Fluoride and the Thyroid: The Controversy
Fluoride and Fluoridated Water's Link to Thyroid Disease
By Mary Shomon
Updated June 03, 2014
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
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Water fluoridation is defined as the addition of industrial-grade
fluoride chemicals -- typically hydrofluorosilicic acid or and sodium
silicofluoride -- to the water supply, with the goal of helping prevent
tooth decay. It's estimated that 70% of the water supply in the United
States is fluoridated. This contrasts with most developed nations,
including all of Japan and most of western Europe, which do not have
fluoridation programs.
The fluoridation of local water supplies in the United States has become an increasingly contentious public issue
in some areas, with vigorous debates taking place in communities that
are considering fluoridation, and in some cases, activists attempting to
overturn existing fluoridation programs.
On one side of the issue are pro-fluoridation scientists -- along with dental professionals and public health officials - who insist that fluoridation of a water supply is generally safe. Their position is that water fluoridation -- along with the use of fluoride toothpastes and mouthrinses -- can significantly reduce the prevalence of cavities. (1) According to the American Dental Association (ADA), water fluoridation reduces tooth decay by 20 to 40 percent. Fluoridation proponents claim that the only significant negative consequence of fluoridation is the risk of dental fluorosis, a discoloration of tooth enamel that occurs with higher rates of exposure to fluoride, and is not a health risk, only a cosmetic issue.
Dental fluorosis is estimated to affect somewhat less than one-fourth of the population aged 6 to 49. (3) The linkage between fluoride levels and fluorosis were studied, to determine what levels of fluoride exposure would minimize or eliminate this side effect. In 2006, a National Research Council committee of 12 members unanimously recommended that the maximum level of 4 mg/L fluoride concentration in water supplies be lowered. Subsequently, the World Health Organization established a guideline of a maximum concentration level of 1.5 mg/L of fluoride in drinking water as a way to avoid fluorosis. (4)
Opponents of fluoride claim that fluoride's benefits are outweighed by a list of health risks that go beyond fluorosis. They claim that fluoride's cavity-fighting benefits are questionable, that the research is inconclusive (or even compromised by dental industry influence). The opponents also claim that cavity-fighting results from topical exposure, and that ingestion of fluoride is not necessary. They claim that excess exposure cannot be avoided when fluoride is in the water supply, and that this exposure over time allows fluoride to accumulate in the body, where it may damage the brain, lower IQ, have neurotoxic effects, and damage bone, among many other health effects. (5)
One of the most controversial issues is the impact of fluoride on the thyroid gland. Many people are not aware that in the first half of the 20th century, fluoride was used medically as an anti-thyroid drug, to slow down the thyroid function in hyperthyroid patients. Fluoride was found to be effective at suppressing or reducing thyroid function, according to research, and the dose needed to reduce thyroid function was low -- 2 to 5 mg per day over a period of months. (6)
Opponents of water fluoridation are concerned that the levels of fluoride used to treat an overactive thyroid are in the same range of exposure (1.6 to 6.6 mg/day) that is estimated in people living in communities with fluoridated water supplies.
While a number of studies have not found any link between fluoride and thyroid disease, other studies (7) have found that fluoride can cause alterations in the thyroid, including
In the meantime, what should thyroid patients do?
As a start, you can stay informed. For pro-fluoride information, a good starting point is the American Dental Association's Fluoride and Fluoridation page. One of the best sources of information regarding the opposition to fluoridation is the Fluoride Action Alert, led by Dr. Paul Connett.
Certainly, thyroid patients have the option to follow the ADA and Centers for Disease Control (CDC) recommendations, and continue to consume fluoridated water, and use fluoridated dental products.
At minimum, however, it's important to be aware of the CDC's warning against overuse of infant formula that is reconstituted with fluoridated water. According to the CDC, if that is a child's sole source of nutrition, "there may be an increased chance for mild dental fluorosis. To lessen this chance, parents can use low-fluoride bottled water some of the time to mix infant formula; these bottled waters are labeled as de-ionized, purified, demineralized, or distilled." (8)
You also may want to determine how much fluoride is in your water supply. A handy link to the CDC database, Fluoride Finder, can help you determine fluoride levels in your county.
