An overview of methods quantifying the influence of biotransformation on bioaccumulation

Biotransformation can reduce the concentration of xenobiotic, chemicals in organisms, and may thus be responsible for and can explain relatively low bioconcentration factors of hydrophobic chemicals. Qualitative information on biotransformation is relatively easily obtained by identifying metabolites either in vivo or in vitro. Quantification of biotransformation, however, is more difficult. A number of methods is presented which enables quantification of the influence of biotransformation for organic chemicals. These methods include enzyme inhibition studies, mass balance studies, hydrophobicity/bioconcentration relationships, and quantification of metabolites. The use of these methods will be illustrated by examples of the contribution of biotransformation to decreased bioconcentration for chlorinated anilines, biphenyls, dibenzo-p-dioxins and dibenzofurans in fish.