Chemicals that prevent grease from seeping through food packaging transform in rats into a suspected carcinogenic compound. This conversion could help explain why that compound—perfluorooctanoic acid (PFOA)—shows up so widely in people's blood, say researchers.
PFOA, used to manufacture nonstick cookware and rain gear, turns up in blood samples worldwide, reaching concentrations of 30 nanograms per milliliter or more. The chemical doesn't degrade, and people excrete it slowly. An advisory group to the Environmental Protection Agency has recommended classifying PFOA as a rodent carcinogen that may harm people.