The EPA stated earlier this year that its draft risk assessment of perfluorooctanoic acid and its salts found "suggestive evidence" of potential human carcinogenicity, based on animal studies.

In a draft report released Monday, the majority of members on an EPA scientific advisory board that reviewed the agency's report concluded that PFOA, also known as C-8, is "likely" to be carcinogenic to humans, and that the EPA should conduct cancer risk assessments for a variety of tumors found in mice and rats.

Environmentalists hailed the report, which will be discussed by EPA officials and SAB members in a public teleconference July 6, as an important step in holding government regulators and the Delaware-based chemical giant accountable.

The board's findings will increase pressure on the EPA to conduct human health risk assessments for liver, breast, pancreatic and testicular cancer, as well as PFOA's potentially toxic effects on the immune system, said Richard Wiles, senior vice president for the Environmental Working Group, an advocacy and research organization.

"This is contrary to the recommendation of the EPA staff and is a very important conclusion," said Wiles, adding that it would be very unlikely for the board to make any significant changes before issuing its final report for review by the EPA.

"This makes it hard for the EPA not to move forward aggressively," he said.

Enesta Jones, a spokeswoman for the EPA's Office of Prevention, Pesticides, and Toxic Substances, said agency officials had not reviewed the advisory board's report and do not comment on board recommendations until they are final.

"We're still working with industry and other people to gather data that will help us better understand PFOA," she said.

DuPont officials would not comment on the report but said in a prepared statement that human health and toxicology studies suggest that PFOA exposure does not cause cancer in humans and does not pose a health risk to the general public.

"To date, 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 company said.

The company also said data from its employee health studies and those conducted by 3M Co., which stopped manufacturing PFOA in 2000, "deserve greater consideration in the EPA's final risk assessment rather than relying solely on animal testing models."

DuPont's studies, which are still ongoing, have found elevated levels of total cholesterol and fats called triglycerides among workers exposed to PFOA, but no indication that PFOA was the cause of increased serum cholesterol and triglycerides.

While PFOA is used to make Teflon, it is not present in Teflon itself, which is applied to cookware, clothing, car parts and flooring. PFOA also is used to produce materials used in firefighting foam, phone cables and computer chips.

Shares of DuPont fell 25 cents to $44.69 in morning trading on the New York Stock Exchange.