Induction of cytochrome P450 as a biomarker for environmental contamination in aquatic ecosystems

Abstract

Representing toxicant‐induced changes in biological systems, biomarkers can serve as linkers between contamination (cause) and biological effects, and therefore provide unique information on ecosystem health. Hence, they are increasingly used for assessing the exposure of organisms to environmental contamination. Here, application of the induction of cytochrome P4501A (CYP1A), certainly the best studied biomarker, in field trials with freshwater and marine fish is reviewed. Moreover, the use of a number of other biomarkers, alone or in concert with CYP1A, is evaluated. Determination of CYP1A in field studies with fish has to consider several influencing factors, such as species, age, reproductive stage, temperature, and possible inhibitors. The overview shows that CYP1A induction is significantly related to contaminant levels in the environment in 93% of the investigated field studies. It is apparent that only certain classes of xenobiotica act as inducers of CYP1A (e.g., PAHs, coplanar PCBs, polychlorinated dibenzofurans, and dibenzodioxins). Induction of CYP1A was found to be more sensitive than other biomarkers at the biochemical, cellular, organ, and population level. Thus, induction of CYP1A can serve as a powerful tool for assessing environmental contamination and health, and its measurement, preferably together with other biomarkers and chemical analysis, is strongly recommended in monitoring programs.