Polar bears are at the top of the arctic marine food chain. Owing to the high lipid content of their diet, polar bears appear particularly prone to bioaccumulate organochlorines. Polar bears from East Greenland and Svalbard have higher contaminant levels than polar bears elsewhere in the Arctic. Levels of PCBs in these areas might negatively affect reproduction and survival. So far more than 130 polar bear samples have been collected since 1999. These samples are being analysed for organochlorines and pathological effects.