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Article Tier 2 Human Health Effects Sign in to save

State of knowledge on current exposure, fate and potential health effects of contaminants in polar bears from the circumpolar Arctic

The Science of The Total Environment 2019 141 citations

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Researchers reviewed decades of data on chemical contamination in polar bears and found that legacy pollutants like PCBs, chlordanes, and PFOS — many of which enter food chains via plastics and industrial runoff — remain the primary chemical threats, disrupting thyroid hormones, immune function, and lipid metabolism. While banned pollutant levels are slowly declining, newer fluorinated compounds (PFCAs) are rising in some populations, underscoring how industrial chemicals continue to accumulate in Arctic apex predators.

Study Type In vitro

The polar bear (Ursus maritimus) is among the Arctic species exposed to the highest concentrations of long-range transported bioaccumulative contaminants, such as halogenated organic compounds and mercury. Contaminant exposure is considered to be one of the largest threats to polar bears after the loss of their Arctic sea ice habitat due to climate change. The aim of this review is to provide a comprehensive summary of current exposure, fate, and potential health effects of contaminants in polar bears from the circumpolar Arctic required by the Circumpolar Action Plan for polar bear conservation. Overall results suggest that legacy persistent organic pollutants (POPs) including polychlorinated biphenyls, chlordanes and perfluorooctane sulfonic acid (PFOS), followed by other perfluoroalkyl compounds (e.g. carboxylic acids, PFCAs) and brominated flame retardants, are still the main compounds in polar bears. Concentrations of several legacy POPs that have been banned for decades in most parts of the world have generally declined in polar bears. Current spatial trends of contaminants vary widely between compounds and recent studies suggest increased concentrations of both POPs and PFCAs in certain subpopulations. Correlative field studies, supported by in vitro studies, suggest that contaminant exposure disrupts circulating levels of thyroid hormones and lipid metabolism, and alters neurochemistry in polar bears. Additionally, field and in vitro studies and risk assessments indicate the potential for adverse impacts to polar bear immune functions from exposure to certain contaminants.

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