 23 275 48
10............................................ 220 38 161 28 334 58
11............................................ 265 46 184 32 379 65
12............................................ 305 53 204 35 412 71
13............................................ 341 59 221 38 438 76
14............................................ 371 64 237 41 458 79
15............................................ 396 68 251 43 475 82
16............................................ 416 72 265 46 488 84
17............................................ 433 75 278 48 499 86
18............................................ 448 77 289 50 509 88
19............................................ 460 79 301 52 516 89
20............................................ 471 81 311 54 523 90
21............................................ 481 83 321 55 528 91
22............................................ 489 84 330 57 533 92
23............................................ 496 86 339 59 537 93
24............................................ 503 87 347 60 541 93
25............................................ 509 88 355 61 544 94
----------------------------------------------------------------------------------------------------------------
Notes: Percent of annual cases ultimately avoidable achieved during each of the first 25 years. The benefits
model estimates 581 (90% CB = 229-1,079) annual cases ultimately avoidable using the Villanueva et al. (2003)
PAR inputs and including uncertainty in these and DBP reductions. EPA recognizes that benefits may be as low
as zero since causality has not yet been established between exposure to chlorinated water and bladder cancer.
Source: Summarized from detailed results presented in Exhibits E.38a, E.38e and E.38i, USEPA 2005a.
D. Costs of the Stage 2 DBPR
National costs include those of treatment changes to comply with
the rule as well as non-treatment costs such as for Initial
Distribution System Evaluations (IDSEs), additional routine monitoring,
and operational evaluations. The methodology used to estimate costs is
described in Section VI.B. More detail is provided in the EA (USEPA
2005a). The remainder of this section presents summarized results of
EPA's cost analysis for total annualized present value costs, PWS
costs, State/Primacy agency costs, and non-quantified costs.
1. Total Annualized Present Value Costs
Tables VI.D-1 and VI.D-2 summarize the average annualized costs for
the Stage 2 DBPR Preferred Regulatory Alternative at 3 and 7 percent
discount rates, respectively. System costs range from approximately $55
to $101 million annually at a 3 percent discount rate, with a mean
estimate of approximately $77 million per year. The mean and range of
annualized costs are similar at a 7 percent discount rate. State costs
are estimated to be between $1.70 and $1.71 million per year depending
on the discount rate. These estimates are annualized starting with the
year of promulgation. Actual dollar costs during years when most
treatment changes are expected to occur would be somewhat higher (the
same is true for benefits that occur in the future).
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2. PWS costs
PWS costs for the Stage 2 DBPR include non-treatment costs of rule
implementation, Initial Distribution System Evaluations (IDSEs), Stage
2 DBPR monitoring plans, additional routine monitoring, and operational
evaluations. Systems required to install treatment to comply with the
MCLs will accrue the additional costs of treatment installation as well
as operation and maintenance. Significant PWS costs for IDSEs,
treatment, and monitoring are described in this section, along with a
sensitivity analysis.
a. IDSE costs. Costs and burden associated with IDSE activities
differ depending on whether or not the system performs the IDSE and, if
so, which option a system chooses. All systems performing the IDSE are
expected to incur some costs. EPA's analysis allocated systems into
five categories to determine the costs of the IDSE--those conducting
standard monitoring, SSS, VSS, 40/30, and NTNCWS not required to do an
IDSE. EPA then developed cost estimates for each option. Tables VI.D-3,
VI.D-4, and VI.D-5 illustrate PWS costs for IDSE for systems conducting
an SMP, SSS, and 40/30, respectively.
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b. PWS treatment costs. The number of plants changing treatment as
a result of the Stage 2 DBPR and which technology various systems will
install are determined from the compliance forecast. The percent of
systems predicted to make treatment technology changes and the
technologies predicted to be in place after implementation of the Stage
2 DBPR are shown in Table VI.D-6. The cost model includes estimates for
the cost of each technology; the results of the cost model for PWS
treatment costs are summarized in Table VI.D-7.
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c. Monitoring costs. Because systems already sample for the Stage 1
DBPR, costs for additional routine monitoring are determined by the
change in the number of samples to be collected from the Stage 1 to the
Stage 2 DBPR. The
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Stage 2 DBPR monitoring requirements for systems are based only on
population served and source water type, while the Stage 1 DBPR
requirements are also based on the number of treatment plants. With
this modification in monitoring scheme, the average system will have no
change in monitoring costs. The number of samples required is estimated
to increase for some systems but actually decrease from the Stage 1 to
the Stage 2 DBPR for many systems. Table VI.D-8 summarizes the
estimated additional routine monitoring costs for systems.
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3. State/Primacy Agency Costs
To estimate State/Primacy Agency costs, the estimated number of
full-time equivalents (FTEs) required per activity is multiplied by the
number of labor hours per FTE, the State/Primacy Agency hourly wage,
and the number of States/Primacy Agencies. EPA estimated the number of
FTEs required per activity based on experience implementing previous
rules, such as the Stage 1 DBPR. State/Primacy Agency costs are
summarized in Table VI.D-9.
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4. Non-quantified Costs
All significant costs that EPA has identified have been quantified.
In some instances, EPA did not include a potential cost element because
its effects are relatively minor and difficult to estimate. For
example, it may be less costly for a small system to merge with
neighboring systems than to add advanced treatment. Such changes have
both costs (legal fees and connecting infrastructure) and benefits
(economies of scale). Likewise, procuring a new source of water would
have costs for new infrastructure, but could result in lower treatment
costs. Operational costs such as changing storage tank operation were
also not considered as alternatives to treatment. These might be
options for systems with a single problem area with a long residence
time. In the absence of detailed information needed to evaluate
situations such as these, EPA has included a discussion of possible
effects where appropriate. In general, however, the expected net effect
of such situations is lower costs to PWSs. Thus, the EA tends to
present conservatively high estimates of costs in relation to non-
quantified costs.
E. Household Costs of the Stage 2 DBPR
EPA estimates that, as a whole, households subject to the Stage 2
DBPR face minimal increases in their annual costs. Approximately 86
percent of the households potentially subject to the rule are served by
systems serving at least 10,000 people; these systems experience the
lowest increases in costs due to significant economies of scale.
Households served by small systems that add treatment will face the
greatest increases in annual costs. Table VI.E-1 summarizes annual
household cost increases for all system sizes.
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Table VI.E-1.--Annual Household Cost Increases.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Percentage Percentage
Median 90th 95th of annual of annual
Total number Mean annual annual percentile percentile household household
of households household household annual annual cost cost
served cost cost household household increase < increase <
increase increase cost cost $12 $120
increase increase (percent) (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Households Served by All Plants
--------------------------------------------------------------------------------------------------------------------------------------------------------
All Systems............................................... 101,553,868 $0.62 $0.03 $0.36 $0.98 99 100
All Small Systems......................................... 14,261,241 2.20 0.10 0.79 2.57 97 100
SW < 10,000............................................... 3,251,893 4.58 0.79 2.69 7.24 95 99
SW >= 10,000.............................................. 62,137,350 0.46 0.02 0.35 1.81 99 100
GW < 10,000............................................... 11,009,348 1.49 0.02 0.39 0.99 98 100
GW >= 10,000.............................................. 25,155,277 0.13 0.00 0.03 0.08 100 100
-----------------------------------------------------------
Households Served by Plants Adding Treatment
--------------------------------------------------------------------------------------------------------------------------------------------------------
All Systems............................................... 10,161,304 $5.53 $0.80 $10.04 $22.40 92 99
All Small Systems......................................... 591,623 46.48 18.47 168.85 197.62 38 89
SW < 10,000............................................... 285,911 43.05 13.79 173.53 177.93 47 85
SW >= 10,000.............................................. 9,060,119 2.83 0.80 6.98 11.31 96 100
GW < 10,000............................................... 305,712 49.69 16.65 109.86 197.62 31 92
GW >= 10,000.............................................. 509,562 5.97 1.37 26.82 33.84 79 100
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Detail may not add to total due to independent rounding. Number of households served by systems adding treatment will be higher than households
served by plants adding treatment because an entire system will incur costs even if only some of the plants for that system add treatment (this would
result in lower household costs, however).
