Waterborne Disease Studies and National Estimate of Waterborne
Disease Occurrence
[Federal Register: August 11, 1998 (Volume 63, Number 154)]
[Notices]
[Page 42849-42852]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11au98-100]
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ENVIRONMENTAL PROTECTION AGENCY
[FRL-6140-8]
Waterborne Disease Studies and National Estimate of Waterborne
Disease Occurrence
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of data availability and request for comments.
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SUMMARY: The Safe Drinking Water Act (SDWA) Amendments of 1996, section
1458(d), provides that within two years of enactment the Environmental
Protection Agency (EPA) and the Centers for Disease Control and
Prevention (CDC) will conduct pilot waterborne disease occurrence
studies for at least five major U.S. communities or public water
systems. Section 1458(d) also provides that, within five years of
enactment, EPA and CDC will prepare a report on the findings of these
pilot studies and develop a national estimate of waterborne disease
occurrence (``the national estimate'').
The purpose of this Federal Register document is to inform the
public about how EPA and CDC are addressing this provision. The
document includes descriptions of planned and ongoing epidemiological
studies and discusses public involvement in developing an approach for
estimating the national level of waterborne disease occurrence.
Comments are requested on issues related to the epidemiological studies
and to developing the national estimate.
DATES: Comments should be postmarked or delivered by hand on or before
November 9, 1998.
ADDRESSES: Send written comments to Susan Shaw, (MC-4607); U.S.
Environmental Protection Agency; 401 M Street, SW, Washington, DC
20460, or by email to shaw.susan@epamail.epa.gov. Comments may also be
hand-delivered to Kimberly Miller, U.S. Environmental Protection
Agency; 401 M Street, SW, Room 3809, Washington, DC 20460.
FOR FURTHER INFORMATION CONTACT: For further general information and
for copies of the reports from the 1997 Atlanta and the Washington,
D.C. workshops discussed herein, contact the Safe Drinking Water
Hotline, Telephone (800) 426-4791. The Safe Drinking Water Hotline is
open Monday through Friday, excluding Federal holidays, from 9 a.m. to
5:30 p.m. Eastern Time. For technical inquiries, contact Susan Shaw,
Office of Ground Water and Drinking Water (MC4607), U.S. Environmental
Protection Agency, 401 M Street, SW, Washington, DC 20460; telephone
(202) 260-8049; email: shaw.susan@epamail.epa.gov. To receive
additional information about the spring 1999 public meeting, contact
Kimberly Miller, Office of Ground Water and Drinking Water (MC4607),
U.S. Environmental Protection Agency, 401 M Street, SW, Washington,
D.C. 20460; telephone (202) 260-0718; email:
miller.kimberly@epamail.epa.gov.
Abbreviations Used In This Document
CDC: Centers for Disease Control and Prevention
EPA: US Environmental Protection Agency
SDWA: Safe Drinking Water Act, as amended in 1986 and 1996
Table of Contents
1. Introduction and Statutory Authority
2. Background
3. EPA and CDC Actions and Strategy to Develop the National Estimate
4. Studies for Developing the National Estimate of Waterborne
Disease Occurrence
A. Cross-Sectional Gastroenteritis and Water Consumption Survey
B. Triple-Blinded Household Intervention Pilot Study
C. Household Intervention--Two Requests for Proposals
D. Three CDC Requests for Proposals
E. Community Intervention Studies
F. Other Studies to Assist in National Estimate Development
5. Conclusions
1. Introduction and Statutory Authority
The Safe Drinking Water Act (SDWA) Amendments of 1996, section
1458(d), provides that within two years of enactment the Environmental
Protection Agency (EPA) and the Centers for Disease Control and
Prevention (CDC) will conduct pilot waterborne disease occurrence
studies for at least five major U.S. communities or public water
systems. Section 1458(d) also provides that, within five years of
enactment, EPA and CDC will prepare a report on the findings of these
pilot studies and develop a national estimate of waterborne disease
occurrence.
The purpose of this Federal Register document is to inform the
public about how EPA and CDC are addressing the provision to conduct
studies on waterborne disease occurrence and to develop a national
estimate of waterborne disease occurrence due to drinking water (the
``national estimate''). The document is organized as follows:
Background: Discussion of the difficulties inherent in quantifying
infectious disease due to drinking water.
EPA and CDC actions and strategy to develop the national estimate:
Describes
[[Page 42850]]
actions taken by EPA and CDC to conduct waterborne disease occurrence
studies, and to develop the national estimate of waterborne disease
occurrence; discusses overall strategy for complying with Section
1458(d), including public involvement.
Waterborne disease studies: Describes ongoing and planned studies
funded by EPA that are expected to contribute directly to developing
the national estimate of waterborne disease occurrence.
