Imidacloprid; Order Denying Objections to Issuance of Tolerance

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: May 26, 2004 (Volume 69, Number 102)]
[Rules and Regulations]
[Page 30041-30076]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26my04-14]
[[Page 30042]]

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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 180
[OPP-2004-0152; FRL-7355-7]

AGENCY: Environmental Protection Agency (EPA).
ACTION: Final order.

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SUMMARY: On four occasions in the first half of 2002, the Natural
Resource Defense Council (NRDC) and various other parties filed
objections with EPA to final rules under section 408 of the Federal
Food, Drug, and Cosmetic Act (FFDCA) establishing pesticide tolerances
for various pesticides. The objections apply to 14 pesticides and over
70 separate pesticide tolerances. Although the objections raise
numerous pesticide-specific issues, they all focus on the potential
risks that the pesticides pose to farm children. This order responds to
NRDC's objections as to the imidacloprid tolerance on blueberries. The
objections are denied as moot because this imidacloprid tolerance has
expired. Because EPA is elsewhere in today's Federal Register
reestablishing the imidacloprid tolerance on blueberries, EPA has
treated NRDC's objections as comments on the petition to reestablish
the blueberry tolerance and has explained in full in this document why
NRDC's objections are not well taken.

ADDRESSES: EPA has established a docket for this action under Docket ID
number OPP-2004-0152 All documents in the docket are listed in the
EDOCKET index at http://www.epa.gov/edocket. Although listed in the
index, some information is not publicly available, i.e., CBI or other
information whosedisclosure 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 in
EDOCKET or in hard copy at the Public Information and Records Integrity
Branch (PIRIB), Rm. 119, Crystal Mall #2, 1921 Jefferson Davis
Hwy., Arlington, VA., Monday through Friday, excluding legal holidays.
The Docket telephone number is (703) 305-5805.

FOR FURTHER INFORMATION CONTACT: William Jordan, Office of Pesticide
Programs, 7506C, Environmental Protection Agency, 1200 Pennsylvania
Ave., NW., Washington, DC 20460-0001; telephone number: (703) 308-4099;
fax number: (703) 308-4776; e-mail address: jordan.william@epa.gov.

SUPPLEMENTARY INFORMATION:

Response to NRDC Objections

Table of Contents

I. General Information
A. Does this Action Apply to Me?
B. How Can I Get Additional Information, Including Copies of this
Document and Other Related Documents?
1. Electronically.
2. In person.
II. Introduction
A. What Action is the Agency Taking?
B. What is the Agency's Authority for Taking this Action?
III. Statutory and Regulatory Background
A. Statutory Background
B. Assessing Risk Under the FFDCA
C. Science Policies
1. Children's Safety Factor Policy.
2. Aggregate exposure policies.
D. NRDC Farmworker Children Petition
IV. NRDC Objections
A. In General
B. Generic Issues
V. Public Comment
A. General
B. Individual Comments
1. The FQPA Implementation Working Group.
2. Inter-Regional Research Project Number 4 (IR-4).
3. Bayer CropScience.
VI. Response to Objections
VII. Analysis of the Issues Raised by NRDC's Objections
A. Children's Exposure to Pesticides in Agricultural Areas.
1. Studies Focusing on exposure to children in agricultural areas.
a. Potential for exposure due to heightened pesticide levels in the
homes of farm children.
b. Whether farm children actually experience increased exposure.
i. Studies allowing comparison of children from agricultural and
non-agricultural areas.
ii. Studies focusing solely on children from agricultural areas.
iii. Ongoing research on farm children exposures.
c. Conclusion.
2. Supplemental information regarding spray drift and drift of
volatilized residues.
3. EPA data on spray drift and the spray drift model.
B. Failed to Retain Children's 10X Safety Factor
1. Introduction.
2. EPA's children safety factor decision.
a. In general.
b. Imidacloprid.
3. Missing Toxicity Data--Lack of DNT.
4. Missing Exposure Data--General.
a. Farm children exposure.
b. Lack of comprehensive DW monitoring data.
i. Models and data.
ii. EPA's drinking water models.
iii. Imidacloprid-specific data.
iv. Conclusion.
5. Missing exposure data--specific.
a. Information on regional consumption.
b. Residential exposure information.
c. Prospective ground water monitoring studies.
6. Missing risk assessment.
7. Conclusion on children's safety factor issues.
C. LOAEL/NOAEL
1. Generic legal argument.
2. Use of LOAELs to assess Imidacloprid risk.
D. Aggregate Exposure
1. Worker exposure.
2. Classification of farm children as a major identifiable
population subgroup.
3. NRDC's 1998 Petition on Farm Children.
4. Adequacy of EPA's assessment of the aggregate exposure of
children, including children in agricultural areas.
5. Residential exposure as a result of use requiring a tolerance.
6. Population percentile used in aggregate exposure estimates.
a. In general.
b. Choice of population percentile.
7. Lack of residential exposure assessment for adults.
8. Percent crop treated.
E. Lack of Emergency
VIII. Response to Comments
A. IWG Comments
B. Citizen Comments
C. IR-4 Comments
IX. Statutory and Executive Order Reviews
X. Congressional Review Act
XI. Time and Date of Entry of Order
XII. References

I. General Information

A. Does this Action Apply to Me?

In this document EPA denies as moot objections to a tolerance
action filed by NRDC. In addition to NRDC, this action will be of
interest to the pesticide manufacturers and pesticide registrants whose
product was the subject of the objections. Further, this action may be
of interest to the following parties who have filed similar objections
with EPA on other pesticide tolerances: Boston Women's Health Book
Collective, Breast Cancer Action, Californians for Pesticide Reform,
Commonweal, Lymphoma Foundation of America, NRDC, Northwest Coalition
for Alternatives to Pesticides, Pesticide Action Network, North
America, Pineros y Campesinos Unidos del Noroeste, SF-Bay Area Chapter
of Physicians for Social Responsibility, and Women's Cancer Resource
Center. Finally, this action may be of interest to agricultural
producers, food manufacturers, or other pesticide manufacturers.
Potentially affected categories and entities may include, but are not
limited to:
? Industry, e.g., NAICS 111, 112, 311, 32532, Crop production, Animal

[[Page 30043]]

production, Food manufacturing, Pesticide manufacturing.
This listing is not intended to be exhaustive, but rather provides
a guide for readers regarding entities who may be interested in this
action.

B. How Can I Get Additional Information, Including Copies of this
Document and Other Related Documents?

1. Electronically. You may obtain electronic copies of this
document, and certain other related documents that might be available
electronically, from the EPA Internet Home Page at http://www.epa.gov/.
To access this document, on the Home Page select ``Laws and
Regulations,'' ``Regulations and Proposed Rules,'' and then look up the
entry for this document under the Federal Register--Environmental
Documents. You can also go directly to the Federal Register listings at
http://www.epa.gov/fedrgstr/.
2. In person. The Agency has opened a docket for this action under
docket ID number OPP-2002-0057. Included in the docket are EPA
documents specifically referenced in this action, any public comments
received during an applicable comment period, and other information
submitted by NRDC. The docket does not include any information claimed
as CBI. The docket is available for inspection in the Public
Information and Records Integrity Branch (PIRIB), Rm. 119, Crystal Mall
#2, 1921 Jefferson Davis Hwy., Arlington, VA, from 8:30 a.m. to
4 p.m., Monday through Friday, excluding legal holidays. The PIRIB
telephone number is (703) 305-5805.

II. Introduction

A. What Action is the Agency Taking?

On four occasions in the first half of 2002, NRDC and various other
parties filed objections with EPA to final rules under section 408 of
FFDCA, 21 U.S.C. 346a, establishing pesticide tolerances for various
pesticides. The objections apply to 14 pesticides and over 70 separate
pesticide tolerances. Although the objections raise numerous pesticide-
specific issues, they all focus on the potential risks that the
pesticides pose to farm children. Further each of the objections makes
two main assertions with regard to the pesticide tolerances in question:
1. That EPA has not properly applied the additional 10X safety
factor for the protection of infants and children in section
408(b)(2)(C) of FFDCA.
2. That EPA has not accurately assessed the aggregate exposure of
farm children to pesticide residues.
NRDC did not exercise the option provided in section 408(h) of
FFDCA to request a hearing on its objections, but instead asked that
the Agency rule on its objections on the basis of its written
objections and attached submissions. Because the objections raised
questions of broad interest, EPA published a representative copy of the
objections in the Federal Register for comment, (67 FR 41628) (June 19,
2002) (FRL-7167-7), and made all of the objections available for public
review on its website. This order responds to NRDC's objections as to
the imidacloprid tolerance on blueberries.
EPA had planned to respond to the four sets of objections in a
single order. That plan has been superceded by the December 31, 2003,
expiration of the objected-to imidacloprid tolerance on blueberries,
the demonstrable agricultural need for continuation of use of
imidacloprid on blueberries, and NRDC's submission in June, 2003 of
significant supplemental information on its objections. Technically,
NRDC's objections to the imidacloprid tolerance on blueberries have
become moot due to the expiration of the tolerance and this order
denies them on that ground. Nonetheless, due to the fact that elsewhere
in today's Federal Register EPA is re-establishing an imidacloprid
tolerance on blueberries, EPA has treated the objections as a comment
on the petition to re-establish the imidacloprid tolerance and is
issuing in this denial order its planned response to the objections as
a response to comments on the proposed establishment of the
imidacloprid tolerance. If NRDC files the same objections to the re-
established imidacloprid tolerance, EPA will re-issue this comment
response as a response to NRDC's objection forthwith. EPA cannot issue
its response to all four sets of NRDC's objections at this time because
EPA has not completed reviewing supplemental information on the
objections submitted by NRDC in June, 2003. As to imidacloprid,
however, specific facts relating to that pesticide allow EPA to address
all of the issues raised by the objections to that tolerance.
The body of this document contains the following sections. First,
there is a background section which explains the applicable statutory
and regulatory provisions, the relevant EPA science policy documents,
and prior NRDC actions with regard to farm children. Second, there is a
section setting forth in greater detail the substance of the
objections. Third, a summary of the public comment is presented.
Fourth, there is a section which denies theobjections to the
imidacloprid tolerance as moot. Finally, EPA's detailed response to the
issues raised by the objections on the imidacloprid tolerance is
included as a part of its action in granting a permanent tolerance for
imidacloprid on blueberries.

B. What is the Agency's Authority for Taking this Action?

The procedure for filing objections to tolerance actions and EPA's
authority for acting on such objections is contained in section 408(g)
of FFDCA and regulations at 40 CFR part 178. 21 U.S.C. 346a(g).

III. Statutory and Regulatory Background

A. Statutory Background

EPA establishes maximum residue limits, or ``tolerances,'' for
pesticide residues in food under section 408 of FFDCA. 21 U.S.C. 346a.
Without such a tolerance or an exemption from the requirement of a
tolerance, a food containing a pesticide residue is ``adulterated''
under section 402 of FFDCA and may not be legally moved in interstate
commerce. 21 U.S.C. 331, 342. Monitoring and enforcement of pesticide
tolerances are carried out by the U.S. Food and Drug Administration
(FDA) and the U. S. Department of Agriculture (USDA).
A pesticide tolerance may only be promulgated by EPA if the
tolerance is ``safe.'' 21 U.S.C. 346a(b)(2)(A)(i). ``Safe'' is defined
by the statute to mean that ``there is a reasonable certainty that no
harm will result from aggregate exposure to the pesticide chemical
residue, including all anticipated dietary exposures and all other
exposures for which there is reliable information.'' 21 U.S.C.
346a(b)(2)(A)(ii). Section 408 of FFDCA directs EPA, in making a safety
determination, to ``consider, among other relevant factors . .
.available information concerning the aggregate exposure levels of
consumers (and major identifiable subgroups of consumers) to the
pesticide chemical residue and to other related substances, including
dietary exposure under the tolerance and all other tolerances in effect
for the pesticide chemical residue, and exposure from other non-
occupational sources.'' 21 U.S.C. 346a(b)(2)(D)(vi). Other provisions
address in greater detail exposure considerations involving
``anticipated and actual residue levels'' and ``percent of crop
actually treated.'' See 21 U.S.C. 346a(b)(2)(E) and (F). Section
408(b)(2)(C) of FFDCA requires EPA to give special consideration to
risks posed

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to infants and children. This provision directs that ``an additional
tenfold margin of safety for the pesticide chemical residue and other
sources of exposure shall be applied for infants and children to take
into account potential pre- and post-natal toxicity and completeness of
the data with respect to exposure and toxicity to infants and
children.'' 21 U.S.C. 346a(b)(2)(C). EPA is permitted to ``use a
different margin of safety for the pesticide chemical residue only if,
on the basis of reliable data, such margin will be safe for infants and
children.'' Id. [The additional safety margin for infants and children
is referred to throughout this notice as the ``children's safety
factor.'']
These provisions establishing the detailed safety standard
for pesticides were added to section 408 of FFDCA by the Food Quality
Protection Act of 1996 (FQPA), an Act that substantially rewrote this
section of the statute.
Tolerances are established by rulemaking under the unique
procedural framework set forth in FFDCA. Generally, the rulemaking is
initiated by the party seeking the tolerance by means of filing a
petition with EPA. See 21 U.S.C. 346a(d)(1). EPA publishes in the
Federal Register a notice of the petition filing along with a summary
of the petition, prepared by the petitioner. 21 U.S.C. 346a(d)(3).
After reviewing the petition, and any comments received on it, EPA may
issue a final rule establishing the tolerance, issue a proposed rule,
or deny the petition. 21 U.S.C. 346a(d)(4). Once EPA takes final action
on the petition by either establishing the tolerance or denying the
petition, any affected party has 60 days to file objections with EPA
and seek an evidentiary hearing on those objections. 21 U.S.C.
346a(g)(2). EPA's final order on the objections is subject to judicial
review. 21 U.S.C. 346a(h)(1).
EPA also regulates pesticides under FIFRA, 7 U.S.C. 136 et seq.
While the FFDCA authorizes the establishment of legal limits for
pesticide residues in food, FIFRA requires the approval of pesticides
prior to their sale and distribution, 7 U.S.C. 136a(a), and establishes
a registration regime for regulating the use of pesticides. FIFRA
regulates pesticide use in conjunction with its registration scheme by
requiring EPA review and approval of pesticide labels and specifying
that use of a pesticide inconsistent with its label is a violation of
federal law. 7 U.S.C. 136j(a)(2)(G). In the FQPA, Congress integrated
action under the two statutes by requiring that the safety standard
under the FFDCA be used as a criterion in FIFRA registration actions as
to pesticide uses which result in dietary risk from residues in or on
food, 7 U.S.C. 136(bb), and directing that EPA coordinate, to the
extent practicable, revocations of tolerances with pesticide
cancellations under FIFRA. 21 U.S.C. 346a(l)(1).

B. Assessing Risk Under the FFDCA

In assessing and quantifying non-cancer risks posed by pesticides
under the FFDCA as amended by the FQPA, EPA first determines the
toxicological level of concern and then compares estimated human
exposure to this level of concern. This comparison is done through
either calculating a safe dose in humans (incorporating all appropriate
safety factors) and expressing exposure as a percentage of this safe
dose (the reference dose (RfD) approach) or dividing estimated human
exposure into the lowest dose at which no adverse effects from the
pesticide are seen in relevant studies (the margin of exposure (MOE)
approach). How EPA determines the level of concern, chooses safety
factors, and estimates risk under these two approaches is explained in
more detail below.
For dietary risk assessment (other than cancer), the dose at which
no adverse effects are observed (the NOAEL) from the toxicology study
identified as appropriate for use in risk assessment is used to
estimate the toxicological level of concern. However, the lowest dose
at which adverse effects of concern are identified (the LOAEL) is
sometimes used for risk assessment if no NOAEL was achieved in the
toxicology study selected. A safety or uncertainty factor is then
applied to this toxicological level of concern to calculate a safe dose
for humans, usually referred to by EPA as an acute or chronic reference
dose (acute RfD or chronic RfD). The RfD is equal to the NOAEL divided
by all applicable safety or uncertainty factors. Typically, a safety or
uncertainty factor of 100 is used, 10X to account for uncertainties
inherent in the extrapolation from laboratory animal data to humans and
10X for variations in sensitivity among members of the human population
as well as other unknowns. Further, under the FQPA, an additional
safety factor of 10X is presumptively applied to protect infants and
children, unless reliable data support selection of a different factor.
To quantitatively describe risk using the RfD approach, estimated
exposure is expressed as a percentage of the RfD. Dietary exposures
lower than 100% of the RfD are generally not of concern.
For non-dietary, and combined dietary and non-dietary, risk
assessments (other than cancer), the same safety factors are used to
determine the toxicological level of concern. For example, when 1,000
is the appropriate safety factor (10X to account for interspecies
differences, 10X for intraspecies differences, and 10X for FQPA), the
level of concern is that there be a 1,000-fold margin between the NOAEL
from the toxicology study identified as appropriate for use in risk
assessment and human exposure. To estimate risk, a ratio of the NOAEL
to aggregate exposures (MOE = NOAEL/exposure) is calculated and
compared to the level of concern. In contrast, to the RfD approach, the
higher the MOE, the safer the pesticide. Accordingly, if the level of
concern for a pesticide is 1,000, MOE's exceeding 1,000 would generally
not be of concern.
For cancer risk assessments, EPA generally assumes that any amount
of exposure will lead to some degree of cancer risk. Using a model
based on the slope of the cancer dose-response curve in relevant
studies, EPA estimates risk in terms of the probability of occurrence
of additional cancer cases as a result of exposure to the pesticide. An
example of how such a probability risk is expressed would be to
describe the risk as one in one hundred thousand (1 X
10-\5\), one in a million (1 X 10-\6\), or one in
ten million (1 X 10-\7\). Under certain specific
circumstances, MOE calculations will be used for the carcinogenic risk
assessment. No further discussion of cancer risk assessment is included
because imidacloprid has not been identified as posing a cancer risk.

C. Science Policies

As part of implementation of the major changes to section 408 of
FFDCA included in FQPA, EPA has issued a number of policy guidance
documents addressing critical science issues. Of particular interest to
the NRDC objections are the science policies covering the children's
safety factor, aggregate pesticide exposure, and the population
percentile of exposureused in estimating aggregate exposure.
1. Children's Safety Factor Policy. On January 31, 2002, EPA
released its science policy guidance on the children's safety factor.
(Ref. 48), [hereinafter referred to in the text as the ``Children's
Safety Factor Policy'']. That policy had undergone an intensive and
extended process of public comment as well as internal and external
science peer review. An EPA-wide task force was established to consider
the children's safety factor in March 1998. Taking into account reports
issued by

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the task force on both toxicity and exposure issues, EPA's OPP released
a draft children's safety policy document in May 1999. That document
was subject to an extended public comment period as well as review by
the FIFRA Scientific Advisory Panel. Id. at 5.
The Children's Safety Factor Policy emphasizes throughout that EPA
interprets the children's safety factor provision as establishing a
presumption in favor of application of an additional 10X safety factor
for the protection of infants and children. Id. at 4, 11, 47, A-6.
Further, EPA notes that the children's safety factor provision permits
a different safety factor to be substituted for this default 10X factor
only if reliable data are available to show that the different factor
will protect the safety of infants and children. Id. Given the wealth
of data available on pesticides, however, EPA indicated a preference
for making an individualized determination of a protective safety
factor if possible. Id. at 11. EPA stated that use of the default
factor could under- or over-protect infants and children due to the
wide variety of issues addressed by the children's safety factor. Id.
EPA noted that ``[i]ndividual assessments may result in the use of
additional factors greater or less than, or equal to 10X, or no
additional factor at all.'' Id. Because EPA thought that individualized
assessments would be able to be made in most cases, EPA indicated that
``this guidance document focuses primarily on the considerations
relevant to determining a safety factor `different' from the default
10X that protects infants and children. Discussions in this document of
the appropriateness, adequacy, need for, or size of an additional
safety factor are premised on the fact that reliable data exist for
choosing a `different' factor than the 10X default value.'' Id. at 12.
In making such individual assessments regarding the magnitude of
the safety factor, EPA stressed the importance of focusing on the
statutory language that ties the children's safety factor to concerns
regarding potential pre- and post-natal toxicity and the completeness
of the toxicity and exposure databases. Id. at 11-12. As to the
completeness of the toxicity database, EPA recommended use of a weight
of the evidence approach which considered not only the presence or
absence of data generally required under EPA regulations and guidelines
but also the availability of ``any other data needed to evaluate
potential risks to children.'' Id. at 20. EPA indicated that the
principal inquiry concerning missing data would center on whether the
missing data would significantly affect calculation of a safe exposure
level (commonly referred to as the Reference Dose (RfD)). Id. at 22;
see 67 FR 60950, 60955 (Sept. 27, 2002) (finding no additional safety
factor necessary for triticonazole despite lack of developmental
neurotoxicity (DNT) study because the ``DNT is unlikely to affect the
manner in which triticonazole is regulated.''). When the missing data
are data above and beyond general regulatory requirements, EPA
indicated that the weight of evidence would generally only support the
need for an additional safety factor where the data ``is being required
for `cause,' that is, if a significant concern is raised based upon a
review of existing information, not simply because a data requirement
has been levied to expand OPP's general knowledge.'' (Ref 48 at 23).
Finally, with regard to the developmental neurotoxicity study (DNT),
EPA listed several important factors addressing the weight of evidence
bearing on the degree of concern when such a study has been required
but has not yet been completed. Id. at 24. Moreover, EPA reiterated
that, like any other missing study, the absence of the DNT does not
trigger a mandatory requirement to retain the default 10X value, but
rather depends on an individualized assessment centering on the
question of whether ``a DNT study is likely to identify a new hazard or
effects at lower dose levels of the pesticide that could significantly
change the outcome of its risk assessment . . . '' Id.
As to potential pre- and post-natal toxicity, the Children's Safety
Factor Policy lists a variety of factors that should be considered in
evaluating the degree of concern regarding any identified pre- or post-
natal toxicity. Id. at 27-31. As with the completeness of the toxicity
database, EPA emphasized that the analysis should focus on whether any
identified pre- or post-natal toxicity raises uncertainty as to whether
the RfD is protective of infants and children. Id. at 31. Once again,
the presence of pre- or post-natal toxicity, by itself, was not
regarded as determinative as to the children's safety factor. Rather,
EPA stressed the importance of evaluating all of the data under a
weight of evidence approach focusing on the safety of infants and
children. Id.
In evaluating the completeness of the exposure database, EPA
explained that a weight of the evidence approach should be used to
determine the confidence level EPA has as to whether the exposure
assessment ``is either highly accurate or based upon sufficiently
conservative input that it does not underestimate those exposures that
are critical for assessing the risks to infants and children.'' Id. at
32. EPA described why its methods for calculating exposure through
various routes and aggregating exposure over those routes generally
produce conservative exposure estimates--i.e. health-protective
estimates due to overestimation of exposure. Id. at 40-43. Nonetheless,
EPA emphasized the importance of verifying that the tendency for its
methods to overestimate exposure in fact were adequately protective in
each individual assessment. Id. at 44.
2. Aggregate exposure policies. As mentioned above, the FQPA-added
safety standard directs that the safety of pesticide residues in food
be based on ``aggregate exposure'' to the pesticide. 21 U.S.C.
346a(b)(2)(A)(ii). Aggregate exposure to a pesticide includes all
``anticipated dietary exposure and all other exposures for which there
is reliable information.'' Id. The statute makes clear that in
assessing aggregate exposure pertaining to a pesticide EPA must
consider not only exposure to the pesticide in the food covered by the
tolerance in question but exposure to the pesticide as a result of
other tolerances and from ``other non-occupational sources.'' Id.
Section 346a(b)(2)(D)(vi). Further, the statute directs EPA to consider
aggregate exposure to other substances related to the pesticide so long
as that exposure results from a non-occupational source. Id. Section
346a(b)(2)(D)(vi). In November 2001, EPA released a science guidance
document entitled General Principles for Performing Aggregate Exposure
and Risk Assessments. This document deals primarily with the complex
subject of integrating distributional and probabilistic techniques into
aggregate exposure analyses. (Ref. 49).
More relevant to the current objections, is the science guidance
document issued in March 2000 addressing the population percentile of
exposure used in making acute exposure estimates for applying the
safety standard under section 408 of FFDCA. (Ref. 52). Traditionally,
EPA had used the 95\th\ percentile of exposure in acute dietary
exposure assessments as representing a reasonable worst case scenario.
Id. at 15. Due to the very conservative (health-protective) assumptions
used for acute exposure assessments, the 95\th\ percentile was viewed
as a reasonable approximation of an exposure level not likely to be
exceeded by any individuals. Id. at 15-17. Generally, such an approach
assumes that all crops for which there is a tolerance are treated with the

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pesticide and all treated crops have residues at the highest level
legally permitted.
More recently, because of the availability of better data on
residue values and new risk assessment techniques, EPA has restructured
its approach to the use of population exposure percentiles in making
safety determinations for acute risks under section 408 of FFDCA. (Ref.
52). EPA has retained the 95\th\ percentile as the starting point of
analysis for worst case (tolerance level) assessments. EPA, however,
generally uses higher percentiles of exposure when less conservative
assumptions are made concerning residue values. Id. For example,
beginning in the late 1990's, EPA has increasingly relied upon
probabilistic assessment techniques for assessing acute dietary
exposure and risk. Because EPA generally uses much more realistic
exposure values (e.g., monitoring data on pesticide levels in food) in
conducting probabilistic assessments, a higher population exposure
percentile was generally found to be necessary to ensure that exposure
for the overall population was not understated. The Percentile Policy
explains and defends EPA's choice of the 99.9\th\ percentile as a
starting point for evaluating exposure and acute risk with
probabilistic assessments.
EPA confirmed in the Percentile Policy document that it would
generally continue to use the 95\th\ percentile of exposure for
deterministic acute risk assessments that used worst case exposure
assumptions. Id. at 17, 29. The conservative (health-protective) nature
of this approach was confirmed by data EPA cited showing that
deterministic assessments of exposure at the 95\th\ percentile assuming
residues at tolerance levels regularly result in exposure predictions
significantly higher than probabilistic exposure estimates of the
99.9\th\ percentile using monitoring data. Id. at 16-17.
Importantly, EPA's Percentile Policy makes clear that in choosing a
population percentile to estimate exposure, EPA is not intending to
define the portion of the population that is to be protected. The
policy explicitly states that: ``OPP's goal is to regulate pesticides
in such a manner that everyone is reasonably certain to experience no
harm as a result of dietary and other non-occupational exposures to
pesticides.'' Id. at 28.

