The Environmental Protection Agency is seeking fines totaling millions of dollars from DuPont on the grounds that the chemical giant failed for two decades to report possible health and environmental problems linked to a key ingredient used in making Teflon, agency officials said yesterday.

The penalty would dwarf any the agency has assessed for toxic contamination and could become the largest environmental levy in U.S. history. Tom Skinner, head of EPA's Office of Enforcement, said the penalty is "intended to send a message to DuPont and everyone else this type of information must be provided" so officials "can make valid assessments of the risks posed by various substances."

The chemical, perfluorooctanoic acid, is a soaplike material used in making stain- and stick-resistant surfaces and materials for a wide array of products, including Gore-Tex and pizza boxes. The substance, also known as C-8 or PFOA, has been linked in industry studies to cancer and birth defects in animals.

The agency had been pressed to act on C-8 by the Environmental Working Group, a private advocacy group, and by Ohio and West Virginia residents who are suing DuPont over claims that it contaminated soil and drinking water around the company's Parkersburg, W.Va., plant. Both welcomed the agency's move but said it could have taken tougher action.

"The good news is, EPA woke up and took notice," said EWG President Ken Cook, whose group filed a petition in 2003 calling on EPA to act. "The bad news is, we have no idea whatsoever what this means for DuPont."

DuPont said yesterday that it plans to fight the complaint, which will be handled through administrative channels but is subject to appeal in federal court.

"DuPont has provided substantial information to EPA supporting our conclusion that we have followed the law," DuPont general counsel Stacey J. Mobley said. "We will . . . vigorously defend our position."

It remains to be seen how big a fine EPA will seek from DuPont, but it could run into the hundreds of millions. The largest fine the agency has imposed under the Toxic Substances Control Act is $2 million, Skinner said. The biggest civil penalty under any federal environmental law was a $30 million fine, plus $5 million in environmental projects, imposed Jan. 13 on Koch Industries Inc. of Wichita for oil spills.

C-8 is not regulated, but under federal law any chemical manufacturer who learns a product presents "a substantial risk" of health or the environmental harm must inform EPA.

EPA is conducting tests to monitor how C-8 degrades in the environment, though Skinner said the agency is not seeking to ban the chemical.

Residents of West Virginia and Ohio who are suing DuPont have alleged they are suffering from health problems -- including respiratory problems and cancer -- they attribute to dumping of C-8.

Howard Varner, a retired pipe fitter from Cutler, Ohio, who has worked on and off in DuPont's facility for the past 20 years, said: "In today's political climate, it surprised me a lot EPA does anything but turns companies loose, but I'm glad they're doing it."

Varner said DuPont knew Ohio drinking water was contaminated more than a dozen years before informing local water officials: "It's just deny, deny, deny, delay, delay, delay. I hope they don't win this time, but they usually do."

Part of EPA's complaint stems from industry studies in 1981 suggesting that C-8 might be linked to birth defects in animals. After two women working in the Parkersburg plant had children with defects that resembled those found in animals, DuPont transferred women of childbearing age away from areas where the chemical was made. The company did not tell EPA about the action, but it did inform the West Virginia Division of Water Resources.

Internal DuPont documents from that time show the company detected C-8 levels exceeding its recommended standard in the blood of childbearing workers and some of their babies' blood. The company sent a letter to female workers saying that it did not know if there was a relationship between human birth defects and the chemical, but "we think this is a matter of sufficient concern that, as a precaution, a female who has [a blood level] above background level should consult with her personal physician prior to contemplating pregnancy."

DuPont spokesman Clif Webb said the company's C-8 supplier later concluded that the chemical did not cause birth defects in animals, and the next year DuPont brought female workers back to areas where C-8 was used.

"We do not reliably ascribe harm to human health and the environment, and therefore it would not be reportable," Webb said.

The company has 30 days to respond to EPA's complaint.