Chlorinated pesticide concentrations, with an emphasis on polychlorinated camphenes (toxaphenes), in relation to cytochrome P450 enzyme activities inharp seals (Phoca groenlandica) from the Barents Sea

Harp seals (Phoca groenlandica) from the Parents Sea were analyzed for blub ber levels of polychlorinated biphenyls (PCBs), polychlorinated camphenes ( PCCs; toxaphenes), DDT and its metabolites, hexachlorobenzene (HCB), hexach lorocyclohexanes (HCHs), and the cyclodiene pesticides, including dieldrin, endrin, and the chlordanes. Also, the hepatic cytochrome P450 (CYP) enzyme activities were measured to assess a possible relation between CYP activit ies and pesticide levels. Furthermore, the bioaccumulation potential and pe rsistency of these compounds were evaluated. PCCs were the dominant contami nants, exceeding the PCB concentrations. Individual PCC congener levels (To x 26 and 50) were fourfold greater than those in the Canadian Arctic and 20 -fold greater than those in seals from the west coast of Svalbard, suggesti ng that the Barents Sea is exposed to PCCs by a local source. The biomagnif ication factor and the metabolic index were greatest for p,p-DDT, HCB, beta -HCH, and the chlordanes trans-nonachlor and U82. The other pesticides show ed lesser values, suggesting metabolism The ethoxyresorufin-O-deethylation activity (CYP1A) was high and not correlated with any of the pesticides, wh ereas a high correlation (r(2) adjusted > 50%) was found between the PCCs a nd testosterone 6-beta hydroxylation activities (CYP3A). This suggests an i nduction of CYP3A-like activity by PCC exposure.