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Bears on Thin Ice
We explain why chemical pollutants are giving polar bears both male and female sex organs. Plus the ringtone links we promised.
 The links
Download polar bear and grizzly roars as .wav files at http://library.thinkquest.org/11922/bears/bears.htm for a mobile ringtone with a difference. In October and November there is a polar bear web cam at www.polarbearsinternational.org
The toxins
‘Most polar bears have several hundred man made chemicals in their bodies and they have never evolved ways to deal with them,’ says Andrew Derocher, a bear biologist at the University of Alberta in Canada. High levels of the now banned PCBs (polychlorinated biphenyls) and other nasties like certain pesticides are part of a group of chemicals that are very long lived in the environment and are called POPs or Persistent Organic Pollutants. Many of these noxious chemicals have been long banned by governments, but because they have such a long life in the environment, will cause problems for many years to come, though researchers have found the first welcome signs that concentrations of PCBs are reducing in both the Arctic environment and in polar bears. One of the worst offenders, and not yet banned are brominated flame retardants. These are added to plastics to stop them catching fire easily and are used in circuit boards in PCs, televisions, office equipment and furniture. Europe is expected to ban them this year.
POPs generally reduce the amount of antibodies in the blood of the polar bear, making the animals susceptible to infections. Some even mimic bear hormones causing behavioural, and sexual problems.
 Andrew Derocher’s team examined 139 bears across the Arctic region from Alaska to Norway. The bears were anaesthetized by dart from helicopters in ten different locations around the Arctic and tested for POPs. The Norwegian bears have ten times the levels of pollutants than Alaskan bears, though scientists are not yet sure why. The worst affected bears were from Norway’s Svalbard Islands. Around one in 50 female bears there is hermaphrodite, having both male and female sex organs. The first ever cubs were found with this condition in 1997. Hermaphroditism is believed to be strongly linked to POP contamination levels in the animals.
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