Chemical giant DuPont Co. withheld information from federal officials that indicates a dozen residents near its Parkersburg, W.Va., plant have high blood levels of perfluorooctanoic acid, an ingredient used to make Teflon that in animal studies has been linked to cancer and birth defects, an environmental advocacy group said yesterday.

The company is already facing as much as $313 million in fines on the grounds that for two decades it did not provide the Environmental Protection Agency with data pointing to health risks associated with the compound, also known as C-8 or PFOA. Next month DuPont is expected to go before an EPA administrative law judge to try to dismiss the government's claims in connection with the soaplike material, which is used in making stick-resistant surfaces and materials.

In a related case, DuPont agreed two months ago to pay as much as $343 million to settle a class-action lawsuit accusing it of contaminating drinking water supplies in Ohio and West Virginia with C-8. DuPont asked an independent lab to examine blood taken from the 12 named plaintiffs in the lawsuit to gauge their exposure to the chemical compound. Lawyers in the suit submitted the study's findings to the EPA in September, so the agency had the results before environmentalists went public yesterday.

Environmental Working Group President Kenneth A. Cook, whose group obtained a copy of the test results from the plaintiffs' lawyers, wrote to EPA Administrator Mike Leavitt yesterday to complain about DuPont's failure to turn over the recent findings.

"Despite EPA's formal complaint and pending hearing, DuPont continues its established pattern of hiding important health information from the agency," Cook wrote.

DuPont officials said they were not required to report the study's conclusions to the EPA because the residents' blood levels of C-8 -- which were 12 times higher than those of average Americans -- did not represent a health threat.

"The Environmental Working Group's latest claims are irresponsible and alarmist," said Stacey J. Mobley, DuPont senior vice president and general counsel. "DuPont is cooperating fully with the U.S. Environmental Protection Agency and is providing all appropriate information to the agency about PFOA, whether required by a statute or not. The EWG is doing all it can to mislead the public on this issue."

The EPA has no established safety level for C-8 exposure, though it is in the midst of a broad scientific review to determine whether it is dangerous. Agency officials have expressed concern that the compound remains in the bodies of exposed people for several years.

EPA spokeswoman Cynthia Bergman said the agency "takes very seriously" the allegation that DuPont failed to fully report possible health problems linked to C-8, which is why it decided in July to seek fines against the company.

"The agency continues to receive and review information, and we have not foreclosed any possibilities, including that of additional claims," Bergman said.

DuPont representatives met with EPA officials on Nov. 2 to determine what information is "of interest to the agency," said DuPont spokesman R. Clifton Webb, adding the company "is committed to share details of all ongoing research on the compound."