In a new report scientists say that a chemical compound used to make Teflon, possibly causes cancer.
The report, which is still in draft, is written by the scientific advisory panel of the Environmental Protection Agency, and has identified perfluorooctanoic acid as a "likely carcinogen".
The EPA has until now classified PFOA as a "suggested" carcinogen, and this demands fewer health precautions.
This latest information is significant because it will probably prompt agency officials for the first time to regulate the processing agent, PFOA.
A major investigation is presently underway by the EPA into how the compound, which is used to make stain and stick resistant surfaces and materials for products including Gore-Tex fabrics and pizza boxes, gets into consumers' blood and if it affects their health.
The EPA is also demanding millions of dollars in fines from DuPont, the producers of PFOA, on the grounds that the chemical giant has neglected for two decades to report possible health and environmental problems associated with the compound.
The panel's 17 members will discuss the draft assessment on July 6 prior to forwarding it to the agency, but does not draw conclusions on whether using products made with PFOA, such as nonstick pans, poses a cancer risk.
However it does say that the fact that animal studies have identified four different kinds of tumors in both male and female rats and mice that had been exposed to the compound, is convincing enough evidence for the majority of its members to believe it to be a likely carcinogen.
Senior Vice President Richard Wiles, of the Environmental Working Group, whose advocacy organization has urged the EPA to regulate the compound, says the panel's findings are "huge", and officials will now be required to conduct a cancer-risk assessment of PFOA.
Eryn Witcher, an EPA spokeswoman, said she could not comment in detail on how the panel's report would affect the agency's risk-assessment process, but EPA administrator Stephen L. Johnson will take its conclusions into account.
Chemical company DuPont, which last year settled a lawsuit brought by residents living near its Parkersburg plant for $300 million, has consistently maintained that it has met all federal reporting requirements and denies that PFOA poses a serious health threat.
Company spokesman R. Clifton Webb, said DuPont's studies on its workers do not suggest that there is a connection between the compound and cancer, and no human health effects are known to be caused by PFOA, even in workers who have significantly higher exposure levels than the general population.
The report will be submitted to the agency next month.