Mercury Exposure and Hashimoto’s Thyroiditis

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Lately, there has been a lot of talk about the potential health issues of mercury and how to avoid them.

It seems that this heavy metal is able to endanger our health in more ways than we are aware of.

One question has especially caught our attention: Can mercury exposure endanger our thyroid health by causing Hashimoto’s thyroiditis?

What is mercury poisoning?

Mercury is a naturally occurring metal commonly found in our environment, including many of the products that we use on a daily basis. However, mercury is only present in small amounts – amounts that are generally considered safe. On the other hand, a mercury build-up is suggested to be highly dangerous and even potentially life-threatening.

At room temperature, mercury is found in a liquid form, often occurring as a product of various industrial processes that are happening in the environment. Mercury can easily and rapidly vaporize in the air. In this form, mercury can travel in the soil, rain, and water, which poses a potential risk for the surrounding plants, animals, and even humans.

Mercury poisoning refers to toxicity that has occurred due to mercury consumption. According to the WHO (World Health Organization), mercury is considered to be one of the top ten toxic chemicals that pose a major public health concern.

Causes of mercury poisoning

There are many causes in which mercury poisoning can take place. The most common cause is consuming too much mercury from eating seafood. In fact, it is in seafood that we find the most poisonous form of mercury called methylmercury. This is the metal that mercury forms once it gets dissolved in water. From the water, sea creatures proceed to absorb it, which is how it reaches us, humans, once we consume seafood.

Another cause for mercury poisoning is through dental fillings or amalgam fillings to be more specific. These dental fillings contain up to 40-50% of mercury. Although the amalgam fillings are rarely being used nowadays, people who have had these fillings in the past and still have them may be exposed to the risk of mercury poisoning.

Mercury poisoning can also occur due to environmental exposure. The best example is artisanal gold mining, which is responsible for around 30% of the world’s mercury emissions. About 10 to 25% of the total gold supply worldwide comes from artisanal gold mining. Research suggests that around 4.6 million women and over 600,000 children are among the 10-15 million artisanal gold miners worldwide who have been in direct contact with toxic mercury, thus being exposed to mercury poisoning and all of the health concerns that come with it.

Other causes for mercury poisoning including broken fever thermometers, using skincare products with added mercury, certain types of jewelry, etc.

The symptoms of mercury poisoning

We need to distinguish a difference between acute and chronic mercury poisoning. Acute mercury poisoning causes a sudden onset of symptoms, whereas chronic mercury poisoning happens over time, as more and more mercury builds-up, which is a more common case.

Characteristic neurological symptoms are caused by mercury poisoning. According to the FDA (U.S. Food and Drug Administration), the following neurological symptoms are expected to happen due to mercury poisoning.

  • Anxiety;
  • Depression;
  • Tremors;
  • Irritability;
  • Memory problems;
  • Numbness, etc.[i]

In adults, severe mercury poisoning often causes more specific symptoms such as:

  • Vision changes;
  • Poor coordination;
  • “Pins and needles” sensations;
  • Excessive shyness;
  • Insomnia;
  • Poor balance;
  • Metallic taste in the mouth;
  • Headaches;
  • Hearing and/or speaking difficulties;
  • Muscle weakness etc.

Health risks of mercury exposure

Exposure to high levels of mercury can not only lead to temporary neurological symptoms, but also permanent neurological changes as well. Often, brain and kidney damage happens due to mercury poisoning. A study published in the Journal of Preventive Medicine and Public Health revealed that mercury poisoning could lead to long-term nerve damage. This, in return, can cause multiple health concerns, including paralysis, numbness, damaged motor skills, low I.Q., and even symptoms of ADHD.[ii]

Mercury poisoning is especially dangerous for children. It has been established that when exposed to mercury, children, even when they are fetuses inside their mother’s womb, can experience a disrupted neurological development. Mercury exposure can easily lead to delays in:

  • Speech;
  • Language development;
  • Fine motor skills;
  • Cognition, etc.

What is Hashimoto’s thyroiditis?

Hashimoto’s thyroiditis, also referred to as Hashimoto’s disease, is an autoimmune disease in which the body attacks its own thyroid gland. White blood cells and antibodies are produced which mistakenly attack the cells of the thyroid gland, thus causing the characteristic symptoms of this common disease. It has been estimated that Hashimoto’s thyroiditis affects 1 to 2% of the general population in the United States alone.[iii]

The exact causes of Hashimoto’s thyroiditis are still unknown. However, over the years, there have been certain risk factors determined to have some influence on the development of Hashimoto’s thyroiditis. Although this disease affects both genders, it is clear that being a female is a major risk factor for Hashimoto’s thyroiditis, since it affects women seven times more commonly as compared to men. The risk is especially high among pregnant women.

Other risk factors including having a family history of Hashimoto’s thyroiditis or any other thyroid issue, as well as having a personal medical history that includes type 1 diabetes, Graves’ disease, Addison’s disease, lupus, etc.

Recognizing the symptoms of Hashimoto’s thyroiditis

Hashimoto’s thyroiditis causes the characteristic symptoms of an underactive thyroid or hypothyroidism. Hypothyroidism is a condition in which the thyroid gland does not produce enough of the needed thyroid hormones – thyroxine and triiodothyronine.

can go by before any symptoms occur, meaning that it can take some time before noticeable thyroid damage is being caused and symptoms are being experienced. In the following, we will list the most commonly reported symptoms caused by hypothyroidism, and with that by Hashimoto’s thyroiditis as well. We hope that knowing the symptoms can help you recognize them and ask for help in time.

  • Dry skin;
  • Constipation;
  • Depression;
  • Hoarse voice;
  • Fatigue;
  • Thinning hair;
  • Irregular or heavy periods;
  • Infertility;
  • Goiter;
  • Cold intolerance;
  • Unexplained weight gain, etc.

