U.S. Fish and Wildlife ServicePhoto credit: U.S. Fish and Wildlife Service

Contaminants and pollution from industrialized parts of the world reach the Arctic via both air and ocean currents. In some Arctic regions, apex predators, like the polar bear, carry high contaminant loads. The presence of contaminants can adversely affect several physiological processes as well as endocrine, immune and reproductive systems which may impact bears at the individual and/or population levels. Being compromised in such a manner may further impede the polar bear’s ability to respond to rising temperatures and shrinking sea ice habitat caused by a warming Arctic environment.

Source: Circumpolar Action Plan

Further reading on the IUCN Polar Bear Specialist website