Common chemical linked to risk for hypothyroidism in women

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Published July 18, 2013

| FoxNews.com

Though many people may try to live organically or ‘go green,’ it’s likely their bodies will still come in contact with a variety of chemicals every day. 

Now, researchers believe that perfluorinated chemicals – compounds that have been widely used to manufacture products such as carpet, fabric, paper coatings and cosmetics – may be putting women at an increased risk for hypothyroidism and other disorders.

“Experimental animal studies and epidemiological findings have demonstrated the effects of PFCs on thyroid function,” study author Dr. Chien-Yu Lin of En Chu Kong Hospital in Taiwan, told FoxNews.com in an email. “However, the relationship between serum PFCs and thyroid function in a nationally representative survey of adults has never been performed (until now).”

PFCs and hypothyroidism

In a study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism, Lin and his fellow researchers analyzed data from 1,181 participants in the 2007-2008 and 2009-2010 National Health and Nutrition Examination Survey (NHANES).

Based on this data, they discovered that study participants who had higher levels of certain types of PFCs in their blood – perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS)  – showed increased levels of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). As a result, women who previously had no history of thyroid disease developed mild hypothyroidism, a condition in which the thyroid gland does not produce enough hormones, leading to symptoms like weight gain and fatigue.  

When the body is functioning normally, the pituitary gland acts as the body’s natural mechanism for regulating the thyroid, signaling when more hormones should be produced. However, among women with higher levels of PFCs, thyroid hormones increased independently. Though levels of hypothyroidism were characterized as “mild,” Lin pointed out that the levels were consistent with previous studies linking PFC exposure to thyroid disease.   

“Since individuals with a reported history of thyroid disease were excluded to avoid the influence of medications on thyroid measure, we only found higher odds of ‘subclinical’ hypothyroidism,” Lin said. “…Nevertheless, these results are comparable to a previous cross-sectional analysis of (PFC) concentrations and reported thyroid disease in adults.”

The dangers of PFCs

Exposure to PFCs is widespread in the United States, despite the fact that manufacturers have been limiting their use of the compound for the past decade.

“PFCs break down very slowly, and it takes a long time for these chemicals to leave the body and the surrounding environment,” Linda Birnbaum, director of the National Institutes of Health's (NIH) National Institute of Environmental Health Sciences, told FoxNews.com.  

In addition to thyroid disease, many epidemiological studies have linked PFC exposure to kidney, liver and heart disease, high cholesterol, certain types of cancers and weakened immune function in children. However, it has been difficult to isolate PFCs as the direct cause for these health problems in human studies, according to Birnbaum.

In 2002, the manufacturing company 3M voluntarily phased out production of PFOS in the United States. Additionally, manufacturers have agreed to work towards total elimination of PFOA by 2014. However, it will be a long time before the public stops seeing the effects of these chemicals, according to Birnbaum.

“It looks like there is some decrease in levels we’re beginning to see in population, but it will take a long time,” Birnbaum said. “And if these continue to be produced in other countries, we will continue to have some contact here.”

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