Do you know that many chemicals in our environment have the potential to affect thyroid function? These chemicals are called endocrine disruptors, and they include both everyday household products and chemicals used in agriculture and manufacturing that end up all over the place–in our water, air, food, and eventually, in our blood, breast milk, and babies. These chemicals often break down very slowly. They can persist in the environment for years after they are banned, and in our bodies even after our exposure to them has ended. They can cause hypo- or hyperthyroidism. They can cause autoimmune problems including Hashimoto’s thyroiditis and Graves disease. Some impair T3 activation of thyroid b-receptor sites on cells, causing a thyroid hormone resistance-like syndrome. In blood tests, this can be seen as high or normal T3 and T4 and low or normal TSH. THAT’S WHY IT’S IMPORTANT TO CHECK BODY TEMPERATURE, NOT JUST HORMONE LEVELS, to determine thyroid function.
Some of these chemicals are suspected of contributing to type 2 diabetes and our current epidemic of obesity. Even our pets, such as cats, are prone to thyroid problems due to environmental toxins or the use of soy meal as a cheap source of protein in pet foods. (Too much soy can impair thyroid function.)
Many people are unaware of their exposure to these potentially harmful chemicals. Here’s a review of commonly encountered chemicals that can hurt your thyroid.
Triclosan, an antibacterial found in hand soaps, toothpastes, deodorants, laundry detergents, fabric softeners, facial tissues, antiseptics, fabrics and toys. Research has found that due to its extensive use in consumer goods, triclosan and its metabolites are present in waterways, fish, human milk, serum, urine and foods. Triclosan was found in 75 % of people tested in government biomonitoring studies. Citizens environmental watch groups have petitioned the Environmental Protection Agency to ban non-medical use of triclosan. You can help limit your exposure by avoiding anti-bacterial soaps and toothpastes, waterless hand sanitizers and other products that contain triclosan. (Ecco Bella and CleanWell Company are part of a growing list of companies that have pledged to not use Triclosan in their products. For a complete list, see http://www.beyondpesticides.org/antibacterial/products.php.)
Phthalates and its many chemical names and abbreviations, found in personal care products, including nail polishes, deodorants, perfumes and cologne, aftershave lotions, shampoos, hair gels and hand lotions. Read labels carefully. Unless a product says it is phthalate-free, don’t count on it. Look to avoid these abbreviations: DBP and DEP, and BzBP. Use natural products with a short list of easy-to-decipher ingredients.
Pesticides and fungicides used to treat crops like strawberries, apples, grapes, and peaches can alter thyroid function. Women seem to be more sensitive than men to these effects. Wives of farmers using these chemicals are at much higher risk of developing thyroid abnormalities than the general population. Avoid exposure by limiting the use of pesticides and fungicides around your house and in your yard. Encourage neighbors to do so, too. Eat organic. This is especially important for the “dirty dozen”–the 12 most contaminated foods: peaches, apples, sweet bell peppers, celery, nectarines, strawberries, cherries, pears, imported grapes, spinach, lettuce, and potatoes.
Perfluorinated chemicals, or PFCs, are compounds used to manufacture fabrics, carpets, paper coatings, cosmetics and a variety of other products. Avoid them by using natural fiber curtains and carpeting. Don’t get stain-protection or fire retardant treatment on furniture or clothes. Avoid using non-stick pans–once the coating starts breaking down, it can emit PFCs. And avoid microwaved popcorn. The inside of a microwave popcorn bag is usually coated with a PFC to prevent oil from seeping through the bag. It can migrate into the food when heated.
Bisphenol A is easier to avoid now than it used to be. It is used in plastics, as resins for coating food cans, and as dental sealants. It interferes with T3 activation of the thyroid hormone b-receptor in rats, causing a thyroid hormone resistance–like syndrome. Use only bisphenol A-free plastics and cans, or avoid using plastic containers to heat food, as water bottles. Choose plastics with the recycling code 1, 2 or 5. Recycling codes 3 and 7 are more likely to contain bisphenol A or phthalates, another endocrine disruptor.
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Goldner WS, Sandler DP, Yu F, et al. Pesticide use and thyroid disease among women in the Agricultural Health Study. Am J Epidemiol. 2010 Feb 15;171(4):455-64.
Li-Li Wen, Lian-Yu Lin, Ta-Chen Su, et. al. Association between Serum Perfluorinated Chemicals and Thyroid Function in U.S. Adults: the National Health and Nutrition Examination Survey 2007-2010. J Clin Endocrin Metab.
Miller MD, Crofton KM, Rice DC et al. Thyroid-Disrupting Chemicals: Interpreting Upstream Biomarkers of Adverse Outcomes. Environ Health Perspect. 2009 Jul;117(7):1033-41.