Identifying Future Drinking Water Contaminants (1999) / Chapter Skim
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Committee Report: A Conceptual Approach for the Development of Future Drinking Water Contaminant Candidate Lists
Committee Report: A Conceptual Approach for the Development of Future Drinking Water Contaminant Candidate Lists
Pages 1-21
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identifying emerging drinking water contaminants and creating a database to support future decision-making on such contaminants, and 3. developing a scientifically sound approach for creating future CCLs.
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In contrast, EPA relied extensively on culling existing lists of chemicals to identify potential chemical drinking water contaminants for inclusion on the first draft CCL. Second, all potential chemical contaminants that were initially considered for inclusion on the CCL were taken directly from 10 (later reduced to 8)
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Due to these limitations of the first CCL development process, the committee contends a new type of screening process should be used to identify and evaluate a broader universe of microbiological, chemical, and other types of potential drinking water contaminants in order to provide a more objective list of contaminants of concern.
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In this regard, the committee believes that EPA can and should develop and use a process that: · starts broadly, using existing lists of potential drinking water contaminants, supplemented by readily available information; · considers microbiological, chemical, and other types of potential contaminants in a common selection process; · takes advantage of structure-activity relationships to help overcome deficiencies in health effects and occurrence data; · expands the knowledge base over time; · uses simple criteria, supplemented by expert judgment, to initially cull the candidates to a preliminary list; and · employs a prioritization scheme, again supplemented by expert judgment, to identify final candidates for inclusion on a CCL. The conceptual approach for developing future CCEs that the committee envisions for EPA is a two-step process, as shown in Figure I
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inventory of commercial chemicals alone includes about 72,000 substances. Lists exist for some categories of potential drinking water contaminants; for others, no lists exist.
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models for chemical contaminants and virulence-activity Identifying Future Drinking Water Contaminants
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In this regard, the committee strongly urges EPA be proactive in identifying and regulating emerging microbiological drinking water contaminants; waiting until after major waterborne disease outbreaks occur is an inadequate and ineffective means to prevent future outbreaks and protect public health. The databases for chemicals shown in Tables 2 and 3 will generate a large list of substances too large to be included on the PCCL in its entirety.
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Identifying Future Drinking Water Contaminants
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A Conceptual Approach for the Developmer't of Future Drinking Water Contaminant Candidate Lists
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Generally, state health departments report cases of disease by county Identifying Future Drinking Water Coniamirlanis
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A third mechanism for EPA to use in shortening the list of potential chemical drinking water contaminants for inclusion on the PCCL could use a screen based on health effects data, when available, and SAR scores, when not. As previously noted, EPA has developed and used SAR scores for thousands of chemicals as part of its TSCA program.
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. Generating the CCL from the PCCL To help narrow the PCCL to a manageable number of contaminants that can be considered for regulation, EPA should develop a single, quantitative tool that can be used to evaluate and prioritize all types of potential drinking water contaminants.
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Therefore, all of these approaches are severely limited in their ability to evaluate nonchemical potential drinking water contaminants. A Cor~ceplual Approach for the Development of Future Drinking Water 13 Coniamir~ant Candidate Lists
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Screening Process Proposed Regulation Development Process Waste Minimization Prioritization Tool Section 4(e) of Toxics Substances Control Act State of California Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65)
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Cadmus Risk Index Approach. The Cadmus approach was developed as a health-risk-based methodology for ranking a candidate list of drinking water contaminants (Cadmus Group, 1992~.
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While this approach is well established and demonstrably useful for evaluating large numbers of commercial chemicals, it would have to be extensively modified to include types of potential drinking water contaminants other than commercially produced chemicals. Its transparency and simplicity of design and use would also need to be improved.
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This scheme could conceivably be used as a too} for prioritizing PCCL drinking water contaminants for future CCEs if modified to be specifically applicable to all types of potential drinking water contaminants. It also would have to specifically evaluate and prioritize contaminants according to appropriate indicators of exposure and toxicity, such as measures of mobility and retention in water, but not ecosystem toxicity or bioaccumulation potential.
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For microbiological contaminants, the approach relied on the recommendations of a pane} of experts who qualitatively evaluated individual microorganisms according to a series of five baseline criteria. in short, the overall approach was limited by "looking under the lamp pose' for relatively few types and numbers of drinking water contaminants compared to the universe of potential contaminants.
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Preparation of a CCL from a PCCL will require collection and evaluation of all available health effects and occurrence data for each substance on the PCCL. To cull a list of thousands of potential drinking water contaminants of all types to approximately a hundred for inclusion on the CCL, EPA must combine expert judgment equally with a single prioritization too} that can be used to evaluate any type of PCCL contaminant.
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Sacramento, Calif.: Office of Environmental Health Hazard Assessment, California Environmental Protection Agency. 20 Iderltifyir~g Future Drinking Water Contaminants
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A Conceptual Approach for the Development of Future Drinking Water 21 Contaminant Candidate Lists
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