Ethoxyresorufin-O-deethylase (EROD) activity in fish as a biomarker of chemical exposure

This review compiles and evaluates existing scientific information on the u se, limitations, and procedural considerations for EROD activity (a catalyt ic measurement of cytochrome P4501A induction) as a biomarker in fish. A mu ltitude of chemicals induce EROD activity in a variety of fish species, the most potent inducers being structural analogs of 2,3,7,8-tetracholordibenz o-p-dioxin. Although certain chemicals may inhibit EROD induction/activity, this interference is generally not a drawback to the use of EROD induction as a biomarker. The various methods of EROD analysis currently in use yiel d comparable results, particularly when data are expressed as relative rate s of EROD activity. EROD induction in fish is well characterized, the most important modifying factors being fish species, reproductive status and age , all of which can be controlled through proper study design. Good candidat e species for biomonitoring should have a wide range between basal and indu ced EROD activity (e.g., common carp, channel catfish, and mummichog). EROD activity has proven value as a biomarker in a number of field investigatio ns of bleached kraft mill and industrial effluents, contaminated sediments, and chemical spills. Research on mechanisms of CYP1A-induced toxicity sugg ests that EROD activity may not only indicate chemical exposure, but also m ay also precede effects at various levels of biological organization. A cur rent research need is the development of chemical exposure-response relatio nships for EROD activity in fish. in addition, routine reporting in the lit erature of EROD activity in standard positive and negative control material will enhance confidence in comparing results from different studies using this biomarker.