It's never been easy to be a polar bear. They may have to go months without eating. Their preferred food, seal, requires enormous luck and patience to catch. Add to that the melting of Arctic sea ice due to climate change, and the poisoning of the Arctic by toxic chemicals, and it's easy to see why polar bears worldwide are in trouble.
Among all the bad news, however, comes one possible bright spot. In a study of PCBs in polar bear cubs in Svalbard, researchers from the Norwegian University of Science and Technology (NTNU) have found that blood levels of PCBs and related contaminants in polar bear cubs appear to have dropped by as much as 59 per cent between 1998 and 2008. At the same time, levels of these contaminants in their mothers were as much as 55 per cent lower over the same period.
"The levels of PCB compounds in blood samples from females are on the decline," says Jenny Bytingsvik, a biologist at NTNU who is completing her doctoral dissertation on the findings. "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."
Banned internationally since 2004
PCBs (polychlorinated biphenyls) were once widely used as a cooling fluids and insulators in transformers and electric motors, but were banned by many industrialized countries 30 years ago because of their harmful effects on humans and animals. More recently, the global production of PCBs has been banned as of May 2004 by the Stockholm Convention on Persistent Organic Pollutants, an environmental treaty designed to eliminate or restrict the production and use of persistent organic pollutants, including PCBs.
Polar bears are particularly at risk from these persistent pollutants because the chemicals are fat-soluble a
|Contact: Bjrn Munro Jenssen|
Norwegian University of Science and Technology