Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus)

Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO2-PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO2-PCB and PBDE congener patterns showed significant differences (p ≤ 0.05) mainly in the liver and the brain relative to the adipose tissue and the blood. OH-PBDEs and MeO-PBDEs were not detected in the brain and liver, but had different patterns in blood versus the adipose tissue. Novel OH-polybrominated biphenyls (OH-PBBs), one tri- and two tetra-brominated OH-PBBs were detected in all tissues and blood. Congener pattern differences among tissues and blood are likely due to a combination of factors, e.g., biotransformation and retention in the liver, retention in the blood and blood–brain barrier transport. Our findings suggest that different congener pattern exposures to these classes of contaminants should be considered with respect to potential target tissue-specific effects in East Greenland polar bears.