The Environmental Protection Agency on Wednesday asked DuPont and seven other chemical companies to work to eliminate use of a chemical that is a key ingredient in the production of Teflon but may pose potential health risks to humans.

While accepting the EPA's challenge, DuPont Co. acknowledged that it has no immediate replacement for the chemical, a key compound in products that accounted for about $1 billion in sales for the Wilmington-based company in 2004.

EPA administrator Stephen Johnson sent letters to DuPont and the other companies Wednesday asking them to commit to the voluntary program by March 1.

The initiative calls for a 95 percent reduction in environmental emissions and product content levels of perfluorooctanoic acid, or PFOA, and associated chemicals by 2010. The companies also are being asked to work toward the elimination of PFOA and associated chemicals from emissions and products by 2015, but the agency conceded that may not be possible because of costs and technological hurdles.

DuPont, one of the largest users of PFOA, has agreed to participate in the program, which EPA officials announced in a teleconference with reporters.

Other companies asked to participate are 3M/Dyneon Arkema Inc., AGC Chemicals/Asahi Glass, Ciba Specialty Chemicals, Clariant Corp., Daikin and Solvay Solexis.

While DuPont has eliminated environmental emissions of PFOA by more than 90 percent in recent years, it does not believe it can eliminate using PFOA to make products any time soon.

"We've been looking for 30 years and we have not found an acceptable substitute for PFOA," David Boothe, business manager for DuPont fluoroproducts, said in a telephone interview.

PFOA is a processing aid used in the manufacturing of fluoropolymers, which have a wide variety of product applications, including nonstick cookware. The chemical also can be a byproduct in the manufacturing of fluorotelomers used in surface protection products for applications such as stain-resistant textiles and grease-resistant food wrapping.

The EPA is awaiting a final decision from a science advisory board reviewing a draft risk assessment of PFOA. A majority of board members concluded in a draft report that the chemical is "likely" to be carcinogenic to humans.

The board's preliminary finding went beyond the EPA's own determination that there was only "suggestive evidence" from animal studies that perfluorooctanoic acid and its salts are potential human carcinogens.

"The science on PFOA is still coming in, but the concern is there," said Susan Hazen, EPA's acting assistant administrator for the Office of Prevention, Pesticides and Toxic Substances.

DuPont agreed last month to pay $10.25 million in fines and $6.25 million for environmental projects to settle allegations by the EPA that the company hid information about the health risks of PFOA.

As part of the settlement, DuPont agreed to pay $5 million for a study examining the potential of nine DuPont fluorotelomer-based products to breakdown to form PFOA, which can be found in the blood of most Americans.

"We know there are questions out there in the public, and this is part of DuPont's use of science to come up with solutions," said DuPont vice president Susan Stalnecker, adding that the company is confident it can meet the goals of EPA's new initiative.

"We think this is a great opportunity for industry to get ahead of the curve and demonstrate leadership in protecting the environment," said Charles Auer, director of EPA's Office of Pollution Prevention and Toxics.

Meanwhile, Hazen said the EPA is working to add PFOA to the agency's Toxic Release Inventory.

"All of that work would continue under this stewardship program," Auer said.

The Environmental Working Group, a Washington, D.C.-based advocacy group that helped prompt EPA's scrutiny of PFOA, applauded the agency and DuPont for their leadership in establishing the stewardship program.

"We will watch it very carefully," said EWG president Ken Cook. "We're taking nothing for granted."