Polar Bear Brains have High Levels of Environment Toxins: Study

Polar bear brains have significant levels of PerFluoroAlkyl Substances (PFASs), a kind of environmental toxins that are known to cause cancers and affect reproduction, a new study reported.

The study was conducted by researchers at the Carleton University in Canada and Aarhus University in Denmark who found that at least eight brain regions of polar bears had significant amount of several PFASs including perfluorooctane sulfonate (PFOS) as well as several compounds of the perfluorinated carboxylate (PFCAs).

PFASs have been widely used around the world, particularly in the manufacture of textiles, food packaging, foams and other water and oil repellent coatings. These chemicals can withstand chemical and biological degradations and have therefore been accumulating in humans and animals from the past six decades.

Research has shown that the livers of polar bears have at least 100 times higher levels of the chemicals when compared to ringed seals, their primary food.

The present study was conducted on polar bears from Scoresby Sound, East Greenland. Earlier it was believed that the main repository for the chemicals is the liver. The current study, however, shows that short chains of these toxins can cross the blood-brain barrier.

"We know that fat soluble contaminants are able to cross the brain-blood barrier, but it is quite worrying that the PFOS and PFCAs, which are more associated with proteins in the body, were present in all the brain regions we analyzed," said Dr. Robert Letcher, Carleton University.

The chemicals don't just affect animals, but also pose health risk for humans. Related studies have shown that dangerous levels of PFAS are present in tap water in Germany and food items in Sweden.

"If PFOS and PFCAs can cross the blood-brain barrier in polar bears, it will also be the case in humans. The brain is one of the most essential parts of the body, where anthropogenic chemicals can have a severe impact. However, we are beginning to see the effect of the efforts to minimize the dispersal of this group of contaminants," Professor Rune Dietz from Aarhus University said in a news release.

The U.S. and other developed countries have stopped using eight carbon chain PFOS and perfluorooctane carboxylate (PFOA) are PFASs. However, countries like China accounted for an increase in the use of these chemicals in manufacturing industries.

Efforts to reduce the use of these chemicals in manufacturing in Europe and the U.S have shown good results. 

The study," Brain region distribution and patterns of bioaccumulative perfluoroalkyl carboxylic and sulfonic acids in highly exposed East Greenland polar bears," is published in the journal Environmental Toxicology Chemistry.