CYTOCHROME-P450, CYTOCHROME-P420 AND MIXED-FUNCTION OXIDASES AS BIOMARKERS OF POLYCHLORINATED BIPHENYL (PCB) EXPOSURE IN HARBOR-SEALS (PHOCA-VITULINA)

Hepatic microsomal cytochrome P450, EROD and ECOD activity were invest igated as biomarkers of PCB exposure in harbour seals (Phoca vitulina) . Due to the difficulty of obtaining undegraded seal liver samples, st andard spectrophotometric methodology was adapted to investigate P420 (degraded P450) as a PCB biomarker with partially degraded samples. To tal PCB burdens in both blubber and liver had positive correlations wi th P450, P420 and MFO activity levels. The use of P420 biomarkers in t his study supports the inclusion of samples from by-caught marine mamm als for future biomonitoring studies. P450 isozymes CYMA (P4501A) and CYP2B (P4502B) in conjunction with MFO activity were investigated as ' 'specific'' biomarkers of PCB exposure. They were found to reliably re flect levels of [MC] and [PB]-type PCB exposure in harbour seal liver. (C) 1997 Elsevier Science Ltd.