Perfluorooctanoic acid (PFOA) poses a greater cancer risk than EPA has estimated, science advisers to the agency said in a draft report released last week.

	EXPOSURE PFOA taints the groundwater near this plant in West Virginia where DuPont makes its Teflon-brand polytetrafluoroethylene. DUPONT PHOTO

The SAB draft says EPA should evaluate the potential for PFOA to cause several types of cancer. Tests on laboratory rodents suggest that the chemical may be linked to tumors of the breast, testes, pancreas, and liver, the draft report notes. In addition, it says the agency should consider possible health problems other than cancer from PFOA exposure, recommending that the agency examine the compound's effects on the immune and nervous systems.

Increasingly found in people and wildlife, PFOA is perhaps best known for its use as a surfactant in the manufacture of polytetrafluoroethylene, including DuPont's Teflon. But a major source of PFOA in the environment is thought to be the degradation of telomers, which are short-chain fluorinated alcohols used as stain- and grease-resistant coatings on carpets, textiles, and paper (C&EN, June 14, 2004, page 44).

In its draft report, SAB faults the agency for not taking data on workers exposed to PFOA into account when assessing the chemical's risk. "Occupationally exposed populations have experienced the highest levels of exposure, and therefore, reported health effects in these studies merit consideration," it says. EPA's draft risk assessment on PFOA said that data on exposed workers was inadequate for risk assessment.

Because the SAB report is in draft form, the board could revise it before formally presenting the document to EPA, probably later this year. For that reason, the agency isn't commenting on the particulars in the draft report.

PFOA maker DuPont said in a statement that it "believes that the weight of evidence suggests that PFOA exposure does not cause cancer in humans and does not pose a health risk to the general public. To date, no human health effects are known to be caused by PFOA, even in workers who have significantly higher exposure levels than the general population."

DuPont is conducting a study of employees exposed to PFOA. "Partial results indicate that there is no association between PFOA exposure and most of the health parameters that were measured," the company said, with "a modest increase in some, but not all, cholesterol fractions in some of the highest exposed workers."

Richard Wiles, senior vice president of the Environmental Working Group, says that at this point in the science advisers' review of PFOA, "it's unthinkable they'd reverse themselves" on their draft recommendation to upgrade the chemical's classification to a likely human carcinogen. If finalized without change, SAB's draft recommendations increase the odds that the agency would regulate PFOA, says Wiles, whose organization is calling for EPA to tightly control the compound.

A panel of SAB is scheduled to discuss the draft report on July 6. The draft is available at www.epa. gov/science1/drrep.htm.