Source: Exhibit 7.15, USEPA 2005a.
F. Incremental Costs and Benefits of the Stage 2 DBPR
Incremental costs and benefits are those that are incurred or
realized in reducing DBP exposures from one alternative to the next
more stringent alternative. Estimates of incremental costs and benefits
are useful in considering the economic efficiency of different
regulatory options considered by the Agency. Generally, the goal of an
incremental analysis is to identify the regulatory option where net
social benefits are maximized. However, the usefulness of this analysis
is constrained when major benefits and/or costs are not quantified or
not monetized. Also, as pointed out by the Environmental Economics
Advisory Committee of the Science Advisory Board, efficiency is not the
only appropriate criterion for social decision making (USEPA 2000i).
For the proposed Stage 2 DBPR, presentation of incremental
quantitative benefit and cost comparisons may be unrepresentative of
the true net benefits of the rule because a significant portion of the
rule's potential benefits are not quantified, particularly potential
reproductive and developmental health effects (see Section VI.C). Table
VI.F-1 shows the incremental monetized costs and benefits for each
regulatory alternative. Evaluation of this table shows that incremental
costs generally fall within the range of incremental benefits for each
more stringent alternative. Equally important, the addition of any
benefits attributable to the non-quantified categories would add to the
benefits without any increase in costs.
Table VI.F-1 shows that the Preferred Alternative is the least-cost
alternative. A comparison of Alternative 1 with the Preferred
Alternative shows that Alternative 1 would have approximately the same
benefits as the Preferred Alternative. The costs of Alternative 1 are
greater due to the additional control of bromate. However, the benefits
of Alternative 1 are less than the Preferred Alternative because the
Agency is not able to estimate the additional benefits of reducing the
bromate MCL. Alternative 1 was determined to be unacceptable due to the
potential for increased risk of microbial exposure. Both benefits and
costs are greater for Alternative 2 and Alternative 3 as compared to
the Preferred Alternative. However, these regulatory alternatives do
not have the risk-targeted design of the Preferred Alternative. Rather,
implementation of these stringent standards would require a large
number of systems to change treatment technology. The high costs of
these regulatory alternatives and the drastic shift in the nation's
drinking water practices were considered unwarranted at this time. (See
Section VI.A of this preamble for a description of regulatory
alternatives.)
Table VI.F-1.--Incremental Costs and Benefits of the Stage 2 DBPR
--------------------------------------------------------------------------------------------------------------------------------------------------------
Annual Annual Incremental costs Incremental benefits Incremental net
WTP for non-fatal bladder cancer costs benefits ---------------------------------------------- benefits
cases Rule alternative -------------------------- ----------------------
A B C D E=D-C
--------------------------------------------------------------------------------------------------------------------------------------------------------
3 Percent Discount Rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lymphoma.......................... Preferred............ $79 $1,531 $79.................. $1,531............... $1,452
Alternative 1 \1\.... 254 1,377 (\1\)................ (\1\)................ (\1\)
Alternative 2........ 422 5,167 343.................. 3,637................ 3,294
Alternative 3........ 634 7,130 212.................. 1,962................ 1,750
Bronchitis........................ Preferred............ 79 763 79................... 763.................. 684
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Alternative 1 \1\.... 254 686 (\1\)................ (\1\)................ (\1\)
Alternative 2........ 422 2,575 343.................. 1,812................ 1,469
Alternative 3........ 634 3,552 212.................. 978.................. 765
-----------------------------------
7 Percent Discount Rate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Lymphoma.......................... Preferred............ $77 $1,246 $77.................. $1,246............... $1,170
Alternative 1 \1\.... 242 1,126 (\1\)................ (\1\)................ (\1\)
Alternative 2........ 406 4,227 330.................. 2,981................ 2,651
Alternative 3........ 613 5,832 207.................. 1,605................ 1,399
Bronchitis........................ Preferred............ 77 621 77................... 621.................. 544
Alternative 1 \1\.... 242 561 (\1\)................ (\1\)................ (\1\)
Alternative 2........ 406 2,105 330.................. 1,484................ 1,154
Alternative 3........ 613 2,904 207.................. 799.................. 593
--------------------------------------------------------------------------------------------------------------------------------------------------------
Notes: Estimates are discounted to 2003 and given in 2003 dollars. Based on TTHM as an indicator, Villanueva et al. (2003) for baseline risk, and
smoking/lung cancer cessation lag model. Assumes 26 percent of cases are fatal, 74 percent are non-fatal (USEPA 1999b). EPA recognizes that benefits
may be as low as zero since causality has not yet been established between exposure to chlorinated water and bladder cancer.
