Evaluation des niveaux acceptables d'exposition aux polluants industriels et environnementaux: problèmes soulevés par l'interprétation des données épidémiologiques.

In order to assess acceptable exposure levels to industrial and environmental pollutants, toxicological data must be collected which derive from two principal sources: in vivo and in vitro experimental studies and epidemiologic studies on exposed subjects. Whatever the extent of the toxicological results obtained on animals, epidemiologic data, when available, must take precedence over animal toxicity studies for setting up acceptable exposure levels. for several practical reasons (identification of exposed groups, adequate exposure gradient), the epidemiologic studies aiming at assessing the no-adverse effect levels of nongenotoxic chemicals are usually performed on occupationally exposed subjects and are cross-sectional. Even when the design of these studies probably exclude the interference of methodological biases, the interpretation of their results may still raise numerous difficulties. This article underlines three particular problems: 1) the adequate characterization of past and current exposure and hence the identification of the causal agent. 2) the health significance of the biomarkers which have been found to be related to exposure and 3) the extrapolation of the observations made on workers to the general population.