D. NRDC Farmworker Children Petition

On October 22, 1998, NRDC and 58 other public interest
organizations and individuals submitted a petition to EPA asking that
EPA ``find that farm children are a major identifiable subgroup and
must be protected under FQPA when setting allowable levels of pesticide
residue in food.'' (Ref. 36 at 2). The Petition claims that ``[a]n
increasing body of scientific evidence, including biomonitoring data
and residential exposure studies, indicates that farm children face
particularly significant exposures and health risks from pesticides.''
Id. at 3. In addition to requesting the ``major identifiable subgroup''
designation, the Petition also asked that EPA use the children's safety
factor to protect farm children, require additional exposure data on
farm children exposure and not issue any new tolerances until such data
are available, deny registration for any pesticide without a validated
method for detecting residues in food, increase research into issues
concerning farm children exposure to pesticides, and honor the
President's Executive order on Environmental Justice.
Although EPA prior to this action has not issued a formal response
to the petition, it has undertaken numerous steps to ensure that it is
adequately protecting farm children including both initiating data
gathering on exposure of children in agricultural areas to pesticides
and programs to enhance compliance with label directions designed to
minimize any bystander exposures to pesticides that could occur. Data
gathering activities include EPA participation in the following studies:
National Agricultural Workers Survey (NAWS). EPA and the National
Institute for Occupational Safety and Health (NIOSH) are currently
providing funding for the NAWS, an ongoing effort by the Department of
Labor. The NAWS is the only national information source on the working
and living conditions of U.S. farmworkers and their families. EPA is
working with the Department of Labor in analyzing over 20,000
interviews since the survey's onset to look at farm worker experiences
over time. The interviews include questions concerning the following:
Demographics, farmworkers' job mobility, day care arrangements, access
to medical care, participation in pesticide training, exposures to
pesticides, and reports of pesticide illness. Results from this survey,
along with other studies, will assist EPA in addressing issues of
pesticide exposures to farmworkers and any secondary exposures to their
families. Additional information on the NAWS survey can be found at
http://www.dol.gov/asp/programs/agworker/naws.htm.
Agricultural health study. The National Cancer Institute (NCI),
EPA, NIOSH, and the National Institute of Environmental Health and
Safety are conducting a long-term epidemiology study of 90,000
certified pesticide applicators and their families in North Carolina
and Iowa. The study is looking at both cancer and non-cancer endpoints
using periodic surveys of the population. Pesticide use practices and
health outcomes are being examined in detail. Additionally, scientists
are conducting other studies on this cohort to learn further about
exposures and potential effects, including birth defects, Parkinson's
disease, asthma, and other disease endpoints. As part of the
Agricultural Health Study, field work in Iowa is being conducted, and
over the next three years detailed exposure analyses on a sub-sample of
families using various agricultural pesticides will be completed. Some
initial results have already been published for high exposure events
and effects to the eye. A detailed listing of these studies and a
number of publications already reporting the results of the
Agricultural Health Study can be found at http://www.aghealth.org/.

The Agency is also pursuing several other research efforts likely
to provide additional information about any pesticide exposure to
farmworkers and their children:
National Human Exposure Assessment Survey (NHEXAS). EPA developed
this survey in the early 1990s to provide critical information about
multi-pathway, multi-media population exposure distribution to
chemicals. The data have been collected and the database is now being
compiled. EPA expects to have the information accessible on the
Internet later this year.
Children's total exposure to persistent pollutants. This study,
conducted by EPA, will add to our understanding of any pesticide
exposures to farmworker families. The data collection for this study,
initiated this year, should be completed and available in 2004.
In terms of actions taken to enhance protections to children so as
to avoid bystander-type exposures, EPA has numerous programs and
materials focusing upon pesticide safety issues for farm workers and
their families both at the national and regional level. A brief
overview of EPA's approaches will be discussed here. However, more
information about EPA's farm worker efforts across its regional offices
can be found in the docket for this action.
An overview of what EPA is doing on the national level includes an
assessment of the EPA's 1992 Worker Protection Standard (WPS). See 40
CFR part 170. The Worker Protection Standard is a regulation intended to

[[Page 30047]]

help reduce the risk of pesticide poisonings and injuries among
agricultural workers and handlers of agricultural pesticides. The WPS
offers protections to over three and a half million people who work
with pesticides at over 560,000 workplaces. The WPS contains
requirements for pesticide safety training, notification of pesticide
applications, use of personal protective equipment, restricted entry
intervals following pesticide application, decontamination supplies,
and emergency medical assistance. The national overview of
implementation and enforcement of WPS programs has been completed and
recommendations are being compiled. The national assessment of WPS was
a collaborative effort of EPA, the USDA, the Department of Labor, the
Department of Health and Human Services (HHS), States, farm workers,
and farmers. The reassessment effort included a great amount of
stakeholder input, and has led to the development of a variety of pilot
programs intended to improve the Agency's outreach to farm workers.
Other examples of activities conducted at the national level
include the Agency's cooperative agreement with the Association of Farm
Worker Opportunity Programs (AFOP) through which EPA funds the National
Pesticide Safety Education Program for agricultural workers and farm
worker children. Working with Americorps members, AFOP trains 25,000
farm workers and farm worker children every year about pesticide safety
using Americorps members in over 50 sites in 16 states. AFOP conducts
pesticide safety training for children at childcare centers, schools,
churches, and community centers, and has developed a handbook in
Spanish. Also, through EPA funding, AFOP has developed radio programs
targeted at preventing pesticide poisonings of children.
Also on the national level, EPA has initiated a program with the
Migrant Head Start Program (MHS) to develop materials and training for
MHS on pesticide safety for migrant families with specific attention to
protecting children from pesticides. MHS is designed to provide
comprehensive Head Start services and programming to migrant families
and their children. A total of 25 grantees and 41 delegate agencies
provide services in 33 States and serve over 30,000 migrant children,
and 25,000 children of seasonal workers, ranging in age from birth to 5
years. The MHS program has a unique emphasis on serving infants and
toddlers as well as pre-school age children, so they will not have to
be cared for in the fields, or left in the care of very young siblings
while parents are working. MHS also teams with Americorps to provide
refresher training on pesticide safety.
EPA on a national level, has also been involved in the development
of two videos on pesticide safety for farmworkers and their families.
The video, ``Chasing the Sun/Siguiendo El Sol,'' is a bilingual
farmworker pesticide safety training video designed to comply with the
agricultural worker training requirements mandated under the Worker
Protection Standard. It was developed by the National Center for
Farmworker Health and funded through an interagency agreement between
EPA and HHS Migrant Health Program. This video is available through
NCEPI and the National Center for Farmworker Health.
Another video, entitled The Playing Field is a bilingual pesticide
safety training video for farmworker families. Through a story about a
girl poisoned by playing in a treated field, the video teaches
farmworkers and farmworker children about the dangers of pesticides and
how to protect themselves from pesticides. The video was developed by
the National Center for Farmworker Health and funded through an
interagency agreement between EPA and the HHS Migrant Health Program.
The video is available through the National Center for Farmworker Health.
Finally, EPA's regional offices have performed, and are performing,
a number of outreach activities. These activities can be divided into
three general categories: Direct outreach; partnerships, where the
Agency provides funding and/or technical assistance, and research.
Examples of EPA's activities on pesticide safety for farm workers and
their families can befound in EPA's docket.

IV. NRDC Objections

A. In General

During the first half of 2002, NRDC submitted four separate sets of
objections on various pesticide tolerances. The dates of the objections
and the pesticides involved are captured in Table 1 of this unit.

Table 1.--Objections Submitted
------------------------------------------------------------------------
Pesticides FR citations
Date submitted involved (respectively)
------------------------------------------------------------------------
February 25, 2002 Halosulfuron- 66 FR 66,333
methyl, (December 26,
pymetrozine 2001); 66 FR
66,778 (December
27, 2002); 66 FR
66,786 (December
27, 2001)
================================
March 19, 2002 Imidacloprid, 67 FR 2580 (January
mepiquat, 18, 2002); 67 FR
bifenazate, zeta- 3113 (January, 23,
cypermethrin, 2002); 67 FR 4913
diflubenzuron (February 1,
2002); 67 FR 6422
(February 12,
2002); 67 FR 7085
(February 15,
2002)
================================
May 7, 2002 2,4-D 67 FR 10622 (March
8, 2002)
================================
May 20, 2002 Isoxadifen-ethyl, 67 FR 12,875 (March
acetamiprid, 20, 2002); 67 FR
propiconazole, 14,649 (March 27,
furilazole, 2002); 67 FR
fenhexamid, 14,866 (March 28,
fluazinam 2002); 67 FR
15,727 (April 3,
2002); 67 FR
19,114 (April 18,
2002); 67 FR
19,120 (April 18,
2002)
------------------------------------------------------------------------

See Objections to the Establishment of Tolerances for Pesticide
Chemical Residues: Halosulfuron-methyl and Pymetrozine Tolerances
(filed February 25, 2002) [hereinafter cited as Halosulfuron-methyl
Objections]; Objections to the Establishment of Tolerances for
Pesticide Chemical Residues: Imidacloprid, Mepiquat, Bifenazate, Zeta-
cypermethrin, and Diflubenzuron Tolerances (filed March 19, 2002)
[hereinafter cited as Imidacloprid et al. Objections], Objections to
the Establishment of Tolerances for Pesticide Chemical Residues: 2,4-D
Tolerances (filed May 7, 2002) [hereinafter cited as 2,4-D Objections];
Objections to the Establishment of Tolerances for Pesticide Chemical
Residues: Isoxadifen-ethyl, Acetamiprid, Propiconazole, Furilazole,
Fenhexamid, and Fluazinam Tolerances (filed May 20, 2002) [hereinafter
cited as Isoxadifen-ethyl et al. Objections]. NRDC was joined in the
objections concerning 2,4-D by the following

[[Page 30048]]

public interest and/or advocacy organizations: Boston Women's Health
Book Collective, Breast Cancer Action, Californians for Pesticide
Reform, Commonweal, Lymphoma Foundation of America, Northwest Coalition
for Alternatives to Pesticides, Pesticide Action Network North America,
Pineros y Campesinos Unidos del Noroeste, SF-Bay Area Chapter of
Physicians for Social Responsibility, and Women's Cancer Resource
Center.
This order responds to the objections filed on March 19, 2002, but
only to the extent those objections apply to the pesticide imidacloprid
and the tolerance for imidacloprid on blueberries.

B. Generic Issues

NRDC raises a myriad of claims in its objections to the
imidacloprid tolerance. Most of these claims fall fairly neatly into
three categories:
? Children's safety factor issues.
? Aggregate exposure issues.
? Issues regarding use of findings from hazard studies in
calculating safe exposure levels-- the ``no observed effect level''
(NOEL) versus ``no observed adverse effect level'' (NOAEL) and the
``lowest observed adverse effect level'' (LOAEL) questions.
In describing these objections, citation is made generally to the
objections filed on the imidacloprid tolerance; however, one of the
other sets of objections is referenced if it provides further
clarification.
1. Children's safety factor issues. For imidacloprid, EPA decided
to use an additional safety factor for the protection of infants and
children that is different from the default 10X value. NRDC claims that
EPA erred in doing so due to the ``significant toxicity and exposure
data gaps'' corresponding to the tolerance established. See, e.g.,
Imidacloprid et al. Objections at 3. Three types of data gaps are cited
by NRDC. First, NRDC notes that EPA has required a developmental
neurotoxicity study but such study has not yet been submitted. Pointing
to various EPA documents recommending that this study be widely
required and EPA's specific finding that this study is required as to
imidicloprid, NRDC argues that use of a factor different than 10X is
precluded. Second, NRDC claims EPA lacks ``pesticide-specific data on
water-based exposure'' on imidacloprid. See, e.g., Imidacloprid et al.
Objections at 6. NRDC argues that exposure estimates EPA calculated
through the use of models cannot qualify as the ``reliable data''
needed to vary from the default 10X value. Id. Third, NRDC claims that
``EPA failed to consider important exposure routes for millions of
infants and children, including exposure to children living on farms
and who accompany their parents into farm fields [], and exposure from
spray drift.'' Isoxadifen-ethyl et al. Objections at 5. Fourth, NRDC
asserts that EPA is missing a prospective groundwater study on
imidacloprid and a short-term residential risk assessment. Imidacloprid
Objections at 5. Finally, NRDC argues that EPA lacks data on regional
blueberry consumption and thus has potentially underestimated exposure
in blueberry-producing states.
2. Aggregate exposure issues. NRDC raises several issues relating
to whether EPA properly estimated ``aggregate exposure'' for
imidacloprid. First, NRDC argues that farm children are a ``major
identifiable subgroup'' and that EPA has failed ``to consider
information concerning the sensitivities and exposures of farm children
as a major identifiable subgroup'' in conducting its aggregate exposure
assessment. According to NRDC, farm children have unique exposures to
pesticides ``from their parents' clothing, dust tracked into their
homes, contaminated soil in areas where they play, food eaten directly
from the fields, drift from aerial spraying, contaminated well water,
and breast milk.'' Imidacloprid et al. Objections at 12. Further, NRDC
asserts farm children's exposure is increased because they ``often
accompany their parents to work in the fields . . . .'' Id. NRDC cites
various studies collected in its Farm Children Petition as well as more
recent studies in support of these claims. Imidacloprid et al.
Objections at 12-13. Second, NRDC argues that EPA's aggregate exposure
assessment is flawed for these pesticides because EPA did not consider
the added exposure to pesticides that farmworkers receive as a result
of their occupation. Id. at 14. NRDC states that EPA's interpretation
of the statute as excluding occupational exposure is incorrect. Id.
Third, NRDC argues that for imidacloprid, EPA has, in effect,
underestimated aggregate exposure by using the 95\th\ population
percentile of exposure instead of the 99.9\th\ percentile in
determining whether exposure to the pesticide meets the safety
standard. Imidacloprid et al. Objections at 19. NRDC claims that this
is inconsistent with existing Agency policy. Id.
3. Reliance on LOAELs and NOAELs. NRDC asserts that, in the absence
of identifying a NOEL in relevant animal studies, EPA cannot make a
safety finding under section 408(b)(2)of FFDCA. In support of this
argument, NRDC cites to legislative history using the term NOEL. NRDC
calls particular attention to the instances where EPA determined safety
relying on a LOAEL. In this regard, it asserts that EPA used a LOAEL in
making a safety finding for acute and chronic toxicity for
imidacloprid. Imidacloprid et al. Objections at 18.
4. Other issues. NRDC claims that the EPA failed to comply with the
statutory requirements pertaining to the use of percent crop treated
for chronic risk assessments with regard to the imidacloprid blueberry
tolerance. NRDC asserts that the use of national percent crop treated
data cannot provide a valid basis for estimating exposure in Michigan
and New Jersey, and, in fact, is likely to understate exposure in those
states. Further, NRDC argues that EPA erred by relying on national
consumption data instead of regional data from New Jersey and Michigan
in estimating the risk posed by imidacloprid. Finally, NRDC, in
comments it filed on its objections, claims that the emergency
exemption approved under FIFRA authorizing the use of imidacloprid on
blueberries in Michigan did not meet the standard in 40 CFR 166.3(d)
for the granting of such exemptions.

V. Public Comment

A. General

On June 19, 2002, EPA published a notice in the Federal Register
calling attention to and requesting comments on the Halosulfuron-methyl
et al. Objections, Imidacloprid et al. Objections, and the 2,4-D
Objections. 67 FR 41628 (June 19, 2002). As part of that notice, EPA
published the full text of the Imidacloprid et al. Objections in the
Federal Register. A period of 60 days was initially allowed for comment
but that period was extended twice and was closed on October 16, 2002.
See 67 FR 58536 (September 17, 2003); 67 FR 53505 (August 16, 2002). In
addition to a large number of form letters (principally supporting the
objections) and the NRDC's comments mentioned in Unit V.B., EPA
received roughly 20 sets of substantive comments. These comments were
for the most part from pesticide manufacturers and each requested
denial of the objections. The most significant of these comments that
pertain to imidacloprid are summarized in Unit V.B. EPA has not
repeated comments in instances where they were made by more than one
commenter.

B. Individual Comments

1. The FQPA Implementation Working Group. Extensive comments were
filed by the FQPA Implementation Working Group (IWG), an organization
comprised of associations representing pesticide

[[Page 30049]]

manufacturers, growers, and food processors. (Ref. 21). The IWG
comments provided two alternative approaches as to why the NRDC's
objections should be denied. First, the IWG asserted that EPA has
misinterpreted the concept of ``aggregate exposure'' ever since passage
of the FQPA, and once this interpretation is corrected, it becomes
clear that the objections, for the most part, are flawed. Second, in
the alternative, the IWG, assuming the EPA's aggregate exposure
interpretation is retained, explained why the objections still are
without merit.
The IWG argues that, under the safety standard in section 408 of
FFDCA, 21 U.S.C. 346a, the concept of aggregate exposure to pesticide
chemical residues is restricted to aggregate exposure to pesticide
residues in food. Id. at 5-6. To support this interpretation, the IWG
cites to language in the safety standard tying aggregate exposure to
exposure to ``pesticide chemical residues.'' The term ``pesticide
chemical residue,'' the IWG notes, is defined as ``a residue in or on
raw agricultural commodity or processed food of . . . a pesticide
chemical . . . .'' 21 U.S.C. 321(q). Under the IWG interpretation, EPA
would not be permitted to consider, in making safety determinations on
tolerances, exposures to pesticides in drinking water, exposures to
pesticides resulting from application of pesticides in residences or
public spaces, or most of the farm children exposures forming the basis
of NRDC's objections. Such an interpretation clearly defeats most of
the NRDC's claims regarding the children's safety factor and estimation
of aggregate exposure.
The IWG also offers a backup legal argument which would, in
execution, reach much the same result. It asserts that even if non-food
exposure is properly considered under section 408 of FFDCA, any non-
food exposure must meet the ``reliable data'' requirement in section
408(b)(2)(ii) of FFDCA. The IWG defines ``reliable data'' to mean
``information to allow OPP to make a reasonable estimate of the actual,
real-world exposure distribution to add to information on dietary
exposure so that probabilistic estimates of aggregate exposure can be
made.'' Id. at 10. According to the IWG, the EPA generally does not
have data meeting this standard as to ``exposure from drinking water or
from residential or other non-occupational exposure routes.'' Id. at 9.
Thus, the IWG's legal interpretation of the ``reliable data''
requirement basically gets the IWG to the same place--EPA should not be
considering non-food pesticide exposures in making safety
determinations under section 408.
Not resting on these legal arguments, the IWG provided detailed
comments on several other of the claims in the NRDC objections,
including the following:
a. Drinking water exposure models. Noting that NRDC claims that
EPA's drinking water models are not conservative, the IWG points out
that NRDC ``gives no reasons for this assertion.'' Id. at 12. The IWG
takes the contrary view arguing that the models are very health
protective (conservative) ``because their input parameters are
extremely conservative.'' Id. at 11. In support, the IWG notes that EPA
models ``assume maximum [pesticide]
application rates, 100% of crop
area treated with a maximum fraction of the watershed planted to the
modeled crop, maximum number of applications per year, minimum
application intervals for multiple applications of the pesticide, and
upper-bound aerobic half-life estimates in soil.'' Id. at 12. The IWG
also cites to data collected by EPA and the U.S. Geological Survey
showing ``concentrations of 178 pesticides and their degradation
products in both raw surface water and finished drinking water from
twelve water-supply reservoirs were all substantially less than those
predicted by EPA's computer models, FIRST and PRZM/EXAMS-Index
Reservoir.'' Id.
b. Farm children subgroup. The IWG argues that NRDC's farm children
subgroup is not an ``identifiable subgroup'' within the meaning of the
statute. Rather, the IWG contends the NRDC's subgroup is ``a whole
series of different groups, including children who live on farms,
children who play near agricultural land, children who attend schools
near agricultural land, children who work on farms, children whose
family members work on farms, children whose family members handle
pesticides as part of their jobs (whether on farms or not), and
children who live in ``agricultural communities'' (whatever that
means).'' Id. at 13. The IWG asserts that these groups ``have nothing
in common other than that they are all children.'' Id. Further, the IWG
argues that the FQPA directs EPA to consider ``major identifiable
subgroups of consumers'' and that NRDC has not demonstrated that there
is anything identifiable about the consumption patterns of its farm
children subgroup. Id. at 14.
c. Farm children's pesticide exposure. The IWG questions whether
NRDC has shown that children who live on farms face higher exposure to
pesticides noting that ``NRDC has cited selective results from
epidemiological studies that relied on retrospective self-reporting
regarding use of pesticides.'' Id. The IWG presented preliminary data
from a study funded by pesticide and chemical companies and
associations. According to the IWG, the results of this study showed
that ``urinary concentration [of pesticides]
was associated with direct
handling and application of pesticides. However, for children and
spouses not involved in pesticide handling and application, exposures
were low and did not vary appreciably by day of study.'' Id. at 15
(emphasis in original).
d. Pesticide exposure from food purchased at farm stands. The IWG
challenges the NRDC's assertion that levels of pesticide residues in
foods purchased at farm stands are higher than residue levels in food
purchased at other retail outlets. The IWG notes that ``NRDC does not
provide information to support its allegations, and we are not aware of
any credible data to suggest that this is the case.'' Id. at 16. The
IWG cites two demonstrable reasons undermining NRDC's claim: First,
label directions and restrictions on pesticide use apply equally to
food grown for sale at farmstands and food grown for distribution
through broader channels of trade; and second, ``[t]he various
circumstances (weather, pest pressure, etc.) that affect residue levels
resulting from a given treatment regimen are the same for those who
grow crops to market through wholesale channels and for those who grow
crops to sell at retail.'' Id. Finally, the IWG notes that assuming
residue levels are at the tolerance value would vastly overstate
exposure amounts given that FDA data has shown ``no pesticide residues
in 41% and 73.5% of fruit and vegetable samples and either no residues
or below tolerance residues in 99.5% and 98.9% of fruit and vegetable
samples.'' Id. at 17.
e. Regional consumption of blueberries. The IWG disputes NRDC's
assertions regarding higher consumption of blueberries in regions that
produce the crop. The IWG notes that there is both a national and
international market for blueberries that makes blueberries widely
available throughout the United States for several months of the year
as a fresh commodity and available year round in the frozen state, the
condition in which over half of the U.S. blueberry crop is marketed.
Id. at 18.
2. Inter-Regional Research Project Number 4 (IR-4). The IR-4 is a
program sponsored by USDA and land grant universities and directed
toward obtaining regulatory approval for pesticide uses on minor and
speciality

[[Page 30050]]

food crops that are not likely to be supported by private sector
companies. In its comments, the IR-4 notes that several of the
pesticides covered in the objections--diflubenzuron, imidacloprid,
halosulfuron-methyl, and fenhexamid--are both ``critical to minor crop
growers'' and safer, reduced risk pesticides. (Ref. 27). The IR-4
asserts that diflubenzuron and imidacloprid provide alternatives to the
organophosphate pesticides and that halosulfuron-methyl is a methyl
bromide alternative. Id.
3. Bayer CropScience. Bayer CropScience notes that the required DNT
has been submitted for imidacloprid. (Ref. 3 at 1). Bayer CropScience
asserts that the 3X children's safety factor imposed by EPA should now
be removed because the ``a clear NOEL was established'' in the DNT. Id.
at 2. Bayer CropScience also claims NRDC errs in contending that
percent crop treated data was relied upon by EPA for blueberries. Bayer
CropScience cites 66 FR 18554, 18556 (April 10, 2001) as showing that
100% crop treated was assumed for blueberries in EPA's risk assessment.
Id. at 10.

