Polar Bear Health Threatened By Environmental Contaminants

Polar bears have enough to worry about with climate change, and now new research shows that their health is threatened by environmental contaminants, which are starting to affect their endocrine system and reproduction.

Climate change is without a doubt the main threat to polar bears (Ursus maritimus) in the Arctic, diminishing the sea ice they rely on to travel, hunt, mate, and den. They also suffer from nutritional stress, reduction of polar ice, human contact and diseases and parasites. But the list doesn't end there.

"The health of the arctic polar bear is being attacked from all fronts, but among many other factors is the exposure to environmental contaminants," María Jesús Obregón, one of the researchers, said in a news release.

The study, led by Norwegian scientists, stresses that plastic pollution and environmental contaminants are affecting the endocrine system and the reproductive system of this mammal.

"This is especially significant in this endangered species," added Obregón. Polar bears are predicted to go extinct by the year 2100 if the current rates of habitat loss continue.

The researchers focused on the exposure of the arctic polar bear that lives in Greenland to growing levels of environmental contaminants, mainly organohalogen contaminants.

"A wide variety of organochlorine compounds and pesticides have an effect on the thyroid hormones in plasma, tissues and deiodinase enzymes, which are in charge of stabilizing the thyroid hormones in tissues," explained Obregón.

The team analyzed more than 50 organohalogen contaminants and their metabolites in bear plasma and tissue, and compared them with normal thyroid parameters in seven adult bears. Previous studies had already demonstrated the relationship between the presence of contaminants and the altered plasmatic levels of the thyroid hormones in the arctic wildlife, but it is the first time that they have been linked to tissue alteration.

Though, it should be noted that due to the small sample size, a cause-and-effect relationship cannot be established.

Unfortunately for these cold-climate bears, environmental contaminants aren't the only form of pollution they have to worry about. Previous research has shown that polar bear penises are weakening due to chemical pollution, threatening their very survival. Not to mention that perfluoroalkly substances (PFAs) - chemical pollution resulting from landfill run-off that leaks into the ocean - are giving polar bears brain damage, impacting their behavior and hormone balance.

The latest study results were published in the journal Environmental Research.

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