Conclusions: CDC and EPA actions to date, and next steps, including
public participation and request for comments
2. Background
Although outbreaks of infectious disease attributable to drinking
water are not common in the United States, they remain a concern and
the extent to which they occur unrecognized by the health authorities
has been the focus of much debate in recent years. One critical
question of interest to those who are concerned about the microbial
quality of drinking water and the associated health effects is: What is
the magnitude of infectious disease in the United States that can be
attributed to drinking water and, in particular, what are the levels of
disease due to drinking water from public water systems that meet state
and federal drinking water standards. There is no obvious and easy
answer to this question. It is generally recognized that cases of
waterborne disease are not likely to be recognized as such, and that
therefore there is little direct information on which to base an
estimate of waterborne disease occurrence and its associated costs to
society. Illnesses caused by contaminated water are generally not
specific to water, e.g diseases such as gastroenteritis could be caused
by contaminated food or person-to-person transmission; moreover most
cases will not result in illness deemed sufficiently serious by the ill
person to require consulting a health care provider. Even if the
disease is serious, it is highly unlikely to be traced back to drinking
contaminated water unless the health care provider notices a sudden
increase in the number of cases beyond what is normally expected, i.e.
more cases than normal background levels within the population. In this
case it is possible that the health authorities may be alerted and may
consider that the increase in cases warrants an investigation which
could lead to determining the vehicle of the disease agent, and thus to
tracing the disease back to contaminated drinking water. This is only
likely to happen in the case of an outbreak where a large fraction of
the population has been infected. In order to detect any background
levels of infectious disease due to drinking water, it is necessary to
conduct targeted epidemiological investigations.
The issue of waterborne disease detection and how to detect disease
within a population that can be attributed to drinking water is
discussed in the reports from the two EPA/CDC workshops described
below. The reports are available from EPA through the Safe Drinking
Water Hotline. This notice describes how EPA and CDC are proceeding to
develop an estimate of the level of waterborne disease in the United
States based on data from targeted epidemiological studies.
3. EPA and CDC Actions and Strategy to Develop the National
Estimate
EPA and CDC are working in close partnership to meet the
requirements of the mandate to conduct studies on waterborne disease
and to develop a national estimate of waterborne disease occurrence.
Based on the legislative history, EPA and CDC interpret the term
``waterborne disease'' to refer to waterborne disease due to disease-
causing microbes (pathogens) in drinking water, rather than to disease
caused by chemical contamination. To the extent possible, EPA and CDC
intend to consider which populations are at greatest risk, the economic
impact of waterborne disease, which infectious agents are causing
waterborne disease and their relative contribution to the overall
incidence of waterborne disease due to drinking water, and the
characteristics of water systems that are more likely to lead to
waterborne disease.
In developing an approach to address the SDWA mandate, EPA and CDC
invited the participation of outside experts and the public in two
jointly-sponsored workshops. An initial workshop of public health
experts from universities and from state and federal government took
place in Atlanta in March 1997. A follow-up public workshop with wider
representation of experts and other interested persons was held in the
Washington, DC area in October 1997. Through this process of
cooperative deliberation, EPA and CDC sought to review existing
knowledge on waterborne disease and associated factors, and to evaluate
different study designs to provide data necessary for calculating the
national estimate of waterborne disease occurrence. Detailed summary
reports of both meetings, including a list of participants, are
available from EPA.
At the Atlanta workshop, attendees suggested that two components
were needed to calculate a national estimate of waterborne disease: the
incidence of gastrointestinal illness and the fraction of
gastrointestinal illness attributable to drinking water. Cross-
sectional surveys of the population were suggested as a straightforward
means of determining the incidence of gastrointestinal illness. The
workshop then focused on reviewing different study designs for
establishing the fraction of gastroenteritis in a population that is
attributable to drinking water. The participants identified the
strengths and weaknesses of various designs and suggested that each be
further evaluated for possible systematic biases, methods available for
controlling bias, number of participants needed for a statistically
stable estimate of increased risk, and the feasibility of measuring the
specific pathogens associated with observed waterborne disease. Most
participants felt that a population-based study, e.g. a household
intervention study, would provide the strongest epidemiological
evidence of waterborne disease and was the best design to determine the
attributable fraction. However, participants also felt that other study
designs were useful for estimating the attributable fraction and that
more convincing evidence of waterborne disease risk and its magnitude
would be provided by implementing several different study designs,
rather than relying on multiple studies of the same design.