VI. Response to Objections

NRDC objected to EPA's extension of a temporary tolerance for the
residues of imidacloprid on blueberries. See Imidacloprid et al.
Objections at 1. That tolerance extension expired on December 31, 2003.
See 67 FR 2580 (January 18, 2002). As the objected-to tolerance is no
longer in existence, NRDC objections are denied as moot. Nonetheless,
NRDC's objections remain relevant to the petition that Interregional
Research Project Number 4 filed to establish a permanent tolerance for
imidacloprid on blueberries. 68 FR 5880 (February 5, 2003) (petition
for imidacloprid tolerance on the crop group bushberries which includes
blueberries). EPA has analyzed NRDC's objections, and considering them
in light of the currently available information on imidacloprid, has
decided to establish the permanent tolerance for imidacloprid on
blueberries. EPA's analysis of the NRDC objections and the comments
received on the objections is below.
As noted in Unit II.A., if NRDC refiles the same objections to the
re-established imidacloprid tolerance relying solely on the information
and arguments already presented, EPA will re-issue this comment
response as a response to NRDC's objection forthwith. If, however, NRDC
adds new issues, cites new information, or makes new arguments in
support of its objections, EPA will have to analyze and respond to
these new items before issuing a response.

VII. Analysis of the Issues Raised by NRDC's Objections

EPA has considered all of the issues raised by NRDC in its
imidacloprid objections in acting on the petition to re-establish the
imidacloprid tolerance on blueberries. For the reasons explained below,
EPA concludes that the safety concerns with the imidacloprid tolerance
asserted by NRDC are without merit.
One consistent theme emphasized by NRDC in its objections is the
potential heightened exposure of ``farm children'' to pesticides.
Accordingly, EPA begins analysis of the issues raised by the
objections, in Unit VII.A., with an examination of the data bearing on
children's exposure to pesticides in agricultural areas. Then EPA turns
to NRDC's more specific claims. Unit VII.B. addresses issues regarding
the children's safety factor. Unit VII.C. covers aggregate exposure
questions. Unit VII.D. responds to claims regarding use of LOAELs and
NOAELs.

A. Children's Exposure to Pesticides in Agricultural Areas

Children can be exposed to pesticides through multiple sources and
pathways. The Agency currently considers children's exposure to
pesticides by three broad pathways: Food, drinking water, and
residential use. NRDC, however, has asserted that children residing in
agricultural communities also are significantly exposed to agricultural
pesticides through additional exposure pathways.
Children in agricultural areas may be exposed to agricultural
pesticides through pathways such as contact with treated fields,
roadsides and other areas; contact with moving spray drift while near
application areas; contact with spray drift residues left by any spray
drift that may reach their homes, yards or other areas they frequent,
such as schools and schoolyards; and contact with pesticide residues
that have volatilized after application. In addition, some of these
children may also be exposed to agricultural pesticides in their homes
via other pathways.
In analyzing the potential exposure of children in agricultural
areas, EPA first focused on data from studies relied upon by NRDC or
otherwise known to EPA that attempted: To measure levels of pesticides
in the homes of children in agricultural areas; to measure levels of
pesticide metabolites in body fluids of children in agricultural areas;
and/or to compare levels of pesticide exposure of farm children to
those experienced by non-farm children, based on similar types of
measurements. In addition, EPA examined data NRDC submitted relating to
airborne levels of pesticides (stemming from spray drift or
volatilization) in farm communities. Finally, EPA reviewed data it has
concerning the potential for pesticides to drift offsite during
application.
Although EPA discusses its views concerning this data in more
detail below, those views can be summarized as follows. First, the data
concerning levels of pesticides in homes or children's bodily fluids
are limited and inconclusive, and do not demonstrate that children in
agricultural areas as a group receive more pesticide exposure than
children in non-agricultural areas. (In fact, some data suggest that
pesticide residues in houses in urban or non-agricultural areas may be
higher than those in houses in agricultural areas.) Second, even if
airborne pathways such as volatilization may lead to significant
exposures to some pesticides, imidacloprid would not be one of those
pesticides. Finally, data already gathered by EPA and processed through
EPA's Spray Drift Model show that the highest off-target deposition
levels from agricultural applications occur adjacent to the treated
area and that deposition levels decrease with increasing distance from
the treatment area; moreover, and in any event, any spray drift from
agricultural applications of imidacloprid, which has residential uses
on turf and pets, is largely irrelevant to the pesticide's aggregate
exposure assessment, because any estimated exposure from spray drift
would be dwarfed by estimated exposure from the lawn and pet use.
1. Studies focusing on exposure to children in agricultural areas.
In examining the first set of data, EPA found it useful to concentrate
first on what the cited studies showed regarding exposure levels in the
children's immediate environment. These types of studies have tended to
focus on exposure levels in the children's homes, with an emphasis on
the level of pesticide residues in house dust. Second, EPA examined the
data bearing on the actual exposure children received in agricultural
areas as compared to the actual exposure levels of children in non-
agricultural areas.
a. Potential for exposure due to heightened pesticide levels in the
homes of farm children. NRDC's argument that farm children experience
higher pesticide exposures than other children relies primarily on
studies purporting to show that there are higher environmental levels
of pesticides in and around the homes of farm children.

[[Page 30051]]

Leaving to one side, for the moment, the issue of whether such
elevated environmental levels of pesticides actually increase farm
children's exposures, EPA first has focused on whether such elevated
levels actually exist. In evaluating this question, EPA has
concentrated on the levels of pesticides in house dust, because nearly
all the contemporary literature addressing the potential exposure of
farmworker children to agricultural pesticides includes a discussion or
measurements of pesticide concentrations in house dust. This matrix is
now widely recognized as a potential reservoir for many environmental
pollutants, including pesticides. In addition, EPA has reviewed not
only studies submitted by NRDC, but also other studies known to EPA.
(Ref. 40).
The house dust evidence, contrary to NRDC's view, is fragmentary at
best as to whether there exists a potential for higher exposure to
``farm children'' due to higher environmental contamination of the
homes of such children. For example, house dust samples collected from
diverse locations such as Cape Cod, MA; Long Island, NY; Iowa City, IA;
Detroit, MI; Seattle, WA; and Los Angeles County, CA have been compared
to house dust samples taken from the homes of farm workers in
agriculturally intensive Yuma County, AZ. Contrary to NRDC's general
hypothesis, in Yuma County, the 90\th\ percentile dust concentrations
([mu]g)/g) for the pesticides chlorpyrifos, diazinon, carbaryl,
propoxur, and the disinfectant ortho phenylphenol all were lower than
those in most, if not all, of the aforementioned urban areas.(Ref. 8).
This may well be due to the fact that, in addition to being
agricultural pesticides, all of these pesticides are widely used
residential pesticides, which may be used substantially in urban areas
as well.
Studies also have been performed in the agricultural area around
Wenatchee, WA, which is situated in the heart of the apple growing
region in that state. For example, Simcox et al. (Ref. 63) designed a
study of housedust and soil samples in this area in an attempt to
determine whether children of agricultural families were exposed to
higher levels of pesticides than children whose parents were not
involved in agriculture. Forty-eight applicator and fourteen reference
families were recruited to participate. Families living within 200 feet
of an orchard were classified as agricultural families, while families
living in homes more than one-quarter mile from an orchard were
classified as reference families. Pooled house dust measurements were
taken from two locations in each house:
? Three feet inside the entry way.
? In the children's play area.
This study's authors reported significantly higher indoor dust
levels of azinphos-methyl, chlorpyrifos, and parathion in agricultural
homes as compared to the reference homes. Analysis of the pesticide
residues in the soil and house dust samples showed that the pesticide
residues present were of agricultural origin, demonstrating in the
authors' view that children of agricultural families have a higher
potential for exposure to agricultural pesticides than children of non-
farm families. In addition, the authors concluded that proximity to
agricultural spray areas appeared to be the predominant but not
exclusive explanation of the increased soil concentrations.
The study's authors, however, focused on a specific and perhaps
unique geographic area. As other study authors have reported,
Wenatchee, WA, can be characterized as being situated in an area of
canyons ``conducive to wind patterns responsible for spray drift''
(Ref. 11). The site-specific characteristics of this area may not
necessarily apply to other agricultural areas, such as those like Yuma
County, which, as mentioned in this unit, is situated on a riparian
flood plain, and is distinct from the canyons of the Wenatchee area in
terms of cropping systems, application techniques and topography. In
fact, when University of Washington investigators began assessing house
dust concentrations of farm worker houses in the Lower Yakima Valley of
Washington, an area of that state that is more expansive than the
Wenatchee area, they did not observe an association between proximity
to fields and house dust concentrations. Rather, these investigators
observed a stronger correlation between house dust concentrations and
dust concentrations in vehicles used by farm workers to commute to and
from work. (Ref. 11). In addition, for chlorpyrifos, a pesticide once
having both residential and agricultural uses, the range of house dust
concentrations reported by Simcox (Ref. 63) (< 0.02-3.6 [mu]g/g) was
exceeded by the median value house dust concentration from non-
agricultural family homes (4.7 [mu]g/g; n=9) reported in Jacksonville,
FL. (Ref. 22).
b. Whether farm children actually experience increased exposure.
Assuming for the purposes of argument, moreover, that contaminated
house dust may indicate activity patterns (in addition to tracked-in
drift) that can lead to the potential exposure of young children to
agricultural pesticides in residential environments (Ref. 9 and Ref.
5), the challenge would remain to find an association between house
dust concentrations and indications of dose based on measurements of
biomarkers of pesticides in farm worker's children. The evidence
likewise is fragmentary, at best, on this point.
Fenske et al., for example, ``were unable to demonstrate a strong
relationship between housedust concentrations and biological levels,''
i.e., levels in study participants, in Wenatchee area residents. (Ref.
14). These researchers suggested that this was due to several factors,
including the tendency of the vacuum system used to capture ``particles
from deep carpet'' areas that ``may not represent chemical available to
children during normal residential activity.'' The researchers also
pointed to ``the complexity inherent in children's exposures'' through
``intermittent contact with surfaces [and]
variable hand-to-mouth
behaviors,'' as well as the ''relatively high variability'' associated
with the spot urine sampling method used to obtain biological values.
Similarly, although Simcox et al. demonstrated the potential
migration of agricultural chemicals from an application site to a
residence under the unique circumstances of the Wenatchee study, they
also questioned the relevance of house dust concentrations in samples
collected by the vacuum system used in the study. Like Fenske et al.,
Simcox and colleagues were not sure if the house dust measurements
taken with the system were representative of the house dust routinely
encountered by children living in those homes. It was suggested that
biological monitoring of these young children ``may serve as an
appropriate and noninvasive means of sampling exposure among small
children.''
For other reasons as well, these and other studies have provided
little data to support either the hypothesis that pesticide levels in
house dust are correlated to exposure levels or the hypothesis that
children in agricultural areas generally receive significantly higher
exposure to pesticide residues than children in the general population.
i. Studies allowing comparison of children from agricultural and
non-agricultural areas. In Fenske 2000a, for example, Fenske et al.
compared the DMTP (dimethylthio phosphate) concentrations reported in a
1995 study of the Wenatchee population with those measured in Seattle
children, and found that concentrations from the Seattle

[[Page 30052]]

children (Ref. 32) appeared to be similar to those of the Wenatchee
reference population--i.e., children in an agricultural area. This
suggested that biological pesticide metabolite levels for agricultural
and non-agricultural children were very similar. Therefore, even if
agricultural children could be said to have the potential for more
routes of exposure, they were not more highly exposed. (Quite possibly,
the metabolites found in the urine represent exposure to the breakdown
products themselves rather than to the parent compounds. (Ref. 15).
Work performed by Higgins et al. (2001) also allows a comparison of
agricultural children to non-agricultural children. This study measured
cholinesterase levels as a biomarker of organophosphate pesticide
exposure in a group of migrant farm workers and their children. The
researchers collected blood samples from two groups of Hispanic
children (age 3--6 years) in the summer of 1997 to compare
cholinesterase levels in populations with varying degrees of contact
with agriculture, and hypothetically varying levels of contact with
organophosphate pesticides. Ninety-eight migrant Hispanic farm worker
children (50% male, 50% female) were recruited from two counties in
Oregon. (Ref. 25). A seasonally and age-matched comparison group of 53
Hispanic, non-agricultural family children (64% male, 36% female) was
also recruited in 1998 from two non-agricultural areas in Oregon.
Results from these two groups showed that cholinesterase levels were
not significantly different between the agricultural and non-
agricultural children (analysis of variation (ANOVA), p=0.69). (Ref.
25). A further analysis of the data using a multiple regression model
to account for potential age and gender effects also supported the
conclusion of no significant difference between the two groups. (Ref. 25).
Finally, in its report entitled Pesticide Exposure and Potential
Health Effects in Young Children Along the U.S.-Mexico Border, EPA
concluded that:
population distributions of OP [organophosphate]
pesticide
exposure in children (either living in close proximity to
agricultural fields, i.e., Yuma Study, or being admitted to health
clinics with flu-like symptoms, i.e., Symptomatic Children Study) as
measured by alkyl phosphate metabolites are not significantly
different than population distributions of OP pesticide exposure for
the general population as measured by NHANES III Studies [National
Health and Nutrition Examination Survey conducted by the Department
of Health and Human Services].
(Ref. 67)
ii. Studies focusing solely on children from agricultural areas.
Other studies have focused solely on children in agricultural areas,
including studies performed in the Wenatchee area by Fenske and his
colleagues at the University of Washington. Loewenherz et al. (1997),
for example, used members of the Wenatchee study population (48
applicator families and 14 Wenatchee-area reference families) to
evaluate and compare levels of OP pesticide metabolites in urine. Their
study aimed specifically to:
? Measure urinary metabolite levels of OP pesticides in
children living with occupationally exposed parents.
? Compare these with a reference population.
? Evaluate the relative importance of the para-occupational
exposure pathway.
One hundred sixty spot urine samples were collected from 88 children,
including repeated measures 3-7 days apart. Because the researchers
detected DMTP with far greater frequency than any other alkylphosphate,
they chose it as this population's most appropriate biomarker of
exposure. Over two sampling rounds, however, Loewenherz and colleagues
detected statistically significant differences in the frequency of DMTP
detectability among applicator and reference children in only one
round, and those differences were only marginally statistically
significant. From this one exposure event, there was no way to conclude
what the potential for exposure could be for each population
participating in this study. Moreover, the sample sizes represented by
the populations were small, and thus diminished the value of the study
in general.
The Loewenherz team, moreover, did not address the potential
sources of exposure to pesticides from gardens, pets, lawns, and diet.
Although the researchers recognized that this population's use of
residential pesticides was less than the national average, it is still
possible that exposures from air, dietary intake, and pesticide use in
other settings where the children may have spent time (i.e., day care
centers, homes of others) may also have contributed to observed urinary
metabolite concentrations. (Ref. 31). In fact, misuse of a non-
residential pesticide for residential purposes was reported in the
study. This may have had a significant impact on the urinary metabolite
levels reported in this paper, as two of the three highest measurements
in the study came from these households.
In addition, a comparison of the exposures of the farm worker
children to the farm workers themselves suggested that it was unlikely
that the exposures experienced by the applicator children in the
Loewenherz study were sufficient to produce acute health effects. (Ref.
31). Finally, a strong relationship between pesticide house dust
concentrations and biological levels in these children was not found.
(Ref. 14).
Using a larger cohort (109 children) from the same region, Lu et
al. (2000) collected environmental and biological samples to evaluate
the total potential exposure of agricultural and reference children.
The researchers took spot urine samples, as well as hand wipe samples,
house and vehicle dust samples, and surface wipe samples from various
surfaces (including steering wheels and work boots). Environmental
measurements indicated that children living with parents who work with
agricultural pesticides (applicator children), or who live in close
proximity to pesticide-treated farmland, have the potential for higher
exposures than do other children living in the same community. (Ref.
33). However, dimethyl OP pesticide metabolite levels in the urine of
agricultural and reference children showed only a marginally
significant difference. Id. The children of farm workers, moreover, had
the same range of urinary DMTP as the reference children, and less
urinary DMDTP (dimethyldithio phosphate) than applicator children. Diet
is likely to have been an important contributor to metabolite
concentrations. Id. Interestingly, 23 agricultural families that
participated in this study also participated in the study reported by
Simcox et al. (Ref. 63). Of these, the four homes that had the highest
house dust concentrations in 1992 had lower concentrations in 1995.
Overall, 16 of 23 households reported lower house dust concentrations
than in the previous study, suggesting that changes in activity
patterns can influence levels of pesticides in house dust.
In addition to the azinphos-methyl and phosmet results reported in
Lu et al. (2000), Fenske et al. (2002) measured chlorpyrifos and
parathion in environmental samples from the homes of the same 109
children and those chemicals' metabolic by-products in biological
samples from the children themselves. In their study, Fenske et al.
relied on more specific urinary metabolites of the diethyl, OP parent
compounds. For chlorpyrifos, the researchers used the metabolite 3,4,6-
trichloro-2-pyridinol (TCPy) as a biological measure, and for parathion
they used 4-nitrophenol as the biological measure. Environmental

[[Page 30053]]

pesticide loadings, however, could not explain the biological levels
measured. (Ref. 13). Fenske et al., stated that the use of OP
pesticides in gardens was associated with an increase in the TCPy
concentrations in children's urine. However, no explanation was offered
for this association. Unfortunately, TCPy is a ubiquitous compound in
the environment and exposure could still be associated with exposure to
both chlorpyrifos and TCPy. The authors reported that most children
studied did not have measureable urinary levels of metabolites of
either chlorpyriphos or parathion. The study concluded that children
living in homes including household members who worked with
agricultural pesticides or that were close to pesticide treated
farmland did not appear to have increased pesticide exposures, even
though their homes showed elevated levels of pesticide concentrations
in house dust.
Using the data gathered in their field studies, Fenske and
colleagues (2000b) also compared spray season and single-day dose
estimates for agricultural and reference children, but only showed a
marginal difference between the two cohorts. (Ref. 15). Moreover, a
majority of the children classified as reference children had
measurable dialkylphosphates in their urine, and a substantial fraction
had doses that exceeded the reference values for azinphos-methyl. Id.
An additional team based at the University of Washington examined
571 farm workers involved in a community intervention project in the
Washington State's Lower Yakima Valley. This project is presented in
Thompson et al. (2003) and Curl et al. (2002) (Refs. 66 and 11). The
cohort consisted of field workers and pesticide handlers (e.g.,
applicators). Questionnaires regarding self reported pesticide exposure
and common sense methods to reduce para-occupational exposure were
evaluated. Sub-samples of urine and other environmental media (house
and vehicle dust) were taken to establish baseline exposure levels of
the intervention and control groups. Intervention was described as
individuals performing common sense hygiene practices such as removing
footwear prior to entering the house.
Based on this research, both Thompson et al and Curl et al.
reported a significant association between levels of dialkyl phosphates
(DAP, a class of breakdown products of organophosphate pesticides) in
urine of adults and their children. There was also a significant
association between house dust and vehicle dust. However, Curl et al
did not report an association between house dust and proximity to
fields and orchards. The DAP metabolites measured were DMP (dimethyl
phosphate), DMTP, DMDTP, DEP (diethyl phosphate), and DETP (diethylthio
phosphate), and may represent exposure to numerous pesticides from
several pathways including diet and pathways associated with
residential use of pesticides. The authors speculate that it is also
possible that some workers may have taken agricultural chemicals from
work for home use.
It has been suggested that the removal of shoes prior to entering
the house, or the use of entry mats, can significantly lower the amount
of pesticide tracked-indoors. (Ref. 38). Other investigators have
observed mixed or inconclusive results. (Refs 33, 11 and 66). When Curl
et al. (Ref. 11) compared concentrations of urinary DAPs and OP
concentrations in house dust and vehicle dust between two groups
(Intervention and Control, Lower Yakima Valley), no significant
differences were seen. The intervention group performed activities such
as washing hands after work, removing footwear prior to entering the
house, washing work clothing separately, and removing work cloths
before holding children. If intervention has no impact, it is not clear
then whether para-occupational pathways are indeed significant. In
general, Thompson et al. (Ref. 66) saw no differences regarding hygiene
practices such as removing shoes prior to entering the house between
households having children and those that did not. However, the authors
suggested the need for continuing current educational efforts. As
compared to field workers, pesticide handlers were more likely to
perform protective practices such as washing hands immediately after
work and removing work clothing before holding children. Yet, in other
studies, concentrations in urine were higher among children of
applicators than among children of field workers. (Ref. 33).
Finally, Mills and Zahm (Ref. 34) conducted a feasibility study to
obtain urine samples from farm workers and their children in an area of
extensive OP use. They tested for six urinary metabolites of OPs,
including DMP, DEP, DMTP, DMDTP, DETP, and DEDTP. They also compared
the levels between adults and children living in the same households. A
total of 27 individuals from 9 families (18 adults and 9 children) were
selected to participate. Levels of OP metabolites were generally very
low in both adults and children in this survey. The frequencies of
detection of DMP, DMTP, and DETP were higher among Fresno-area farm
workers and their children than among the general population sampled
during the National Health and Nutrition and Examination Survey
(NHANES) II survey. However, informational data on pesticide use
practices in the U.S. general population supplied by the authors
suggested that this comparison was unfair, since NHANES II was survey
data collected through 1980, when the prevalence of OP pesticide use
was only just beginning to increase. In a second comparison, Mills and
Zahm showed that the frequencies of detection and mean levels of DMTP
among Fresno children were intermediate between those found by Fenske
and his co-workers among Wenatchee, Washington applicator and reference
children. Id. No statistical analyses were conducted on these data
comparisons. Thus, it was unclear whether the urinary metabolite levels
seen in the Fresno children were significantly different from the
applicator and reference children studied in Washington State.
iii. Ongoing research on farm children exposures. Preliminary
information from the Farm Family Exposure Study (FFES) conducted by
investigators at the University of Minnesota and Emory University bears
on the question of whether farm children have higher levels of
pesticide exposure than non-farm children, and whether farm children
should be identified as a major, identifiable subgroup of consumers. In
this study, researchers identified urinary pesticide concentrations for
95 farm families before, during, and for 3 days after an application of
glyphosate, 2,4-D or chlorpyrifos. In their preliminary reporting of
results, the researchers stated that they found `` appreciable
variation by chemical in the proportion of farm family members with
detectable urinary concentrations.'' See http://www.farmfamilyexposure.org/
html/abstracts.html#ser/. However, it was
only in the case of farmers--not spouses and children--that the
researchers claimed to have detected significant differences in urinary
pesticide concentrations and patterns of uptake and elimination. Id.
``For the vast majority of spouses and children, urinary concentrations
did not change appreciably after pesticide application.'' Id. Moreover,
the researchers asserted, based on their findings, that ``little
pesticide exposure is received through . . . living on a farm, per
se,'' and that it is the following, specific behaviors instead that are
associated with elevated pesticide exposure for farm children:
? ``[d]irect contact with chemicals in the mixing or
application area.''

