Variation in space-use is common within mammal populations. In polar bears, Ursus maritimus, some individuals follow the sea ice (offshore bears) whereas others remain nearshore yearlong (coastal bears). Polar bears that hunt furthest north in the Barents Sea area - part of the Arctic Ocean - have 30-35% higher concentration of perfluoroalkyl substances (PFASs) in their blood compared with coastal bears, and also increased eastward, a Norwegian-Russian study has found. Scientists tracked 152 female bears over a five-year period and analysed their blood samples for concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), PFASs and hydroxylated-PCBs. On the basis of the results the authors conclude that space-use of Barents Sea female polar bears influences their pollutant exposure, in particular plasma concentrations of PFAS.

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