Why Thyroid Health Matters
Every cell in your body depends on your thyroid gland to function properly. Specifically, your cells use the hormones produced by your thyroid to regulate a range of metabolic processes, including getting energy from the food you eat.
Your thyroid hormones also help regulate your body temperature and play a role in the proper functioning of your brain, heart, muscles and other organs. When working properly, your pituitary gland will release thyroid-stimulating hormone (TSH), triggering your thyroid to produce the thyroid hormone thyroxine (T4), which is then converted into triiodothyronine (T3) – all of this in the precise amount the body needs to thrive.
This very delicate system is easily disrupted by outside influences, including the ubiquitous chemicals in our environment. These chemicals are being increasingly linked to disruptions of the thyroid, and these disruptions can seriously impact your health.
What Types of Chemicals Can Disrupt Your Thyroid?
There are concerns regarding numerous chemicals currently abundant in the environment. According to research from Current Opinion in Endocrinology, Diabetes and Obesity:
“A large variety of ubiquitous chemicals have been shown to have thyroid-disrupting properties, and the combination of mechanistic, epidemiological and exposure studies indicates that the ubiquitous human and environmental exposure to industrial chemicals may impose a serious threat to human and wildlife thyroid homeostasis.”
Among these chemicals, nine primary offenders have been identified.
Phthalates are widely used chemicals often used to make plastic more flexible. They’re commonly found in shower curtains, medical tubing, and plastic toys, as well as in numerous personal care products, such as fragrances, nail polish, and lotions. Because the chemicals are so widely used, they can also be present in drinking water.
Known to cause reproductive and developmental toxicity in animal studies, phthalates can also decrease thyroid hormone receptor activity, even at levels found in drinking water. Currently, drinking water treatments do not effectively remove thyroid-disrupting chemicals like phthalates from water supplies.
- Flame Retardants
Polybrominated diphenyl ether (PBDE) are flame retardant chemicals commonly used in furniture foam, carpets, upholstery, clothing, toys, draperies, electronics and more. It’s estimated that up to 97 percent of Americans have PBDEs in their blood.
These chemicals easily accumulate in your fat cells, and increased levels have been linked to a decrease in TSH and an increased risk of subclinical hyperthyroidism in pregnant women.
- Bisphenol A (BPA)
BPA is another plastics chemical commonly used in polycarbonate water bottles, baby bottles, plastic toys, medical tubing, food packaging, dental sealants, and more. Widely known as an endocrine disrupter that can cause developmental problems, early puberty, genital deformities, and more, BPA has also been linked to thyroid disruption.
In one study of frog tadpoles, low levels of BPA exposure — similar to those found in human infants — interfered with the T3 hormone and thereby suppressed genes controlled by T3, resulting in slowed development and other changes. Previous animal studies have also linked BPA to disruptions in thyroid receptors and thyroid function.
Dioxin is a group of chemicals — including polychlorinated biphenyls (PCBs), polychlorinated dibenzo dioxins (PCDDs), and polychlorinated dibenzo furans (PCDFs) — that are formed as byproducts from industrial processes like chlorine paper bleaching, pesticide manufacturing, and smelting. Dioxin was also a part of the toxic “Agent Orange” used during the Vietnam War.
PCBs, another type of dioxin, were widely used prior to 1977, when they were banned due to environmental concerns. However, they and other dioxins still exist in abundance in the environment, including in your food (especially meat, dairy, and seafood).
Not only is dioxin a known carcinogen, but it has also been found to interfere with the production, transportation, and metabolism of thyroid hormones.
- Perfluorinated Chemicals (PFOA)
PFOA and a related chemical called PFOS (perfluorooctane sulfonate) — commonly used in nonstick cookware, stain-resistant materials, and food packaging — can also cause trouble with your thyroid.
One study found that people with high levels of PFOA in their blood were twice as likely to have thyroid problems as those with the lowest levels, while past studies have linked the chemical to decreased thyroid hormone levels. It’s not known how PFOA may cause thyroid disease, or whether the chemical directly impacts the thyroid or the immune system, causing it to attack the thyroid gland.
