Hibernation concentrates chemicals

Some pollutants build up in grizzly bears even as they doze through the winter, tests of the animals' hair and fat indicate.

Hibernating bears don't drink, eat, or excrete waste, so food- and waterborne contaminants neither enter nor leave their bodies. Nevertheless, chemical concentrations in the animals' fat may change as they use up that energy source.

The body converts some compounds into water-soluble metabolites that get excreted in urine. In a slumbering grizzly, such metabolites might accumulate.

Researchers led by Peter S. Ross, a Sidney, British Columbia–based mammal toxicologist with the government agency Fisheries and Oceans Canada, tested 11 grizzlies in the fall of 2003 and 14 others the fo