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Stain-Resistant Fabrics May Boost Thyroid Hormones

From MedPage Today:

Perfluorinated chemicals (PFCs), a class of chemicals used in products ranging from stain-resistant fabrics to fire extinguishers, may increase levels of thyroid hormones, particularly among women, researchers reported.

In an analysis of NHANES data, there was a significant positive relationship between perfluorooctanoate (PFOA) and total T3 and between perfluorohexane sulfonate (PFHxS) and total T3 and total T4 among women, Chien Yu Lin, MD, PhD, of En Chu Kong Hospital in New Taipei City in Taiwan, and colleagues reported online in the Journal of Clinical Endocrinology and Metabolism.

For men, they saw an inverse association between PFHxS and free T4.

"These findings suggest an effect of low-dose PFOA and PFHxS in humans, although the potential biological significance of this effect is small and subclinical in the general U.S. population," they wrote.

PFCs are widely used in consumer and industrial goods, including fabrics, carpets, surfactants, lubricants, paper coatings, cosmetics, and fire-fighting foams. They are characterized by highly stable carbon-fluoride bonds.

In addition to PFOA and PFHxS, other PFCs include perfluorooctane sulfonate (PFOS) and perfluorononanoic acid (PFNA). The researchers noted that PFOA and PFOS are largely being phased out and replaced with short-chain PFCs such as PFHxS.

Although further study is needed to clarify whether there's a causal relationship between PFC concentrations and thyroid function -- the study was limited by its observational nature and by its cross-sectional design -- the researchers said the findings "provide clues about where to focus future epidemiologic and toxicology research."

Posted: 7/18/2013 11:42:00 AM

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Chemicals Linked to Early Menopause

From WebMD:

Women exposed to high levels of chemicals called perfluorocarbons (PFCs) may enter menopause earlier, new research suggests.

PFCs are man-made chemicals found in many household products such as food containers and stain-resistant clothing as well as in water, soil, and plants.

''Before this study, there was strong evidence from animal research that PFCs were endocrine disruptors," says researcher Sarah Knox, PhD, professor of epidemiology at the West Virginia University School of Medicine, Morgantown.

For the study, she evaluated the levels of two PFCs, called PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoate) in nearly 26,000 women, ages 18 to 65.

Overall, she found, ''the higher the perfluorocarbons, the earlier the menopause." Women between ages 42 and 64 with the highest blood levels of the PFCs were more likely to have experienced menopause than those with the lowest levels.

One of the chemicals, PFOS, affected levels of the hormone estradiol, a form of estrogen. "The higher the levels of PFOS, the lower the levels of estradiol," she says. As estradiol declines, menopause approaches.

The research is published in the Journal of Clinical Endocrinology & Metabolism.

Posted: 3/28/2011 11:17:00 AM

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Chemical May Be Linked to Thyroid Disease

From WebMD:

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.

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.

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.

Posted: 1/22/2010 10:25:00 AM

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