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

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Abstract
Harp seals (Phoca groenlandica) from the Barents Sea were analyzed for blubber levels of polychlorinated biphenyls (PCBs), polychlorinated camphenes (PCCs; toxaphenes), DDT and its metabolites, hexachlorobenzene (HCB), hexachlorocyclo‐hexanes (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 activities and pesticide levels. Furthermore, the bioaccumulation potential and persistency of these compounds were evaluated. PCCs were the dominant contaminants, exceeding the PCB concentrations. Individual PCC congener levels (Tox 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, suggesting that the Barents Sea is exposed to PCCs by a local source. The biomagnification factor and the metabolic index were greatest for p,p‐DDT, HCB, β‐HCH, and the chlordanes trans‐nonachlor and U82. The other pesticides showed lesser values, suggesting metabolism. The ethoxyresorufin‐O‐deethylation activity (CYP1A) was high and not correlated with any of the pesticides, whereas a high correlation (r2 adjusted > 50%) was found between the PCCs and testosterone 6‐β hydroxylation activities (CYP3A). This suggests an induction of CYP3A‐like activity by PCC exposure.