London, Aug. 8: The coating on non-stick pans used in millions of kitchens throughout the world has been linked to birth defects in humans and to the deaths of pets.

Chemical firms face claims that perfluorinated organic chemicals, such as perfluorooctanoic acid (PFOA), which is in Teflon — first used in 1945 — and oil- and water-resistant coatings, are a health threat.

Du Pont, which makes Teflon, has to answer accusations in the US this week that it had evidence about dangers posed by PFOA but deliberately and illegally kept it secret.

The US Environmental Protection Agency says that Du Pont concealed its own 1981 research showing that its pregnant workers were passing the chemical to their unborn children.

In addition, in 1991, it failed to report evidence that the chemical had contaminated the water supply to 12,000 people. Du Pont has four days left to contest the charges — and a potential fine of $300 million (£160 million).

Bucky Bailey is a member of one of eight families living near the Du Pont factory in Parkersburg, West Virginia, who are suing the company over the effects of PFOA.

His mother, Sue Bailey, was a factory worker exposed to PFOA while pregnant. Bailey was born with only one nostril and other facial defects for which he has had 30 operations. He has recently married, but does not intend to have children in case they inherit his condition. He is now determined to hold Du Pont to account.

“I want them to admit that they made a mistake, to say they messed up and that they’re going to do everything they can to help,” Bailey said.

Tim Kropp, the senior scientist at the Environmental Working Group, an organisation in Washington DC, said: “The Environmental Protection Agency should force Du Pont to pay a punishing fine such that it sends out a signal to all chemical manufacturers that it is not profitable to withhold critical information.”

“The Teflon chemical PFOA, like other fluorochemicals, is in people everywhere. It never breaks down in the environment and it’s toxic at or near levels found in humans.”

Clifton Webb, Du Pont’s director of public affairs, denied that his company had acted incorrectly.

“We believe that we acted completely within the law and we have the facts that will substantiate our position,” he said. Webb added that despite evidence of exposure in the womb, and of water contamination, there was no evidence that actual harm resulted from PFOA exposure and so the company was not legally bound to release its findings.

“We stuck to the letter of the law,” he said. “We have had 50 years of experience with PFOA and none of that experience suggests harmful effects resulting from exposure.”

A separate health concern over Teflon is that when non-stick pans are overheated they release fumes that cause “Teflon flu”. Webb said that the condition, which causes aches and chills, was “temporary and soon passes”.

Pet birds, however, are easily killed by the fumes.