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DRAFT METHODOLOGY FOR DERIVATION OF WATER QUALITY CRITERIA FOR THE PROTECTION OF AQUATIC LIFE BASED ON MODE OF ACTION
Development and body functions of many organisms are directed by the endocrine system. Endocrine Disrupting Chemicals (EDCs), are those exogenous (and endogenous) compounds that may interfere with this regulatory function because they may either mimic or suppress the action of the body’s natural hormones. Because these chemicals are increasingly present in the environment as a result of human activities and they only require tiny amounts to disrupt endocrine functions, EDCs may have major impacts on ecology and particularly aquatic life as evidenced by the abundance of field observations verified by both laboratory and controlled in situ experiments. The Clean Water Act § 304(a)(1) authorizes the Administrator to develop and publish criteria for water quality that are protective of aquatic life. Traditionally, ambient water quality criteria for the protection of aquatic life have been derived using the 1985 Guidelines (Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Life and Their Uses). These guidelines have comprehensive data requirements for toxicity tests using a variety of aquatic taxa, thus ensuring protection of the existing aquatic assemblage, and helping to ensure a goal of protecting and restoring “ecological integrity”. Some “Pharmaceuticals and Personal Care Products” (PPCPs), particularly those exhibiting endocrine disrupting activity, have two unique features, which distinguish them from other agents. First, they do not appear to exhibit conventional toxicological dose-response characteristics. In contrast to conventional contaminants, they may cause significant problems at very low levels. Second, EDCs are very powerful during the early stage of life, but their impacts may have a long lag time, which may not be observable in the offspring until, after they reach adulthood. Effects such as intersex, sex ratios, and reductions in adult female fecundity, as well as altered sexual behavior are potential examples of this characteristic. PPCP criteria present several challenges. First, while the 185 Guidelines require data from diverse aquatic taxa, the current knowledge base for aquatic effects implies that only certain taxa may actually be affected through the hypothalamic-pituatary, or gonadal axis. This may be due to phylogenetic conservation of the system, or may be due to a receptor or hormone that is lacking in a particular taxa. In any case, taxa requirements for criteria derivation for these compounds will require a thorough scientific analysis. Another issue with respect to criteria derivation is the use of non-traditional endpoints for use in criteria development. Many of the effects of these compounds (some outlined previously), have not been used for criteria derivation in the past. Since these compounds have very specific modes of action, and low acute toxicity combined with potentially latent effects, the traditional endpoints of mortality, growth and reproduction may not apply, or may need further assessment with respect to the nuances presented by more subtle reproductive endpoints. Finally, because these compounds demonstrate low acute toxicity, the “1985 Guidelines” calculation methods do not seem to apply to this type of effects data. More appropriate would be a “chronic-only” criteria, since acute effects may only happen at concentrations that would not be expected to occur under normal circumstances in the environment. An intra-agency workgroup (OST, ORD) has convened to provide a thorough scientific assessment of the criteria derivation issues that the EPA is faced with when attempting to regulate these compounds. A white paper will be produced that will provide analysis of the issues and the workgroup’s technical recommendations will be presented to Office of Water management for consideration.
Development of methodology for aquatic life criteria that will be appropriate for personal care products and pharmaceuticals as well as other endocrine disrupting chemicals.
Record Details:Record Type: DOCUMENT
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER