National Academies Press: OpenBook

Issues in Risk Assessment (1993)

Chapter: Uncertainties Identified In the Case Studies

« Previous: General Discussion: Models and Risk Assessment
Suggested Citation:"Uncertainties Identified In the Case Studies." National Research Council. 1993. Issues in Risk Assessment. Washington, DC: The National Academies Press. doi: 10.17226/2078.
  • Models are perceived as being too difficult to use and requiring too many data;

  • Risk managers do not understand the models and have little faith in their results;

  • The models are too difficult for risk assessors to use routinely;

  • Models sometimes lack credibility with decision-makers, because of lack of validation or conflicting results from alternative models.

The group agreed on four possible steps to increase the use of models in ecological risk assessment:

  • Development of a collaborative approach to risk assessment that includes both managers and modelers (risk assessment should be regarded as a process, not a discrete event);

  • Development of models with easier-to-use front ends or expert systems to ease risk assessors into the routine use of models;

  • Development of databases in tandem with models and risk assessments to provide means of validation and evaluation;

  • Encouragement of quantification of uncertainty through the use of Monte Carlo methods and multiple models that incorporate alternative process formulations.


R. Kimerle and E. P. Smith

Evaluation of uncertainty is a critical component of all risk assessments. Sources of uncertainty include limitations in knowledge, limitations in the use of models to approximate the physical world, and limitations in the parameters that are estimated and used in models to predict risk.

Uncertainties Identified In the Case Studies

The discussion group identified three general categories of uncertainty common to all six case studies:

Suggested Citation:"Uncertainties Identified In the Case Studies." National Research Council. 1993. Issues in Risk Assessment. Washington, DC: The National Academies Press. doi: 10.17226/2078.
Page 327
Next: Implications of Uncertainty for Ecological Risk Assessment »
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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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