At the Washington workshop, specific ongoing and proposed studies
and study designs were reviewed with respect to how they could
contribute to the national estimate, and participants proposed
alternate designs and combinations of designs. CDC presented an
analysis of why it had decided to proceed with a pilot household
intervention study. The participants again felt that it would be
advantageous to conduct a variety of different study designs. This
position is reflected in the request for proposals that was recently
issued by CDC for three additional studies to provide data towards the
national estimate in which the choice of study design is open to the
researcher. In addition, EPA's in-house research program is conducting
waterborne disease studies using other study designs.
EPA and CDC plan to host another public workshop in the spring of
1999 to review ongoing and planned studies and the need for specific
additional information, and to discuss ideas on feasible approaches to
developing the national estimate, taking cost and the development
schedule into consideration. EPA and CDC welcome
[[Page 42851]]
comments on issues related to this proposed workshop, and encourage
people who are interested in participating or who would like to receive
notice of future meetings to notify EPA.
Since the initial workshop in March 1997, a total of $3.0 million
from EPA's fiscal year 1997 and 1998 appropriations has been
transferred to CDC to allow funding for seven studies on waterborne
disease occurrence: A pilot household intervention study, two full-
scale household intervention studies, a cross-sectional gastroenteritis
and water consumption survey, and three epidemiological studies of
unspecified design. CDC is managing the above projects; however, EPA
and CDC work together in the review and selection of the study
proposals. In addition to the above CDC/EPA collaborative studies, EPA,
through its National Health and Environmental Effects Research
Laboratory is funding research to characterize microbial enteric
disease in a series of ``community intervention'' studies. These
studies are described in more detail below.
In combination, these studies will provide a considerable amount of
new data to support the development of a national estimate of
waterborne disease occurrence by August 2001. However, EPA and CDC
share a concern that given the two to two-and-a-half year duration for
completion of some of the studies (the two household intervention
studies), some of the data may not have undergone a full review by mid-
2001. If this turns out to be the case, the national estimate will be
revised if necessary by August 2002.
4. Studies for Developing the National Estimate of Waterborne
Disease Occurrence
This section provides a brief summary of EPA and CDC's planned and
ongoing studies that will contribute to developing the national
estimate, including the study objectives, design, and population.
Information from other studies by other organizations on waterborne
disease, and relevant aspects of water quality and water treatment,
will also be considered in the development of the national estimate.
A. Cross-Sectional Gastroenteritis and Water Consumption Survey
This study is being conducted as part of the CDC's FoodNet Survey,
and is based on a randomized telephone survey to detect the incidence
of foodborne disease, including gastroenteritis, at seven sites within
the United States, including specific populations in California,
Oregon, Minnesota, Georgia, New York, Maryland, and Connecticut.
Approximately 9000 interviews are conducted annually. The questionnaire
has recently been expanded to include questions on type and quantity of
water consumption. The survey will provide data on which to base an
estimate of the national incidence of gastroenteritis and national
drinking water consumption patterns. The national incidence of
gastroenteritis and the fraction of gastroenteritis that can be
attributed to drinking water in a community (data from some of the
studies described below) will provide useful information towards
calculating an estimate of the national incidence of gastroenteritis
due to drinking water. Other useful information from the survey
includes data on measures of disease impact such as time lost from work
or school, use of outpatient medical care, and hospitalization for
gastrointestinal illness. However, the survey is unlikely to provide
any information regarding causative pathogens or the relationship of
water quality indicators with gastrointestinal illness.
B. Triple-Blinded Household Intervention Pilot Study
This is an experimental study in which persons in different
households are randomly assigned to drink regular tap water or
specially treated water that is expected to be pathogen free. The
difference in tap water quality is achieved by installing identical
looking devices at the water taps of homes of both groups; however, one
group receives a device that further filters and disinfects the regular
tap water, whereas the other group receives sham devices that do not
provide additional treatment. If the group with the sham device has a
higher incidence of gastroenteritis than the otherwise similar group
with the real treatment device (the ``intervention''), then the
difference will be assumed to be attributable to contamination in the
regular tap water. The ``triple blinding'' refers to the design feature
of ``blinding'' the researchers, statisticians and participants until
the end of the study as to which households have regular tap water and
which the specially treated tap water. Of particular interest for this
type of study is whether persons in the households can detect (i.e. are
blinded to) whether they are drinking regular tap water or the
specially treated water, since knowing what group they are in might
bias their response regarding whether or not they experience
gastrointestinal illness.
CDC and EPA considered it necessary to perform a pilot study to
test whether blinding is possible and to develop guidance regarding the
logistics of future household intervention studies. The triple-blinded
household intervention study design is favored because its random
assignment of treatment reduces the effects of confounding, and the
blinding of all participants avoids biases that affect most other study
designs. The Atlanta workshop participants generally agreed that this
study design, a so-called population-based intervention study, would
provide the strongest epidemiological evidence of waterborne disease
risk and the best estimate of the attributable risk due to drinking
water. However, of all the studies evaluated, it is the most expensive
to conduct. For this reason, EPA and CDC presently envision performing
this type of study in only two large public water systems: a surface
water site and a ground water site.
