Erod Activity

Measurement of ethoxyresorufin-O-deethylase (EROD) activity in fish is a well-established in vivo biomarker of exposure to certain planar halogenated and polycyclic aromatic hydrocarbons (PHHs and PAHs) and other structurally similar compounds (Bucheli and Fent 1995; Stegeman and Hahn 1994). EROD is a highly sensitive indicator of contaminant uptake in fish, providing evidence of receptor-mediated induction of cytochrome P450-dependant monooxygenases (the CYP1A subfamily specifically) by xenobiotic chemicals. Numerous laboratory experiments, simulated field studies, and natural field studies have examined EROD induction in more than 150 species of fish. In addition to PHHs and PAHs, an extensive list of individual contaminants and complex environmental mixtures has been examined for teleost EROD potential. Although EROD activity is best viewed as an indicator of exposure, the relationship between EROD and biological effects at higher levels of organization is the subject of intense investigation. It is becoming clear that the mechanism of CYP1A induction is closely related to, if not directly involved in, detrimental effects such as apoptosis and embryonic mortality seen in fish exposed to EROD-inducing contaminants (Cantrell et al. 1996). Apart from xenobiotic induction, EROD activity can be influenced by a large number of abiotic and biotic factors such as water temperature, age and reproductive phase (Andersson and Förlin 1992). An understanding of these factors is critical to the design and interpretation of field studies utilizing this biomarker.