The Environmental Working Group claimed that DuPont violated federal law by failing to turn over a document in 1981 showing the risks of perfluorooctanoic acid, or C8, a chemical used to manufacture Teflon.

Teflon is a widely available household product used to keep clothing such as jackets dry or to prevent food from sticking to pots and pans.

"They obviously had no intention of ever turning this over to the EPA," said Richard Wiles, a vice president of the advocacy group. "This is very damning evidence. It's not surprising to us that they withheld it, and who knows what else they've withheld?"

The group asked the Environmental Protection Agency (news - web sites) to investigate and determine if the company broke federal law by failing to immediately disclose the health impacts of the chemical.

The EPA said it was reviewing the document and did not have an immediate comment.

Wilmington, Delaware-based DuPont denied the allegations by the Environmental Working Group that the company violated the Toxic Substance Control Act by not reporting information about C8.

The environmental group cited a 1981 internal study by DuPont that measured the blood levels of seven women who worked at the company's Teflon plant in West Virginia. All had detectable levels of the chemical in their bodies, according to the document.

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The DuPont study also said one woman gave birth to a child with an eye and tear duct defect, and another employee bore a child with a nostril and eye defect. That same year, DuPont reassigned 50 women from the plant to reduce their exposure to the chemical, the Environmental Working Group said.

Residents near the West Virginia plant have filed a class-action lawsuit against DuPont over contamination of area water supplies. The DuPont report on C8 came to light in the course of that lawsuit.

"There is no evidence or data that demonstrates (C8) causes adverse human health effects, including developmental or reproductive effects, in any segment of the human population," said Robert Rickard, director of DuPont's Haskell Laboratory for Health and Environmental Sciences.

DuPont said the company recorded the women's low-level exposure but did not conduct a formal study evaluating C8 or its effect on human health.

The federal Toxic Substance Control Act only requires companies to report information when the public is at risk, DuPont said, and it added there were no adverse effects to humans exposed to the chemical.

DuPont said its records showed one birth defect, but added there was "no indication" it was linked to exposure to C8.

The Teflon chemical C8 is part of a broader family called perfluorochemicals. Tests have shown that C8 and similar chemicals can cause liver damage and reproductive problems in rats, according to scientists.

The Environmental Working Group said laboratory studies have linked exposure to perfluorochemicals to cancer, hypothyroidism and brain damage.

In 2000, 3M Corp. pulled its stain repellent Scotchgard from the market after the EPA expressed concern that a sister chemical to C8 posed serious health risks. 3M has since stopped making all perfluorochemicals.

The EPA last September began a priority review of C8 under the Toxic Chemicals Control Act, which can be used to ban chemicals that can lead to health problems or defects.

An EPA official said the agency planned to release a final version of its report on Monday.

In a draft copy released last month, the EPA found that C8 accumulates in the blood system and has toxic chemicals that pose a risk for childbearing women. The agency urged further study of the chemical's impact on humans.