The pilot study was awarded to the California Emerging Infections
Program. The site selected for the study is the Contra Costa Water
District in California. Specific data that will be collected in this
pilot study include amount of water consumption; symptoms of
gastrointestinal illness; results of stool, sera and saliva tests; and
impact of illness. The study is expected to be completed at the
beginning of 1999.
C. Household Intervention--Two Requests for Proposals
In October 1998, CDC expects to issue a request for proposals for
conducting two household intervention studies: One in a municipality
receiving drinking water from a conventionally treated surface water
source, and a second in a municipality with ground water source. In
addition to determining the fraction of gastrointestinal illness due to
drinking water, the project includes the collection of water quality
and water treatment plant data in order to evaluate the relationship
between water quality and disease incidence.
Initial funding available for the epidemiological aspects of the
two projects amounts to $1.8 million. Additional funds will be
available to fully fund the projects and to collect water quality data.
The projects are expected to be awarded in the spring of 1999.
D. Three CDC Requests for Proposals
CDC issued a request for proposals for three additional studies to
estimate the incidence of waterborne disease due to microbial
contamination of drinking
[[Page 42852]]
water and/or to identify and describe the relationship between measures
of water quality and health outcomes or evidence of infection due to
gastrointestinal pathogens. The choice of study design is open to the
researcher. Combined funding available for these projects amounts to
$450, 000, and is anticipated to be awarded in the fall of 1998.
E. Community Intervention Studies
EPA is conducting a series of community intervention studies that
are designed to characterize microbial gastroenteritis associated with
drinking water that originates from selected surface water and
groundwater sources. By studying communities that are planning to make
improvements to their water treatment systems (e.g., adding filtration
units or changing disinfectants), a ``natural experiment'' can be
conducted which evaluates the enteric disease that may be present both
before and after the implementation of the new system. The specific
objectives of the first community study, which was conducted between
June 1996 and December 1997, were to: (1) Determine rates of
gastroenteritis; (2) determine the relative source contribution of
factors implicated in gastroenteritis; (3) identify the microbial cause
of gastroenteritis; and (4) assess surveillance methods of
gastroenteritis. The data collected during the study are currently
being analyzed. A community for the next community intervention study
has been identified and data collection is slated to begin in the fall
of 1998. EPA is also considering communities that use either ground
water or surface water supplies as possible sites for future studies.
EPA would welcome suggestions from the public on additional community
studies.
F. Other Studies To Assist in National Estimate Development
In its development of the national estimate of waterborne disease
occurrence and interpretation of the data from the epidemiological
studies, EPA and CDC expect to use data from other relevant studies and
databases. Information to be considered includes completed or ongoing
epidemiological studies not specifically associated with the EPA/CDC
effort, data on pathogen occurrence currently being collected by many
utilities, studies on the effectiveness of water treatment, the dose-
response relationship of certain pathogens, and studies on factors that
affect the susceptibility of persons to infectious disease and disease
severity.
5. Conclusions
EPA and CDC have committed to conducting waterborne infectious
disease occurrence studies in at least five major U.S. communities or
public water systems. One such study--a community intervention study--
is nearing completion and a second community intervention study is
scheduled to begin this fall. A pilot study for the two household
intervention studies is underway and the two full-scale household
intervention studies are expected to be awarded by April 1999. Three
additional epidemiological studies of non-specified design are expected
to be awarded in the fall of 1998.
In 1997, at two public workshops, EPA and CDC proposed one possible
approach to developing the national estimate. However, EPA and CDC
intend to continue the dialogue on this and other approaches to
developing the national estimate at a public meeting scheduled for late
next spring. EPA will announce the meeting in the Federal Register;
however, to facilitate planning the meeting, EPA suggests that people
who are interested in attending the meeting, or in receiving additional
information about the meeting, notify EPA now (see section FOR FURTHER
INFORMATION above) . EPA and CDC welcome comments on the issues
discussed in this notice, as well as the reader's opinion on the extent
to which, and how, the national estimate should address the social and
economic impact of waterborne disease, the contribution of specific
pathogens to the prevalence of waterborne disease, and the
characteristics of public water systems and water quality indicators
that are associated with a higher risk of waterborne disease. (For
information on whom to address comments, see section ADDRESSES above.)
Dated: August 3, 1998.
J. Charles Fox,
Acting Assistant Administrator for Water.
[FR Doc. 98-21343 Filed 8-10-98; 8:45 am]
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