Members of a federal scientific review board agreed Wednesday to revise their draft report on the potential risks of a chemical used by DuPont Co. to make Teflon in order to better reflect opposing viewpoints among themselves.
In a draft report released late last month, the majority of members on a scientific advisory board that reviewed the Environmental Protection Agency’s draft risk assessment for PFOA concluded that the chemical is “likely” to be carcinogenic to humans.
That finding went beyond the EPA’s own determination that there is only “suggestive evidence” from animal studies that perfluorooctanoic acid and its salts are potential human carcinogens.
During a public teleconference Wednesday to discuss the report, some panel members expressed concern that the change in wording, which they revealed was the subject of extensive debate at a February meeting, may lead people to make unwarranted assumptions about PFOA.
Panel members agreed to revise the report to incorporate more text on the range of their opinions, but they gave no indication that any significant changes would be made in their conclusions.
“I actually think there’s been a remarkable amount of consensus on this panel, and I would be careful about using phraseology that suggests there was not,” said David Ozonoff, a professor of environmental health at Boston University.
But Melvin Andersen of the Centers for Health Research in Research Triangle Park, N.C., a private, nonprofit organization founded by chemical industry leaders in the 1970s, said he was “uncomfortable” with the draft report, and that it does not address the breadth of opinions on PFOA’s cancer-causing potential.
“I’m more comfortable with the ‘suggestive evidence’ than a ‘likely’ carcinogen,” he said.
James Kehrer, head of the Division of Pharmacology and Toxicology at the University of Texas in Austin said he, too, favors the “suggestive” descriptor.
“PFOA is clearly a funny chemical,” he said. “Rodents don’t seem to be very good model for human effects.”
But other panel members noted that the use of the term “likely” is based not on any quantitative risk assessments of PFOA, which the report recommends be undertaken, but on the EPA’s guidelines for determining the carcinogenic potential of chemicals.
Those guidelines include five possible descriptors for a chemical’s cancer-causing potential in humans, with “likely” being the middle ground between “suggestive evidence” and “carcinogenic.”
In its report, the science advisory board said “likely” is typically used as a descriptor when an agent has “tested positive in more than one species, sex, strain, site or exposure route, with or without evidence of carcinogenicity in humans.”
“The panel was only talking about the EPA descriptor, and not whether it’s likely or not to cause cancer,” said Michael Kamrin, professor emeritus of environmental toxicology at Michigan State University, noting the absence of any quantitative studies.
Norman Drinkwater, an oncology professor at the University of Wisconsin, said the evidence from animal studies exceeded the criteria for “suggestive evidence.”
“The current and proposed EPA guidelines for the cancer descriptions didn’t really provide us with an ideal description, given the state of the data for PFOA,” he said.
Panel members agreed to submit their proposed changes for the draft report to the EPA by July 20, and expect to have a revised draft ready for their review by early August. The report would then be forwarded to the full science advisory board for its approval before being submitted to the EPA, which can accept or reject its findings.
Meanwhile, DuPont officials reiterated Wednesday that initial findings from a study of more than 1,000 workers at DuPont’s Washington Works facility near Parkersburg, W.Va., have found no evidence to suggest that PFOA exposure can cause cancer.
“This worker population appears to be healthy, from an overall health standpoint,” DuPont toxicologist Gerald Kennedy told the EPA advisory board members.
In February, the Delaware-based chemical giant agreed to pay $107 million to settle a class-action lawsuit by West Virginia and Ohio residents who claimed that PFOA from the Washington Works plant contaminated their water supplies. The company, which agreed to pay as much as $343 million to resolve the case, denied any wrongdoing.
DuPont also has set aside $15 million to settle EPA complaints that the company failed to report information over two decades about the potential environmental and human health risks of PFOA, although no agreement has been reached. In May, the company was served with a subpoena from a federal grand jury in Washington D.C., for documents related to PFOA.