July 4, 2005
Chemical & Engineering News, Volume 83, Number 27, p. 5, ENVIRONMENT
PFOA CALLED LIKELY HUMAN CARCINOGEN
EPA science advisers say agency needs
to assess cancer risk from compound
By CHERYL HOGUE
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.
The draft report from EPA's Science Advisory Board (SAB) says
the agency should classify the chemical as a "likely"
carcinogen in humans. In contrast, an agency draft risk assessment
released in January found only "suggestive evidence"
that PFOA could cause cancer, and concluded that current information
is "not sufficient to assess human carcinogenic potential"
(C&EN, Jan. 17, page 28).
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
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.
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