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M/DBP Research Meeting
November 19, 1997
EXECUTIVE SUMMARY
EPA held a public meeting on November 19, 1997, in Washington, D.C.,
to discuss the adequacy of the microbial pathogen and disinfection byproduct
(M/DBP) research in support of the Long-Term 2 Enhanced Surface Water
Treatment Rule (LT2ESWTR) and the Disinfection Byproducts Stage 2 Rule
(Stage 2 DBPR). The purpose of the meeting was to present EPA's assessment
of whether the current M/DBP research will provide the information needed
to support the LT2ESTWR and Stage 2 DBPR and to receive feedback from
the public on EPA's judgement.
EPA summarized the findings from a draft "white paper" that was developed
in advance of the meeting. This draft provided a detailed evaluation of
the adequacy of the research for microbial pathogens and DBPs in the areas
of health effects, occurrence, methods, treatment, and risk assessment
in support of the LT2ESWTR and the Stage 2 DBPR.
Background
EPA is in the process of developing drinking water regulations for microbial
pathogens and disinfectants and disinfection byproducts (M/DBP rules).
To assist in the development of the M/DBP rules, EPA initiated a formal
regulatory negotiation process in 1992 to develop new and revised standards
for microbial pathogens and DBPs. During the course of the negotiations,
the participants found that more specific information on the occurrence
and treatment of contaminants, as well as additional information on their
health effects was needed in order to assess the impact of controlling
the level of DBPs while maintaining adequate microbial protection. The
participants agreed that public water systems (PWSs) would collect additional
occurrence and treatment data associated with DBPs and microbes. The data
collection effort was formalized in the ICR. In addition, EPA agreed to
conduct further research on health effects and treatment.
In response to the need to conduct significantly more research, EPA has
developed a research plan which identifies over $50 million in M/DBP research
needed to support the development of the rules noted above. Concurrent
with revising the research plan, EPA developed a draft "white paper" that
provides the public with EPA's evaluation of the adequacy of the M/DBP
research to provide the information needed to develop the Stage 2 DBPR
and the LT2ESWTR.
Summary
The meeting was divided into three areas: introduction; research for
microbial pathogens; and research for DBPs. The introduction provided
participants with: information on the schedules for the M/DBP rules; the
key information needed to develop drinking water regulations; the importance
of research to provide this information; the use of the research tracking
system developed by EPA; and an overview of the "white paper" developed
for the meeting.
The Agency first presented their judgement on the adequacy of the health
effects and assessment research for microbial pathogens. EPA concluded
that the dose-response research will provide data on the range of potential
risks from Cryptosporidium and that epidemiology studies should provide
information that will indicate the magnitude of the risk from different
pathogens including Cryptosporidium. In regard to methods research for
microbial pathogens, and research on pathogen occurrence and indicators,
EPA concluded that the research should be sufficient to allow the characterization
of Cryptosporidium occurrence for individual systems and the classification
of source waters based on different levels of microbial contamination.
For treatment, EPA concluded that research on physical treatment optimization
will be adequate and that research on removal of microbial surrogates
for Cryptosporidium removal may provide a method for assessing overall
Cryptosporidium removal. Supplemental research on the reliability of indicators
(e.g., turbidity) to monitor the effectiveness of treatment to consistently
achieve high levels of Cryptosporidium removal could provide a greater
level of confidence in treatment capability. For inactivation research,
EPA concluded that the use of surrogates and the integrated disinfection
design framework may be useful to supplement the inactivation map for
Cryptosporidium and that an expert workshop in January will provide more
direction in this area. For small systems, EPA concluded that research
on treatment processes was adequate, but that additional research on innovative
and cost-effective technologies was desirable to facilitate higher levels
of microbial control for small systems.
For DBPs, EPA divided the health effects area into three issues: risk
from chlorinated waters; risk of DBPs from disinfectants other than chlorine
(e.g., ozone); and the risks from brominated species. For chlorinated
waters, EPA concluded that research was adequate in some areas (e.g.,
toxicology studies for individual chlorinated DBPs), but additional research
was needed in several areas including improving exposure assessments for
epidemiology studies. For determining risks from DBPs from alternative
disinfectants, EPA concluded that additional research may be needed depending
on the recommendations from expert panels on reproductive epidemiology
and complex mixtures. In regard to the risks from brominated species,
EPA concluded that research should provide a substantial body of information
for the Stage 2 DBP rule. EPA concluded that the research for health assessments,
occurrence, methods, and treatment technologies was generally adequate
to support the Stage 2 DBP rule. Several areas that may warrant additional
research include improving methods for MX and cyanogen chloride if they
are included in the Stage 2 rule and developing better control and formation
models for bromate.
Next Steps.
EPA requested comments within two-weeks on the "white paper". Based on
these comments, EPA will revise the "white paper". In addition, EPA indicated
that another meeting would be scheduled for March or April to provide
the public with an update on several efforts that were not completed in
time for the November 19th meeting, but which are important for understanding
the appropriate research direction. Finally, EPA requested comments on
ways to improve its research tracking system.
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