WASHINGTON — The Environmental Protection Agency is concerned that a synthetic chemical found in nonstick cooking pans, stain-resistant carpets and other common products may cause developmental problems in children, officials said Monday.
The concern was prompted by an industry laboratory study submitted to the EPA a year ago. It showed unexpected deaths and slowed sexual development in the pups of female rats exposed to the chemical, perfluorooctanoic acid.
In addition, low levels of the chemical have been found in the blood of the general human population.
In response to those two developments, the EPA has taken the unusual step of ordering an accelerated study of the risks to humans posed by the widely used chemical.
EPA officials hope that by the end of the year they will be able to tell Americans whether it is dangerous.
"To ensure consumers are protected from any potential risks, the agency will be conducting its most extensive scientific assessment ever undertaken on this type of chemical," said Stephen L. Johnson, the assistant EPA administrator who heads the Office of Prevention, Pesticides and Toxic Substances.
Johnson said it is impossible to say yet whether the chemical poses an unacceptable risk to humans -- or that it doesn't -- because of the scientific uncertainties surrounding it.
Scientists do not know how the chemical gets into the bloodstream, nor do they know enough about the animal study to determine whether its findings apply to humans, he said.
"Because of the uncertainties, EPA has not determined whether [the chemical] poses an unreasonable risk," Johnson said.
DuPont, the Wilmington, Del.-based chemical corporation that makes perfluorooctanoic acid and uses it in the manufacture of many products, rejected any possibility that the chemical is harmful.
"DuPont remains confident that our use of [the chemical] over the past 50 years has not posed a risk to either human health or the environment, and that our products are safe," said Richard J. Angiullo, vice president and general manager for DuPont Fluoroproducts. "Our confidence is based on an extensive scientific database."
None of DuPont's employees, who have been exposed to much more of the chemical than the general population and have higher levels of it in their blood, have developed adverse health effects, company officials said.
Environmental activists who have studied the chemical were pleased that the EPA was moving aggressively to determine the extent of the risk posed by it.
"We think they took an important first step," said Ken Cook, president of the Washington-based Environmental Working Group, a nonprofit research organization. Environmental Working Group scientists, who have been delving through thousands of documents detailing the tests done on the chemical for the last few years, disagreed with the company's assessment of the risk posed by perfluorooctanoic acid.
"We think this stuff has got to go," Cook said.
One reason for environmentalists' concerns is that, unlike almost all other chemicals, perfluorooctanoic acid does not seem to break down in the environment. Since other synthetic chemicals appear to break down into perfluorooctanoic acid, the amount of the chemical in the environment would continue to increase even if it were banned.
The chemical is also very persistent in humans. It takes more than four years for a body to excrete half the perfluorooctanoic acid in the blood.
EPA officials said that despite their concern, they do not advise consumers to stop using nonstick pans or any other consumer or industrial products.
Perfluorooctanoic acid is used in the manufacture of fluoropolymers, which make products resistant to stains, water, grease or oil. But the finished products are not expected to contain the chemical, except perhaps in trace quantities, so it is not clear that people are exposed to perfluorooctanoic acid from these products.
The EPA is looking into possible exposure from another synthetic chemical, fluorinated telomers, which are used in firefighting foams and cleaning products and in the manufacture of water and stain repellents for carpets, textiles, leather and paper. Although perfluorooctanoic acid is not used to make telomers, some data suggest that telomers may break down in the environment to form perfluorooctanoic acid.
The companies that make perfluorooctanoic acid and use it in their products and those that make telomers have agreed to sponsor tests to learn more about how their products release the chemical into the environment and how humans are exposed to it.
In a sign of the agency's concern, Johnson gathered representatives from the companies and told them what additional information is needed to fill in the gaps in the science so that agency officials can assess the risk posed by the chemical.