Chemical May Be Linked to Thyroid Disease
Study Raises Questions About Non-Stick Chemical Known as PFOA
DuPont: PFOA Emissions Reduced continued...
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.”
Thyroid Disease Link
Thyroid disease is much more common in women than in men. But the researchers found no evidence of a statistically different effect of PFOA exposure in women and men.
They did find a link between thyroid disease and higher concentrations of PFOS in men, but not in women.
Previous studies examining people living in communities where PFOA and PFOS are manufactured have shown little association between exposure to the chemical and thyroid hormone functioning.
But findings from the largest-ever study of PFOA exposure have not yet been made public.
In the ongoing C8 Study, researchers measured PFOA levels and health outcomes among nearly 70,000 residents of West Virginia who drank water contaminated with PFOA.
The study is funded by a $107 million lawsuit settlement agreed to by DuPont in 1998.
Preliminary findings suggest high PFOA levels may be linked to high blood pressure, high cholesterol, and impaired liver function.
University of Massachusetts thyroid researcher Thomas Zoeller, PhD, tells WebMD that thyroid disease is increasing, but the reasons for this remain unknown.
“There is almost certainly an environmental component to this, but we don’t know what that environmental component is,” he says.
He says PFOA and PFOS may be environmental triggers, but this remains to be proven.
And because it is not clear how people become exposed, there is no easy message for reducing exposure to these chemical compounds, he says.
“Right now, I don’t think we have the ability to know what kind of exposures we are getting and where it is coming from,” he says.