June 21st, 2010
12:01 AM ET

Common chemicals may alter thyroid function

By Caleb Hellerman
CNN Senior Medical Producer

Flame retardant chemicals found in a wide variety of products may affect the function of the thyroid gland, according to a study published Monday by researchers at the University of California, Berkeley. Known as polybrominated diphenyl ethers (PBDEs), the chemicals are used in television and computer screens, as well as in polyurethane foam for furniture and carpeting.

Researchers examined 270 pregnant women, checking the level of PBDEs in their bloodstream, and the level of TSH, a hormone linked to thyroid function. On average, higher levels of PBDEs were linked to lower TSH levels – which means that women with a high PBDE exposure tended to have overly active thyroid glands. (The lower the TSH level, the more active the thyroid gland).

The study is published in the journal “Environmental Health Perspectives.”

When low TSH is found alongside high levels of another hormone, T4, a patient can be diagnosed as hyperthyroid. In pregnant women, “hyperthyroidism is associated with miscarriage, birth defects and fetal growth problems,” says Brenda Eskenazi, one of the study authors. The TSH levels noted in the study are not enough to warrant a diagnosis of hyperthyroidism, but Eskenazi says the findings are worrisome because the level of PBDEs in the women were fairly typical, compared with levels in the overall U.S. population. She worries that the risk of hyperthyroidism may rise for people with more exposure – such as long-time residents of California, where flame retardants became ubiquitous with the passage of state laws in the 1970s.

Health concerns about PBDEs are not new. In December, the Environmental Protection Agency announced steps to phase out the chemicals. Albemarle and Chemtura, two large manufacturers of PBDEs, as well as ICL, a major importer, signed letters promising to end their use in new electronics products by the end of 2010, and in all products by January 1, 2013.

Ray Dawson, an official with Albemarle, questioned the relevance of the new paper, saying most of the chemicals detected are an older type – so-called "pentaBDEs" – that were phased out several years ago.

Eskenazi says the changes are welcome, but says that PBDEs can linger in fatty tissue, and notes that older products with PBDEs will remain in use. “I’m sitting on a couch with foam cushions, right now,” she told a CNN reporter over the phone.  “As the foam of this couch continues to disintegrate, I will continue to be exposed to PBDEs. We’ll be living with this stuff for a long time.”

Read more about toxic chemicals in Dr. Sanjay Gupta's investigation, "Toxic America."

Editor's Note: Medical news is a popular but sensitive subject rooted in science. We receive many comments on this blog each day; not all are posted. Our hope is that much will be learned from the sharing of useful information and personal experiences based on the medical and health topics of the blog. We encourage you to focus your comments on those medical and health topics and we appreciate your input. Thank you for your participation.

soundoff (88 Responses)
  1. bs

    My Dr. discovered my hypothyroidism when I was pregnant with my first child. She has hyperthyroidism and graves disease. My next child, a boy has hyperthyroidism and had thyroid cancer removed and also
    radiation killing what was left. He is on synthroid for the rest of his life.
    My daughter lost her baby at 23 weeks pregnant. He lived for four hours.
    I Always wondered if the thyroid could have caused it.
    I believe it is genetic, because my twin sister has hypothyroidism, two of my brothers, and several nieces and nephews have thyroid issues.

    June 23, 2010 at 21:15 | Report abuse | Reply
  2. John M.

    Diagnosed in Oct of 2009, I am recovering slowly from a cognitive stand point. Physically doing much better, lost about 15 lbs, body fat % down to normal and working out normally. A career firefighter for almost 20 years at different departments current department for 11 years. I am looking for any information regarding studies or statistics of Firefighters and hypothyroidism. Not pushing an issue but trying to protect my future career and benefits. There are alot of studies and inforamtion regarding the FDNY and their post 9-11 issues but have not been able to find studies or information outside of that issue. Just a couple of blogs or stories no concrete information. If any one can point me in the right direction I would be greatful.

    August 1, 2010 at 11:13 | Report abuse | Reply
  3. lin

    More information about hypothyroidism and hyperthyroidism will be beneficial to many readers and possibly their families and friends. I had the clinical symptoms of hypothyroidism so the P.A. that was working on my case agreed to let me try a small dose of thyroid supplement. It seems like some medical staff are informed about thyroids and some aren't as informed unfortunately. There are some that even treat a condition called adrenal fatigue for those who might still be fatigued out there. Another less known possibility for some of us is that someone with hypothyroidism who eats a large amount of vitamin K foods might experience temporary setbacks in energy.....mine happened the next day. I've felt like I was on a 'energy' roller coaster. For those on blood thinner RX, I think that you're supposed to really be careful with vitamin K foods anyway. Hypothyroidism can include low blood pressure so possibly the K foods can make your blood vessels too relaxed or your blood thinner possibly??? (That's sort of a question if anyone else has information on that connection.) Over the years I've found that eating balanced nutritious meals and practically cutting out less healthy foods(?) and alcoholic beverages has made a difference in how I feel as well. It's easy to pick on others who have weight issues, but there could be either a health problem and/or lack of healthy food information or funds. Helping someone kindly vs. harassment is the better option. At least leave them alone so that they don't get upset and munch out instead of reading CNN health or MSN health websites. Stress is sometimes considered a possible cause of endocrine system problems. Not only can cats be affected as the one person commented, but dogs as well. There has been more information about people's extra weight situations in general, but the article writers were trying to address additional causes of female weight gain information that hasn't been available to a number of puzzled people. Oh, I'm curious about the methods to curb hyperthyroidism. A friend had the surgery and RX replacement years ago so I'm aware of the symptoms. Is it possible to go from hypothyroidism to hyperthyroidism? If I finally feel like I'm at a decent energy level, I'm not as inclined to take the thyroid supplement every single day. From tests this year, it's possible that part of my fatigue was also due to Lyme. : /

    August 11, 2010 at 18:37 | Report abuse | Reply
    • lin

      Now that my health seems to be somewhat improved, my blood pressure is up to a more normal level. I do eat portions of vitamin K foods more often without as much consequence as in earlier years. Part of my stress level could have been due to people and unfortunately some medical staff who tried to convince me that my lower blood pressure was due to my 'good' state of health. Not hardly. Was too tired too often. Too much of each day.

      August 11, 2010 at 18:44 | Report abuse |
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  7. Kathy Klein

    I have hypothyroidism. I worked at least 10 years in a position of producing polyurathane foam furniture cushions and mattresses. Many times there were large amounts of dust. Could the hypothyroidism be job related?
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.