Waterborne Disease
Workshop
EXECUTIVE SUMMARY
November 19, 1997
BACKGROUND
On October 9-10, EPA held a public meeting for information exchange on
issues related to developing a national estimate of endemic waterborne
disease occurrence. The meeting brought together over 55 participants,
including experts in the fields of epidemiology, biostatistics, public
health and related fields. The experts represented academia; water utilities;
government; and environmental, professional, and industry organizations.
The objectives of the workshop were to:
- provide background of the Safe Drinking
Water Act (SDWA) mandate to carry out waterborne disease occurrence studies
and develop a national estimate of waterborne disease incidence; - discuss
how these studies fit into the larger public policy framework on providing
safe drinking water; - discuss planned and ongoing epidemiological
studies and EPA/CDC activities related to these mandates; - identify
data gaps, research needs, and opportunities for improved methodologies;
and - discuss next steps and opportunities for coordination and communication.
Topics of the workshop included: a brief review of the SDWA mandate to
develop a national estimate of waterborne disease occurrence; review and
discussion of current approaches to developing this national estimate,
including planned and ongoing epidemiological studies, the goals and methodologies
of these studies, and additional studies that might be useful in improving
the national estimate.
SUMMARY
1996 SDWA Amendments: Waterborne Disease Occurrence Study
The 1996 Amendments to the SDWA require EPA and the Centers for Disease
Control and Prevention (CDC) to jointly conduct waterborne disease occurrence
studies and develop a national estimate of waterborne disease occurrence
attributable to drinking water.
Representatives from EPA and CDC discussed ongoing and planned activities
to address the mandate. EPA has redirected $1 million of their $10 million
health effects research budget for FY 97 towards the first of a series
of new epidemiological studies to be done by CDC on waterborne disease.
Additional funds for this purpose are expected in FY 98, and will be made
available in an open solicitation process. EPA and CDC have not decided
on a research design for the next step in this process and welcomed the
input of participants on this matter.
Current Approaches to Estimating National Occurrence of Waterborne
Disease
EPA outlined the process the Agency currently uses to estimate drinking
water related waterborne disease. In this process EPA calculates the effects
of exposure to pathogens (the number of infections that occur as the result
of drinking water) based on source water pathogen occurrence data, estimates
of treatment effectiveness, and a dose-response relationship that defines
the probability of infection resulting from exposure to drinking water
pathogens.
Ongoing Epidemiological Studies
EPA and CDC representatives discussed four ongoing epidemiological studies.
Newly funded studies include a cross-sectional telephone survey to estimate
the incidence of gastrointestinal illness, and the first phase of a triple-blinded
household intervention study to capture the percentage of illness attributable
to drinking water. In the intervention study, the incidence of gastrointestinal
illness will be compared for two groups of households (one with additional
in-house water treatment units, and the others with sham units). Combined,
these two studies can provide an estimate of gastrointestinal illness
attributable to drinking water in the comparable larger population. Other
ongoing studies include a community intervention study comparing the occurrence
of gastrointestinal disease in a community before and after the installation
of a filtration plant; and a study comparing serum Cryptosporidium
antibody response in two communities (one with a ground water, and the
other with a surface water source of drinking water) to determine what
percentage of the population has been exposed to the microbe.
Discussion of Approaches Towards a National Estimate
Participants discussed several types of studies as well as issues to
be addressed regarding study designs and information needed to develop
a national estimate. This discussion also focused on the use of epidemiological
studies to confirm the magnitude of calculated risk estimates based on
source water quality and treatment information. Opportunities for epidemiologists
and water utilities to collaborate in the planning and implementation
of epidemiological studies at sites where extensive microbial occurrence
and treatment data will be collected were also discussed. Other study
approaches presented by participants included a randomized community trial,
a time series study, and a randomized national household intervention
study. Participants recommended these approaches be included in a "portfolio"
of studies that would be used in developing a national estimate of waterborne
disease incidence.
NEXT STEPS
The Agencies plan on using the workshop comments and ideas to plan the
next series of research studies to develop a national estimate of waterborne
disease incidence.
The workshop summary is available upon request by contacting Valerie
Blank at 401 M St., S.W., MC 4607, Washington, D.C. 20460 or by e-mail
at: blank.valerie@epamail.epa.gov, or by calling the SDWA Hotline at 1-800-426-4791.
|
