Tissue Distribution of Polychlorinated Biphenyls and Organochlorine Pesticides and Potential Toxicity to Alaskan Northern Fur Seals Assessed Using PCBs Congener Specific Mode of Action Schemes
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The fur seal (Callorhinus ursinus) population has decreased in their primary breeding grounds in the Bering Sea; contamination is among suspected causes. Our goal was to better understand the extent of contamination of seal tissues with certain organochlorine compounds by measuring the concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in fur seal tissues from St. Paul Island, to gain a better perspective of tissue congener distribution and to evaluate the observed PCB levels against toxicologically significant levels for modes of action. Concentrations of 145 PCB congeners (∑145PCBs) and 12 OCPs were measured with gas chromatography–ion trap mass spectrometry in 8 different tissues of 10 male northern fur seals. The mean concentrations of ∑OCPs [in ng/g lipid weight (lw)] were 1180 in blubber, 985 in the heart, 1007 in the liver, 817 in the kidney, 941 in muscle, 660 in reproductive tissues, 204 in the brain, and 322 in the lung. The mean concentrations of ∑145PCBs (in ng/g lw) were 823 in blubber, 777 in the liver, 732 in the heart, 646 in reproductive tissues, 638 in muscle, 587 in the kidney, 128 in the lung, and 74.3 in brain tissues. Concentrations of PCBs affecting the aryl hydrocarbon receptor expressed as total PCB toxic equivalents (∑PCB-TEQs) ranged from 0.3 to 545 pg/g lw for the various tissues. The major contributors to ∑PCB-TEQs are CB-118 in muscle, brain, lung, kidney, and liver, CB-126 in blubber, and CB-118 and CB-126 equally in the heart and reproductive tissues. Concentrations of PCBs affecting Ca2+ homeostatsis expressed as the neurotoxic equivalent (NEQ) showed ∑PCB-NEQs ranged from 17.7 to 215 ng/g lw in all tissues. Although no composite measure of perturbation of thyroid function is available, sufficient amounts of congeners with high binding to the thyroxine transport system were present to warrant consideration of this mode of action in future studies. Analyses of 145 PCBs and mode of action evaluation suggest that PCB contamination could potentially exert an effect on the Alaskan northern fur seal population although the PCB concentrations have been decreasing in the fur seals over the last decade.
KeywordsPCBs Harbor Seal Chicken Heart Indicator PCBs Pribilof Island
The fur seal tissue samples were collected with the help of the Aleut Community of St. Paul Island Tribal Government Ecosystem Conservation Office. This study was supported in part by the Alaska SeaLife Center (contract to QXL). This work was also funded in part by the Pollock Conservation Cooperative Research Center (grant to JM & SA), School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Alaska. However, the findings and conclusions presented by the authors are their own and do not necessarily reflect the views or positions of the Center or the University of Alaska.
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