Members of a federal science panel reviewing the safety of a controversial chemical used to make fluoropolymers appear to be split over its potential to harm humans.
Just nine days after the Environmental Protection Agency-appointed panel came out with a draft report saying that perfluorooctanoic acid is a ``likely'' human carcinogen, some of its members took issue with that and said they thought evidence pointed to PFOA being only a much weaker ``suggestive'' source of cancer.
The discussion, which boiled over at a July 6 public teleconference called to review the panel's draft report, highlights apparent scientific uncertainty surrounding PFOA, which has attracted significant attention from EPA because it is in the blood of many Americans at low levels.
Members of EPA's Science Advisory Board did not appear ready to alter their basic conclusion, but seemed to suggest they were open to revising the report to reflect the range of opinion. The SAB panel now will revise its report before presenting it to the full SAB and then EPA.
Melvin Anderson, a director at the Centers for Health Research in Research Triangle Park, N.C., said the evidence points to PFOA being labeled suggestive, a point echoed by several other members of the panel.
``I think this is an area where there was a great deal of difference on the panel, and that difference did not come out in the report,'' said Michael Kamrin, a professor emeritus at Michigan State University. The panel was not making a broad statement that PFOA is likely to cause cancer, only discussing how it fit into EPA categories, he said.
But several others said the evidence is stronger than a label of suggestive. Norman Drinkwater, a University of Wisconsin professor, said PFOA is linked to multiple cancer end points, which ``takes it beyond the suggestive level.''
Boston University professor Michael Ozonoff said the panel had discussed the issue extensively at a two-day February meeting, and felt that the evidence supported labeling it a likely carcinogen, but not a stronger term.
An EPA staff report in January had labeled PFOA a suggestive carcinogen, but the agency appointed the outside scientists to review its conclusions.
SAB also heard a report from DuPont Co. that it found no connection between PFOA exposure and health effects of more than 1,000 workers at one of its factories, except for an increase in cholesterol in some employees.
