Polar bears exposed to chemical cocktail from melting ice
By Mark Tamhane
Posted Fri Aug 6, 2010 6:03pm AEST Polar bears, the icon of the Arctic, are under threat from the twin challenges of climate change and chemicals that are not breaking down in the region’s cold waters. Research published in the journal Science of The Total Environment shows the retreat of sea-ice in the Arctic could increase the exposure of species such as polar bears to persistent organic pollutants, which include flame-retardants and substances used to harden plastics. Scientists believe the pollutants, locked in the polar ice for decades, could be released into the ocean as the ice melts due to climate change. It is estimated annual summer sea-ice cover in the Arctic is now up to a third less than it was thirty years ago. According to study co-author Professor Bjorn Munro Jenssen, an eco-toxicologist from the Norwegian University of Science and Technology (NTNU), polar bears are particularly at risk, because they are at the very top of the Arctic food chain. “These contaminants are bio-accumulated and bio-magnified up the food chain. So the higher you are, the higher the contaminants,” says Professor Munro Jenssen. The fact that a polar bear’s favourite meal is seal does not help. “These contaminants accumulate in fat and the polar bear only eats the fat of seals. And they eat maybe a few hundred or a thousand seals per year,” he said. “These contaminants are toxic, even in low concentrations. So they can affect the hormone system, the immune system probably the reproduction rate and the survival of the bears … maybe not a lot, but enough to have an effect on the numbers of polar bears.” Even though the Arctic covers a vast area, it is estimated there are currently only 20,000 to 25,000 polar bears. …
