Environmental Toxins and their Role in Thyroid Diseases

Mindd Foundation

Thyroid diseases - toxins

Thyroid diseases are more common than you may believe and affect millions of people worldwide. Recently, thyroid diseases have been increasing, and this has motivated researchers to investigate the cause. They found that several environmental toxins are at least contributing to thyroid diseases and should be avoided to protect thyroid health.

This guide outlines the information most crucial to maintaining thyroid health and minimizing environmental toxin exposure including:

  • Why the thyroid is at risk for damage
  • How different environmental toxins affect the thyroid
  • Thyroid diseases induced by environmental toxins
  • Nine steps that protect the thyroid from environmental damage

Why the Thyroid Is at Risk of Damage

The thyroid gland is located at the base of the neck overlying the trachea (windpipe) and plays a vital role in the endocrine system. Despite its small size, the thyroid is one of the largest endocrine glands.

Following stimulation by thyroid-stimulating hormone (TSH) produced by the pituitary gland, the thyroid releases the hormone, thyroxine (T4), which must be converted by the liver into an active form called triiodothyronine (T3). T3 assists in regulating cardiovascular and neurological function along with supporting immunity, metabolism, and energy levels.

It is not so much the size of the thyroid that makes it susceptible to damage; it’s the structures of the hormones it produces. The thyroid requires iodine and selenium to produce its hormones, and these elements are chemically attracted to the structure of thyroid hormones (T3 or T4).  This chemical attraction is referred to as “affinity,” and it can also occur between other substances and thyroid hormones. Thus, many environmental toxins with structures similar to thyroid hormones are mistaken for iodine and selenium and accumulate in the thyroid gland.

How Different Environmental Toxins Affect the Thyroid

Environmental toxins that mirror thyroid hormone structure and invade the thyroid gland can be categorized as:

  • Heavy metals
  • Household toxins
  • Industrial chemicals and
  • Agricultural agents

Heavy Metals

While heavy metals are abundant in the environment, four specific heavy metals damage the thyroid the most. Those heavy metals are aluminum, cadmium, lead, and mercury.

Commonly found in toiletries like deodorant, over-the-counter medications like antacids, food additives, cookware, and vaccines, aluminum oxidizes the thyroid, inhibits iodide uptake, limits thyroid hormone production, and can mislead the immune system to attack the thyroid, as seen in autoimmune disease.

Cadmium is released via mining and smelting activities and is present in batteries, pigments, plastics, sewage, and phosphate-based fertilizers. Cadmium triggers thyroid enlargement, produces multinodular goiters of the thyroid, reduces thyroglobulin secretion, and can induce thyroid cancer.

One of the earliest heavy metals recognized for its toxicity, Lead remains high in the environment thanks to its use in the paint used in old housing, some metal jewelry, children’s toys, mining, and other forms of industrialization. Lead exposure in work environments alone has been linked to reduced thyroid function and increased levels of thyroid-stimulating hormone (TSH). Mercury, found in seafood, dental amalgams, and pollution produced by coal-burning power plants, lowers iodide uptake in the thyroid and prevents thyroid hormone production.

Household Toxins

Polybrominated diphenyl ethers (PBDEs), more commonly referred to as flame retardants, populate many areas of the modern-day home such as furniture, carpet padding, clothing made of synthetic materials, and the screens of electronic devices. PBDEs imitate thyroid hormone structure allowing PBDEs to bind to a particular class of proteins called transporters that T4 usually binds to, thereby blocking T4 from being transported in the blood. This activity disturbs estrogen function making postmenopausal women especially vulnerable to PBDEs.

Bisphenol A (BPA) and phthalates, ingredients used to make plastic for water bottles, children’s toys, and food storage containers, imitate the structures of other hormones found naturally in the body and disrupt the entire endocrine system along with the thyroid.BPA changes the structure of the thyroid gland and inhibits T3 from binding to another class of proteins called receptors which T3 uses to produce changes in the body while phthalates also inhibit T3 from binding to its receptors. Thyroid function is also diminished by triclosan, an antibacterial agent found in some liquid hand soaps, and perfluorooctanoic acid, or PFOA, an agent used in stain-resistant fabrics, food wrappers, and non-stick cookware.