[[Page 30054]]

? ``[w]orking as a co-applicator.''
? ``[t]ouching containers without gloves.''
? ``[p]laying barefoot in the area where pesticides are
being mixed and loaded[.]''
See http://www.farmfamilyexposure.org/html/the_study.html.
EPA recognizes that these representations of the researchers are
only preliminary. Nevertheless, the fact that the FFES researchers'
preliminary views point in the same direction as the analysis above
should not escape note.
In sum, as discussed in this unit the studies and information,
whether concerning children in agricultural areas and non-agricultural
areas or children in agricultural areas alone, and whether concerning
environmental levels, biological levels, or both, shows that there is
little or no evidence to indicate that EPA has ignored a significant
source of exposure in calculating the potential aggregate exposure from
pesticides.
c. Conclusion. In conclusion, the limited number of studies
containing data relevant to NRDC's arguments, taken together, fail to
demonstrate that children in agricultural areas experience
significantly higher levels of exposure than children in non-
agricultural areas. In EPA's judgment, the weight of currently
available evidence relating to pesticide residues in house dust or on
other surfaces fails to establish that children living in agricultural
areas or children living nearer to agricultural pesticide use areas
experience higher exposures to pesticides than children in the general
population. Similarly, biomonitoring data available for comparing the
levels of pesticide exposure experienced by agricultural children with
other children is fragmentary and does not show that there are
significant differences between these groups of children. Thus,
regardless of whether such children constitute a ``major identifiable
subgroup of consumers,'' it does not appear that such children
consistently receive more pesticide exposure than the groups of
children (those at the upper percentile of estimated exposure) used by
EPA in its current approach to assessing aggregate risk.
This is not to say, however, that issues addressed in these
materials do not bear further research. On the contrary, the government
is engaged in or supporting, or has recently engaged in or supported,
relevant research in a number of ways. These efforts include, for
example, the Minnesota and South Carolina study discussed in this unit.
These efforts also include:
? A similar study which the federal government itself is
conducting with children in North Carolina and Iowa.
? A systematic analysis which EPA is undertaking to review
the raw data underlying the Wenatchee, WA area and Yuma County, AZ
studies discussed in this unit.
? A study of pesticide exposure pathways for farm workers'
children in the Yakima Valley.
? An assessment of sources of pesticide contamination,
concentrations in pathways, and exposure-prone behavior in Salinas, CA.
? A study of ingestion of pesticides by children in an
agricultural community on the U.S./Mexico border.
? An assessment of exposure of children to pesticides in
Yuma County, AZ.
EPA will review the results of this ongoing research and take
appropriate steps to address any exposure concerns regarding children
that are documented.
2. Supplemental information regarding spray drift and drift of
volatilized residues. On June 19, 2003, NRDC supplemented its
submission to the Agency with several pieces of additional information.
Included was a report generally addressing the issue of spray drift
from pesticide applications in California (Ref. 7) (hereinafter cited
as the CFPR Report). Although EPA defines spray drift as the movement
of droplets off-target during or shortly after application, which is
independent of the chemical properties of the pesticide being sprayed,
the CFPR Report looked more broadly at atmospheric pesticide transport
including pesticide volatilization as a potential mechanism by which
pesticides travel beyond treated fields.This section of the document
discusses drift as a result of volatilization. Drift of the pesticide
spray is addressed in the following section of the document. Also
included in NRDC's supplemental information was a research article
entitled ``Community Exposures to Airborne Agricultural Pesticides in
California: Ranking of Inhalation Risks,'' containing an analysis of
the degree of inhalation risk posed by certain migrating pesticides in
California, based on ambient air monitoring data gathered, in part, by
the California Air Resources Board and the California Department of
Pesticide Regulation. (see Ref. 29, hereinafter referred to as the
Ranking Study). EPA is still examining the information in these studies
but presents its preliminary views on these studies in this unit.
The Ranking Study conducted screening level assessments for many of
the pesticides ranked as having the highest potential as toxic air
contaminants as well as several pesticides categorized as hazardous air
pollutants. The screening level assessment only identified four soil
fumigants as potentially presenting non-cancer acute or chronic risks
of concern. Id. at 1179. The study concluded that ``vapor pressure is a
significant predictor of []
ranking of inhalation risks.'' Id. at 1182.
The CFPR Report examined the potential health risks from air levels of
three pesticides characterized as moderate to highly volatile
(chlorpyrifos, diazinon, and molinate) measured at the field boundary
and at more distant locations. The Report concluded that in many
instances the measured air levels of these pesticides posed risks of
concern. The Report also concluded that drift due to volatilization was
not a concern for pesticides that are not highly volatile. CFPR Report
at 40.
Even assuming that volatilization may lead to significant exposures
to some pesticides, imidacloprid would not be one of those pesticides.
EPA is in general agreement that vapor pressure is the key factor in
predicting whether a pesticide has the potential to volatilize and
drift offsite in significant amounts. Because soil fumigants
traditionally have very high vapor pressures, and thus are highly
volatile, EPA is now accounting for potential exposure due to
volatilization of these pesticides in calculating their aggregate
exposure. Imidacloprid is a solid at room temperature with a low vapor
pressure (1.5 x 10-\9\ mmHg). In fact, imidacloprid's vapor
pressure is not only much lower than pesticides used as soil fumigants,
it is also substantially lower than the pesticides presented in NRDC's
supplementary submission: chlorpyrifos (1.87 x 10-\5\ mmHg);
diazinon (1.4 x 10-\4\ mmHg); molinate (5.3 X
10-\3\ mmHg). Thus, any losses due to volatilization for
imidacloprid are expected to be minimal at most.
3. EPA Data on Spray Drift and the Spray Drift Model. EPA has
gathered substantial data on the potential of pesticides, as applied,
to drift offsite through the work of the Spray Drift Task Force (SDTF).
The SDTF is a group of pesticide registrants who have worked
collaboratively to develop a database to meet the majority of their
collective spray drift data requirements under 40 CFR 158.440. The
group was chartered on April 17, 1990, and its formation was announced
in PR Notice 90-3. Since its formation, the SDTF has generated
standardized data on spray drift levels resulting from different
application methods under varying meteorological conditions. The data
developed by the

[[Page 30055]]

SDTF was reviewed by EPA internally, through external peer review
workshops, and through FIFRA Scientific Advisory Panel meetings. The
reviews generally identified the data set associated with aerial
applications to be the most robust, followed by the data sets from
ground boom applications, orchard/vineyard airblasting, and
chemigation, respectively. After the spray drift data were available,
the SDTF worked with EPA's Office of Research and Development, as well
as the USDA's Agricultural Research Service and Forest Service to use
the data in the development/evaluation of the AgDRIFT model. (See
generally Refs. 4, 24, and 65).
The AgDRIFT model and the SDTF data show that the highest off-
target deposition levels from agricultural applications occur adjacent
to the treated area and that deposition levels decrease with increasing
distance from the treatment area. See Table 2 of this unit.

Table 2.--High-end Downwind Spray Drift Deposition Levels by Application Method
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spray drift deposition (percent of application rate)
--------------------------------------------------------------------------------------------------------------------
Lawn placement relative to airblast\3\
application area ----------------------------------------------
aerial\1\ ground boom\2\ dense or tall granular\4\
dormant orchards canopies
--------------------------------------------------------------------------------------------------------------------------------------------------------
10 to 60 ft downwind 34.1 9.3 25.0 8.4 0
------------------------------------
20 to 80 ft downwind 31.6 6.4 16.1 6.0 0
------------------------------------
40 to 90 ft downwind 27.9 4.1 8.0 3.7 0
------------------------------------
80 to 130 ft downwind 22.0 2.4 3.0 1.9 0
------------------------------------
160 to 210 ft downwind 14.9 1.3 0.8 0.9 0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ ASAE very fine to fine spray, 10 mph wind, 10 ft release height and other standard AgDRIFT 2.01 default inputs.
\2\ Tier 1 AgDRIFT 2.01 ground boom inputs: 90\th\ percentile, high boom, fine spray.
\3\ Tier 1 AgDRIFT 2.01 airblast inputs: model outputs multiplied by 3 to approximate an upper 90\th\ percentile value.
\4\ Particle drift from granular applications is generally considered to be insignificant in EFED assessments.

The AgDRIFT model helps EPA assess the relative [upper bound]
magnitude of residues from direct residential use of a pesticide versus
residues that might occur as a consequence of spray drift. As of yet,
EPA has not included data from the AgDRIFT model as a standard
component of its residential exposure assessments. In responding to
NRDC's objections other than as to imidacloprid, EPA is still examining
how this data informs the understanding of aggregate exposure generally
and how this data can be considered in a meaningful way in assessing
aggregate exposure. Nonetheless, even prior to completing this
analysis, some conclusions can be made concerning pesticides such as
imidacloprid which have broad residential uses. What the data for
imidacloprid show is that predictions of exposure based on the spray
drift model are largely irrelevant to the pesticide's aggregate
exposure assessment because any estimated exposure from spray drift
would be dwarfed by estimated exposure from the lawn and pet use. An
explanation of EPA's residential exposure assessment for imidacloprid
and the operation of the AgDRIFT model for imidacloprid will clarify
this point.
EPA estimates residential exposure by incorporating pesticide-
specific information in exposure scenarios that are built based on data
on human behavior and human physical statistics (e.g., body surface
area). (See Refs. 35, 55, and 61) EPA's scenario for estimating
exposure due to turf uses assumes that children play for a substantial
period (2 hours) on lawns immediately after treatment with the
pesticide. The scenario models both dermal exposure from contact
between skin (arms and legs) and the lawn and oral exposure resulting
from soil ingestion, mouthing grass, and hand-to-mouth behavior
(placing hands repeatedly in mouth after being in contact with treated
lawn) (Refs. 35, 55 and 61). With the pet treatment, EPA also uses
scenarios for both dermal and oral exposure. For dermal exposure, EPA
uses a pet hug scenario which assumes a child hugs the pet immediately
after treatment. EPA assumes that 20% of the applied dose is available
on the surface of the pet for transfer to the child and that the child
essentially wraps its full body around the pet such that one-half of
the child comes in contact with the pet. The child is assumed to be
wearing a short-sleeved shirt and short pants. EPA assumes 100%
transfer where the child's skin touches the pet and 50% transfer to the
child's skin where the child's clothing touches the pet (Refs. 35, 55
and 61). For oral exposure, EPA used a combination of imidacloprid
specific data and its standard exposure scenario. EPA had imidacloprid
data on the transfer of imidacloprid to hands from petting dogs that
was gathered by petting a treated dog 10 minutes after imidacloprid
application wearing cotton gloves. EPA assumed that a child put its
hand in its mouth 20 times/hour for 2 hours and each time the hand
contained the exposure level measured on the glove. (See Ref. 44 at 51-
57 and Refs. 35, 55 and 61)
Using these scenarios, EPA estimated the exposures and MOE's for
imidacloprid residential exposures presented in Table 3 of this unit.

[[Page 30056]]

Table 3.-- Residential Exposures for Imidacloprid
----------------------------------------------------------------------------------------------------------------
Exposure in milligram/
Use Route of exposure kilogram/day (mg/kg/ MOE
day)
----------------------------------------------------------------------------------------------------------------
Lawn oral 0.0059 1,700
--------------------------------------------------------------------------
dermal 0.001 10,000
--------------------------------------
Pet oral 0.0027 3,600
--------------------------------------------------------------------------
dermal 0.036 280
----------------------------------------------------------------------------------------------------------------

(Ref. 44 at 51-52).
In calculating potential drift, it is important to consider the
maximum amount that may be applied and the manner of application.
Imidacloprid is approved for use on residential turf at 0.4 lb/acre/
year. This amount may be applied in a single application. This
application rate is comparable to the maximum agricultural yearly rate
(0.5 lb/acre/year) and exceeds most single agricultural application
rates. Imidacloprid application methods differ for various crops with
some uses being restricted to soil incorporation of granules and others
permitting aerial spraying. The agricultural use that has the potential
for the greatest spray drift is on cranberries. The label permits
imidacloprid to be applied at 0.5 lb/acre/year for cranberries and that
amount of pesticide may be applied in a single application. Further,
the label does not prohibit, and therefore permits aerial application.
For cranberries this would generally mean application from a
helicopter. In EPA's experience aerial application to cranberries is
relatively uncommon. The use having the second highest potential for
drift is on artichokes where 0.25 lb/acre may be applied aerially in a
single application.
To calculate exposure and risk (in terms of MOEs) from imidacloprid
spray drift, EPA multiplied the agricultural application rates by the
high-end prediction of spray drift deposition (shown in Table 2 of this
unit) and then applied the standard residential exposure estimation
methods. The estimated exposure and MOE's from spray drift from these
uses are presented in Table 4 of this unit.

Table 4.--Spray Drift Exposures for Imidacloprid on Lawns
----------------------------------------------------------------------------------------------------------------
Exposure in mg/kg/day on lawns 10-
Use Route of exposure 60 feet from edge of field MOE
----------------------------------------------------------------------------------------------------------------
Cranberries oral 0.0025 4,000
--------------------------------------------------------------------------------
dermal 0.00035 29,000
--------------------------------
Artichokes oral 0.00127 7,900
--------------------------------------------------------------------------------
dermal 0.000175 57,000
----------------------------------------------------------------------------------------------------------------

(Ref. 39).
Comparing the potential exposure from spray drift onto lawns from
cranberries with the highest residential exposure already incorporated
into EPA's aggregate assessment, the pet hug scenario, shows that worst
case exposure at the edge of the field from drift is an order of
magnitude lower. Thus even assuming that a child who received maximum
exposure from hugging a treated dog was exposed to imidacloprid at the
edge of a treated cranberry bog, the exposure and risk assessment for
that child would not be meaningfully different.

B. Failed to Retain Children's 10X Safety Factor

1. Introduction. NRDC's objections concerning the children's safety
factor focus on the question of whether EPA properly applied a
children's safety factor of other than 10X given that EPA is allegedly
missing data on each of the pesticides. Particular emphasis is placed
by NRDC on the fact that a DNT has been required for imidacloprid but
not yet submitted. In addressing the issues raised by these objections,
EPA first has summarized its children's safety factor decision that was
relied upon in approving the imidacloprid tolerance and a re-analysis
of that decision that has been performed in light of the objections and
the revision to EPA's children's safety policy released in mid-2002.
Second, EPA addresses NRDC's contentions regarding the lack of a DNT
study. Third, EPA explains its response to each allegation NRDC makes
regarding general and pesticide-specific data that NRDC asserts is
missing and necessitates retention of the 10X factor.
2. EPA's children safety factor decision--a. In general. In making
decisions regarding the children's safety factor, EPA's OPP, from 1999
until early 2002, looked primarily to an internal committee to make
recommendations on the children's safety factor decision and to
articulate a rationale for that decision. This committee, the FQPA
Safety Factor Committee, was constituted solely for this purpose. To a
lesser extent, during this period, OPP relied upon the another internal
committee, the Hazard Identification and Assessment Review Committee
(HIARC) to explain EPA's rationale. Within the last year or so, OPP has
administratively restructured such that most of the work regarding
toxicity issues and the children's safety factor falls within the
jurisdiction of the HIARC. Consideration of exposure issues falls in
the first instance to the team of scientists of OPPs' HED assigned to
the specific pesticide. That judgement is then reviewed by the Risk
Assessment Review Committee (RARC). It is the RARC's responsibility to
ensure adequate rationale is provided for the decision on the
children's safety factor and to ensure consistency with current policy
and similar pesticides/circumstances. The RARC's recommendation and
complete rationale

[[Page 30057]]

is included in the risk assessment document for the pesticide.
Two particular aspects of that new policy are worthy of mention.
First, the policy emphasizes that in applying the provision the focus
should not be simply on whether the young have a greater sensitivity to
a pesticide but rather on what reliable data show with regard to the
safety of infants and children in situations where studies have shown
that the young are more sensitive to a pesticide. Thus, where increased
sensitivity is demonstrated, EPA examines how well-defined that
sensitivity is by the existing toxicity data and whether that
sensitivity has been adequately taken into account in calculating a
safe MOE.
Second, the policy stresses that when data are missing or
inadequate the focus should be on whether there are reliable data to
show that any additional safety factor different than the 10X default
value is protective of the safety of infants and children. This issue
has arisen frequently with regard to the developmental neurotoxicity
study (DNT), a study that EPA is now requiring to be submitted for more
pesticides. In evaluating whether a different factor than 10X would be
protective of infants and children where a required DNT is absent, EPA
examines related studies in the database to develop a sense for the
likely range in which effects may be seen in the DNT (and therefore,
the range of doses which will be used in the DNT). When the expected
doses in the DNT are substantially higher than the doses that are
presently providing the regulatory endpoint, a different and lower
additional safety factor may be appropriate depending on the degree of
difference between the doses for the DNT study and the current
regulatory endpoint. On the other hand, where the range of expected
doses in the DNT parallels the levels at which effects have already
been identified in the database, it is less likely that there will be a
reliable basis for assigning an additional factor lower than 10X.
b. Imidacloprid. The FQPA Safety Factor Committee recommended an
additional safety factor of 3X for imidacloprid for the protection of
infants and children. Although available studies demonstrated no
indication of increased sensitivity of rats or rabbits to in utero and/
or postnatal exposure to imidacloprid, the Committee concluded that an
additional factor of 3X was needed due to the fact that there was data
indicating a potential for developmental neurotoxicity (and, therefore,
a need for a DNT study) and the potential for exposure to young
children given the pet and outdoor residential uses of imidacloprid.
The data indicating a potential for developmental neurotoxicity
included structure activity relationship information and data from a 2-
year study in rats showing neurotoxic effects following a single oral
dose. (Ref. 56 at 6).
The DNT has now been submitted and reviewed. It showed evidence of
an increased qualitative susceptibility in the rat. At the highest dose
tested (750 parts per million (ppm)), maternal effects consisted
largely of slight decreases in food consumption and body weight gain
during early lactation, while pup effects included decreased body
weight, decreased motor activity, decreased caudate/putamen width,
females only (post-natal days 11 and adult), and slight changes in
performance in the water maze, males only, at the same dose. The NOAEL
identified in the DNT (20 mg/kg/day) was higher than the NOAELs
previously identified (ranging from 5.7 to 10 mg/kg/day) and thus the
DNT results had no impact on regulatory endpoint selection and the risk
assessment. The HIARC concluded the DNT indicated no residual concerns
regarding post-natal toxicity based on:
? The effects in pups are well-characterized with a clear NOAEL.
? The pup effects occur in the presence of maternal toxicity
with the same NOAEL for effects in pups and dams.
? The doses and endpoints selected for regulatory purposes
are protective of the pup effects noted at higher doses in the
developmental neurotoxicity study.
(Ref. 46 at 9).
EPA ultimately determined that, other than a 3X factor for acute
risk assessments to address the lack of a NOAEL in an acute study, no
other additional safety factors were needed to protect the safety of
infants and children. This conclusion was based upon:
? There is no quantitative or qualitative evidence of
increased susceptibility of rat and rabbit fetuses to in utero exposure
in developmental studies. There is no quantitative or qualitative
evidence of increased susceptibility of rat offspring in the multi-
generation reproduction study.
? There is evidence of increased qualitative susceptibility
in the rat developmental neurotoxicity study, but the concern is low
since:
1. The effects in pups are well-characterized with a clear NOAEL.
2. The pup effects occur in the presence of maternal toxicity with
the same NOAEL for effects in pups and dams.
3. The doses and endpoints selected for regulatory purposes are
protective of the pup effects noted at higher doses in the
developmental neurotoxicity study.
Therefore, there are no residual uncertainties for pre-/post-natal
toxicity in this study.
? The toxicological database is complete for FQPA assessment.
? The acute dietary food exposure assessment utilizes
existing and proposed tolerance level residues and 100% [crop-treated]
CT information for all commodities. By using these screening-level
assessments, actual exposures/risks will not be underestimated.
? The chronic dietary food exposure assessment utilizes
existing and proposed tolerance level residues and % CT data verified
by [OPP's Biological and Economic Analysis Division]
BEAD for several
existing uses. For all proposed uses, 100% CT is assumed. The chronic
assessment is somewhat refined and based on reliable data and will not
underestimate exposure/risk.
? The dietary drinking water assessment utilizes water
concentration values generated by model and associated modeling
parameters which are designed to provide conservative, health
protective, high-end estimates of water concentrations which will not
likely be exceeded.
? The residential handler assessment is based upon the
residential [Standard Operating Procedures]
SOPs in conjunction with
chemical-specific study data in some cases and [Pesticide Handlers
Exposure Database]
PHED unit exposures in other cases. The majority of
the residential post-application assessment is based upon chemical-
specific [Turf Transferable Residue]
TTR data or other chemical-
specific post-application exposure study data. The chemical-specific
study data as well as the surrogate study data used are reliable and
also are not expected to underestimate risk to adults as well as to
children. In a few cases where chemical-specific data were not
available, the SOPs were used alone. The residential SOPs are based
upon reasonable ``worst-case'' assumptions and are not expected to
underestimate risk. These assessments of exposure are not likely to
underestimate the resulting estimates of risk from exposure to
imidacloprid. (Ref. 44 at 22).
Although the HIARC's conclusions regarding exposure are stated in
terms of the imidacloprid exposure estimates not being expected to
``underestimate risk,'' in all likelihood, the imidacloprid exposure
assessments substantially

[[Page 30058]]

overstate exposure. This overestimate of exposure is a result of the
aggregation of worst case or, at the least, very conservative (health
protective) estimates of, exposure through each pathway of exposure -
food, water, and residential. For food, EPA used a worst case approach
of assuming all food which can be legally treated with imidacloprid
bears imidacloprid residues at the tolerance level for assessing acute
risk. Tolerance values are chosen to be slightly higher than any
expected residue values at the time of harvest assuming maximum
application practices are followed (See Ref. 51 at 11). Assuming
tolerance values in food fails to take into account that pesticides are
infrequently used on more than a relatively small fraction of a crop,
that pesticides are not uniformly applied at the maximum application
rate, that even when pesticides are applied at the maximum application
rate much of the treated crop will have residues well below the
tolerance level, and that pesticides often degrade substantially
between the time of harvest and consumption naturally or as the result
of food processing or cooking. Id. at 10-12, 17-30. For assessing
chronic risk, EPA took only a slightly less conservative approach by
incorporating percent crop treated data for approximately
1/89/21/13/23/87/83/8 of the commodities having tolerances.
All treated commodities were still assumed to bear tolerance level
residues.
For water, EPA estimated possible exposure with a surface water
exposure model (Pesticide Root Zone Model and the Exposure Analysis
Model System) that generally produces very conservative (health
protective) estimates of exposure. As the analysis in Unit
VII.B.4.b.ii. shows, this model generally substantially over predicts
residue levels in water, frequently by orders of magnitude. Finally,
for residential exposure, EPA relied on models using conservative
(health protective) assumptions that are also likely to overstate
actual exposure. These assumptions are described in detail in Unit
VII.A.3.
3. Missing toxicity data - lack of DNT. NRDC contends that ``the
absence of required developmental (DNT) tests for imidacloprid,
mepiquat, and zeta-cypermethrin is a crucial data gap that by itself
should prohibit EPA from overturning the default 10X safety factor.''
See, e.g., Imidacloprid Objections at 6. Given, however, that the DNT
has now been submitted and incorporated into the imidacloprid risk
assessment, this objection is no longer relevant to the imidacloprid
tolerance on blueberries.
4. Missing exposure data - general--a. Farm children exposure. NRDC
argues that EPA is lacking data on exposure to farm children and thus
may not remove the additional 10X safety factor. EPA disagrees. As
discussed above, the data submitted by NRDC have not shown that there
are significant exposures to farm children that occur as a result of
living in close proximity to agricultural operations. EPA concluded
that the evidence presented by NRDC is fragmentary, at best, as to
whether pesticide exposure levels in homes of children living in
agricultural areas are significantly different than levels in other
homes and whether children living in agricultural areas have
significantly different exposures than non-agricultural children.
After reviewing all of this data, EPA concludes it has sufficient
reliable data to find that an additional 10X factor is not needed to
protect the safety of infants and children with regard to any
uncertainties due to lack of data on exposure of farm children to
pesticides. Specifically with regard to imidacloprid, EPA is confident
that its exposure assessment is protective of all children given that
it has taken into account, in its aggregate exposure assessment, that
imidacloprid is registered for use on pets and turf. EPA's aggregate
assessment has assumed that children will come in direct contact with
treated pets and turf. Indirect exposure from agricultural uses is
unlikely to be significant compared to direct exposure to treated pets
and turf. Additionally, EPA has found the chance of pesticide exposure
as a result of the volatilization of pesticide residues in the field to
be extremely slight given the vapor pressure of imidacloprid.
b. Lack of comprehensive DW monitoring data. NRDC contends that
because EPA used a model for calculating drinking water exposure to
imidacloprid that, as a definitional matter, EPA does not have
``reliable data'' for choosing a factor different than the 10X default
value. Similar comments were made during the development of EPA's
Children's Safety Policy. For the reasons below, EPA rejects NRDC's
claims.
i. Models and data. Modeling is a necessary part of both the hazard
and exposure components of risk assessment. In the absence of perfect
data, EPA must extrapolate through the use of modeling from the
individual data available to more general conclusions concerning
hazard, exposure, and risk. (See Ref. 48 at A-7). As EPA noted in
responding to NRDC's comments on its Children's Safety Factor Policy,
''short of measuring the pesticide residues in every sip of water and
every bite of food as it is being consumed, OPP must model or estimate
exposure values for residues in drinking water and food. The need for
models exists whether the exposure estimate is based on monitoring
values in drinking water and food, residue values from field studies,
or data on a pesticide's properties and characteristics which are used
to predict anticipated residue levels in water and food.'' (See Ref. 47
at 149) Accordingly, NRDC errs to the extent it attempts to cast models
as the antithesis of data. The question is not whether EPA is relying
on reliable data or a model but whether the model EPA is using is based
on reliable data. Id. (``[T]he reliability of any method of estimating
exposure will have to be evaluated based on what data the method relies
upon'').
For imidacloprid, EPA relied on a combination of modeling
information and pesticide-specific data. EPA concluded that use of this
information was unlikely to underestimate exposure to the imidacloprid
in drinking water. EPA believes that a description of its drinking
water models and their underpinnings, an evaluation of how these models
have performed generally, and a review of the data pertaining to
imidacloprid demonstrates that this conclusion was reasonable. Hence,
EPA finds that in using these models and the pesticide-specific
imidacloprid data it was acting on the basis of reliable data. (See
Ref. 48 at A-7) (``OPP does not interpret the reliable data requirement
in the infants and children's provision as mandating that any specific
kind of data be available, just that the data and information that form
the basis for the selection of a different safety factor must be
sufficiently sound such that OPP could routinely rely on such
information in taking regulatory action.'')
ii. EPA's drinking water models. Although the availability of
drinking water monitoring data has increased dramatically in the last
several years, EPA still finds it necessary to rely for most pesticides
upon various exposure models to estimate exposure levels in drinking
water. As explained below these models are based on generic data
regarding fate and transport of pesticides in the environment, and they
operate by combining this generic data with pesticide-specific data on
chemical properties to estimate exposure.
EPA has primarily used its drinking water models to ``screen''
those pesticides that may pose unacceptable risks due to exposures in
drinking water from pesticides not likely to result in such exposures.
To accomplish this

[[Page 30059]]

goal, the models are based on data from studies at sites that are
highly vulnerable to runoff of pesticides to surface water or leaching
of pesticides to ground water. If a pesticide fails this conservative
(health-protective) screen, EPA would investigate whether the model is
significantly overstating the residue levels that actually occur.
EPA has developed models for estimating exposure in both surface
water and ground water. EPA uses a two-tiered approach to modeling
pesticide exposure in surface water. In the initial tier, EPA uses the
FQPA Index Reservoir Screening Tool (FIRST) model. FIRST replaces the
GENeric Estimated Environmental Concentrations (GENEEC) model that was
used as the first tier screen by EPA from 1995-1999. If the first tier
model suggests that pesticide levels in water may be unacceptably high,
a more refined model is used as a second tier assessment. The second
tier model is actually a combination of the models, Pesticide Root Zone
Model (PRZM) and the Exposure Analysis Model System (EXAMS). For
estimating pesticide residues in ground water, EPA uses the Screening
Concentration In Ground Water (SCI-GROW) model. Currently, EPA has no
second tier ground water model.
Whether EPA assesses pesticide exposure in drinking water through
monitoring data or modeling, EPA uses the higher of the two values from
surface and ground water in assessing overall exposure to the
pesticide. In most cases, pesticide residues in surface water are
significantly higher than in ground water.
Table 5 describes what models were used to estimate drinking water
residue levels with regard to imidacloprid both for the 2002 tolerance
and the 2004 tolerance. The table also indicates which model estimates
were used in assessing overall exposure to the pesticide.

