Tuesday, July 21, 1998 Published at 10:22 GMT 11:22 UK
Norway's androgynous polar bears
Bear cubs: Poisoned by their mother's milk
Scientists in the Arctic region of Norway have warned that polar bears are at risk because of high levels of chemical pollution from the rest of Europe and East Asia.
The bears have been found with both male and female sexual organs.
Polar bear birth-rates are already falling, and the Norwegian Polar Institute has detected high levels of PCBs (polychlorinated biphenyls) in the bears' blood.
Polar bear research scientist Andrew Derocher said the effects of PCBs on the polar bear could be devastating.
"Even a very small change in reproductive rates can cause a very slow decline in the population level, and if this happens you could see a population greatly reduced or in the worst case go to extinction," he said.
Causes of contamination
Research indicates there are hot spots of PCBs scattered across the Norwegian Arctic.
They are believed to be carried to the Arctic Circle in air and sea currents from Europe and Asia.
Most countries banned PCBs in the 1980s, but once released into the environment they can persist for decades.
At each step in the food chain, more PCBs accumulate in the body fat.
The polar bear cubs are in the greatest danger because they receive very high doses through their mothers' milk.
Humans could be next
Scientists are worried that humans may also be at risk from PCBs, whose effects are felt much further afield than the Arctic Circle.
A large fall in human male fertility over the last 50 years has been reported in Denmark, France and Britain, and many believe that industrial chemicals, including PCBs are to blame.