Industrial Chemicals

The most prevalent industrial chemicals are dioxin, perchlorate, perfluorinated chemicals, or PFCs, and polychlorinated biphenyls, or PCBs. All four of these pollutants negatively affect thyroid function. Dioxin, a byproduct of pesticide production, plastic making, and other manufacturing processes, reduces thyroid function by mimicking thyroid hormone structure and decreasing T4 levels. These effects arise even at standard dioxin levels; that is, low levels of dioxin that exist in the environment, yet are considered unavoidable.

Small concentrations of perchlorate arise naturally in the soil of arid regions, but the high levels polluting the environment come from applications involving the development of airbags, batteries, fireworks, leather, paint, jet/rocket fuel, and rubber. From there, perchlorate seeps into surface water, groundwater, drinking water, soil, and ultimately food grown in the ground. Once in the body, perchlorate lowers T4 levels, competes with iodide for uptake into the thyroid gland, and reduces thyroid hormone production. Even low levels of perchlorate toxicity can produce these effects yet consuming more iodine may protect the thyroid from perchlorate.

The use of PFCs has been on the decline, however, from mattresses and detergents to food packaging and fire extinguishers, many imported goods still contain PFCs. PFCs disrupt overall thyroid function by either increasing thyroid hormone production to dangerously high levels or decreasing thyroid hormone production to dangerously low levels. These effects appear to depend on gender, as women with PFC toxicity tend to develop hyperthyroidism while men with PFC toxicity tend to develop hypothyroidism.

For their ability to resist pressure and temperature, PCBs are widely used as lubricants, in electrical equipment, and for adhesive, paint, or plastic production.

PCBs disturb thyroid function by:

  1. reducing the number of receptors available for T3 to bind to
  2. decreasing the amount of T4 circulating in the bloodstream (T4 is needed for conversion into T3), and
  3. preventing liver enzymes from converting T4 into T3.

Other studies have found that PCBs enlarge the thyroid and can increase TSH levels to the point of making the body resistant to thyroid hormones. Again, PCBs achieve these effects by copying the structure of thyroid hormones.

Agricultural Agents

Perhaps the first culprits to come to mind in discussions of environmental toxins; pesticides, herbicides, and fungicides weaken thyroid function to the point of causing hypothyroidism or “low thyroid.” Hypothyroidism induced by agricultural agents is typically seen in women overexposed to pesticides containing organochlorine, paraquat herbicide, benomyl fungicide, or maneb/mancozeb fungicide. Men with hypothyroidism induced by agricultural agents are usually overexposed to organophosphates, carbamates, or other pesticides. Agricultural agents wreck thyroid function by altering thyroid hormone gene expression, preventing the uptake of iodine into the thyroid, blocking thyroid hormone from binding to its transport proteins, lowering the absorption of thyroid hormone into thyroid cells, and promoting thyroid hormone removal from the body.

Thyroid Diseases Induced by Environmental Toxins

Among all heavy metal toxins, chronic toxicity with aluminum, lead, and mercury can further damage the thyroid by recruiting antibodies to attack the thyroid. This process contributes to the development of autoimmune thyroid diseases (AITD), such as Graves’ disease and Hashimoto’s thyroiditis. Research has yet to determine the physiological mechanisms by which AITD manifests; however, two causes have been identified—environmental toxicity and genetic predisposition.

Because the production of antibodies against the thyroid does not always escalate into AITD, AITD arises in approximately only 5% of individuals and those individuals are more often women. Studies explain the reason for this is that females’ immune systems are more reactive than males’ even in other species. This evolutionary feature helps females fight off disease more effectively, most likely to ensure reproduction for healthy population growth. However, in humans, this places the woman’s thyroid at even greater risk of AITD. Men are not entirely excluded from AITH with their less reactive immune systems though, as scientists have found that contracting any of the following viruses enhances the incidence of Thyroid Diseases:

  • Acquired Immunodeficiency Syndrome (AIDS)
  • Enterovirus
  • Epstein-Barr Virus
  • Hepatitis C (HCV)
  • Herpes Simplex Virus
  • Human Immunodeficiency Virus (HIV)
  • Human Parvovirus B19 (EVB19)
  • Human T-cell Lymphotropic Virus-1
  • Mumps
  • Rubella

The Most Common Thyroid Diseases

Hashimoto Thyroiditis, a relative to chronic fatigue syndrome and fibromyalgia, affects mostly women and tops the list of conditions responsible for low thyroid (hypothyroidism). Hashimoto’s is so common that 97% of individuals taking thyroid medication are believed to have the disease but are not diagnosed. People with Hashimoto’s often express feeling like they are getting older because they experience symptoms such as anxiety, brain fog, cold intolerance, depression, fatigue, heart palpitations, hair loss, loose bowels, and an inability to lose weight. All these symptoms indicate a dysfunctional thyroid.

Graves’ Disease is the most common cause of overactive thyroid (hyperthyroidism) and also typically arises in women under 40 years of age. This AITD presents symptoms similar to Hashimoto’s with some exceptions: a fine tremor of the hands or fingers, heat sensitivity, weight loss, bulging eyes, thyroid enlargement, reduced libido, erectile dysfunction (in men), and menstrual cycles changes (in women). Graves’ disease may also produce a thick, red patch of skin on the anterior portion of the leg or dorsum (top) of the foot referred to as Graves’ dermopathy.

Whether general AITD or a more specific form (Hashimoto Thyroiditis or Graves’ Disease), AITD is most effectively diagnosed with a thyroid antibody test. Given the high prevalence of undiagnosed thyroid diseases, researchers now deem normal TSH ranges as unreliable because undiagnosed individuals were most likely studied to determine those ranges. Thyroid antibody tests can disclose the presence of anti-thyroid antibodies as much as ten years before TSH levels test as abnormal. While medical professionals do not characteristically perform thyroid antibody tests, patients can request them thereby giving themselves the best chance to prevent Graves’ disease and Hashimoto’s Thyroiditis.

Thyroid disease - seaweed salad9 Steps that Protect the Thyroid from Environmental Damage

Given the widespread presence of thyroid-damaging toxins in the environment, prevention should center on strengthening the thyroid along with avoiding environmental toxins as much as possible. The following are some recommended ways for doing this:

  1. Convert to all-natural toiletries and beauty products free of heavy metals
  2. Avoid using hand soaps and other cleaning agents with anti-bacterial properties
  3. Limit use of plastic containers for drinking and food storage or at least opt for BPA-free varieties (realize that  they may still contain other bisphenol derivatives)
  4. Invest in a quality, reverse-osmosis water filter for water used for consumption and bathing
  5. Consume foods rich in iodine and selenium like seaweed, pastured dairy products, brazil nuts (organic) and fish (avoid farmed fish and opt for white or oily fish that have a short lifespan to avoid build-up of heavy metals like mercury), or take a supplement
  6. For other foods, eat organic varieties as often as possible to avoid toxic agricultural agents
  7. Replace non-stick cookware items with stainless steel or enameled cast iron options
  8. Stop using pesticides, herbicides, and fungicides (or fertilizers that contain them) in the yard and garden
  9. Make all living and working environments as serene as possible to reduce stress and support hormonal balance within the endocrine system

No matter an individual’s gender or genetics, maintaining a healthy, toxin-free environment both externally and internally is the best way to support thyroid health and avoid autoimmune thyroid disease. Pay close attention to changes in energy, weight, and sleep and schedule a thyroid antibody test with an Integrative Health Practitioner today.

References

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Brent, G. A. (2010). Environmental exposures and autoimmune thyroid disease. Thyroid, 20(7): 755-761. https://doi.org/10.1089/thy.2010.1636

Cole, W. (2014, January). 11 everyday toxins that are harming your thyroid. Retrieved from MBG at https://www.mindbodygreen.com/0-12346/11-everyday-toxins-that-are-harming-your-thyroid.html

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Kresser, C. (2017, September). How environmental toxins harm the thyroid. Retrieved from Kresser Institute at https://kresserinstitute.com/environmental-toxins-harm-thyroid/

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