SCIENTISTS will soon launch a study on polar bears to determine how chemical pollutants are affecting their health. Researchers from the Norwegian Polar Institute (NPI) in Tromsoe, have planned to investigate the effect of high concentrations of polychlori-nated biphenyls (PCBS) and the pesticide dichlorodiphenyl trichloroethane (DDT) on the immune systems of bears in Norway's Arctic island of Spitzbergen.

Andrew Derocher of the NPI is planning to tag and study 50 bears. He is worried that the chemicals may be attacking the first line of defence in the polar bears' immune systems.

"We fear the polar bears on Spitzbergen are on the limit of what they can tolerate when it comes to PCBS," he said. PCBS do not break down easily and build up through the food chain. Polar bears and the Norwegian animals are exposed to PCB levels six times higher than their Canadian counterparts. The researchers will vaccinate the bears and examine them six weeks later to see how their immune systems have reacted.