Assessment Factors for Human Health Risk Assessment: A Discussion Paper |
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Authors: | Theo Vermeire Hantzen Stevenson Moniek N. Pieters Monique Rennen Wout Slob Betty C. Hakkert |
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Affiliation: | 1. National Institute of Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, the Netherlands;2. TNO Nutrition and Food Research Institute, Department of Occupational Toxicology, P.O. Box 360, 3700 AJ Zeist, the Netherlands |
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Abstract: | The general goal of this discussion paper is to contribute toward the further harmonization of human health risk assessment. It first discusses the development of a formal, harmonized set of assessment factors. The status quo with regard to assessment factors is reviewed, that is, the type of factors to be identified, the range of values assigned, as well as the presence or absence of a scientific basis for these values. Options are presented for a set of default values and probabilistic distributions for assessment factors based on the state of the art. Methods of combining default values or probabilistic distributions of assessment factors are also described. Second, the effect parameter, the no-observed-adverse-effect level (NOAEL), is discussed. This NOAEL as selected from the toxicological database may be a poor substitute for the unknown, true no-adverse-effect level (NAEL). New developments are presented with respect to the estimation of the NAEL. The already widely discussed Benchmark Dose concept can be extended to obtain an uncertainty distribution of the Critical Effect Dose (CED). This CED distribution can be combined with estimated uncertainty distributions for assessment factors. In this way the full distribution of the Human Limit Value will be derived and not only a point estimate, whereas information on dose-response relations is taken into account. Finally, a strategy is proposed for implementation of the new developments into human health risk assessments. |
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