Good news for polar bears

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Recently I wrote a post on Arctic pollution, describing the deposit of toxic mercury through bromine 'explosions'. This subject utterly depresses me. But luckily it isn't all doom and gloom for the polar bears, at least with regards to pollution.

Apparently the concentration of PCBs and other industrial poisons in polar bears has gone down in the past decade. CFKs, PCBs have been or are being reduced, maybe GHGs are next? Because accumulating poisons is one thing, but loss of Arctic sea ice is even more dangerous for polar bears and many other creatures (such as homo sapiens).

From the Alaska Dispatch:

Polar bears accumulating fewer industrial poisons

A new study of polar bears prowling the ice-bound shores of Svalbard has found them carrying lower levels of the PCBs and other industrial poisons than a decade ago, offering some good news for a species that may face critical loss of ice habitat as the Arctic warms.

Blood levels of PCBs and other contaminants in cubs dropped as much as 59 percent between 1998 and 2008, with PCB levels dropping 55 percent in the blood of their mothers, according to research by Norwegian and Canadian scientists.

"The levels of PCB compounds in blood samples from females are on the decline," said lead author Jenny Bytingsvik, a doctoral student at the Norwegian University of Science and Technology, in this story.

"For newborn, vulnerable cubs, this is a very positive trend. Reduced levels of PCBs in the mother bears' blood mean that there is also less contamination in their milk. Even though the PCB levels we found are still too high, this shows that international agreements to ban PCBs have had an effect."

PCBs, or polychlorinated biphenyls, come from a family of industrial chemicals used for decades in electrical transformers, oils, plastics and paints. Although banned in the United States since 1979 and throughout the world by the 2004 Stockholm Convention on Persistent Organic Pollutants, they continue to be used in some parts of Asia and the Third World.

Over decades, these contaminants accumulate in the Arctic, where they work up the food chain, finally accumulating in the blood and fatty tissue of top predators like polar bears, seals and killer whales.