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Classifying Drinking Water Contaminants for Regulatory Consideration
quires the commission to establish a List of Substances based on their risk to the aquatic environment and to human health through the aquatic environment. To create such a list expediently, the EC decided that a simplified risk-based assessment procedure was needed that would account for the intrinsic health and environmental hazards of substances of concern based on monitoring and modeling data. More specifically, the approach should consider the aquatic ecotoxicity and human toxicity of a substance through various aquatic exposure routes and other related factors that may indicate the possibility of widespread environmental contamination, such as chemical production volume and use patterns.
On this basis, the COMMPS procedure was developed in collaboration with the (German) Fraunhofer Institute for Environmental Chemistry and Ecotoxicology and subsequently accepted by the European Commission to establish the priority list. The current Version 2 of COMMPS is based on an approach that combines automated risk-based ranking with subsequent expert judgment for the final selection of priority substances. That is, the procedure is essentially a series of simplified substance-by-substance risk assessments. (Notably, only chemicals were assessed and included on the first priority list.) The report, Proposal for a European Parliament and Council Decision Establishing the List of Priority Substances in the Field of Water Policy (EC, 2000) summarizes the background, design, development, intended uses, and other related information concerning COMMPS. Further information about the European Commission and COMMPS is available on the Web at http://www.europa.eu.int.
In brief, the automated risk-based assessment results in two different types of ranking lists—one type based on monitored exposure levels and the other on modeled exposure estimates—which are in turn based on production volumes, use patterns, environmental distribution, and biodegradation as input parameters. More specifically, the first use of the COMMPS procedure comprised the following five steps:
Selection of candidate substances for the ranking procedure. For this step, a “list-based” approach was used in which the original candidate substances were selected from eight existing official lists and monitoring programs. (The committee notes that this approach is very similar to the approach used by the EPA to develop the draft 1998 CCL; EPA, 1997;NRC, 1999b.)
Calculation of exposure scores. In this step, two ranked lists were established for organic chemicals in the aquatic compartment, one