Table 5.--Drinking Water Model Projections for Imidicloprid
----------------------------------------------------------------------------------------------------------------------------------------------------------------
Surface Water Surface Water Ground Water Model Used for
Year Residue Surface Water Model Ground Water Model acute chronic acute and chronic Exposure Assessment
----------------------------------------------------------------------------------------------------------------------------------------------------------------
1998 Imidacloprid parent PRZM/EXAMS SCI-GROW 4.1 ppb 0.1 ppb 1.1 ppb PRZM/EXAMS (acute);
SCI-GROW (chronic)
--------------------------
2003 Parent and degradates FIRST SCI-GROW 36.04 ppb 17.24 ppb 2.09 ppb FIRST (acute and
chronic)
-------------------------
2003 Parent FIRST SCI-GROW 35.89 16.52 1.43 N/A
----------------------------------------------------------------------------------------------------------------------------------------------------------------

The increase in estimated levels in surface and ground water in the
2003 assessment is due to the use of different models (for surface
water), the addition of new uses, and more updated information on
aerobic soil and water half-lives and use of the organic carbon
normalized soil/water equilibrium partition coefficient
(K_OC) instead of the soil/water equilibrium partition
coefficient (K_D) (Refs. 45 and 59) For the recent tolerance
action, EPA used the surface water estimates for calculating aggregate
exposure because they are higher than the levels projected for ground
water.
a. Surface water--i. GENEEC. GENEEC uses readily-available
pesticide properties to estimate peak and time-averaged pesticide
concentrations in a ``farm pond,'' 20 million liters (5.3 million
gallons) in capacity, located at the edge of a 10-hectare
(approximately 25 acres) treated field. GENEEC is designed to simulate
reasonable worst case pesticide levels in this farm pond following a
major rainfall event. It assumes that a maximum of 10% of the applied
pesticide is removed by rainfall and washed into the adjacent waterbed.
The underlying data supporting GENEEC is an extensive study of the
level of pesticide residues in runoff studies. (Ref. 69). That paper
provided a summary of 122 study values and revealed that the amount of
pesticide transport off of the treated field by rainfall ranged from a
low of 0.00% to a high of 22% of the applied pesticide, with most of
the values clustered toward the lower end. Only 4 of the 122 study
values were above 10%. The study author recommended that percentage
loss estimates for the pesticides most likely to be carried away by
runoff should be from 2 to 5% based on slope of the field. (Id.; see
Ref. 30) (``Under natural conditions, pesticide runoff losses in the
10% range would be rare.''). GENEEC assumes that the 10% figure
corresponds to pesticides with the greatest solubility and that
pesticides which have a greater tendency to bind to soils are
transported to the farm pond in lower amounts on a percentage basis.
The capacity of a chemical to dissolve in water or, conversely, to bind
to soil is generally expressed as the soil/water equilibrium partition
coefficient (K_D) or the organic carbon normalized soil/water
equilibrium partition coefficient (K_OC). The higher the
K_D or K_OC value for a pesticide, the greater
tendency it has to adsorb or bind to soil; there is a partial
correlation with the solubility of the pesticide with strong adsorption
generally associated with lower solubility. An individual pesticide's
K_D or K_oc value is used to estimate the
percentage of pesticide applied that is likely to enter the farm pond.
In estimating the amount of pesticide entering the pond and hence the
concentration of the pesticide in the pond, the instructions for the
model recommend use of the assumption that the pesticide was applied at
the maximum rate permitted on the pesticide label. The concentration of
the pesticide in the pond over time is calculated taking into account
the aerobic aquatic metabolic half-life, the hydrolysis half-life, and
the photolysis half-life, of the pesticide in question.
GENEEC produces a conservative estimate of levels in surface water
due to the fact that the model is constructed based on the highest
values of pesticide residues found in farm ponds and that it assumes
pesticides are applied at maximum application rates. Further
conservatism is added by, among other things, the assumption that the
entire drainage area surrounding the farm pond is planted to crops for
which the pesticide is registered and 100% of those crops are treated.
Additionally, GENEEC tends to overstate residue values in a drinking
water location because it is designed to represent a water body in the
upper reaches of the agricultural watershed. Drinking water reservoirs
typically have contributions from multiple sources. (Ref. 54 at 6)

[[Page 30060]]

In the SAP's review of GENEEC in 1997, ``nearly all the Panel
members agreed that the pesticide concentration estimates provided by
GENEEC are most likely overly conservative.'' (Ref. 18 at 18). In late
1999, EPA revised GENEEC by substituting a reservoir for the farm pond
in the model. As indicated above, this model is designated the FQPA
Index Reservoir Screening Tool (FIRST).
ii. FIRST. FIRST provides a slightly more realistic model for
estimating pesticide residues in drinking water than GENEEC because it
models a small drinking water reservoir instead of a static farm pond.
It maintains, however, many of the conservative features of GENEEC.
Like GENEEC, FIRST is based on data concerning residue in actual water
bodies and the data chosen to construct the model represent a
reasonable worst case scenario.
The drinking water reservoir that EPA chose to use as the Index
Reservoir for modeling pesticide levels is Shipman City Lake in
Shipman, Illinois (Ref. 60 at 17). Shipman City Lake is representative
of a number of reservoirs in the central midwestern United States that
are known to be vulnerable to pesticide contamination. Id. at 18. The
site at Shipman, Illinois was chosen for the IR because of extremely
high pesticide concentrations found there by the Acetochlor
Registration Partnership (ARP) monitoring program and because of its
hydrologic simplicity for modeling purposes (Refs. 1 and 2). In 1996,
Shipman City Lake had one of the highest atrazine concentrations of the
lakes monitored. (Ref. 60 at 8). Two or three of the other ARP
reservoirs had slightly higher annual peak concentrations but presented
substantial modeling difficulties.
The FIRST model was constructed in a very similar manner to GENEEC.
FIRST assumes that up to a given percentage of a pesticide may run off
into an adjacent drinking water reservoir with the precise percentage
being a factor of the pesticide's K_D or K_oc
value. After considering the concentrations of atrazine found in
Shipman City Lake and other ARP reservoir monitoring sites, atrazine's
K_D value, atrazine application rates, and various potential
percentages of pesticide runoff, EPA determined that, with a reservoir
model, assuming that up to 8% of the pesticide applied could reach the
reservoir was a conservative (health protective) value. Like GENEEC,
FIRST assumes that a pesticide is applied at its maximum application rate.
Although FIRST, also like GENEEC, assumes that all cropped area is
100% treated with the pesticide in question, FIRST attempts to be
slightly more realistic and does not assume that 100% of the drainage
area for the reservoir is planted to the treated crop. As to four major
crops (corn, soybeans, wheat, cotton), FIRST uses a value representing
the maximum drainage area for a reservoir that could be expected to be
planted to the crop in question. These values are derived from
geoprocessing analysis that combines U.S. Department of Agriculture
data on crop coverage with U.S. Geological Service data on watershed
boundaries. (Ref. 57 at 8). For all other crops, EPA assumes that 87%
of the pond's drainage area is cropped and 100% of that cropped area is
treated. (See Ref. 53 at 24) (explaining choice of 87% is based on fact
that 87% cropped was the largest cropped area in any 8-digit hydrologic
unit in the continental United States).
The SAP has endorsed the concept of using a reservoir as
reasonable, but questioned the representativeness of the reservoir EPA
chose to model. (See Ref. 17 at 3). Based on SAP comments, EPA
undertook a comprehensive review of its Index Reservoir model. EPA
considered 82 reservoirs as candidates for modeling (Ref. 54 at 15) and
selected 20 for further investigation. Factors evaluated included depth
and volume of the reservoirs, percentage of the reservoir that is
cropped, the ratio of drainage area to normal reservoir capacity, and
the availability of sufficient years of monitoring data. Following this
evaluation, EPA again selected Shipman City Lake as the most
appropriate reservoir to serve as a basis for modeling. The other three
best candidate reservoirs which were not selected were Springfield,
Illinois (watershed too large for the model), Gillespie, Illinois (two
reservoirs used alternatively by the city) and Higginsville (reservoir
has a pre-settling basin which cannot be accurately modeled.)
iii. PRZM/EXAMS. The EPA PRZM and EXAMS models used together are a
more complex modeling system that provide a more realistic estimate of
residue levels in surface water by incorporating more site-specific
information than GENEEC or FIRST. The PRZM component of the model is
designed to predict the pesticide concentration dissolved in runoff
waters and carried on entrained sediments from the field where a
pesticide has been applied into an adjoining edge-of-field surface
water body. The model can simulate specific site, pesticide, and
management properties including soil properties (organic matter, water
holding capacity, bulk density), site characteristics (slope, surface
roughness, field geometry), pesticide application parameters
(application rate, application frequency, spray drift, incorporation
depth, application efficiency, application methods), agricultural
management practices (tillage practices, irrigation, crop rotation
sequences), and pesticide environmental fate and transport properties
(aerobic soil metabolism half-life, soil:water partitioning
coefficients, foliar degradation and dissipation, and volatilization).
EPA selects a combination of these different properties to represent a
site-specific scenario for a particular pesticide-crop regime.
The EXAMS component of the model is used to simulate environmental
fate and transport processes of pesticides in surface water, including:
abiotic and biotic degradation, sediment:water partitioning, and
volatilization. Currently, OPP is using an index reservoir and a farm
pond as benchmark surface water bodies for human health and aquatic
exposure assessments, respectively.
For each component of PRZM/EXAMS, the values used are derived from
real world data. For example, the EPA-approved product label is the
source of the application rate, frequency, and method of pesticide
application. Pesticide environmental fate properties used in PRZM and
EXAMS modeling come from registrant-submitted data used for pesticide
registration or reregistration. The values used for soil properties and
site characteristics are chosen from real world databases appropriate
for the sites on which the pesticide may be used. For example, if the
pesticide is approved for use on cotton, OPP uses data reflecting the
soil types in the Cotton Belt. The index-reservoir being modeled is
based on and represents an actual, fairly typical, small flow-through
reservoir used for drinking water. Finally, the weather inputs for the
model are taken from site-specific weather data, based on the USDA
Major Land Resource Areas. PRZM modeling is generally simulated for 30
or 36 years in order to calculate the variability of the pesticide
concentration in the surface water body due to variations in weather
over time and the value used for risk assessment is the 90th percentile
value.
Despite the fact that PRZM/EXAMS uses much greater site-specific
information than either GENEEC or FIRST, it still provides high end or
upper bound estimates of pesticide values in surface water. The high
end/upper bound estimates result from the conservative manner in which
PRZM/EXAMS selects and combines values

[[Page 30061]]

derived from real world data. EPA intentionally chooses values for the
model which are likely not to underestimate the potential levels of
pesticide residue in surface water. For example, the application rate
and frequency used in the model are the highest allowed by the product
label. In addition, PRZM/EXAMS modeling is assumed to be conservative
because both the farm pond and index reservoir represent a vulnerable
water supply; conservative fate parameters are used in the model; 100%
of the cropped area in the watershed is assumed to be treated with
pesticide; for all but four major crops (corn, soybeans, wheat, and
cotton) 87% of the watershed is assumed to be cropped and treated; site
conditions (annual rainfall and soil) are chosen to represent a site
especially vulnerable to runoff taking into account all of the sites on
which the specific crop is grown across the United States; and the
simulation is run for up to 36 years and the results are reported at
the 90% highest year. For the crops corn, soybeans, wheat, and cotton,
46%, 41%, 56%, and 20%, respectively of the watershed is assumed to be
cropped and treated. Further compounding the tendency of these
assumptions to overstate exposure, EPA also assumes that all of the
pesticide in the watershed is applied simultaneously using the
application method most likely to produce maximum runoff. Assuming
simultaneous application tends to exaggerate residue estimates in
drinking water because that means all potentially treated area in the
watershed will have pesticide residues (from a maximum application
applied with the technique most likely to produce runoff) available
when the next rainfall event occurs. Assuming staggered application
between growers would be more realistic but data is not currently
available that would allow that level of sophistication in the model.
All these factors lead to an assessment that PRZM/EXAMS is expected to
predict high end or upper bound concentrations. (Ref. 53 at 20-21).
EPA sought SAP review of the PRZM/EXAMS modeling system in 1995 as
part of the SAP's review of the report entitled ``Aquatic Dialogue
Group Report: Pesticide Risk Assessment and Mitigation''. The SAP was
complementary of this overall approach to exposure assessment modeling
(See Ref. 19 at 7-9). In addition, the PRZM/EXAMS model has been before
the SAP in the context of the issue of the introduction of
incorporation of a ``percent cropped area'' [PCA]
factor in OPP's
drinking water models. In 1999, EPA requested SAP review of the
appropriateness of using PCA and presented the results of several
modeling exercises using PCA in connection with both PRZM/EXAMS and
GENEEC. Comparisons of these modeling exercises to monitoring data
showed that in most cases, the models overstated residues by an order
of magnitude or greater. In other cases, the models overstated residues
by factors less than 10. Finally, in two instances, the models
understated values found in vulnerable water bodies.
The SAP generally endorsed the use of the concept of PCA for
drinking water models. (See Ref. 16 at 67). Further, the SAP concluded
that ``[u]se of the maximum PCA appears to result in an appropriately
conservative assessment for most chemicals for major-use compounds.''
Id. The SAP, however, was skeptical of the conservativeness of the use
of PCA with regard to minor crops. Id. at 68. This appears to have been
due to the fact that the two instances in which PRZM/EXAMS under
predicted drinking water concentrations involved minor crops.
Accordingly, EPA has used a default PCA value of 87% in conducting
PRZM/EXAMS modeling for minor crops for drinking water assessments.
Further examination of the two cases of under prediction, however,
suggest that not too much weight should be attached to these results.
As to one of the cases (methomyl), the comparison was between PRZM/
EXAMS modeling for minor crop (lettuce and peaches) and monitoring data
on a major crop (corn). Further, the relatively higher concentration
value found in monitoring was not from a drinking water reservoir but a
stream adjacent to a corn field. In the other case (methidathion), the
monitored value was from a river (the San Joaquim River in California)
that is largely composed of irrigation return flow from agricultural
fields. Such a river is generally not a drinking water source (the
portion of the San Joaquim River where the samples were drawn is not
used for drinking water) and PRZM/EXAMS is not structured so as to
predict levels in such an environment.
Both the PRZM and EXAMS models have been the subject of extensive
validations. The FIFRA Environmental Model Validation Task Force
recently completed a review of PRZM. (Ref. 28). That study was an
industry-sponsored calibration effort, but EPA scientists participated
in the design and conduct of the study. The study's report concluded
that PRZM ``provides a reasonable estimate of chemical runoff at the
edge of the field.'' Id. at 6. The study found that ``[s]imulations
based on the best choices for input parameters (no conservatism built
into parameters) are generally within an order of magnitude of measured
data with better agreement observed both for larger events and for
cumulative values over the study period.'' Id. When simulations were
run using conservative input parameters such as employed by EPA,
according to the study, ``substantial over-prediction of runoff losses
occur.'' Id. at 6, 8, 49. This conclusion regarding over-prediction
only considered estimated values at the edge of the field and did not
take into account the substantial conservatism introduced by EPA's
assumptions regarding pesticide application amount, the percentage of
the watershed receiving pesticide treatment, and the timing of
application on adjacent fields.
EXAMS has also been the subject of extensive validation efforts.
Satisfactory validation has been achieved in studies conducted in the
Monogahela River, USA, an outdoor pond in Germany, a bay on the each
coast of Sweden, Japanese rice paddies, and rivers in the United
Kingdom and South Dakota, USA. (Ref. 6).
The most important validation of these models is not the abstract
study of these models but how well the models have worked in practice
when used by EPA in pesticide risk assessment. To do such an
evaluation, EPA compared its surface water estimates from GENEEC,
FIRST, and PRZM/EXAMS to data on pesticides in surface water compiled
through the U.S. Geological Survey's National Water-Quality Assessment
(NAWQA) Program. NAWQA is designed to provide ``consistent and
comparable information on water resources in 60 important river basins
and aquifers across the Nation.'' (Ref. 68)These river basins and
aquifers account for approximately 60 to 70% of the country's water
use. Id. EPA found 47 instances in which it had estimated pesticide
residues in surface water resulting from the pesticide's use on a
particular commodity using either GENEEC (14), FIRST (3), or PRZM/EXAMS
(30) and there was also NAWQA data on the pesticide in surface water.
(Ref. 41)See Table 6 below. In each instance, the peak modeled value
exceeded the maximum value in the NAWQA data. In fact, in 42 of the 47
cases, the modeling value was nearly an order of magnitude or more
higher. This further confirms that reliable data support EPA's
conclusion that use of these surface water models is not likely to
underestimate drinking water exposure. To the contrary, these data
confirm that these models produce

[[Page 30062]]

conservative (health-protective), and often extremely conservative,
results.

Table 6.--Comparison of Simulation Model Outputs with Upper Level NAWQA Monitoring Values
----------------------------------------------------------------------------------------------------------------
Peak
Pesticide Model(s) Crop Modeled NAWQA NAWQA
Value* 95th%ile Maximum
----------------------------------------------------------------------------------------------------------------
2,4-D FIRST Sugarcane 132.00 0.35 15(E)
-----------------------------------
2,4-D PRZM/EXAMS Apples 118.00 0.35 15(E)
-----------------------------------
Acetochlor PRZM/EXAMS Corn 284.00 0.17 25.1(E)
-----------------------------------
Acifluorfen PRZM/EXAMS Soybeans 14.00 < 0.04 1.10
-----------------------------------
Alachlor GENEEC Corn/Soybeans 199.00 0.10 10.90
-----------------------------------
Aldicarb PRZM/EXAMS Citrus 2.03 < 0.550 0.51(E)
-----------------------------------
Atrazine PRZM/EXAMS Sugarcane 205.00 2.86 201(E)
-----------------------------------
Azinphos methyl PRZM/EXAMS Peaches 16.00 < 0.05 0.5(E)
-----------------------------------
Benfluralin PRZM/EXAMS Apples 61.00 < 0.01 0.01
-----------------------------------
Bentazon PRZM/EXAMS Not given 122.00 0.15 8.60(E)
-----------------------------------
Bentazon GENEEC Not given 100.20 0.15 8.60(E)
-----------------------------------
Butylate GENEEC Corn 33.10 < 0.002 1.40
-----------------------------------
Carbaryl PRZM/EXAMS Citrus 494.00 < 0.041(E) 5.2(E)
-----------------------------------
Carbofuran PRZM/EXAMS Grapes 39.40 0.043(E) 7.00(E)
-----------------------------------
Chlorothalonil PRZM/EXAMS Tomatoes 43.80 < 0.48(E) 0.29(E)
-----------------------------------
Chlorpyralid FIRST Canola 17.10 < 0.230 < 0.230
-----------------------------------
Chlorpyrifos GENEEC Sweet corn 56.50 0.01 0.26
-----------------------------------
Chlorpyrifos PRZM/EXAMS Sweet corn 40.60 0.01 0.26
-----------------------------------
DCPA PRZM/EXAMS Cabbage 160.00 0.02 100(E)
-----------------------------------
Diazinon PRZM/EXAMS Citrus 540.00 0.02 2.50
-----------------------------------
Dichlobenil GENEEC Turf 951.00 < 1.2(E) 0.01(E)
-----------------------------------
Disulfoton PRZM/EXAMS Potatoes 15.51 < 0.021 0.43
-----------------------------------
Diuron GENEEC Orchard 152.00 0.26 14(E)
-----------------------------------
EPTC PRZM/EXAMS Citrus 57.35 0.02 7.30
-----------------------------------
Ethalfluralin PRZM/EXAMS Sunflowers 2.27 < 0.009 0.07
-----------------------------------
Ethoprop PRZM/EXAMS Sweet Potato 127.00 < 0.005 0.45
-----------------------------------
Linuron PRZM/EXAMS Carrots 1.30 < 0.035 1.40
-----------------------------------
Malathion PRZM/EXAMS Citrus 324.00 < 0.027 0.52
-----------------------------------
Methomyl GENEEC Lettuce 409.00 < 0.020 0.67
-----------------------------------
Methomyl PRZM/EXAMS Corn 60.00 < 0.020 0.67
-----------------------------------
Metolachlor PRZM/EXAMS Corn 134.60 1.38 77.6(E)
-----------------------------------
Metribuzin GENEEC Sugarcane 390.00 0.05 6.61
-----------------------------------
Norflurazon GENEEC Cane Berry 72.10 < 0.040 1.24
-----------------------------------
Norflurazon PRZM/EXAMS Citrus 396.00 < 0.040 1.24
-----------------------------------

[[Page 30063]]

Oxamyl GENEEC Pineapple 321.80 < 0.020 0.16
-----------------------------------
Parathion GENEEC Cotton 166.00 < 0.008 0.14
-----------------------------------
Pebulate PRZM/EXAMS Not given 2.90 < 0.004 0.08
-----------------------------------
Propargite PRZM/EXAMS Cotton 34.30 < 0.023 2.62
-----------------------------------
Propochlor GENEEC Sorghum 202.00 < 0.010 0.51
-----------------------------------
Propochlor PRZM/EXAMS Sorghum 64.00 < 0.010 0.51
-----------------------------------
Propyzamide (Pronamide) FIRST Ornamentals 390.00 < 0.004 0.28
-----------------------------------
Tebuthiuron PRZM/EXAMS Pasture/Range 15.10 0.02 0.95
-----------------------------------
Terbufos PRZM/EXAMS Sorghum 21.70 < 0.017 0.56
-----------------------------------
Thiobencarb GENEEC Celery 186.00 < 0.005 3.66
-----------------------------------
Triallate PRZM/EXAMS Wheat 5.50 < 0.001 0.65
-----------------------------------
Triclopyr GENEEC Pasture 364.00 < 0.25 16(E)
-----------------------------------
Trifluralin PRZM/EXAMS Sugarcane 3.44 < 0.009 0.17
----------------------------------------------------------------------------------------------------------------
* = 1-in-10 year peak value; (E) = NAWQA Estimate

A review of drinking water assessments by the pesticide industry
reached a similar conclusion. In this study, results from FIRST
modeling (conducted for the purpose of the study) and PRZM/EXAMS
modeling (from EPA exposure assessments) were compared with data from a
USGS/EPA monitoring program.(Ref. 23). The monitoring data was gathered
from small drinking water reservoirs in areas with high pesticide use
in 12 geographically disparate regions in the United States. The study
compared acute prediction values with the maximum value from the
monitoring data and the chronic prediction values with 95th percentile
of a time weighted average of monitored values. The result was that
``[f]or both acute and chronic exposure the models systematically
overestimate measured exposure typically by 10 to 10,000 fold for the
majority of cases.'' Id. There was no instance in which a model
underestimated exposure. Id. The study concluded that the
overestimation occurred due to ``[c]ompounding conservative
assumptions, without considering associated probabilities of
occurrence/co-occurrence.'' Id. The conservative assumptions identified
as most likely leading to this result are (1) maximum label rate
application on the highest percent cropped area in the United States;
(2) reservoir immediately bordered by treated field; and (3) highest
mobility, upper percentile half life, no reservoir dilution effects,
and no soil photolysis. Id.
b. Ground water. As mentioned above, EPA uses the SCI-GROW model
for estimating residues of pesticides in ground water. SCI-GROW is a
regression model that uses chemical-specific data on a pesticide's
adsorption (i.e. the soil/water partition coefficient of K_D
or K_oc value) and the pesticide's persisence (i.e. the soil
metabolism half-life) in combination with the assumption that the
pesticide is being applied at its maximum application rate. The model
is based on data obtained from ten prospective monitoring studies
measuring the degree to which various pesticides leached to ground
water. These studies were conducted in hydrogeologically-vulnerable
sites (i.e., shallow aquifers; sandy, permeable soils; and substantial
rainfall or irrigation to maximize leaching). SCI-GROW provides a
screening value which is applied to both peak and chronic exposure
screening.
In its review of the SCI-GROW model in 1997, a majority of the SAP
concluded that it was ``highly conservative.'' (See Ref. 18 at 10) The
SAP summarized the reasons for this conservatism as follows:
a. SCI-GROW is based mainly on OPP prospective ground water
studies designed to maximize the opportunity for pesticides to leach
into ground water:
? Soil site highly vulnerable to leaching (very sandy,
little clay, low organic matter).
? Rainfall supplemented with irrigation to ensure higher
than average monthly rainfall for each consecutive month of study.
Supplementation of rain with irrigation errs on the side of greater
opportunity for encountering rainfall amounts in excess of normal patterns.
? Sites with shallow water tables.
? Sites that represent an unknown but very low percentage
of the ground water used as drinking water.
? Sites with wells totally surrounded by treatment area;
no dilution with clean water.
? Sites with wells directly adjacent to treatment area;
short path to well.
? Maximum rate of pesticide application; multiple
treatments may be applied as one massive application.
b. Development of SCI-GROW ignored PGW [prospective ground
water]
studies with no ground water detections; only those that
produced concentrations were included in the regression data set.
Therefore, SCI-GROW reflects a filtered data set that implies
greater frequency of observed concentrations than what actually
occurred in the PGWs.
Id. at 12.
As with the surface water models, EPA has examined how well the
models have worked in practice when used by EPA in pesticide risk
assessment. To do such an evaluation, EPA compared its ground water
estimates from SCI-GROW to data on pesticides in ground water compiled
through the NAWQA program. Comparisons of the SCI-GROW screening model
have been made to various upper bound distributions (99.0,

