Commonly Used Chemicals Found in Polar Bears’ Brains
It has been too well documented that polar bears‘ survival is threatened as their habitat, the sea ice, melts. The disappearance of the ice has been linked to a possible decline in the number of polar bear births as well as to an increase in companies drilling for oil in the Arctic.
Another threat they face is from industrial chemicals that are resistant to thermal, biological and chemical degradation. A recent study has found that these are present in the brain tissue of polar bears in East Greenland.
The chemicals, PerFluoroAlkyl Substances (PFASs) and precursor compounds, are resistant to thermal, biological and chemical degradation. Over the past six decades, they have widely been used in a number of commercial and industrial products as coatings for textiles, paper products, carpets, upholstery and food packaging that are water, oil and soil repellent. They are also found in pharmaceuticals, cleaning products and fire-fighting foams.
As scientists from Carleton University in Canada and Aarhus University in Denmark underscore, these compounds can be carcinogenic and neurotoxic to wildlife and humans. That is, while PFASs and related substances do not directly cause the deaths of polar bears, the accumulation of them in their systems is dangerous, especially as they damage their bones, organs and reproductive systems. The new study says that that PFASs can also damage polar bears’ brains as the chemicals have been shown to cross the blood-brain barrier.
In fact, one particular type of PFAS, perfluorooctane sulfonate (PFOS), has been found at concentrations in polar bears’ livers that are 100 times higher than those in harp seals, which the bears feed on.
The use of PFASs and related compounds has risen dramatically in the past four decades. Due to concerns about safety, PFOS has not been produced in the western world since 2002 as these chemicals are exceptionally persistent (meaning that they only break down in the environment over a very long period of time) and can “bioaccumulate” in an animal’s system. Currently, the only known source of these chemicals is China. Even though there are replacements for these substances, the production of PFOS has actually ”increased by roughly a factor of 10, since it was phased out in the USA,” the scientists note.
Industrial chemicals are entering the Arctic via air and sea currents and their presence is likely to increase. The melting of the sea ice has meant that the Arctic is far more accessible to humans, via tourism and industry. Some companies are already planning to use Arctic waters as a regular shipping route. The result can only be an increase in contaminants entering the Arctic ecosystem.
The use of PFASs in everyday products is, the scientists underscore, “widespread.” As the presence of these chemicals is only rarely declared on many products, the least we can do is to seek out environmentally-labeled products. Even if we can slow down the rate at which temperatures around the world are rising and slow down the speed at which sea ice is melting, polar bears are still threatened by our activities.
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