Pollution Giving Polar Bears Brain Damage

As if polar bears don't have enough problems, not only are they suffering due to climate change-related sea ice loss, but now new research indicates that pollution is giving them brain damage.

Scientists have found that key processes in the brains of polar bears are being disrupted by man-made chemicals such as stain repellents and water-proofing treatments, which are accumulating in the Arctic. The chemicals, known as perfluoroalkly substances (PFAs), are the result from landfill run-off that leaks into the ocean and contaminants food that these bears feed on. As years of these pollutants build up in the bears' brains, it starts to impact their behavior and hormone balance to the point that it can potentially threaten their ability to survive.

"Results from our study support the hypothesis that PFAS concentrations in polar bears from East Greenland have exceeded the threshold limits for neurochemical alterations," the researcher wrote in the journal Environmental Research. "Given the importance of these systems in cognitive process and motor function, the present results indicate an urgent need for a better understanding of neurochemical effects of PFAS exposure to wildlife."

To better understand how PFAs are directly effecting polar bears, Katherine Eggers Pedersen, a toxicologist at the University of Copenhagen who led the research, and her team examined the brains of nine polar bears that had been killed by hunters in East Greenland. They then measured the levels of PFASs in different regions of the brain and compared them to levels of enzyme activity there.

They found that the highest levels of PFAs were in the brainstem, which controls vital life functions, and the cerebellum, which is responsible for coordinating movement and balance.

But it was perfluorooctane sulfonate (PFOS) in particular, which is a strain repellent treatment for fabrics, and perfluorinated carboxylic acid, used to make non-stick coatings, that were associated with changes to key neurotransmitters in the bear's brains.

"We don't know whether the disruption of enzymes and signal substances is enough to have an effect on the polar bears' senses and behavior," researcher Professor Bjarne Styrishave told Science Nordic. "The brain is plastic and may adapt itself and compensate for the damage to a certain extent."

"It's difficult to say whether we are a long way from the limit, or very close to it," he added. "It's the fundamental processes vital to being a bear that can potentially be disturbed by the substances."

This isn't the first time that chemical pollution has posed a problem to these endangered animals. Bizarre research published back in January showed that polar bear penises are weakening due to high levels of pollutants called organohalogens - specifically polychlorinated biphenyls, or PCBs.

This puts them at risk of literally breaking their penises, which could have disastrous consequences for mating and the survival of this endangered species, already expected to go extinct by the year 2100.

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