Chemical May Be Linked to Thyroid Disease

Jan. 21, 2010 -- A chemical compound used to make non-stick cookware, food
wrappers, and water-resistant coatings for carpets and fabrics has been linked
to an increased risk for thyroid disease in an early study.
Perfluorooctanoic acid (PFOA) has previously been shown to influence thyroid
hormone levels in animals.
But the newly reported study is among the first to suggest that exposure to
PFOA might cause thyroid disease in humans.
The study included nearly 4,000 adults who took part in the CDC’s ongoing
nationwide Health and Nutrition Examination (NHANES) study between 1999 and
2006.
Researchers found that participants who had the highest levels of PFOA in
their blood also had the highest self-reported incidence of thyroid
disease.
Specifically, women with the top 25% of PFOA concentrations were more than
twice as likely to report taking drugs for thyroid disease as the 50% of
participants with the lowest concentrations. A similar trend was seen in men,
although it didn’t reach statistical significance.
The study does not prove that PFOA exposure is a direct cause of thyroid
disease, researcher David Melzer, PhD, of Peninsula Medical School in Exeter,
England, tells WebMD.
“I personally am far from sure, but it might prove to be an important risk
factor for people who are already susceptible,�? he says.
DuPont: PFOA Emissions Reduced
PFOA, also known as C8, and the related chemical perfluorooctane sulphonate
(PFOS) are used by companies like DuPont and 3M in the manufacture of a range
of products, including Teflon, Stainmaster, and Scotchgard.
Concerns have been raised about the man-made chemicals because they are now
found in low levels in the environment and in the blood of most people and they
remain in the blood for many years.
It is not clear how PFOA gets into the blood. Manufacturers claim their
products do not contain it or contain only trace amounts of the chemicals.
The Environmental Protection Agency (EPA) is investigating the compound, but
at present it considers the routine use of consumer products made with it to be
safe.
In 2006, the EPA and eight major companies, including DuPont and 3M, agreed
to work to eliminate global emissions of PFOA and related compounds by
2015.
A spokeswoman for DuPont tells WebMD the company has reduced PFOA emissions
at its manufacturing sites worldwide by about 98% since that time, exceeding
the interim target of 95% emission reduction by this year.
In response to the latest study, Janet Smith of DuPont points to research in
communities with high PFOA exposures that show little or no impact on the
thyroid.
“As the authors of the study indicated, it is not clear whether the
associations they observed are causal,�? she says. “Epidemiological studies
involving workers who have had much higher levels of PFOA exposure than the
general public haven’t shown any changes that would indicate impact on the
thyroid.�?
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