Search for unknown adducts: increase of sensitivity through preselection by biochemical parameters.

Electrophilically reactive compounds or metabolites that occur in humans can be monitored through their reaction products with proteins and DNA. The identification of genotoxic risk factors, e.g., by haemoglobin (Hb) adducts, comprises both the identification of the causative factor and an estimate of the contribution to risk. The problems involved are illustrated by efforts to trace the origin of the observed background hydroxyethylations in Hb from persons without occupational exposures. Earlier work showed influences of smoking and, in animal studies, of dietary fat and intestinal flora on the levels of hydroxyethyl adducts to N-terminal valine. Efforts to measure adducts originating from ethene in environmental tobacco smoke and urban air show, however, that the resolving power of the methods used for identifying unknown risk factors must be increased. Studies of groups with excessive living habits and biochemical parameters that favour higher tissue doses of electrophiles would also enhance the possibilities of identifying risk factors.