The chemical in question is perfluorooctanoic acid, known as PFOA or C-8, used to make Teflon and other stain- and stick-resistant materials including Gore-Tex fabrics and pizza boxes. In June 2005 a scientific advisory panel to the U.S. Environmental Protection Agency (EPA) identified PFOA as a "likely carcinogen" but drew no conclusions as to whether products made with it pose a cancer risk to humans. However, it did say that animal studies have identified four types of tumors in rats and mice exposed to PFOA.
The panel's findings should prompt the EPA to undertake a cancer-risk assessment of PFOA to see if it influences the development of cancer in humans. A study now underway is looking at potential health problems among thousands of residents of Ohio and West Virginia who have filed a lawsuit alleging that DuPont withheld information concerning the threat to human health posed by PFOA. Concentrations of the chemical have been found in drinking water from supplies near a DuPont plant in West Virginia. Also at issue for the EPA: the question of whether the DuPont company, which manufactures Teflon, knew that PFOA was a likely carcinogen and kept that information to itself.
Note that the danger of exposure to PFOA concerns those involved in the manufacturing of Teflon, not users of Teflon-coated cookware. Teflon itself appears safe unless it is heated to high temperatures, when it emits fumes toxic enough to poison caged birds in kitchens (birds are much more sensitive to these fumes than humans and other mammals). The exact temperature at which this occurs is not clear. DuPont has long acknowledged that heating Teflon cookware to temperatures as low as 464 degrees is harmful to birds but has said that the fumes aren't a problem for humans because most consumers don't exceed that temperature when cooking. But that may not be so, especially if you leave a Teflon-coated pan unattended on the stove. If Teflon fumes can poison birds, what can they do to us? Probably nothing good.
I have a Teflon coated skillet that is very convenient, but I use it for controlled-temperature sauteing (i.e., with some liquid in the pan) and never let it get too hot.
Andrew Weil, M.D.