Influences on toxicological risk assessments

Abstract: The aim of this thesis is to characterize and discuss two kinds of influences on the outcome of a toxicological risk assessment. One kind of influence has to do with values and the role played by value-based judgment. Currently, many toxicological risk assessments are characterized by scientific uncertainties. When this is the case, risk assessors are to some extent dependent on assumptions and judgment, and this has consequences for the outcome of the assessment. Another other kind of influence comes from the quality and accuracy of the empirical studies that risk assessments are based on. If toxicological research and testing are affected by systematic errors (bias), this will influence the ensuing risk assessment. In order to improve toxicological risk assessments work must be done both on understanding and dealing with the impact of values and on getting better and more efficient methods for gathering facts. The two papers that make up this licentiate thesis may be seen as a contribution to each of these objectives.Article 1: Values in science and risk assessment It is a widely accepted claim that scientific practice contains valuejudgments, i.e. decisions made on the basis of values. This paper clarifies the concepts involved in this claim and explains its implications for risk assessment. It is explained why values are necessarily a part of science and of risk assessment. A certain type of values that contribute to the aim of science, so-called epistemic values, are identified as rationally justified as basis for judgment in science. It is argued that the aims of pure science and risk assessment differ in some aspects and that consequently pure science’s epistemic values are not sufficient for risk assessment. I suggest how the epistemic values may be supplemented in order to align better with the aim of risk assessment.Article 2: Bias in toxicology In this article, the potential for bias in toxicological research and in the performance of standardized toxicological testing in discussed. Due to the lack of empirical studies of bias in toxicology, very little is known aboutits prevalence and impact. Areas to consider for such studies are pointed out, and it is suggested that such investigations should be given priority.