[[Page 30064]]

99.5, and 99.8 percentiles) rather than to the absolute maximum values
in the NAWQA data (as was done with the surface water model). No higher
percentiles were calculated because such calculation would not be
reasonable given the sample size. The reason for not using maximum
values, as was done with surface water evaluation above, is the
difference in the nature of ground water and most surface water sources
sampled in the study. Surface water bodies sampled were generally
streams, reservoirs, or lakes which represent a significant amount of
mixing of runoff water from a watershed that may be tens or hundreds of
square miles in area. Well water often is most representative of
pesticides leaching from a much smaller geographic area. Furthermore,
there is a significant risk that at least some individual wells in any
large sample will be severely impacted by pesticides because of either
poor well construction (allowing direct influx of pesticide residues
from the surface) or spillage from pesticide mixing/loading activities
or leakage from pesticide storage facilities. Contamination levels in
individual wells can be much, much higher from these sources than would
occur in ground water solely from maximum agricultural applications of
pesticides to the surface. The consequence of this is that the highest
values of pesticides observed in a large scale survey of ground water
cannot be assumed to represent contamination from normal outdoor uses
of pesticides.
EPA identified 39 instances in which it had estimated pesticide
residues in ground water resulting from the pesticide's use on a
particular commodity using SCI-GROW and there was also NAWQA data on
the pesticide in ground water. (Ref. 42). In all but three instances,
the peak modeled value exceeded the 99.8th percentile value from the
NAWQA data. No exceedances occurred for any of the 39 compounds at the
99.5 percentile level or below. Most estimates, even at the 99.8th
percentile, were substantially above the NAWQA value. For example, in
24 cases, the modeling value was an order of magnitude or more higher
than the 99.8th percentile NAWQA value. Of the three cases in which the
monitoring value exceeded the projected value, in each instance the
difference was less than a factor of 2x. In two of the three cases both
the projected and monitored values were extremely low both absolutely
and relative to other exposure values for the pesticide. For example,
malathion had SCI-GROW and NAWQA ground water values (99.8th
percentile) of 0.006 ppm and 0.007 ppm, respectively, compared to PRZM-
EXAMS and maximum NAWQA surface water values of 324 ppm and 0.39 ppm,
respectively. Additionally, tolerance values for malathion range from
0.1 ppm to 135 ppm with most values for agricultural crops either 4 ppm
or 8 ppm. The other instance where a monitored value exceeded the
modeled value involved alachlor. There, SCI-GROW predicted a value of
0.82 ppm and the monitored value was 1.2 ppm or a factor of 1.5x
higher. Preliminary results of comparisons with alachlor concentration
frequency distributions from other large scale surveys, including those
targeted for alachlor or at least for corn use areas (the major crop
use for alachlor) are inconclusive with regard to the conservativeness
of the SCI-GROW prediction. Id. EPA plans to look more closely at the
data on alachlor to determine if any adjustment of SCI-GROW is
warranted. Primarily needed for this are the completion of analysis of
new monitoring data recently submitted to support the registration of
acetochlor (which includes some very useful concentration distribution
information for alachlor as well as two other corn herbicides) and the
analysis of a large amount of additional ground-water monitoring for
multiple pesticides conducted by USGS in more recent phases of the
long-term NAWQA project. EPA expects that any adjustment to SCI-GROW
would be slight.
iii. Imidacloprid-specific data. EPA has received and reviewed two
prospective ground water studies for imidacloprid (Refs. 43 and 45).
Such studies are designed to measure maximum concentrations of
pesticides likely to occur in ground water under geological conditions
vulnerable to ground water contamination. The studies were conducted in
Montcalm County, Michigan and Monterrey County, California.
At the Michigan study site, imidacloprid parent was consistently
detected in one of six monitoring well clusters in the treated field
beginning about 500 days after application and continuing through the
close of the study some 5 years after application. No degradation
products were detected in ground water during this period (there were a
very few detections before application that may have been due to
previous uses nearby or sample contamination). The maximum
concentration of imidacloprid parent detected in ground water in any
one sample at the Michigan study site was 0.24 ppb. EPA concluded that
the 0.24 ppb level might increase slightly over time as imidacloprid
continues to leach into ground water; however, the level was not
expected to increase dramatically given that the levels seen at the 3
and 12 foot soil depths was 1.63 ppb and 1.31 ppb, respectively. (Ref.
43)
Data from the California site is less useful due to the fact that
there appears to have been very little ground-water recharge occurring
during the course of the study as evidenced by the almost complete lack
of detection of the bromide tracer (applied concurrently with
imidacloprid) in ground water. The maximum combined residue of
imidacloprid parent and degradates found in the suction lysimeters was
0.62 ppb at 633 days post application. The maximum combined
imidacloprid residue in the ground water at the California site was
0.14 ppb found 149 days post application. EPA concluded that low (sub-
ppb) level contamination of potable ground water might occur in this
region following application to irrigated vegetable or fruit crops. Id.
Additionally, extensive ground water monitoring data that has
recently been submitted from the New York State Department of
Environmental Conservation, Division of Solid and Hazardous Materials
for Nassau and Suffolk Counties of New York includes data on
imidacloprid. Nassau and Suffolk counties have ground water that is
exceptionally vulnerable to pesticide contamination and have a long
history of a number of pesticides being banned from use in these
counties over the years. This exceptional vulnerability to
contamination is due to the very rapid infiltration of pesticides that
occurs in the sandy soils present in the agricultural areas of Long
Island and the tendency for pesticides to persist in the ground water.
These conditions have been documented from many years of monitoring
ground water in this area (many of early detections for pesticides that
were subject to scrutiny for ground-water contamination in the 1960s
and 1970s were from Long Island. (Ref. 26).
For imidacloprid, there have been about 27 detections of
imidacloprid above a detection limit of 0.2 ppb in about 5,000 ground
water samples taken by the Suffolk County Department of Health
Services, to date, with much of the monitoring targeted to areas with
known histories of imidacloprid use and previously documented ground-
water contamination issues. Overall, imidacloprid detections are rare
in drinking water wells. Three wells had detections above the model-
predicted maximum of 1.4 ppb. After closer investigation, however, EPA
has concluded that those three wells are not reliable indicators of
imidacloprid

[[Page 30065]]

values that can be expected in ground water from agricultural use of
imidacloprid. The first of these wells is a private well in Mattituck,
Long Island in which imidacloprid was found at a level of 6.69 ppb. An
investigation by the New York authorities, however, concluded that
these high levels were due to misuse of the pesticide in a greenhouse
adjacent to the well where imidacloprid contaminated water was drained
onto the ground in the immediate vicinity of the well. The second well
was one of five shallow monitoring wells installed directly down
gradient from imidacloprid use sites for the purpose of monitoring
pesticide levels. One of those wells, ``Jamesport B-2'', showed levels
of imidacloprid as high as 2.06 ppb. It was discovered, however, that
this well was in all likelihood contaminated as a result of a manmade
sump nearby that was constructed to alleviate ponding in the field and
directly connected surface water to ground water. Imidacloprid was
detected in only one of the other five wells, and the level of
imidacloprid detected in the other well did not exceed 0.24 ppb.
Finally, imidacloprid has been detected in shallow ground water wells
directly downgradient from a site investigating use of tree injection
treatments of imidacloprid. The highest level of imidacloprid found in
these wells was 3.9 ppb. These wells, however, are not representative
of wells used to supply ground water for drinking water. The wells were
screened at extremely shallow depths (screens beginning only 4 to 10
feet from surface) due to the fact that the depth to ground water
averaged about five feet. It was concluded that these wells are ``no
more representative of what would likely occur in drinking water
supplies than pesticide concentrations in samples taken from a weir
draining an agricultural field are representative of what would occur
in a community water supply drawing from a river or reservoir
downstream.'' (Ref. 43)
iv. Conclusion. Based on the above analysis of EPA's drinking water
models, EPA concludes that they are based on reliable data and have
produced estimates that EPA can reliably conclude will not
underestimate exposure to pesticides in drinking water. The model
estimates EPA used for assessing the aggregate exposure to imidacloprid
(37.6 ppb for acute and 17.52 ppb for chronic from the FIRST surface
water model) are substantially higher than any actual data on
imidacloprid residues in drinking water including the imidacloprid
prospective ground water study and even the extraordinary and
unrepresentative values seen in ground water on Long Island as a result
of pesticide misuse, a direct connection between ground water and
surface water, or extremely shallow ground water.
5. Missing exposure data - specific--a. Information on regional
consumption. NRDC contends that, for imidacloprid, EPA relied on
estimates of national consumption of blueberries and not regional or
state-specific data for its granting tolerances in connection with the
approval of emergency exemptions under FIFRA for use of the pesticide
on blueberries in the States of New Jersey and Michigan. NRDC argues
that the fresh nature of the food and the potential for heavy local
consumption with a strong seasonal component strongly suggests that
national consumption data may underestimate consumption in localized
areas in New Jersey and Michigan.
EPA is confident that the methodologies used in its estimation of
exposure and the percentile of regulation selected do not
systematically underestimate exposures to major identifiable
subpopulations. This is based, in part, on the extensive food
consumption survey data from USDA (its Continuing Survey of Food Intake
by Individuals or CSFII) which surveyed more than 20,000 individuals
from all States and results in more than 40,000 unique person-days of
consumption. EPA notes that, contrary to the assertion by NRDC,
consumption is not averaged throughout the year, but instead the CSFII
includes each reported consumption amount in the form of a frequency
distribution of actual reported single-day consumptions. Each
individual consumption event thus can be considered separately when
such consideration is appropriate to risk assessment as for risk
assessments estimating acute risks.
Accordingly, the CSFII survey is adequate to capture the high-end
consumers about which NRDC raises concerns. The survey is statistically
designed to be representative of the U.S. population and reflects
variability in consumption over all seasons and geographic regions. Due
in part to this design and the fact that fresh blueberries are widely
available in season in states where they are not grown, EPA does not
believe that the high-end consumption estimates present in the USDA
CSFII survey materially or systematically underestimate the consumption
patterns of consumers in blueberry-producing states (either overall or
during harvest and other ``high-availability'' seasons). (Ref. 52).
It should be emphasized that in objecting to EPA's reliance on this
scientifically designed consumption survey, NRDC has offered nothing
other than speculation to support its claim that EPA is underestimating
blueberry consumption. For this reason alone, NRDC's argument lacks merit.
For the reasons detailed above, NRDC's allegations concerning
blueberry consumption do not indicate that EPA has underestimated
exposure of consumers in Michigan and New Jersey to imidacloprid.
NRDC's objection to the children's safety factor decision on this
ground, therefore, is without merit.
b. Residential exposure information. NRDC claims that EPA failed to
include several residential exposure scenarios in its aggregate
exposure estimate for imidacloprid based on low toxicity. Imidacloprid
Objections at 16. Previously, EPA had concluded that certain
residential exposure scenarios did not present any significant risk
either because the toxicity data did not reveal any relevant adverse
effects for the duration of exposure in question (intermediate-term
exposure for all population groups) or because imidacloprid exposure
was not expected for a particular population group (short-term adult
exposure). See 66 FR at 56229, 56231. On October 8, 2002, however, the
Health Effects Division (HED) Hazard Identification Assessment Review
Committee (HIARC) re-reviewed the hazard and exposure database for
imidacloprid and established additional endpoints. Endpoints were
chosen for each of the following exposure scenarios: acute dietary,
chronic dietary, short-term oral, intermediate-term oral, short-term
dermal, intermediate-term dermal, long-term dermal, short-term
inhalation, intermediate-term inhalation, and long-term inhalation.
Additionally, it was concluded that short-term exposure was likely for
adults by the dermal and inhalation route. Oral exposure for adults is
not expected from the residential uses for imidacloprid (e.g., turf,
ornamental, pets) because adults do not generally engage in the type of
hand-to-mouth behavior that can produce such pesticide exposure in
young children. Accordingly, an aggregate risk assessment for short-
term dermal and inhalation exposure for adults was conducted. 68 FR
61624, 61632 (October 29, 2003). Intermediate-term risk assessments
(i.e. risk assessments that aggregate exposure from food, water, and
residential exposures for comparison to intermediate risk endpoints)
were not conducted because, based on residential application

[[Page 30066]]

practices and the half-lives observed in the turf transferable residue
study, residential exposures to imidacloprid are not expected to be
continuous for periods of 30 to 90 days. 68 FR at 61632; (see Ref. 44
at 51).
c. Prospective ground water monitoring studies. As discussed above,
these studies have been received and reviewed. The levels of
imidacloprid found in ground water were below the levels from modeling
used to calculate aggregate exposure.
6. Missing risk assessment. NRDC claims that a short-term
residential risk assessment is missing as to imidacloprid. Imidacloprid
Objections at 5. EPA would note, however, that such a risk assessment
was conducted and is summarized on pages 39,046 and 39,047 of the
Federal Register notice. 67 FR 39041, 39046-39047 (July 21, 1999). See
also 68 FR 61624, 61632 (October 29, 2003).
7. Conclusion on children's safety factor issues. In the challenged
tolerance action, EPA applied an additional safety factor of 3X to
address the missing DNT study. As discussed above, that study has now
been received and reviewed. Taking into account the results of that
study as well as all of the arguments raised by NRDC, EPA has concluded
that there are reliable data supporting removal of the additional
safety factor for infants and children for all risk assessments other
than the acute risk assessment relying on the acute neurotoxicity study
in rats to project a safe dose in humans. As to the acute risk
assessment using the acute neurotoxicity study in rats, there are
reliable data supporting use of an additional 3X factor instead of 10X.
See Unit VII.C.2. The 3X safety factor has been incorporated into the
acute risk assessment by dividing the LOAEL from the acute
neurotoxicity study by 3 in deriving the acute reference dose.

C. LOAEL/NOAEL

NRDC argues that EPA cannot legally make the reasonable certainty
of no harm finding for imidacloprid because EPA has relied on a LOAEL
in assessing the safe level of exposure to the pesticide. NRDC claims
EPA ``cannot lawfully establish tolerances in the absence of a no-
observed-effect-level (NOEL).'' Imidacloprid Objections at 18. Implicit
in this argument is that EPA cannot use a no-observed-adverse-effect-
level (NOAEL) in making a safety finding. In later objections, NRDC
confirmed that in fact it was contending that section 408's safety
standard does not permit EPA to rely on a NOAEL in concluding a
tolerance is safe. Rather, according to NRDC, EPA may only make a
safety finding for a pesticide where EPA has determined the dose in
animals at which no effects, adverse or otherwise, are elicited from
exposure to the pesticide. Isoxadifen-ethyl Objections at 17-18. Below
EPA identifies the flaws in NRDC's generic argument concerning LOAELs
and NOAELs and addresses the pesticide-specific concerns NRDC raises
with regard to use of a LOAEL as to imidacloprid.
1. Generic legal argument. EPA believes that it can make a
reasonable certainty of no harm finding based on a LOAEL from an animal
study (where no NOAEL was found) in appropriate circumstances. Whether
or not a reasonable certainty of no harm finding can be made when only
a LOAEL is identified in a study depends on whether EPA has sufficient
toxicological evidence to estimate with confidence a projected NOAEL
that is unlikely to be higher than the actual NOAEL. Typically, when a
LOAEL but not a NOAEL has been identified by a study, EPA will, when
the data support it, project a NOAEL for that study by dividing the
LOAEL by a factor, usually 3X.
There is nothing in the statutory safety standard explicitly
addressing the use of NOAELs or LOAELs. Moreover, nothing in the phrase
``reasonable certainty of no harm'' legally precludes use of LOAELs to
make a finding regarding the likelihood that harm will occur at a given
dose. Whether a LOAEL provides a sufficient basis for a reasonable
certainty of no harm finding is a question of scientific fact.
NRDC correctly notes that the House Commerce Committee indicated
that its ``expect[ation]'' was that EPA would be able to make a
reasonable certainty of no harm finding where there was an ample margin
of safety between exposure levels and -
the level at which the pesticide chemical residue will not cause
or contribute to any known or anticipated harm to human health. The
Committee further expects, based on discussions with the
Environmental Protection Agency, that the Administrator will
interpret an ample margin of safety to be a 100-fold safety factor
applied to the scientifically determined ``no observable effect''
level when data are extrapolated from animal studies.
H. Rep.104-669, pt. 2 , 41 (1996).
Congress' expectation, however, that a reasonable certainty of no harm
finding could be made under one set of circumstances (100-fold safety
factor applied to the ``no observable effect'' level), certainly does
not preclude the finding being made in a different set (e.g., 300-fold
safety factor applied to the lowest observable effect level). Moreover,
Congress made clear that it was adopting the reasonable certainty of no
harm standard based on EPA's ``current application of the standard.''
Since the passage of FFDCA section 409 in 1958, both FDA and EPA have a
long history of applying that standard. In no instance, has either
agency indicated that reliance on LOAELs, although it has been an
accepted practice generally, (See Ref. 12) was barred by the reasonable
certainty of no harm standard. To the contrary, EPA has relied on
LOAELs to make reasonable certainty of no harm findings under section
409. (See 61 FR 33041, 33042 (June 26, 1996) (establishing food
additive regulation for flutolanil); 55 FR 23736 (June 12, 1990)
(establishing food additive regulation for pirimphos methyl). In fact,
FDA and EPA interpreted the reasonable certainty of no harm standard to
permit a safety finding to be made in circumstances where a NOAEL
cannot be identified - that is, when a substance is believed not to
have a threshold below which no adverse affect will result - and the
House Commerce Committee in its Report on the FQPA specifically
recognized and approved that approach. Id. Thus, the legislative
history, if anything, supports the proposition that a LOAEL may provide
a sufficient basis for a reasonable certainty of no harm finding.
EPA also rejects NRDC's argument that a safety finding for a
threshold effect can only be made based on a ``no observed effect
level'' (NOEL) as opposed to a ``no observed adverse effect level''
(NOAEL). EPA's Office of Pesticide Programs (``OPP'') in a response to
comment document has explained the Agency's reasoning. Although noting
the House Commerce Committee Report uses the term ``NOEL'', OPP
concluded that:
the legislative history does not indicate that Congress
intentionally used the term NOEL because it did not think it
appropriate for OPP to consider the NOAEL. H. Rept. 104-669, 104th
Cong., 2d Sess. 41 (1996). In fact, Congress appears to have assumed
NOELs are NOAELs. For example, in defining ``threshold effect''
Congress stated that this ``is an effect for which the Administrator
is able to identify a level at which the pesticide chemical residue
will not cause or contribute to any known or anticipated harm to
human health.'' Id. (emphasis added). If Congress had intended that
threshold effects be based on NOELs rather than NOAELs, it would not
have used the word ``harm'' in defining the effect.
Congress seems to have used the term NOEL because it was common
usage for OPP at the time FQPA was passed. However, prior to 1998,
in OPP's discussion of the hazard identification process of
evaluating pesticide toxicity, the term NOEL was used to describe

[[Page 30067]]

the dose level at which no significant adverse effects were noted.
OPP's terminology was not consistent with the rest of the Agency, as
illustrated in EPA's Integrated Risk Information System (IRIS). This
system included more hazard terms than OPP generally employed,
including NOAEL, LOAEL, and FEL (Frank Effect Level). On September
2, 1998, this apparent semantic inconsistency was eliminated by HED
Standard Operating Procedure (SOP) 98.3 which indicated that OPP
would commence using the terms NOAEL and LOAEL in their scientific
reviews and documents. It also stated, ``In a practical sense, the
terms NOEL and NOAEL have been used interchangeably in OPP. As a
general rule, OPP would consider as appropriate for hazard
identification and risk assessment only those effects which are
adverse or potentially adverse. This inclusion of the term NOAEL
should not change any of our hazard endpoints for regulation but add
to the quality of the risk assessment.''
(Ref.47 at 165-166)
NRDC claims that only by relying on a NOEL can the Agency legally
make the required reasonable certainty of no harm finding. Isoxadifen-
ethyl Objections at 17-18. Yet, NRDC's legal argument here both ignores
the language of the statute and relies on unsupported factual
generalities. NRDC asserts use of a NOEL is required because only by
use of a NOEL is ``the risk assessor []
assured that regulatory
decisions are based on a dose at which no effect is elicited.''
Isoxadifen-ethyl Objections at 17 (emphasis added). The statute,
however, defines the safety standard in terms of protecting against
``harm,'' not ``effects.'' NRDC also argues that the ``adverse''
effects used to define NOAELs are ``crude toxicological endpoints,''
and that ``a NOAEL may represent a dose high enough to elicit
significant unpleasant and harmful effects . . . .'' Id. NRDC, however,
provides no data or explanation to support such assertions. EPA
believes it applies the NOAEL standard in a way that takes into account
sensitive indicators of adverse effects. EPA's use of cholinesterase
inhibition as an adverse effect is only one example of this. (Ref. 50).
In any event, general claims about the non-protectiveness of NOAELs are
insufficient to contest a specific finding of safety by EPA. An
objector must explain why the specific safety finding, taking into
account its component parts (e.g., the NOAEL or LOAEL identified, the
safety factors used), does not provide a reasonable certainty of no
harm. NRDC has not even attempted to make this case with regard to the
NOAELs used in making the safety finding for imidacloprid.
2. Use of LOAELs to assess imidacloprid risk. NRDC asserts that EPA
relied upon a LOAEL in assessing both acute and chronic toxicity to
imidacloprid. Imidacloprid Objections at 18. NRDC is mistaken as to
chronic toxicity. In assessing chronic risk, EPA set the RfD using the
NOAEL of 5.7 mg/kg/day based upon thyroid effects at the next highest
dose of 16.9 mg/kg/day in the imidacloprid combined chronic/
carcinogenicity study in rats. 64 FR 39041, 39044 (July 21, 1999); see
Imidacloprid Risk Assessment at 26, Table 4. The acute toxicity
endpoint was based upon a LOAEL of 42 mg/kg/day from an acute
neurotoxicity study in rats. This value was adjusted with a safety
factor of 3X to approximate the value of a NOAEL. EPA has high
confidence that this value of 3X is sufficient for several reasons.
First, the LOAEL (42 mg/kg) from the acute neurotoxicity study is
comparable to the LOAELs seen in adults in the developmental rat study
(30 mg/kg/d) and the two-generation reproduction study (47/52 mg/kg/d
(male/female)) and in the offspring in the DNT study (55 mg/kg/d).
Second, the extrapolated NOAEL of 14 mg/kg (42/3 = 14) is comparable to
the NOAEL of 20 mg/kg/d established in the offspring in the DNT.
Importantly, the LOAEL in DNT study like the acute neurotoxicity study
was based on decreased motor activity, and the DNT established a clear
NOAEL for that effect. Finally, the neurotoxic effects on motor
activity in the acute neurotoxicity study showed a good dose response
which resulted in minimal effects on motor activity and locomotor
activity at the LOAEL.

D. Aggregate Exposure

1. Worker exposure. EPA has interpreted ``aggregate exposure'' to
pesticide residues not to extend to pesticide exposure occurring at the
workplace based on the language in section 408(b)(2)(D) explaining what
exposures are included in the term ``aggregate exposure:''

[T]he Administrator shall consider, among other relevant factors
. . . available information concerning the aggregate exposure levels
of consumers (and major identifiable subgroups of consumers) to the
pesticide chemical residue and to other related substances,
including the dietary exposure under the tolerance and all other
tolerances in effect for the pesticide chemical residue, and
exposure from other non-occupational sources . . . .

