DuPont Co., the third-largest chemical maker in the US, says that one of its new worker health studies suggests that a chemical in Teflon used to make nonstick products is not carcinogenic.

The study covered more than 6,000 employees who worked at a West Virginia factory from 1948 to 2002, and discovered that they had lower mortality rate than the general population of West Virginia and the US. The plant makes PFOA, or perfluorooctanoic acid, which is a chemical used to produce nonstick coatings and stain-resistant clothing and carpets.

The study "supports a conclusion that there are no human-health effects known to be caused by PFOA,'' Dr. Sol Sax, DuPont chief medical officer, said in the statement. "If health effects were associated with PFOA exposure, they almost certainly would be more prevalent among employees who are occupationally exposed to the compound.'

Environmental Protection Agency regulators have said that PFOA is most likely a human carcinogen based on its studies on animals. DuPont has promised to eliminate almost all PFOA exposure from factories and products by 2015. The company says it has slashed PFOA emissions by 95 percent in US plants since 2000.

"The bottom line on this is that this is a study to look for effects of (perfluorooctanoic acid) on mortality, and there were none in this worker population,' said David Boothe, global business manager for DuPont fluoroproducts. "Our belief is we have a study that's very statistically powerful here.'