A group of scientific advisers to the Environmental Protection Agency voted unanimously Wednesday to approve a recommendation that a chemical used in the manufacture of Teflon and other nonstick and stain-resistant products should be considered a likely carcinogen.
The approval of the EPA's Science Advisory Board is conditioned on minor clarifications being made to a draft report submitted by a review panel, but no major changes will be made to the panel's findings.
The revisions called for by the SAB include making a cover letter to EPA Administrator Stephen Johnson more reader-friendly and clarifying the scope of dissent among members of the SAB panel that reviewed the EPA's draft risk assessment of perfluorooctanoic acid, also known as C-8.
Board members also agreed that the report should clarify why some unpublished scientific studies were considered by the panel while others weren't, and that the panel's findings should not be considered the last word on PFOA but should be updated as additional data become available.
PFOA is a processing aid used in the manufacturing of fluoropolymers, which have a wide variety of product applications, including nonstick cookware.
The chemical also can be a byproduct in the manufacturing of fluorotelomers used in surface protection products for applications such as stain-resistant textiles and grease-resistant food wrapping.
Wilmington, Del.-based DuPont Co., owner of the Teflon brand, is the sole producer of PFOA in North America.
Some members of the review panel disagreed with the majority view that PFOA should be classified as a "likely carcinogen," a finding that went beyond the EPA's own determination that there was only "suggestive evidence" from animal studies that PFOA and its salts are potential human carcinogens.
"Are we talking two-fifths of the panel, or are we talking about a small number?" asked SAB Chairman M. Granger Morgan, head of the department of engineering and public policy at Carnegie Mellon University.
Deborah Cory-Slechta, chair of the PFOA risk assessment review panel, said dissent from the majority views of the 16-member panel on issues it was asked to study typically was limited to three or four members.
Cory-Slechta also noted that an unpublished study from the 1980s linking PFOA to mammary tumors in laboratory rats was considered by the panel because it was peer-reviewed within the EPA and included in the original risk assessment submitted by the agency for review.
The same could not be said for a 2005 review sponsored by the DuPont and 3M Co. challenging the earlier study's conclusion.
"We do not feel that it rose to the same level of scrutiny as the other information we were considering," she said.
But 3M scientist John Butenhoff accused the panel of making "selective use" of information to make an unwarranted recommendation about PFOA's potential carcinogenicity.
Robert Rickard, director of health and environmental sciences at DuPont's Haskell Laboratory, said the company had asked the review panel after its February 2005 meeting if it would be appropriate to submit new data, and was told it could.
The only SAB member to offer significant criticism of the PFOA review panel was James Bus, a lead toxicologist for Dow Chemical Co.
Bus, who did not submit his written comments until shortly before Wednesday's meeting, said the review panel should have considered the DuPont-3M paper, and should have offered a stronger rationale for upgrading the recommended cancer descriptor from "suggestive evidence" to "likely carcinogen."
Johnson, the EPA administrator, is free to accept the SAB's recommendations regarding PFOA, or to reject them.
The EPA will use the report "as well as all new information that becomes available, to formulate the next steps in our continuing assessment of these chemicals," said Oscar Hernandez, director of the risk assessment division in the EPA's Office of Pollution Prevention and Toxics.