For those who feel that the concerns raised by opponents are valid, Richard Shames, MD, author of a number of books on thyroid disease, and a Harvard-trained integrative physician, has said:
(1) Petersen, P. et. al., "Effective use of fluorides for the prevention of dental caries in the 21st century: the WHO approach," Community Dentistry and Oral Epidemiology, Volume 32, Issue 5, pages 319-321, October 2004, Abstract
(2) American Dental Association, "Flouride & Fluoridation," Fact Sheet, www.ada.org
(3) Beltrán-Aguilar, E. et. al."Prevalence and Severity of Dental Fluorosis in the United States, 1999-2004," NCHS Data Brief, Number 53, November 2010, Online
(4) Fagin D,"Second thoughts about fluoride". Scientific American 298 (1): 74-81. January 2008
(5) Connett, Paul, "50 Reasons to Oppose Fluoridation, September 2012," Fluoride Action Network, Online
(6) Galletti P, et. al. 1958. "Effect of fluorine on thyroidal iodine metabolism in hyperthyroidism. Journal of Clinical Endocrinology," 18(10):1102-1110. 1958
(7) Susheela AK, et al. "Excess fluoride ingestion and thyroid hormone derangements in children living in New Delhi, India." Fluoride, 38:98-108. 2005. National Research Council. "Fluoride in drinking water: a scientific review of EPA's standards." National Academies Press, Washington D.C. 2006.
(8) "Overview: Infant Formula and Fluorosis," Centers for Disease Control and Prevention, Online
(9) Shames, Richard, MD. "Why We Changed Our Minds About Water Fluoridation," About.com Online.
On one side of the issue are pro-fluoridation scientists -- along with dental professionals and public health officials - who insist that fluoridation of a water supply is generally safe. Their position is that water fluoridation -- along with the use of fluoride toothpastes and mouthrinses -- can significantly reduce the prevalence of cavities. (1) According to the American Dental Association (ADA), water fluoridation reduces tooth decay by 20 to 40 percent. Fluoridation proponents claim that the only significant negative consequence of fluoridation is the risk of dental fluorosis, a discoloration of tooth enamel that occurs with higher rates of exposure to fluoride, and is not a health risk, only a cosmetic issue.
Dental fluorosis is estimated to affect somewhat less than one-fourth of the population aged 6 to 49. (3) The linkage between fluoride levels and fluorosis were studied, to determine what levels of fluoride exposure would minimize or eliminate this side effect. In 2006, a National Research Council committee of 12 members unanimously recommended that the maximum level of 4 mg/L fluoride concentration in water supplies be lowered. Subsequently, the World Health Organization established a guideline of a maximum concentration level of 1.5 mg/L of fluoride in drinking water as a way to avoid fluorosis. (4)
Opponents of fluoride claim that fluoride's benefits are outweighed by a list of health risks that go beyond fluorosis. They claim that fluoride's cavity-fighting benefits are questionable, that the research is inconclusive (or even compromised by dental industry influence). The opponents also claim that cavity-fighting results from topical exposure, and that ingestion of fluoride is not necessary. They claim that excess exposure cannot be avoided when fluoride is in the water supply, and that this exposure over time allows fluoride to accumulate in the body, where it may damage the brain, lower IQ, have neurotoxic effects, and damage bone, among many other health effects. (5)
One of the most controversial issues is the impact of fluoride on the thyroid gland. Many people are not aware that in the first half of the 20th century, fluoride was used medically as an anti-thyroid drug, to slow down the thyroid function in hyperthyroid patients. Fluoride was found to be effective at suppressing or reducing thyroid function, according to research, and the dose needed to reduce thyroid function was low -- 2 to 5 mg per day over a period of months. (6)
Opponents of water fluoridation are concerned that the levels of fluoride used to treat an overactive thyroid are in the same range of exposure (1.6 to 6.6 mg/day) that is estimated in people living in communities with fluoridated water supplies.
While a number of studies have not found any link between fluoride and thyroid disease, other studies (7) have found that fluoride can cause alterations in the thyroid, including
- reduced T3 levels
- increased TSH levels
- thyroid enlargement (goiter)
In the meantime, what should thyroid patients do?
As a start, you can stay informed. For pro-fluoride information, a good starting point is the American Dental Association's Fluoride and Fluoridation page. One of the best sources of information regarding the opposition to fluoridation is the Fluoride Action Alert, led by Dr. Paul Connett.
Certainly, thyroid patients have the option to follow the ADA and Centers for Disease Control (CDC) recommendations, and continue to consume fluoridated water, and use fluoridated dental products.
