Although hitherto animal data have been used  for risk assessment, mechanistic knowledge has made it possible to also involve in vitro studies for that purpose. We here demonstrate the possibility to use in vitro data for mutation induction to support a cancer risk assessment based on the radequivalent model. More specific, we want to: 1) investigate quantitatively the mutageniciy of benzo(a)pyrene, dibenzo(a,l)pyrene, dibenzo(a,h)anthracene, benzo(c) phenanthrene and fluoranthene, including their ultimate metabolites, 2) calculate the mutagenicity per adduct followed by radequivalence to be used for risk assessment, 3) apply developed methods, based on LC-MS techniques, for the measurement of adducts to DNA and to serum albumin (SA) of diolepoxides of the model PAH for investigations of DNA repair and observed deviations in dose distribution.