Most municipal drinking water supplies in the United States contain added fluoride, a measure that’s intended to reduce rates of tooth decay. It can also enter water supplies from fluoride-rich rocks and soils.
Studies have shown that exposure to fluoride can result in decreased thyroid function, including at exposure levels of 4 mg/L or less, which is the EPA maximum allowable concentration for fluoride in drinking water. The effects may be especially problematic for children and people who drink a lot of water.
Perchlorate is a byproduct of rocket fuel production that is now a widespread contaminant in drinking water, certain fruits and vegetables, and dairy products from cows that have eaten contaminated grasses.
Research suggests this chemical can inhibit your thyroid’s ability to absorb iodine, leading to an underactive thyroid, or hypothyroidism, even at low-level exposure. In a study by the Centers for Disease Control and Prevention, it was estimated that 44 million U.S. women — including those who are pregnant, have lower iodine levels, or have subclinical hypothyroidism — could be at increased risk of thyroid problems from perchlorate exposure.
Thiocyanate is a chemical found in cigarettes and certain foods. It may inhibit iodine uptake by the thyroid, leading to decreased production of thyroid hormone.
Thyroid disease has also been linked to pesticide exposure from a variety of sources. Among women whose spouses were licensed pesticide applicators using organochlorine insecticides, rates of hypothyroidism were 1.2 times higher than in the general population. Increased rates of thyroid disease were also found among women exposed to fungus killers, herb killers, and other types of pesticides.
How to Reduce Your Exposure to Thyroid-Disrupting Chemicals
Chemicals are inescapable in our environment, but there are steps you can take to help cut back your exposure.
- Use natural personal care products with ingredients you are familiar with. At the very least, look for phthalate-free options.
- Buy children’s toys and products made of natural materials, or at least phthalate- and BPA-free plastics.
- Avoid exposure to old carpeting, carpet pads, and polyurethane foam products (upholstered furniture, mattresses, pillows) manufactured prior to 2005 (these are most likely to contain PBDEs).
- Store your food and beverages in glass or ceramic containers instead of plastic, and do not reheat foods in plastic containers or covered in plastic wrap.
- Limit your use of canned goods and soda cans (the linings often include BPA), or look for BPA-free canned items.
- Trim the fat from your meats to cut back on dioxins stored in animal fats, and choose leaner cuts of meat.
- Avoid polyvinyl chloride (PVC) plastics, such as plastic milk jugs.
- Look for unbleached versions of household products like coffee filters, tampons, diapers, paper towels, etc.
- Avoid using non-stick cookware and choose stainless steel, ceramic, or other inert materials instead.
- Install a reverse osmosis water filtration system in your home to remove fluoride from your drinking water, and consider a comprehensive filter to remove other chemicals like perchlorate.
- Avoid smoking cigarettes and exposure to secondhand smoke.
- Choose organic foods whenever possible to limit your exposure to pesticides. Also, do not use the chemicals around your home (including chemical lice treatments and flea and tick products for pets).
Between evidence increasingly showing that exposure to environmental chemicals – even at very low levels – can negatively impact your thyroid and knowing that even small changes in your thyroid homeostasis can influence your overall health, it’s important to reduce exposure as much as possible.
By making small changes in your food choices and personal care products and paying special attention to finding household goods made primarily from natural sources, you’ll be off to a great start in protecting your thyroid function from these pervasive toxins.
2Environmental Science and Technology 2010, 44 (17), pp 6863–6868
310 Common Sources of Endocrine Disruptors and How to Avoid Them
4Endocrinology Vol. 150, No. 6 2964-2973
5Alternative Medicine Review 2009 Dec;14(4):326-46.
6Environmental Health Perspectives 118(5) May 2010
7Committee on Fluoride in Drinking Water, National Research Council, Fluoride in Drinking Water: A Scientific Review of EPA’s Standards, 2006
8Environmental Working Group News Release October 4, 2006
9American Journal of Epidemiology (2010) 171 (4): 455-464.