Luckily, in most cases of Hashimoto’s thyroiditis, great success is made in terms of eliminating the symptoms and stimulating the thyroid gland. Thanks to the use of levothyroxine, which is a synthetical, man-made form of thyroxine, the patient can introduce this synthetical form of thyroxine to its body, thus eliminating the symptoms and living a healthy life. Additional lifestyle changes may be required as well, according to the patient’s overall health status, age, gender, etc.

The link between mercury exposure and Hashimoto’s thyroiditis

Yet another health concern when it comes to mercury exposure is its link to multiple autoimmune diseases, including Hashimoto’s thyroiditis, Graves’ disease, lupus, rheumatoid arthritis, Sjogren’s syndrome, and many more. Yes, you read that right – mercury exposure does serve as a trigger for Hashimoto’s thyroiditis while causing additional health issues.

Although more research needs to be done in order to clear out the link between mercury exposure and autoimmune diseases, there are three theories that we need to discuss.

The first one – mercury is considered to either alter or damage the cells of various tissues and body organs. By doing that, the body’s immune system recognizes the altered or damaged cells as foreign ones and attacks them, thus leading to an autoimmune disease. Depending on which cells and tissues are being attacks, different autoimmune diseases occur, including Hashimoto’s thyroiditis in the case where the cells of the thyroid gland have been attacked.

Moving to the second theory. It has been suggested that heavy metals, such as mercury, stimulate the immune system, adding a high amount of stress to it. Over time, the stressed-out immune system is no longer able to function properly and becomes unable to make a difference between the body’s one tissues and the foreign invaders. Eventually, it starts attacking the body’s tissues, thus causing an autoimmune disease to take place. And as expected – if it is the tissues of the thyroid gland that are being attacked by the immune system, Hashimoto’s thyroiditis is expected to develop.[iv]

And the third and last theory that we have is a bit more complex and refers to how the immune system cells are being educated. The T cells are responsible for the various immune system responses. After they have been produced in the bone marrow and transported to the thymus, they begin to distinguish the difference between the body’s own tissues and the foreign invaders. Some of these T cells procced to be educated to become the so-called regulatory T cells, making sure that the rest of the T cells are doing their job right. However, when toxins and metals, such as mercury, are building up in the body, they can shrink the thymus, thus preventing it from producing enough regulatory T cells. And since there is nothing to regulate the rest of the T cells and their work, it is easier for them to start mistakenly attack the body’s own tissues instead of the foreign invaders. As expected, an autoimmune disease such as Hashimoto’s thyroiditis is highly possible to happen.

Another reason why mercury exposure is being linked to thyroid issues such as Hashimoto’s thyroiditis and Graves’ disease is because of how similar mercury and iodine look alike. Your thyroid gland needs iodine in order to produce its thyroid hormones. But because mercury and iodine are so chemically similar to each other, it is easy for your thyroid to absorb mercury instead of iodine. By doing so, the thyroid gland will no longer have enough place to store iodine, thus being unable to produce enough thyroid hormones, which leads to hypothyroidism.[v] On the other hand, by absorbing and storing iodine, an autoimmune disease can easily happen due to the theories that we discussed before.

How to protect yourself against mercury exposure

In the following, we will list some much-helpful tips and tricks that are meant to help you protect yourself and your close ones from any mercury exposure. Please implement these tips as much as possible as a part of your everyday life.

  • Wash your hands right away if you think you have been exposed to any form of mercury
  • Get tested for any mercury poisoning before conceiving by getting a blood or urine test for mercury done
  • Be careful what Shushi are you choosing since many sushis are made by using mercury-contaminated fish
  • Avoid fish that contain high levels of mercury during pregnancy, including sushi
  • Consult your doctor about getting any amalgam dental fillings removed
  • Eat lots of low-range methylmercury fish such as shrimp, oysters, sardines, crawfish, etc. but be careful how much high-range methylmercury fish such as shark, tilefish, and swordfish you are eating, etc.[vi]


As you can see, there are many risks and health concerns to come with even the slightest exposure to a dangerous heavy metal such as mercury. The neurological symptoms that it causes threaten to become permanent, even causing developmental issues and distributions within young children.

One of the great risks that mercury exposure carries is the risk of Hashimoto’s thyroiditis, among other serious thyroid issues. When it comes to mercury exposure, the key is prevention, and we can only hope that the prevention tips that we mentioned as a part of today’s article will find their place in your everyday life, helping to preserve your life and health.


[i] Commissioner, Office of the. “Mercury Poisoning Linked to Skin Products.” U.S. Food and Drug Administration, FDA
Retrieved from

[ii] Hong, Young-Seoub, et al. “Methylmercury Exposure and Health Effects.” Journal of Preventive Medicine & Public Health, vol. 45, no. 6, 2012, pp. 353–363., doi:10.3961/jpmph.2012.45.6.353.
Retrieved from

[iii] “Hashimoto Thyroiditis – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health
Retrieved from

[iv] Pollard, K. Michael, et al. “Mercury-Induced Inflammation and Autoimmunity.” Biochimica Et Biophysica Acta (BBA) – General Subjects, vol. 1863, no. 12, 2019, p. 129299., doi:10.1016/j.bbagen.2019.02.001.
Retrieved from

[v] Duntas, Leonidas H. “Environmental Factors, and Autoimmune Thyroiditis.” Nature Clinical Practice Endocrinology & Metabolism, vol. 4, no. 8, Aug. 2008, pp. 454–460., doi:10.1038/ncpendmet0896.
Retrieved from

[vi] Layton, Julia. “What Are the Dangers of Mercury Exposure?” HowStuffWorks, HowStuffWorks, 14 Apr. 2010
Retrieved from

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