Classifying Drinking Water Contaminants for Regulatory Consideration (2001) / Chapter Skim
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3The Universe of Potential Contaminants to the Preliminary CCL INTRODUCTION As noted in Chapter 1, the Safe Drinking Water Act (SDWA) Amendments of 1996 require the U.S.
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two-step process (see Figure 1–3) for the creation of future CCLs that would take a much broader approach to contaminant selection than that used to create the 1998 CCL and, thus, would have a better potential to identify high-risk contaminants.
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list than the universe of potential contaminants. As such, a PCCL should contain individual substances and groups of related substances, including microorganisms, that merit further consideration for inclusion on the CCL.
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TABLE 3–1 Universe of Potential Drinking Water Contaminants Category Examplesa Naturally occurring substances Nitrates, humic acid, terpines, arsenic, lead, radon Microbial agents Naturally occurring agents in water Legionella, toxic algae Agents associated with human feces Enteric viruses, coxsackie B viruses, rotavirus Agents associated with human and animal feces Enteric protozoa and bacteria, Cryptosporidium, Salmonella Agents associated with human and animal urine Nanobacteria, microsporidia Agents associated with water treatment and distribution systems Biofilms, Mycobacterium Chemical agents Commercial chemicals Gasoline and additives, chlorinated solvents, trichloroethylene, 1,4-dioxane, cumene Pesticides Atrazine, malathion Pharmaceuticals Diclofenac (anti-inflammatory) , acetaminophen (analgesic)
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TABLE 3–2 Examples of Existing and Planned Information Sources for Chemicals Demonstrated or Having the Potential to Cause Adverse Health Effectsa Name Responsible Agency or Organization Notes Endocrine Disruptor Priority-Setting Database EPA Health effects data on endocrine disruption collected from a variety of databases Everything added to Food in the United States Database U.S. Food and Drug Administration (FDA)
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Name Responsible Agency or Organization Notes Toxic Substances Control Act Test Submissions -- Health Effects EPA Information on unpublished health effects data for industrial chemicals TOXLINE NLM Abstracts of peerreviewed toxicologyrelated studies a Includes acute and chronic health effects, such as genotoxicity, developmental toxicity, reproductive toxicity, immunotoxicity, and carcinogenicity. SOURCE: Adapted from EDSTAC, 1999; NRC, 1999b.
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TABLE 3–3 Examples of Existing and Planned Information Sources for Identifying Chemicals with Demonstrated or Potential Occurrence in Drinking Water Supplies Name Responsible Agency or Organization Notes Chemicals in Consumer and Cosmetic Products FDA Information on chemicals that have been registered voluntarily by manufacturers Comprehensive Environmental Response, Compensation, and Liability Act Information System EPA Contaminant data for Superfund sites Endocrine Disruptor Priority-Setting Database EPA Health effects on endocrine disruption collected from a variety of databases. Environmental Monitoring and Assessment Program EPA Monitoring information for air, groundwater, surface water, biota, and soil contaminants Food Quality Protection Act (FQPA)
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Name Responsible Agency or Organization Notes National Stream Quality Accounting Network U.S. Geological Survey (USGS)
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TABLE 3–4 Examples of Existing and Planned Information Sources for Occurrence and Health Effects of Water-Associated Microbial Agents Name Responsible Agency or Organization Notes FoodNet Centers for Disease Control and Prevention (CDC) Provides data on incidence of diseases associated with key enteric bacteria GenBank National Institutes of Health-National Library of Medicine Internet-based database with information on gene sequences for key microorganisms (see Chapter 6 for further information)
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Name Responsible Agency or Organization Notes National Notifiable Diseases Surveillance System NCHS Compiles U.S. statistics on diseases.
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TABLE 3–5 Additional Considerations for Identification of the Universe of Potential Drinking Water Contaminants Potential to Occur in Drinking Water Potential to Cause Adverse Health Effects Any gasoline additive, constituent, or contaminants of a petroleum product Any substance "routinely" stored in an underground storage tank Any halogenated hydrocarbon Any constituent found in a landfill leachate Any soluble component of "normal" soil (e.g., arsenic) Any disinfectant by-product Any constituent of wastewater treatment or septage Any chemical produced in "high volume" (use a cutoff)
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fecal loading) and health criteria (e.g., toxicity data, structure-activity relationships [SARs]
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effectively delineate the four "rings" for health effects and occurrence (and their intersections) from the universe of potential drinking water contaminants requires the development and use of screening criteria that define "demonstrated" versus "potential" for each characteristic (see more below)
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TABLE 3–6 Examples of Venn Diagram Contaminants Area of Venn Diagram Chemical Microbial Area I Aldicarb Diethylhexyl phthalate Lead Vinyl chloride Campylobacter jejuni Cryptosporidium parvum Escherichia coli O157:H7 Area II n-Hexane Salicylate Cyclospora Helicobacter pylori Microsporidia Area III Dacthal degradates (DCPA) Pseudomonas aeruginosa Area IV Pyrethrin Triethylene glycol Cyanobacteria Nanobacteria Demonstrated occurrence ring Citric acid Phosphate Potassium ion Coliphage Potential occurrence ring Acetic acid Glucose Glycine Stachybotrys Demonstrated health effects ring Sodium pentothal Ebola virus Haemophilus influenzae Streptococcus pneumoniae West Nile virus Potential health effects ring Bilirubin Cyanophage (viruses for blue-green algae)
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use common sense as a guide and err on the side of public health protection. GUIDELINES FOR DEVELOPING SCREENING CRITERIA Criteria for Potential and Demonstrated Health Effects The information that can be used to identify contaminants with potential and demonstrated health effects includes human data from epidemiological studies, clinical studies, and case reports; toxicological laboratory animal studies or field studies; and predictive biological activity or effects models (e.g., SARs)
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given greater weight. The issues of a contaminant's potency and the severity of its health effects are discussed in greater detail in Chapter 4 for going from a PCCL to a CCL.
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for chemical occurrence in watersheds and aquifers. These properties include persistence and mobility in aquatic systems.
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drinking water. (However, expert judgment in considering the potent biological effects of this compound might well place it on a PCCL.)
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nature, the PCCL should not be expected to maintain a more or less fixed number of potential drinking water contaminants. SUMMARY: CONCLUSIONS AND RECOMMENDATIONS The first CCL, published in March 1998, was prepared in a short time period by EPA with the assistance of NDWAC to meet the statutory requirements and mandated time line of the SDWA Amendments of 1996.
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• EPA should rely on databases and lists that are currently available (see Tables 3–2 and 3–3 for chemicals and Table 3–4 for microorganisms) and under development, along with other readily available information to begin identifying the universe of potential contaminants that may be candidates for inclusion on the PCCL.
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• The committee recommends the use of a Venn diagram approach (see Figure 3–1) to conceptually distinguish a PCCL from the universe of potential drinking water contaminants.
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be available for public and other stakeholder input (especially through the Internet) and should undergo scientific review.
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