EPA Science Advisers reconsider Labeling C-8 likely Carcinogen

posted on:
July 12, 2005

author:
Staff

category:
Environmental

Members of EPA’s Science Advisory Board (SAB) are wavering on an earlier draft recommendation that the agency elevate the risk ranking of the chemical C-8, which is widely used in making consumer products, to a “likely” human carcinogen.

The hesitation could provide EPA with justification to pursue a less intensive risk assessment and possible regulations given the agency’s initial labeling of C-8 as a “suggestive” carcinogen.

The SAB, which has convened a panel to review an EPA draft risk assessment of the chemical, held a July 6 teleconference to discuss the board’s own preliminary recommendations for the risk review. A preliminary draft of the SAB review released late last month identified C-8 as a likely carcinogen, prompting widespread news reports about the potential public health risks because low levels of the chemical have been detected in 95 percent of blood samples from the general population, according to the Centers for Disease Control and Prevention. Relevant documents are available at InsideEPA.com.

But several scientists on the SAB panel are now expressing discomfort with the classification of likely carcinogen, saying the chemical falls somewhere between EPA criteria for “suggestive evidence of carcinogenic potential” and “likely to be carcinogenic to humans.”

The chemical C-8, more formally known as perfluorooctanoic acid (PFOA), is used to produce various consumer products, such as non-stick cookware and water resistant apparel. DuPont, the company that makes PFOA, currently faces class-action lawsuits over alleged adverse health effects by residents living near the company’s plants, as well as EPA enforcement action that claims the company failed to disclose the potential risks of the chemical (Risk Policy Report, Nov. 30, 2004, p3).

The SAB panel is expected to complete its revisions in about four weeks, when the panel will give its final recommendations to the full board for review.

EPA did not return calls seeking comment on the board’s recommendations.

A DuPont spokesperson says, “There were a number of divisive views that came across” during the teleconference, and added that there is more work to be done before the panel makes its final recommendation.

Several members of the SAB panel said they would feel more confident placing PFOA in the “suggestive” category. But others expressed frustration with the debate, arguing that a conclusion had been reached before the panel issued its June 27 draft review of the risk assessment.

“The reason that there were qualifications here is that the panel, while at the consensus that ‘suggestive’ didn’t do the job, was not willing to go all the way to say ‘more likely than not,’” one panelist said.

An executive summary of SAB’s draft report says, “The majority of panel members concluded that … the carcinogenicity of PFOA was stronger than proposed in the draft document, and suggested that PFOA is a ‘likely’ carcinogen in humans.” But panel members said the report might indicate a unanimous decision by the board.

If EPA adopts the board’s suggestion to elevate the classification of PFOA to likely carcinogen, it could lead to an enhanced risk assessment and stricter regulatory policies on the chemical based on the new risk findings.

The panel is reviewing EPA’s draft risk assessment on PFOA at the agency’s request. Initially, EPA listed PFOA as a “suggestive” carcinogen, but at a February meeting, the panel indicated the risks may be greater than EPA’s classification. Even then, panelists showed concern that the phrase “likely” might cause state and federal agencies to devise overly cautious risk assessments (Risk Policy Report, March 1, p1).

These EPA criteria, known as “descriptors,” are used to classify chemicals that may induce cancer, and are frequently used by state and federal agencies developing regulations. The EPA classifications, finalized earlier this year, define “suggestive evidence” as small incidences of cancer in animal or human studies that may not be statistically significant. The category of “likely to cause cancer” is broader, and can include evidence that a chemical induces tumors at multiple sites or in multiple species or sexes. The SAB’s draft review cites this standard as the basis for the panel’s recommendation.

Several scientists on the SAB panel suggested the guidelines are too vague, and said “likely” is too strong a term for the criteria. “I think the report needs to distinguish and make it very clear that the panel was only talking about a descriptor, and not whether PFOA was likely to cause cancer,” one scientist said.

Environmental groups are encouraging EPA to strongly support the SAB’s draft recommendation, saying the panel made the right choice. “We need to see a clear commitment on the side of the agency to err on the side of public health if there’s uncertainty here,” says a source with the Environmental Working Group, which is closely following the SAB decision and the overall PFOA debate.

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