Induction of drug-metabolizing enzymes by polycyclic aromatic hydrocarbons: mechanisms, and some implications in environmental health research.

The mechanisms by which administration of polycyclic aromatic hydrocarbons (PAH) stimulates drug-metabolizing enzymes are summarized. The hepatic monooxygenase system of marine and freshwater fish is also induced by PAH-type compounds, including chlorinated dioxins and certain polychlorinated and polybrominated biphenyl isomers, and these chemicals are, or are suspected to be, toxic to humans. Consequently, there is considerable interest in whether or not PAH-type induction in fish can be used as a sentinel or early warning indicator for certain classes of toxic pollutants in the aquatic environment. We have investigated various aspects of PAH-type induction in marine fish and have found that approximately 50% of the winter flounder (Pseudopleuronectes americanus), captured near Mount Desert Island, Maine, appear to have induced hepatic monooxygenase systems, which suggests that they are exposed to PAH-type chemicals in the environment. The potential advantages and limitations of using PAH-type enzyme induction as a sentinel system for pollutants in aquatic ecosystems are discussed.