\1\ Alternative 1 appears to have fewer benefits than the Preferred Alternative because it does not incorporate the IDSE, as explained in Chapter 4.
Furthermore, this EA does not quantify the benefits of reducing the MCL for bromate (and potentially associated cancer cases), a requirement that is
included only in Alternative 1. This means that Alternative 1 is dominated by the Preferred Alternative in this analysis (having higher costs than the
Preferred Alternative but lower benefits), and so it is not included in the incremental comparison of alternatives (Columns C-E). OMB states this in
terms of comparing cost effectiveness ratios, but the same rule applies to an incremental cost, benefits, or net benefits comparison: ``When
constructing and comparing incremental cost-effectiveness ratios, [analysts]
* * * should make sure that inferior alternatives identified by the
principles of strong and weak dominance are eliminated from consideration.'' (OMB Circular A-4, p. 10)
Source: Exhibit 9.13, USEPA 2005a.
G. Benefits From the Reduction of Co-occurring Contaminants
Installing certain advanced technologies to control DBPs has the
added benefit of controlling other drinking water contaminants in
addition to those specifically targeted by the Stage 2 DBPR. For
example, membrane technology installed to reduce DBP precursors can
also reduce or eliminate many other drinking water contaminants
(depending on pore size), including those that EPA may regulate in the
future. Removal of any contaminants that may face regulation could
result in future cost savings to a water system. Because of the
difficulties in establishing which systems would be affected by other
current or future rules, no estimate was made of the potential cost
savings from addressing more than one contaminant simultaneously.
H. Potential Risks From Other Contaminants
Along with the reduction in DBPs from chlorination such as TTHM and
HAA5 as a resultof the Stage 2 DBPR, there may be increases in other
DBPs as systems switch from chlorine to alternative disinfectants. For
all disinfectants, many DBPs are not regulated and many others have not
yet been identified. EPA will continue to review new studies on DBPs
and their occurrence levels to determine if they pose possible health
risks. EPA continues to support regulation of TTHM and HAA5 as
indicators for chlorination DBP occurrence and believes that
operational and treatment changes made because of the Stage 2 DBPR will
result in an overall decrease in risk.
1. Emerging DBPs
Iodo-DBPs and nitrogenous DBPs including halonitromethanes are DBPs
that have recently been reported (Richardson et al. 2002, Richardson
2003). One recent occurrence study sampled quarterly at twelve surface
water plants using different disinfectants across the U.S. for several
iodo-THMs and halonitromethane species (Weinberg et al. 2002). The
concentrations of iodo-THMs and halonitromethane in the majority of
samples in this study were less than the analytical minimum reporting
levels; plant-average concentrations of iodo-THM and halonitromethane
species were typically less than 0.002 mg/L, which is an order of
magnitude lower than the corresponding average concentrations of TTHM
and HAA5 at those same plants. Chloropicrin, a halonitromethane
species, was also measured in the ICR with a median concentration of
0.00019 mg/L across all surface water samples. No occurrence data exist
for the iodoacids due to the lack of a quantitative method and
standards. Further work on chemical formation of iodo-DBPs and
halonitromethanes is needed.
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