July 23, 2013
PFS Toxins Found In Polar Bear Brain Tissues
Susan Bowen for www.redorbit.com - Your Universe Online
As if polar bears didn't have enough problems, researchers have found Perflouroalkyl substances (PFS's) in their brains. Scientists are becoming increasingly aware of the toxicity of these compounds. They can cause gene mutations and cancers. They can also affect reproduction and development, in addition to being toxic to the nervous system, the endocrine system and the immune system.
These compounds are extremely persistent in nature and resist chemical, thermal and biological degradation. They are used in water and oil repellent coatings for textiles, paper products, carpets, food packaging and pharmaceuticals. They are also used as a surfactant in cleaning products and fire-fighting foams. As their use has increased over the last four decades, they have shown a huge increase and dispersal around the world.
Previous studies noted dramatic increases in PFS's in animals at the top of the food chain. Polar bears were found to have a hundredfold higher concentration of them in their livers than in the ringed seals that are their prey.
The new study was conducted by researchers from Carleton University in Canada and Aarhus University in Denmark. Researchers have used the polar bears as sentinel species for humans and other top predators. They found PFS's in eight brain regions of polar bears from eastern Greenland.
Dr. Robert Letcher of Carleton University explains why these findings are so worrying. "We know that fat soluble contaminants are able to cross the brain-blood barrier, but is it 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." Professor Rune Dietz of Aarhus, adds, "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 chemicalsÂ can have a severe impact." Most proteins can't cross the brain-blood barrier.
The good news is that PFS's are decreasing in the environment. They have been phased out and are no longer produced in the western world. However, they are still being produced in China, which has seen production increase by a factor of ten.
North American and European wildlife have seen a decline the concentrations in PFS's. Greenlandic polar bears and ringed seals started to experience the decline after 2006. Rune Dietz comments, "It is promising to see that the PFAS are on the decline. This development should be encouraged by the authorities globally."
"In the meantime," he counsels, "my best advice to the consumers is to go for environmentally labeled products. But avoiding products is difficult, because PFASs are so widespread in many kind of products and they are rarely declared."