Validity of biomarkers in environmental health studies: The case of PAHs and benzene

Exposure biomarkers, which have long been restricted to the framework of oc cupational hygiene, currently arouse increasing interest in the field of en vironmental pollution. To assess their validity, we propose here a conceptu al framework that is based on their intrinsic characteristics and on proper ties related to the procedures for their analysis. The most important crite ria are specificity for the toxic substance under consideration and sensiti vity, that is, the ability to distinguish contrasted levels of exposure. Th eir analytic sensitivity and specificity are also important. Fulfilling the se criteria is especially important in the context of environmental polluti on, because the levels of exposure, and thus the contrasts, are low. This f ramework is used to assess the validity of some biomarkers for polycyclic a romatic hydrocarbons (l-hydroxypyrene and DNA adducts) and for benzene (uri nary and serum benzene, trans, trans muconic acid, and S-phenylmercapturic acid). This evaluation shows that the most relevant biomarkers for estimati ng individual exposure to environmental pollution are I-hydroxypyrene for p olycyclic aromatic hydrocarbons and urinary benzene and S-phenylmercapturic for benzene.