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Appendix B Statement of Task of the Committee on Improving Risk Analysis Approaches Used by the Environmental Protection Agency An NRC committee will develop scientific and technical recommendations for improv- ing the risk analysis approaches used by the Environmental Protection Agency (EPA). Taking into consideration past evaluations and ongoing studies by the NRC and others, the committee will conduct a scientific and technical review of EPAâs current risk analysis concepts and practices. The committee will consider analyses applied to contaminants in all environmental media (water, air, food, soil) and all routes of exposure (ingestion, inhalation, and dermal absorption). The committee will focus primarily on human health risk analysis and will comment on the broad implications of its findings and recommenda- tions to ecological risk analysis. In making recommendations, the committee will indicate practical improvements that can be made in the near term (2-5 years) and improvements that would be made over a longer term (10-20 years). The committee will address topics such as the following: â¢ Increased role for probabilistic analysis in risk analysis, including the potential expanded role for expert elicitation. â¢ Scientific bases for and alternatives to default assumption choices made in areas of uncertainty. â¢ Quantitative characterization of uncertainty resulting from all steps in the risk analysis. â¢ Approaches for assessing cumulative risk resulting from multiple exposures to con- taminant mixtures, involving multiple sources, pathways, routes. â¢ Variability in receptor populations, especially sensitive subpopulations and critical life stages. â¢ Biologically relevant modes of action for estimating dose-response relationships, and quantitative implications of different modes. â¢ Improvements in environmental transport and fate models, exposure models, physi- ologically based pharmacokinetic (PBPK) models, and dose-response models. 281
282 SCIENCE AND DECISIONS: ADVANCING RISK ASSESSMENT â¢ How the concepts and practices of ecological risk analysis can help inform and improve the concepts and practices of human health risk analysis, and vice versa. â¢ Scientific basis for derivation of uncertainty factors. â¢ Use of value-of-information analyses and other techniques to identify priorities and approaches for research to obtain relevant data to increase the utility of risk analyses.