This language quite plainly directs EPA to limit consideration of
aggregate exposure of pesticide residues and other related substances
to those exposures arising from non-occupational sources. NRDC's claim
that EPA erred by not considering worker risks in making tolerance
decisions under section 408 runs afoul of Congress' explicit mandate
that such exposures not be included. Although there is some ambiguity
as to precisely how the factors listed in section 408(b)(2)(D) relate
to the safety finding described in section 408(b)(2)(A)(ii), for the
reasons set forth below, NRDC's interpretation of the statutory
language is unreasonable.
NRDC argues occupational exposures must be considered because the
general safety standard as set forth in section 408(b)(2)(A)(ii)
describes ``aggregate exposure'' broadly without any exclusion for
occupational exposures. This reading, however, renders section
408(b)(2)(D)'s limitation of aggregate exposure to ``non-occupational''
exposures without effect. Three important principles of statutory
construction suggest that such an approach is insupportable. First, the
language in the statute should be construed in a manner that accords
meaning to all provisions. United States v. Menasche, 348 U.S. 528,
538-539 (1955) (``It is our duty to give effect, if possible, to every
word, clause and sentence of a statute.'') It is not lightly presumed
that Congress enacted a meaningless or superfluous provision. Asiana
Airlines v. FAA, 134 F.3d 393, 398 (D.C. Cir. 1998) (``A cardinal
principle of interpretation requires us to construe a statute `so that
no provision is rendered inoperative or superfluous, void or
insignificant.'''). EPA's interpretation gives meaning to the
occupational exposure exclusion in section 408(b)(2)(D). Second, and
similarly, statutory language should be construed in a harmonious
fashion to the greatest extent possible. Citizens to Save Spencer
County v. EPA, 600 F.2d 844, 871 (D.C. Cir. 1979) (``[T]he maximum
possible effect should be afforded to all statutory provisions, and,
whenever possible, none of those provisions rendered null or void.'')
``The cardinal principle of statutory construction is to save and not
to destroy.'' Menasche, 348 U.S. at 538. Although EPA's interpretation
does not relieve all potential tension between section 408(b)(2)(A)(ii)
and section 408(b)(2)(D), NRDC's approach treats the two sections as
directly contradictory, negating the specific language in subsection
(b)(2)(D)(vi) pertaining to occupational exposure. Third, specific
language should control over general. Ohio Power Co. v. FERC, 954 F.2d
779, 784 (D.C. Cir. 1992) (``Of course, it is black letter law that
when a conflict arises between specific and general provisions of the
same legislation, the courts should give voice to Congress's specific
articulation of its policies and preferences.'') Hence, the more detailed

[[Page 30068]]

explanation in section 408(b)(2)(D) concerning the scope of aggregate
exposure should be relied upon to help to provide a harmonious
construction of the two sections.
NRDC, pointing to the ``among other relevant factors'' language in
section 408(b)(2)(D), objects that this section should not be viewed as
controlling because this section is intended to be ``illustrative'' and
not ``exhaustive.'' EPA fully agrees that section 408(b)(2)(D) was not
intended to list exhaustively all of the considerations appropriate to
making safety determinations under section 408, but cannot accept the
proposition that the ``other relevant factors'' language somehow undoes
the express limitation in subsection (b)(2)(D)(vi) concerning
occupational exposure. Not only does NRDC's approach once again fail to
give meaning to the occupational exposure exclusion in subsection
(b)(2)(D)(vi) but it fails to take into account Congress' directive
that EPA could consider ``other relevant factors.'' When used in this
fashion, the word ``relevant'' restricts EPA to considering factors
that are relevant to the safety determination under section 408(b) -
that is, relevant to whether a pesticide's aggregate exposure meets the
reasonable certainty of no harm test. Presumably, Congress provided an
important reference point for determining relevance by the long list of
factors it required that EPA consider. Relevance, moreover, is
indicated not only by the factors that Congress included but by the
aspects of those factors that Congress expressly directed were not to
be considered. Thus, EPA believes that Congress, by excluding
occupational exposures from the term ``aggregate exposure'' in
subsection (b)(2)(D)(vi) was, in effect, determining the relevance of
occupational exposure to aggregate exposure and the safety
determination under section 408.
Finally, NRDC has argued, in a Petition which it has appended to
its objections, that even if worker exposure generally is excluded from
aggregate exposure, ``in utero'' exposures resulting from the presence
of pregnant women in the workplace should not be excluded from
consideration. NRDC, Petition for a Directive that the Agency Designate
Farm Children as a Major Identifiable Subgroup and Population (1998).
NRDC points to the statutory language directing EPA to consider ``in
utero'' exposures and cases under state worker compensation statutes
that have held that children who are injured ``in utero'' as a result
of their mother's employment are not barred by worker compensation
schemes from bringing an action against the employer. These cases have
held that the bar to seeking a tort remedy against the employer applies
only to ``employees'' and an in utero fetus is not an employee. See,
e.g., Snyder v. Michael's Stores, Inc., 945 P.2d 781 (Calif S.Ct. 1997).
Although the statutory language on this issue may permit multiple
readings here, EPA believes it is reasonable to exclude workplace
exposures to the in utero fetus from aggregate exposure. EPA is not
suggesting that the fetus is an employee - the issue involved in the
worker compensation cases cited by NRDC. The language of section 408 is
significantly different than worker compensation statutes. Section 408
does not bar consideration of exposure to ``employees'' but rather
exposure from ``occupational sources.'' Given this statutory language
EPA believes it is reasonable to focus upon whether the exposure is
principally due to exposure in an occupational setting or not. An
exposure to a fetus that results from the fetus' mother's presence in
an occupational setting would fall well within this approach. This
interpretation also makes sense in terms of the overall statutory
scheme. Presumably, Congress excluded occupational exposures from
section 408 because it determined that acceptable levels in food for
the general public should not be set using the discrete, and highly
regulated (including regulation by EPA under FIFRA), exposures
occurring in the workplace as an assumed underlying exposure. If
occupational exposure to pregnant women is included in aggregate
exposure under section 408, however, occupational exposure will
invariably be an aspect of the section 408 safety finding for
pesticides involved in agriculture or other commercial enterprises
because EPA would generally have to assume that pregnant women may be
in the workforce.
2. Classification of farm children as a major identifiable
population subgroup. NRDC points out that FFDCA section 408 directs EPA
to consider not just the general population in assessing aggregate
exposure but also ``major identifiable subgroups of consumers.'' 21
U.S.C. 346a(b)(2)(D)(vi). In this regard, NRDC argues that children
living in agricultural communities should be treated as such a major
identifiable subgroup. These children are an identifiable subgroup,
according to NRDC, because of the allegedly heightened exposure to
pesticides that they receive due to their proximity to farm operations
and farm land and, for some, due to their contact with parents involved
in agriculture. Isoxadifen-ethyl Objections at 11-12. NRDC claims these
children comprise a ``major'' subgroup citing statistics showing that
``320,000 children under the age of six live on farms in the United
States[], . . . many hundreds of thousands of children play or attend
schools on or near agricultural land, . . . [and]
[t]he nation's 2.5
million farm workers have approximately one million children living in
the United States.'' Id.
Whether or not EPA attaches the label ``major identifiable
subgroup'' to farm children, EPA's risk assessment approach to
children, including the major identifiable subgroups of children used
in its risk assessments, adequately takes into account any pesticide
exposures to children - whether as a result of living close to
agricultural areas or otherwise. For some time, EPA has treated infants
and children grouped by ages (e.g., infants younger than 1 year,
children 1 - 2 years) as major identifiable subgroups. These age
groupings have been chosen to reflect different eating patterns of the
age groups. In evaluating exposure to these or any other subgroup,
however, EPA considers the range of exposures across the subgroup not
just as a result of pesticide residues in food but from all non-
occupational exposures. If a significant number of any of the
population subgroups of children have higher exposures due to a non-
food source (e.g., residential uses of a pesticide, proximity to
agricultural areas), EPA believes that that exposure is appropriate to
consider in evaluating the range of exposures for the subgroup. The
fact that the children in the subgroup receiving the higher exposures
are not themselves labeled a major identifiable subgroup in no way
lessens EPA's consideration of their exposures. This approach is nicely
illustrated by the imidacloprid risk assessment.
In the imidacloprid risk assessment, EPA not only considered
imidacloprid exposure from food but also exposures resulting from use
of imidacloprid on lawns and pets. The residential use scenario that
produced the highest estimate of exposure was a toddler hugging the pet
right after imidacloprid treatment. In evaluating aggregate exposure to
toddlers (children 1-2 years-old), EPA aggregated imidacloprid exposure
from the pet hug scenario with imidacloprid exposure from food and
water. This was done even though (1) children living with pets capable
of receiving a full body hug are not designated a major identifiable
subgroup; (2) it is likely that only a minority of the children in the
age subgroup of 1-2 years-old live with pets

[[Page 30069]]

of this size; and (3) the number of 1-2 year-old children that may
actually experience the exposures estimated by the pet hug scenario is
likely to be exceeding small. Similar to the manner in which
residential exposure was incorporated in the aggregate exposure
assessment, if EPA had information showing meaningful exposure to
children as a result of living close to agricultural areas, those
exposures would receive full consideration in assessing aggregate
exposure to the existing children's subgroups. Thus, the fact that EPA
has not labeled farm children as a major identifiable subgroup has not
in any way affected EPA's consideration of exposures that are unique to
farm children. For the reasons discussed in the Units VII.A. and
VII.D.4, however, EPA concludes that its exposure assessment has
adequately considered any potentially greater exposures to children in
agricultural areas.
That being said, EPA does not believe that NRDC has made an
adequate case that the group of children NRDC designates as ``farm
children'' are an identifiable group. Many of the commenters protested
NRDC's designation of ``farm children'' as a major identifiable
subgroup, noting the heterogeneous nature of the group and NRDC's lack
of precision in defining the group. To be sure, NRDC's suggested
subgroup is constructed differently than EPA's historical practice with
regard to population subgroups. That practice has focused on
categorizing individuals by age, ethnicity, and region of the country.
Similarly, NRDC is, in fact, far from precise in defining the limits of
the suggested subgroup. For example, NRDC does not clarify whether
urban or suburban children on the borders of areas that exist side-by-
side with agricultural areas should be included in the alleged
subgroup, or whether it would include in the subgroup children in
agricultural areas who might live no closer to application sites than
some urban or suburban children.
Moreover, several of the reports submitted by NRDC undermined its
contention that farm children are an identifiable subgroup based on
exposure. The CFPR Report, for example, in a number of places
highlights the degree to which, not only farm-area residents, but also
urban and suburban residents are exposed to pesticides. The asserted
exposures suffered by urban dwellers, moreover, include spray drift not
only from urban area applications (e.g., from home and garden
applications, as well as other structural applications), but long-range
spray drift from agricultural area applications. These aspects of the
report run counter to NRDC's suggestions that: (1) farm children are a
major subgroup that receives greater exposure than non-farm children;
and (2) farm children are a major identifiable subgroup, in that the
lines in the report between farm area children and non-farm-area
children exposed to agricultural spray drift are blurred.
In addition, although in places the CFPR Report cites to studies
purportedly showing that farm children suffer more exposure to
pesticides than other children, on account of spray drift, it largely
relies on the Washington State studies discussed above. For reasons
already mentioned, the Agency does not believe that those studies
support the designation of farm children as a major identifiable subgroup.
The Ranking Study, for its part, also emphasized that ``an
increasing number of children live along the nation's agricultural-
urban edge.'' As discussed above, this phenomenon clouds the potential
for a distinction between farm and non-farm children. Moreover, the
authors of the study identified ``[n]otable uncertainties'' in their
risk assessment, and would go only so far as to suggest that
``farmworker/farm children'' constitute a subgroup ``potentially at
higher risk.'' Thus, it, too, fails to support the identification of
farm children as a major identifiable subgroup, as distinguished from
children generally.
NRDC also alleges that farm children have ``unique . .
.sensitivities to exposure'' that must be considered by EPA.
Imidacloprid Objections at 11-12. NRDC, however, cites no unique
toxicological sensitivities of farm children but rather focuses on the
allegedly unique exposure patterns of farm children. At most, NRDC
points to the fact that children generally may be more toxicologically
sensitive than adults because their internal organs and bodily
processes are still developing. Id. at 13. But the fact that children
may have different toxicological sensitivities than adults does not
support any claim regarding differences in sensitivities between
children generally and farm children.
In sum, the above studies and information, whether concerning
children in agricultural areas and non-agricultural areas or children
in agricultural areas alone, and whether concerning environmental
levels, biological levels, or both, provide no sufficient basis for
designating ``farm children'' as a major identifiable subgroup. It thus
was reasonable for EPA to assess aggregate exposure to the challenged
pesticide tolerances without identifying farm children as an additional
major identifiable subgroup of consumers. EPA's approach, described
above, of examining the range of exposures in each of the age-based
subgroups of children is adequately protective of children to the
extent they experience higher exposures from proximity to agricultural
areas.
3. NRDC's 1998 petition on farm children. As previously mentioned,
NRDC petitioned EPA in 1998 to designate farm children as a major
identifiable subgroup under section 408 and take several other various
steps regarding farm children's exposure to pesticides. For the reasons
stated above, EPA does not believe it is appropriate to designate farm
children as a major identifiable subgroup although, as indicated, EPA
will consider reliable data on the range of pesticide exposures
received by children, including data pertaining to such issues as spray
drift, volatilization, and farmworker take-home exposures that were
raised by the 1998 petition.
The 1998 petition also requested that EPA: (1) retain the
additional 10X safety factor for the protection of children where EPA
lacks data on farm children exposure; (2) make specific determinations
as to the exposure of farm children from all pathways; (3) require data
from registrants where data is lacking on farm children's exposure and
not issue a tolerance until such data is submitted; (4) refuse to
register a new pesticide unless a validated scientific method is
available to detect residues of the pesticide in food; (5) increase
research into exposures and health status of farm children; and (6)
honor the Executive Order on environmental justice.
As explained above, EPA has initiated a myriad of different
research and outreach programs concerned with pesticide exposure to
farmworkers and their families. The most important of these include, on
the research front, EPA work with the National Agricultural Workers
Survey (NAWS), and the Agricultural Health Survey (AHS). In terms of
outreach, EPA has many ongoing programs, but would like to highlight
two projects in particular. The Agency's work with the Association of
Farmworker Opportunity Programs (AFOP), and its work on the National
Strategies for Health Care Providers: Pesticide Initiative.
Through the Agency's cooperative agreement with the Association of
Farmworker Opportunity Programs (AFOP), EPA funds the National
Pesticide Safety Education Program for agricultural workers and farm
worker children. Working with Americorps

[[Page 30070]]

members, AFOP trains 25,000 farm workers and farm worker children every
year about pesticide safety using Americorps members in over 50 sites
in 16 states. AFOP conducts pesticide safety training for children at
childcare centers, schools, churches, and community centers, and has
developed a handbook in Spanish. The National Strategies for Health
Care Providers: Pesticide Initiative is an initiative created by the
EPA and the National Environmental Education and Training Foundation
(NEETF) in collaboration with the U.S. Departments of Health and Human
Services, Agriculture and Labor. It is aimed at incorporating pesticide
information into the education and practice of health care providers.
The goal is to improve the recognition, diagnosis, management, and
prevention of adverse health effects from pesticide exposures. This
initiative also serves as a model for broader efforts to educate health
care providers about the spectrum of environmental health issues. Seven
federal agencies and 16 professional associations of health care
providers were involved in launching this initiative. These actions
address the Petition's request regarding increased research and
fidelity to the Executive Order on Environmental Justice.
EPA agrees that where additional data are needed to characterize
farm children's exposure to a specific pesticide it will retain the
additional 10X safety factor unless reliable data exist that support
selection of a different safety factor. Further, EPA will seek
additional data on farm children exposure where necessary. Any decision
on whether to approve a tolerance where additional data has been
required will have to be a case-by-case determination considering other
data that is available on the pesticide and the ability of use of
additional safety factors to address any uncertainty raised by the
requested data. As to making specific findings on all possible pathways
of exposure to farm children, EPA will follow a pesticide-specific
approach which considers both the generic information and pesticide-
specific information in regards to whether a particular pathway has the
potential for significant exposure. Finally, EPA agrees that it should
not register a new pesticide for use on food unless it has approved an
analytical method for detecting the level of pesticide residues in food
or found that such a method is unnecessary.
4. Adequacy of EPA's assessment of the aggregate exposure of
children, including children in agricultural areas. EPA believes that
it has adequately assessed the aggregate exposure of children to
imidacloprid generally (including both farm children and non-farm
children), through its assessment of exposure through food, drinking
water and residential use pathways. In support of its objection to this
assessment, NRDC cites numerous studies for the proposition that other
pathways (e.g., track-in) increase farm children's exposures, and it
also cites information purportedly suggesting that volatilization and
spray drift lead to higher exposures among farm children. For reasons
discussed above, however (see Unit VII.A.), EPA does not believe that
this information demonstrates that the pathways asserted, to the extent
they exist, lead to farm children experiencing imidacloprid exposure
levels higher than those experienced by other children. Rather, these
studies are inconclusive, and suggest that farm children and non-farm
children generally receive similar levels of exposure. Nor does the
information bearing on volatilization and spray drift demonstrate that
farm children receive greater imidacloprid exposures through these two
additional pathways. For example, as stressed above, imidacloprid
exposures due to residential and pet uses common to farm and non-farm
areas would dwarf any exposures that might be attributable to either
volatilization or spray drift in agricultural areas.
5. Residential exposure as a result of use requiring a tolerance.
NRDC also argues that EPA has erred in not including the added
residential exposure that occurs in the home when an additional
agricultural use is added. The reasons explained above as to why any
additional exposure to children as a result of their proximity to
farming operations is expected to be insignificant as regards
imidacloprid apply with equal or more force as to this contention.
6. Population percentile used in aggregate exposure estimates--a.
In general. NRDC contends that EPA in making the reasonable certainty
of no harm finding must make such a finding as to ``all children'' -
that is, EPA must find that ``no children will be harmed'' by exposure
to the pesticide. Although EPA is somewhat uncertain as to precisely
what approach to risk assessment and safety findings NRDC is
advocating, EPA believes that its approach to implementing the
reasonable certainty of no harm standard is consistent with the
statutory framework. As specified in the statute, EPA focuses its risk
assessment and safety findings on major identifiable population
subgroups. 21 U.S.C. 346a(b)(2)(D)(vi). For children EPA has identified
the following subgroups: nursing infants (0-6 months); non-nursing
infants (6 months - year); 1-2 year-olds; etc. EPA evaluates each of
these subgroups to determine if it can be determined that there is a
reasonable certainty of no harm for individuals in these subgroups.
(See Ref. 48 at 46 and Ref. 51 at 14)
b. Choice of population percentile. NRDC asserts that EPA erred by
allegedly making its safety decision as to the acute risk posed by
imidacloprid based on only a portion of the population, leaving the
rest of the population unprotected. According to NRDC, EPA only
considered 95% of the affected population. EPA admits using the
population percentage cited by NRDC in estimating acute exposure for
imidacloprid. EPA most definitely was not, however, acting in a manner
designed to only protect 95% of the population. To the contrary, EPA's
exposure estimates were designed to capture the full range of exposures
in each population subgroup.
As explained in its science policy paper on this subject, EPA, in
estimating acute exposure for population subgroups, generally considers
various population percentiles of exposure between 95 and 99.9,
depending on the extent of overestimation in the residue data used in
the assessment.(See Ref. 52) In each exposure assessment EPA is
attempting to reasonably estimate the full range of exposures in a
subgroup. The use of a particular percentile of exposure is a tool to
estimate exposures for the entire population and population subgroups
and not a means to eliminate protection for a certain segment of a
subgroup. When inputs for pesticide residue values in the exposure
estimate are high end (e.g., assuming all food contains tolerance level
residues), a lower percentile of exposure (e.g., 95%) is thought to be
representative of exposure to the overall population as well as
subgroups. As increasingly realistic residue values are used (e.g.,
information from pesticide residue monitoring), a higher percentile of
exposure (e.g., 99.9%) is generally necessary to be protective of the
overall population and its subgroups.
This issue was the subject of some attention when EPA began
performing probabilistic acute exposure (risk) assessments using
monitoring data for residue values and increasingly used a population
percentile of 99.9 to estimate exposure. Some affected parties became
concerned that EPA was determining that only 99.9% of the population
were entitled to protection from potentially unsafe pesticide residues.
EPA

[[Page 30071]]

addressed this issue in a policy paper, noting that:
just as when OPP uses the 95th percentile with non-probabilistic
exposure assessments OPP is not suggesting that OPP is leaving 5% of
the population unprotected, OPP is not by choosing the 99.9th
percentile for probabilistic exposure assessments concluding that
only 99.9% of the population deserves protection. Rather, it is
OPP's view that, with probabilistic assessments, the use of the
99.9th percentile generally produces a reasonable high-end exposure
such that if that exposure does not exceed the safe level, OPP can
conclude there is a reasonable certainty of no harm to the general
population and all significant population groups.
Id. at 31.
Other parties had the opposite concern - namely, that by using the
99.9 percentile EPA was grossly overstating exposure to the population.
Interestingly for the purpose of the NRDC's claims regarding
imidacloprid, EPA's analysis of the reasonableness of its exposure
assessments demonstrated that exposure estimates using high end residue
values and the 95th percentile of exposure were significantly greater
than exposure estimates for the same pesticide relying on monitoring
data and 99.9th percentile. Id. at 16-17 (citing an example showing
exposure estimates over an order of magnitude lower when using 99.9th
percentile with monitoring data rather than 95th percentile assuming
tolerance level residues).
For imidacloprid, EPA estimated acute exposure using the gross
overestimate of all crops covered by the tolerance containing residues
at tolerance levels. Thus, EPA believes it acted reasonably in using
the 95th percentile of exposure in estimating imidacloprid exposure to
the overall population and major identifiable subgroups in making its
reasonable certainty of no harm finding as to the acute risks posed by
imidacloprid.
7. Lack of residential exposure assessment for adults. NRDC objects
to EPA's decision not to conduct residential exposure assessments for
adults despite the fact that imidacloprid has numerous residential
uses. Imidacloprid Objections at 16. As explained in Unit VII.B.5.
above, EPA has now determined that residential exposure assessments are
appropriate as to short-term dermal and inhalation exposures but that
other types of residential exposure are unlikely to occur (e.g., short-
term adult oral exposure and intermediate-term exposure).
8. Percent crop treated. NRDC asserts that EPA's use of percent
crop treated data pertaining to blueberries in calculating aggregate
exposure for imidacloprid is in violation of the requirements specified
in section 408(b)(2)(F). That section imposes certain conditions upon
EPA's use of percent crop treated data when assessing chronic dietary
risk. Among the specified conditions are the requirements that EPA find
that ``the data are reliable and provide a valid basis to show what
percentage of the food derived from such crop is likely to contain such
pesticide chemical residue . . . [and]
the exposure estimate does not
understate exposure for any significant subpopulation group . . . .''
21 U.S.C. 346a(b)(2)(F). NRDC claims that, because EPA used national
percent crop treated data on blueberries even though imidacloprid use
on blueberries is only permitted in Michigan and New Jersey, EPA had no
``valid basis'' for projecting the percent crop treated in those two
states. Additionally, NRDC argues that use of national percent crop
treated data on blueberries will ``understate exposure'' for the
significant population group of blueberry consumers in Michigan and New
Jersey.
NRDC's argument here is without merit because EPA assumed that 100%
of the blueberries consumed in the United States would be treated with
imidacloprid in conducting the imidacloprid risk assessment. Although
the Federal Register notice explaining the basis for the imidacloprid
blueberry tolerance does note that ``percent crop treated data [was]
used of selected commodities,'' 64 FR 56225, 56228 (November 7, 2001),
those commodities did not include blueberries. (Ref. 58; see also Ref.
44 at 43-44)

E. Lack of Emergency

In comments filed on its own objections, NRDC advances a new
challenge to the imidacloprid tolerance on blueberries. This challenge
is unrelated to the safety issues raised in its objections; rather, it
is instead tied to the fact that this imidacloprid tolerance was
established in conjunction with EPA's approval of the use of
imidacloprid under section 18 of FIFRA to address an emergency
situation in the state of Michigan. Section 18 of FIFRA gives EPA the
authority to exempt States and Federal agencies from the requirements
of FIFRA in emergencies. NRDC claims that the ``alleged'' emergency
justifying the approval of imidacloprid on blueberries, and
correspondingly the blueberry tolerance, does not meet the criteria for
an emergency in EPA regulations.
Under EPA regulations, EPA may authorize an emergency exemption if
it determines, among other things, that an ``emergency condition
exists.'' 40 CFR 166.25(b)(1)(i). An ``emergency condition'' is defined
as ``an urgent, non-routine situation . . . .'' 40 CFR 166.3(d). The
regulations deem an emergency condition to exist when (1) no effective,
registered pesticides are available to address the conditions; (2) ``no
economically or environmentally feasible alternative practices which
provide adequate control are available;'' and (3) the situation will
cause ``significant economic loss . . . .'' Id. Applicants for
emergency exemptions are required to submit information to EPA
addressing these issues. 40 CFR 166.20. EPA may ``discontinue
processing'' of incomplete applications, 40 CFR 166.30(a)(1), and deny
an application for a information gap but must reconsider the
application when the information gap is filled. 40 CFR 166.30(a)(2).
EPA first approved the State of Michigan's request for an emergency
exemption for the use of imidacloprid on blueberries in July, 2001. The
problem faced by growers in Michigan was that the Japanese beetle (an
invasive pest introduced to the United States in 1916) was increasingly
contaminating shipments of harvested blueberries. Although the beetle
does not reduce the production of blueberries in the field, the
presence of the beetle mixed in with harvested blueberries has resulted
in wholesale rejection by fruit buyers of shipped blueberries.
Purchasers, according to Michigan, follow a ``one beetle is too many''
approach. Michigan cited one instance in the prior year (2000) in which
two shipments of blueberries totaling 1.7 million pounds of blueberries
were rejected at the point of delivery. Looking to the future, Michigan
noted that ``the three largest buyers of Michigan blueberries for
yogurt production have chosen not to purchase blueberries from Michigan
in 2002, because of Japanese beetle contamination in previous years.''
These buyers alone purchased 5 million pounds of the 65 million pound
Michigan blueberry crop. Michigan stated that this contamination had
occurred despite the addition of more workers on packing lines and
investment in expensive color sorting technologies. No pesticides were
then registered for control of Japanese beetle grubs in blueberries and
the two products registered for control of adult Japanese beetles in
blueberries are of limited effectiveness.
The basis for NRDC's challenge to EPA's conclusion that an
emergency condition existed in Michigan is (1) that Michigan did not
demonstrate that the ``alternative solutions [of using

[[Page 30072]]

additional workers or color sorting technologies]
are economically or
environmentally infeasible;'' and (2) that Michigan has failed to
provide economic data on estimated net and gross revenues with and
without the pesticide. As to whether Michigan adequately demonstrated
the infeasibility of addressing the Japanese beetle problem by using
additional workers or sorting technology, EPA believes that Michigan's
reliance on the fact that use of these practices has in the past failed
to solve the problem is an adequate demonstration. Regarding data on
potential economic losses, Michigan's data was not as detailed as EPA
would have preferred, but in the context of an emergency situation,
providing information indicating that close to 10% of the Michigan
blueberry crop had already been threatened by the lack of control of
Japanese beetles (the loss of purchasers for 5 million pounds out of
Michigan's 65 million pound crop) is sufficient to show a ``significant
economic loss.''
In any event, this issue has no relevance to the action being taken
today to establish a permanent tolerance for imidacloprid on
blueberries because it is not being done in connection with an
emergency exemption under FIFRA.

VIII. Response to Comments on NRDC's Objections

EPA has responded to the comments submitted that pertained
specifically to imidacloprid to the extent the comments were relevant
above. The only remaining comments that EPA believes are appropriate to
address are the comments filed by the IWG raising legal objections to
EPA's consideration of data bearing on exposure to pesticides other
than through pesticide residues in food. EPA has also included a short
response to the comments received from citizens and IR-4.

A. IWG Comments

To recap, the IWG's argument is based on the presence of the
defined term ``pesticide chemical residue'' in the critical statutory
injunctive that a pesticide tolerance is safe only if ``there is
reasonable certainty that no harm will result from aggregate exposure
to the pesticide chemical residue, including all dietary exposures and
all other exposures for which there is reliable information.'' 21
U.S.C. 346a(b)(2)(A)(ii). The term ``pesticide chemical residue'' is
defined to mean a residue of the pesticide, or any substance present as
a result of metabolism or degradation of the pesticide, ``in or on raw
agricultural commodities or processed food.'' 21 U.S.C. 321(q)(2). The
IWG argues that, because aggregate exposure is described only in terms
of exposure to the ``pesticide chemical residue'' and a pesticide
chemical residue is defined as only including residues in food,
aggregate exposure must be limited to exposure to pesticide residues in
food. Under this interpretation, EPA may not consider exposures from
non-food sources such as residues in drinking water, or residues in or
around the home from residential uses of a pesticide in making the
safety determination under section 408.
In its initial construction of the FQPA, and consistently
thereafter, EPA has taken a distinctly different approach to section
408's safety finding. EPA's interpretation has been that the statute
requires EPA, in making a section 408 safety finding, to consider all
exposures to the pesticide and related substances, whether the exposure
is from food, water, or other sources, with the exception that
occupational exposures are excluded. See, e.g., 61 FR 48843, 48844
(September 17, 1996) (Aggregate exposure ``includes exposure through
drinking water, but does not include occupational exposure.''); 62 FR
17096, 17097 (April 9, 1997) (``In examining aggregate exposure, FQPA
directs EPA to consider available information concerning exposures from
pesticide residue in food, including water, and all other non-
occupational exposures. The aggregate sources of exposure the Agency
looks at includes food, drinking water or ground water, and exposure
from pesticide use in gardens, lawns, or buildings (residential and
other indoor uses).''); (Ref. 62) (``EPA must now consider other non-
occupational sources of pesticide exposure when performing risk
assessments and setting tolerances. This includes dietary exposure from
drinking water, non-occupational exposure, exposure from like
pesticides that share a common mechanism of toxicity as well as other
exposure scenarios.''). (Ref. 48 at 36 and Ref. 49 at 8). Since August
3, 1996, the date of the passage of the FQPA, EPA has promulgated
hundreds of tolerance rulemakings and conducted thousands of tolerance
reassessments based on this interpretation of the statute.
EPA's interpretation that it must consider all non-occupational
exposures to pesticides and related substances under section 408 rests
on the plain language of the FQPA, its statutory structure, and its
legislative history. Section 408, by its very terms, in some places
dictates that pesticide chemical residues being referred to are
residues ``in or on food'', see, e.g., 21 U.S.C. 346a(a)(1), and yet,
in other places omits this ``in or on food'' modifying language. Most
notably, the ``in or on food'' qualification is omitted from the
aggregate exposure provisions. See 21 U.S.C. 346a(b)(2)(A)(ii);
346a(b)(2)(C)(ii)(I); 346a(b)(2)(D)(vi). Because Congress at times
paired the term ``pesticide chemical residue'' with the phrase ``in or
on food'' and other times (such as in describing aggregate exposure)
did not, EPA believes that Congress' usage of the term ``pesticide
chemical residue'' should not be interpreted as restricted to residues
in or on food unless Congress explicitly directed in its specific usage
of the term ``pesticide chemical residue'' that the residue must be in
or on food. Admittedly, the definition in section 201 of ``pesticide
chemical residue'' as being a residue in or on food creates ambiguity
as to Congress' precise intent with regard to its use of the term
``pesticide chemical residue'' in section 408. As explained below,
however, EPA's interpretation is the only reasonable interpretation
considering the language, structure, and history of section 408.
First, other plain language in the statute confirms the
reasonableness of EPA's interpretation. On two occasions, Congress
explicitly referenced other ``sources'' of exposure as being relevant
to section 408's safety standard. First, in the provision addressing
aggregate exposure, Congress directed that EPA consider aggregate
exposure ``to the pesticide chemical residue and to other related
substances, including dietary exposure under the tolerance and all
other tolerances in effect for the pesticide chemical residue, and
exposure from other non-occupational sources.'' 21 U.S.C.
346a(b)(2)(D)(vi) 346a(b)(2)(C) (emphasis added). Second, in expanding
the protection for infants and children, Congress specified that, for
the purposes of making a safety finding as to infants and children,
``an additional tenfold margin of safety for the pesticide chemical
residue and other sources of exposures shall be applied . . . .'' 21
U.S.C. 346a(b)(2)(C)(emphasis added). Thus, Congress could not have
intended that residues in food would be the only ``source'' considered
in calculating aggregate exposure. The legislative history is quite
clear on this point, explicitly noting that aggregate exposure includes
both exposure under all tolerances for the pesticide and exposure from
other sources:
The Committee understands ``aggregate exposure'' to the
pesticide chemical residue to include dietary exposures under all
tolerances for the pesticide chemical residue, and exposure from
other non-occupational sources.

[[Page 30073]]

H. Rept.104-669, Part 2, 40 (July 23, 1996)
Second, the structure of the statute confirms that considering
other ``sources'' of pesticide exposure in section 408's safety
determination is the only reasonable interpretation of this section.
Congress required consideration of aggregate exposure not just to
pesticide chemical residues but also to ``other related substances.''
21 U.S.C. 346a(b)(2)(D)(vi). In including ``other related substances,''
however, Congress imposed no limitation that aggregate exposure to
these ``other related substances'' was confined only to aggregate
exposure to these substances in food. It would be unusual indeed to
suggest that Congress intended that the section 408 safety
determination on a pesticide tolerance be constrained in the type of
pesticide exposures that could be considered (i.e., only pesticide
exposures in food but not exposures from other sources such as drinking
water or residential uses) but that no such limitations applied to
exposures to substances related to pesticides (i.e., consider exposures
to related substances from all sources including food, drinking water,
and residential uses).
In contrast to the reasonable coherence between EPA's approach to
interpreting what pesticide residues should be considered in making the
section 408 safety determination and the language, structure, and
history of the FQPA, the IWG's construction is frequently at odds with
these guides to interpretation and, in the end, even if accepted fails
to achieve the IWG's goal of excluding EPA's consideration of pesticide
residue sources other than food.
The IWG's narrow approach to aggregate exposure cannot explain both
the statute's and legislative history's references to other ``sources''
of exposure. The IWG's position is that Congress' reference to ``other
non-occupational sources'' is a reference to dermal exposure to
pesticides from handling of food containing pesticide residues during
food preparation. Yet, exposure to pesticides from food handling does
not constitute a different source of pesticide exposure than
consumption of food bearing pesticide residues. In either case, the
source is the food. Further, strictly following the definition of the
term ``pesticide chemical residue'' introduces numerous redundancies,
see, e.g., 21 U.S.C. 346a(a) (defining when a ``pesticide chemical
residue in or on a food'' is unsafe); 21 U.S.C. 321(s) (where the
definition of the term ``food additive'' states that it excludes ``a
pesticide chemical residue in or on a raw agricultural commodity or
processed food''); 21 U.S.C. 346a(o)(2) (requiring EPA to provide
information to retail grocers concerning actions taken ``that may
result in pesticide chemical residues in or on food . . . .''), and
even anomalies into the statute. For example, if each reference in the
FFDCA to ``pesticide chemical residue'' must be to a pesticide residue
in a food, then under section 402(a)(2)(B), a food is only rendered
adulterated by the presence of a pesticide if it is a pesticide residue
that is already in a food, since to be adulterated a food must ``bear[]
or contain[]
a pesticide chemical residue [in or on a raw agricultural
commodity or processed food]
. . . .'' 21 U.S.C. 342(a)(2)(B)
(bracketed language inserted from the definition of pesticides chemical
residues in 21 U.S.C. 321(q)(2)). Although such an approach might be
understandable as concerns prepared foods which are a mixture of
different commodities, it makes no sense as to raw agricultural
commodities which are, and have been, the focus of FDA monitoring
efforts regarding pesticide residues in food (Ref. 20 at 3 and
Appendices A and B) (``Emphasis is on the raw agricultural product,
which is analyzed unwashed and whole (unpeeled).'').
Finally, the reasonableness of the IWG argument is called into
question because, even if followed, it seems to make no difference in
what substances are to be considered in making section 408 safety
determinations. In other words, IWG's construction does not accomplish
the IWG objective of limiting the safety determination under section
408 to consideration of pesticide residues in food. This is due to the
fact that EPA is required to consider both exposures to ``pesticide
chemical residues'' and exposures to ``other related substances.'' If
pesticide residues in water, in the air, and on surfaces in and around
the home or public spaces are not ``pesticide chemical residues'', they
certainly would qualify under the plain meaning of the term ``other
related substances.'' For if the IWG position is accepted that every
substance that would qualify under the dictionary definition of a
pesticide chemical residue does not actually fall within the FFDCA
definition of pesticide chemical residue, it follows necessarily that
non-FFDCA-qualifying pesticide chemical residues have to be some other
type of substance. Further, such other substances are clearly related
to FFDCA-defined pesticide chemical residues given that it is only the
limiting nature of the statutory definition that keeps them from being
considered the same substance. Notably, there is no language in the
statute suggesting that ``other related substances'' only pertains to
such substances in or on food.
EPA cannot accept the argument that, because the term ``related
substances'' appears in the pre-FQPA version of FFDCA section 408 and
EPA allegedly has never stated that ``related substances'' extends to
substances residing in exposure sources other than food, Congress's
repetition of the term ``related substances'' in the FQPA enacted EPA's
supposed sub silentio interpretation of the term ``related substances''
as meaning ``related substances in food.'' Courts have found
reenactment of administratively-interpreted language to be a
ratification of the administrative interpretation but only in
circumstances where a longstanding administrative interpretation has
been affirmatively brought to Congress' attention and Congress has
clearly expressed its approval. AFL-CIO v. Brock, 835 F.2d 912, 915
(D.C. Cir. 1987); accord, Micron Technology, Inc. v. U.S., 243 F.3d
1301, 1310-1311 (Fed. Cir. 2001). These circumstances are completely
absent here. EPA had not affirmatively interpreted ``related
substances'' in the manner suggested by IWG in an administrative
proceeding prior to FQPA's enactment, and Congress never explicitly
addressed the issue of interpretation of the term.
For all of these reasons, EPA reaffirms its contemporaneous and
consistent interpretation of FFDCA section 408 as requiring
consideration of all exposures to pesticide residues and other related
substances other than those exposures occurring in the occupational
setting. Relevant exposures include pesticide residues in food and
water and exposures to pesticides around the home or in public from
sources other than food and water.
Alternatively, the IWG argues that the requirement that data on
``all other exposures'' be based on ``reliable data'' precludes the
consideration of exposure information regarding pesticides in drinking
water and pesticides used around the home or in public spaces. EPA has
repeatedly rejected this argument in the past in issuing policy
statements regarding implementation of the FQPA. (See Ref. 47 at 135-
155). After reviewing the IWG's latest reiteration of the argument, EPA
finds no reason to differ from its earlier conclusions.

B. Citizen Comments

As mentioned above, EPA received several thousand comments from
private citizens in support of NRDC's

[[Page 30074]]

objections. These comments, for the most part, use identical language.
NRDC has urged EPA not to dismiss the citizen comments because they
``raise a wide range of issues reflecting the different ways that
people are personally affected by EPA's tolerance decisions.'' (Ref. 37
at 4). EPA has considered the citizen comments but finds their
significance to be limited because they contain only unsubstantiated
claims regarding the harms of pesticides or general policy arguments as
to why fewer pesticides should be used instead of providing reliable
information pertaining to the safety standard in section 408(b)(2).

C. IR-4 Comments

EPA appreciates that, as IR-4 mentioned, imidacloprid is critical
for minor crop growers and has an important role as an organophosphate
replacement. Consideration of information on pesticidal benefits,
however, that is often relevant under FIFRA, see 7 U.S.C. 136(bb),
plays a very limited role under section 408, see 21 U.S.C.
346a(b)(2)(B), and is not applicable to pesticides such as imidacloprid
which only poses threshold-type risks. 21 U.S.C. 346a(b)(2)(B)(i)(I).

IX. Regulatory Assessment Requirements

As indicated previously, this action announces the Agency's final
order regarding an objection filed under section 408 of FFDCA. As such,
this action is an adjudication and not a rule. The regulatory
assessment requirements imposed on rulemakings do not, therefore, apply
to this action.

X. Congressional Review Act

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, does not
apply because this action is not a rule for purposes of 5 U.S.C. 804(3).

XI. Time and Date of Entry of Order

For the purposes of 28 U.S.C. 2112(a), the date of issuance of this
order shall be May 26, 2004.

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(1990).
31. Loewenherz, C., Fenske R. A., Simcox N. J., Bellamy G., Kalman
D., Biological Monitoring of Organophosphorus Pesticide Exposure among
Children of Agricultural Workers in Central Washington State, 105
Environmental Health Perspectives 1344 (December 1997).
32. Lu, C., Knutson, D. E., Fisker-Andersen, J, Fenske, R.
A.,Biological Monitoring Survey of Organophosphorus Pesticide Exposure
among Pre-school Children in the Seattle Metropolitan Area, 109
Environmental Health Perspectives 299 (March 2001).
33. Lu, C., Fenske, R. A., Simcox, N. J., Kalman, D., Pesticide
Exposure of Children in an Agricultural Community: Evidence of
Household Proximity to Farmland and Take Home Exposure Pathways,
Environmental Research Section A 84, 290 (2000).
34. Mills, P. K., Zahm, S. H., Organophosphate Pesticide Residues
in Urine of Farmworkers and Their Children in Fresno County,
California, 40(5) American Journal of Indistrial Medicine 571 (2001).
35. National Center for Environmental Assessment, U.S. EPA,
Exposure Factors Handbook, Vol. 1 (1997).
36. Natural Resources Defense Council et al., Petition For A
Directive That the Agency Designate Farm Children as a Major
Identifiable Subgroup and Population at Special Risk to Be Protected
under the Food Quality Protection Act (October 22, 1998).
37. Natural Resources Defense Council, Letter from Aaron Colangelo,
NRDC, to Office of Pesticide Programs, EPA,OPP-2002-0057 - Additional
Data on Exposure from Pesticide Drift, and Summary of Citizen Comments
(June 19, 2003).
38. Nishioka, M.G., Burkholder, H.M, Brinkman, M.C., and Lewis,
R.G., Distribution of 2,4-Dichlorophenoxyacetic Acid in Floor Dust
Throughout Homes Following Homeowner and Commercial Lawn Applications:
Quantitative Effect of Children, Pets, and Shoes, 33 Environ. Sci.
Technol. 1359-1365 (1999).
39. Office of Pesticide Programs, US EPA, Memorandum, Jeffrey Evans
to Betty Shackleford,Spray Drift Estimates for Imidacloprid (April 30,
2004).
40. Office of Pesticide Programs, US EPA, Memorandum from Jeffrey
Evans to Betty Shackleford, Review of Data on Farm Children Exposure
(April 29, 2004).
41. Office of Pesticide Programs, US EPA, Memorandum from Ronald
Parker to Betty Shackleford, Comparison of EFED Surface Water Model
Estimates with USGS NAWQA Monitoring Values (April 8, 2004).
42. Office of Pesticide Programs, US EPA, Memorandum from Michael
R. Barrett to Betty Shackleford, Comparison of Ground Water Model
Estimates and NAWQA Monitoring Values (April 30, 2004).
43. Office of Pesticide Programs, US EPA, Memorandum from Michael
R. Barrett to Betty Shackleford, Review of Imidacloprid Ground Water
Residue Data from Prospective Ground Water Studies and Long Island
Monitoring Studies (April X, 2004).
44. Office of Pesticide Programs, US EPA, Memorandum, from Jennifer
R. Tyler to Robert Forrest, Imidacloprid in/on Cranberry; Okra; Pop
corn; Watercress; Guava, Papaya, Lychee, Avocado and Related
Commodities; Root and Tuber Vegetables (Except Sugar Beets); Leaves of
Root and Tuber Vegetables; Artichoke; Bushberry; Lingonberry;
Juneberry; Salal; Legume Vegetables (Except Soybeans); Strawberry and
Stonefruit. Health Effects Division (HED) Risk Assessment. PC Code:
129099. DP Barcodes: D286101, D284746, D282414, D280766, D278760,
D286722, D280447, and D285741, (March 4, 2003).
45. Office of Pesticide Programs, US EPA, Memorandum from Michael
R. Barrett to Jennifer Tyler, Imidacloprid: Tier I Drinking Water EEDs
for Use in the Human Health Risk Assessment (February 25, 2003).
46. Office of Pesticide Programs, US EPA, Memorandum, Imidacloprid
- Report of the Hazard Identification Assessment Review Committee (TXR
# 0051292) (October 31, 2002).
47. Office of Pesticide Programs, US EPA, Office of Pesticide
Programs' Policy on the Determination of the Appropriate FQPA Safety
Factor(s) For Use in the Tolerance Setting Process: Response to
Comments (February 28, 2002) (available at
http://www.epa.gov/oppfead1/trac/science/fqpa_resp.pdf).
48. Office of Pesticide Programs, US EPA, Determination of the
Appropriate FQPA Safety Factor(s) in Tolerance Assessment (January 31,
2002) (available at
http://www.epa.gov/oppfead1/trac/science/determ.pdf).
49. Office of Pesticide Programs, US EPA, General Principles for
Performing Aggregate Exposure and Risk Assessments (November 28, 2001)
(available at
http://www.epa.gov/pesticides/trac/science/aggregate.pdf).
50. Office of Pesticide Programs, US EPA, The Use of Data on
Cholinesterase Inhibition for Risk Assessments of Organophosphorous and
Carbamate Pesticides (August 18, 2000)(available at
http://www.epa.gov/pesticides/trac/science/cholin.pdf).
51. Office of Pesticide Programs, U.S. EPA, Available Information
on Assessing Pesticide Exposure From Food: A User's Guide (June 21,
2000) (available at
http://www.epa.gov/fedrgstr/EPA-PEST/2000/July/Day-12/6061.pdf).
52. Office of Pesticide Programs, US EPA, Choosing a Percentile of
Acute Dietary Exposure as a Threshold of Regulatory Concern (March 16,
2000) (available at
http://www.epa.gov/pesticides/trac/science/trac2b054.pdf).
53. Office of Pesticide Programs, US EPA, Drinking Water Screening
Level Assessment Part B(PublicComment Draft 2000) (available at
http://www.epa.gov/oppfead1/trac/science/reservoir.pdf).
54. Office of Pesticide Programs, US EPA, Estimating the Drinking
Water Component of a Dietary Exposure

[[Page 30076]]

Assessment (November 2, 1999) (available at
http://www.epa.gov/fedrgstr/EPA-PEST/1999/November/Day-10/6044.pdf).
55. Office of Pesticide Programs, U.S. EPA, Overview of Issues
Related to The Standard Operating Procedures For Residential Exposure
Assessment, Health Effects Division of the Office of Pesticide Programs
(August 5, 1999)(available at
http://www.epa.gov/oscpmont/sap/1999/september/resid.pdf).
56. Office of Pesticide Programs, US EPA, Memorandum, IMIDACLOPRID
- Report of the FQPA Safety Factor Committee (HED DOC. NO. 013581)
(July 21, 1999).
57. Office of Pesticide Programs, U.S. EPA, Proposed Methods for
Determining Watershed-derived Percent Crop Areas and Considerations for
Applying Crop Area Adjustments to Surface Water Screening Models (May
27, 1999) (available at
http://www.epa.gov/oscpmont/sap/1999/may/pca_sap.pdf).
58. Office of Pesticide Programs, US EPA, Memorandum from William
Cutchin to Yan Donovan,Dietary Exposure Analysis for Imidacloprid in/on
Cranberries and Blueberries, Attachment 1 (April 27, 1999).
59. Office of Pesticide Programs, US EPA, Memorandum from Jim
Carleton to William Wassell, Drinking water assessment for Imidacloprid
(July 15, 1998).
60. Office of Pesticide Programs, US EPA, Proposed Methods for
Basin-scale Estimation of Pesticide Concentrations in Flowing Water and
Reservoirs for Tolerance Reassessment (1998) (paper presented to FIFRA
Scientific Advisory Panel)(available at
http://www.epa.gov/oscpmont/sap/1998/index.htm).
61. Office of Pesticide Programs, U.S. EPA,Standard Operating
Procedures for Residential Exposure Assessment (1997)(available at
http://www.epa.gov/oscpmont/sap/1997/september/sopindex.htm).
62. Pesticide Registration Notice 97-1, Agency Actions Under the
Requirements of the Food Quality Protection Act Sec. IV (January 31, 1997) .
63. Simcox, N.J, Fenske, R.A., Wolz, S.A., Lee, I.-C. and Kalman,
Pesticides in Household Dust and Soil: Exposure Pathways for Children
of Agricultural Pathways, 103(12) Environ Hlth Perspect 1126-34 (1995).
64. Solomon, K.R., Harris, S.A. and Stephenson, G.R., Applicator
and Bystander Exposure to Home Garden and Landscape Pesticides,
American Chemical Society, Pesticides in Urban Environments, Chapter
22, pp. 262-274 (Eds. Racke and Leslie) (1993).
65. Teske, Milton E., Bird, Sandra L., Esterly, David M.,
Curbishley, Thomas B., Ray, Scott L., and Perry, Steven G., AgDRIFT: A
Model for Estimating Near-field Spray Drift from Aerial Applications,
21 Environmental Toxicology and Chemistry 659-671 (2002).
66. Thompson, B., Coronado, G.D., Grossman, J.E., Puschel K.,
Solomon, C.C., Islas, I, Curl, C.L., Shirai, J.H., Kissel, J.C., and
Fenske, R.A., Pesticide Take-Home Pathway among Children of
Agricultural Workers: Study Design, Methods, and Baseline Findings, 45
Journal of Occupational and Environmental Medicine. 2003, 42-53 (2003).
67.US EPA, Pesticide Exposure and Potential Health Effects in Young
Children Along the U.S.-Mexico Border, 600/R-02/085 (November, 2002).
68. U.S. Geological Survey, National Water-Quality Assessment
Program, Report 94-70 (1994).
69. Wauchope, R.D. The Pesticide content of surface water drainage
from agricultural fields: A review, 7 Journal of Environmental Quality
459-472 (1978).

List of Subjects

Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Recordkeeping and
requirements.

Dated: May 14, 2004.
James Jones,
Director, Office of Pesticide Programs.
[FR Doc. 04-11779 Filed 5-25-04; 8:45 am]
BILLING CODE 6560-50-S

Notices For
2009
2008
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2003
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Imidacloprid; Order Denying Objections to Issuance of Tolerance

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