The significance of the renal lesions is not well understood. This study provides the first evidence of adverse effects to polar bears from long-term exposure to OHCs, which include DDT, polychlorinated biphenyls (PCBs), and polybrominated diphenylethers (PBDEs).

PCBs and PBDEs are known for their ability to act as flame retardants. These compounds have hundreds of uses in such products as electronic circuit boards and cases, furniture, building materials, pesticides and lubricants.

Among the 75 polar bears examined in the study, seven different types of renal lesions were found. Six of the seven types were related to age.

However, because the lesions were similar to those of OHC-contaminated Baltic seals and other exposed laboratory animals, the authors decided that OHCs were a cofactor in the development of the renal lesions. Metals and recurrent infections were not ruled out as other possible factors.

In polar bears, OHCs are transferred from mother to fetus and to offspring by lactation. The study forms the basis for research on other OHC-contaminated wildlife and raises the possibility of OHC transfer to human populations who rely on what may be contaminated food sources in the Arctic.

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