National Academies Press: OpenBook

Issues in Risk Assessment (1993)

Chapter: Definition of Risk Characterization

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Suggested Citation:"Definition of Risk Characterization." National Research Council. 1993. Issues in Risk Assessment. Washington, DC: The National Academies Press. doi: 10.17226/2078.

There was a consensus that modeling for retrospective and prospective analysis will likely play a more important role in ecological exposure assessment than it normally does in human health risk assessment. Direct measurements with personal monitors or tissue-fluid analysis, the preferred methods of human exposure assessment, usually are not feasible or are prohibitively expensive in ecological assessments. Modeling was at least an underlying concept in all the case studies.

Test of the Definition

The group tested its proposed definition by attempting to fit it to the case studies and the 13 issues addressed by the EPA Science Advisory Board (SAB) Relative Risk Reduction Project (EPA, 1990). The group concluded that the new definition fit all six case studies, but that the definition provided in the Red Book fit only the three chemical case studies. Similarly, the new definition fit all 13 of the issues addressed by SAB, but the Red Book definition fit only about half. Two of the six case studies (on species introductions and harvesting) were related to issues not addressed by SAB.


G. W. Suter II and W. A. Farland

This group first developed a definition of risk characterization for ecological assessment and then applied the definition to the six case studies. As in health risk assessment, the principal objectives of risk characterization are to integrate information on exposure and effects and organize the results for presentation to risk managers, stake-holders, and the public.

Definition of Risk Characterization

The group determined that integration of exposure and exposure-response assessments is a complex process that requires a great deal of expert judgment. For the relatively straightforward case of predictive

Suggested Citation:"Definition of Risk Characterization." National Research Council. 1993. Issues in Risk Assessment. Washington, DC: The National Academies Press. doi: 10.17226/2078.
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The scientific basis, inference assumptions, regulatory uses, and research needs in risk assessment are considered in this two-part volume.

The first part, Use of Maximum Tolerated Dose in Animal Bioassays for Carcinogenicity, focuses on whether the maximum tolerated dose should continue to be used in carcinogenesis bioassays. The committee considers several options for modifying current bioassay procedures.

The second part, Two-Stage Models of Carcinogenesis, stems from efforts to identify improved means of cancer risk assessment that have resulted in the development of a mathematical dose-response model based on a paradigm for the biologic phenomena thought to be associated with carcinogenesis.

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