At minimum, however, it's important to be aware of the CDC's warning against overuse of infant formula that is reconstituted with fluoridated water. According to the CDC, if that is a child's sole source of nutrition, "there may be an increased chance for mild dental fluorosis. To lessen this chance, parents can use low-fluoride bottled water some of the time to mix infant formula; these bottled waters are labeled as de-ionized, purified, demineralized, or distilled." (8)
You also may want to determine how much fluoride is in your water supply. A handy link to the CDC database, Fluoride Finder, can help you determine fluoride levels in your county.
For those who feel that the concerns raised by opponents are valid, Richard Shames, MD, author of a number of books on thyroid disease, and a Harvard-trained integrative physician, has said:
We know that 4 or 5 mg per day of fluoride is too much, but the problem is that no one knows how much people are actually getting. Those who exercise and drink a lot of water, bathe frequently, swim in pools, etc. or use fluoridated toothpaste or mouthrinses, may be overexposed to fluoride without realizing it. The first step to take is to stop drinking fluoridated water. You will need more than the standard carbon cannister water filters for this purpose. Instead, you will need a reverse osmosis or distillation unit. I also suggest non-fluoridated toothpaste, which is easily available with a bit of looking carefully at the health food store shelf. I realize that it is possible that children not using fluoride could possibly have more cavities, but this has not been proven to every doctor's satisfaction. I personally believe that the benefits of fluoride, even for children, have been overstated, and the risks minimized. For those who feel a need to use fluoridated products for their children's teeth, as with many health matters, moderation is the key. Use it sparingly and under close supervision, and do not allow children to swallow products containing fluoride.Sources
(1) Petersen, P. et. al., "Effective use of fluorides for the prevention of dental caries in the 21st century: the WHO approach," Community Dentistry and Oral Epidemiology, Volume 32, Issue 5, pages 319-321, October 2004, Abstract
(2) American Dental Association, "Flouride & Fluoridation," Fact Sheet, www.ada.org
(3) Beltrán-Aguilar, E. et. al."Prevalence and Severity of Dental Fluorosis in the United States, 1999-2004," NCHS Data Brief, Number 53, November 2010, Online
(4) Fagin D,"Second thoughts about fluoride". Scientific American 298 (1): 74-81. January 2008
(5) Connett, Paul, "50 Reasons to Oppose Fluoridation, September 2012," Fluoride Action Network, Online
(6) Galletti P, et. al. 1958. "Effect of fluorine on thyroidal iodine metabolism in hyperthyroidism. Journal of Clinical Endocrinology," 18(10):1102-1110. 1958
(7) Susheela AK, et al. "Excess fluoride ingestion and thyroid hormone derangements in children living in New Delhi, India." Fluoride, 38:98-108. 2005. National Research Council. "Fluoride in drinking water: a scientific review of EPA's standards." National Academies Press, Washington D.C. 2006.
(8) "Overview: Infant Formula and Fluorosis," Centers for Disease Control and Prevention, Online
(9) Shames, Richard, MD. "Why We Changed Our Minds About Water Fluoridation," About.com Online.
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Richard Shames, MD, apparently needs to spend less time marketing his practice, his "supplements" and his books, and spend more time reviewing the peer-reviewed science.
ReplyDeleteFirst of all, in recommending a cessation of drinking fluoridated water and use of fluoridated dental products, he contradicts the recommendations of the American Academy of Pediatrics, the American Dental Association, the United States Centers For Disease Control, and the World Health Organization, among over 100 other highly respected healthcare and healthcare related organizations worldwide. In so doing, he contradicts the recommendations of the past 5 United States Surgeons General, and the Deans of the Harvard Schools of Medicine, Dentistry, and Public Health. In so doing, he contradicts the opinion of the Chair of the 2006 NRC Report on Fluoride which is cited in this article.
If Dr. Shames would care to do a proper review of the scientific literature, he would find that there is no valid evidence linking fluoride at the optimal level as utilized in water fluoridation, to thyroid problems or any other adverse effect.
The 2006 NRC Committee on Fluoride was charged with evaluating the adequacy of the EPA primary and secondary MCLs of fluoride, 4.0 ppm and 2.0 ppm respectively, to protect the public against adverse effects. After an exhaustive, 3 year review of the pertinent fluoride literature, the Committee recommended that the EPA primary MCL be lowered from 4.0 ppm. The sole stated reasons for this recommendation were the risk of severe dental fluorosis and bone fracture with chronic consumption of water with a fluoride content of 4.0 ppm or higher. No other reasons. Had this Committee had any concerns about thyroid or any other disorders being associated with fluoride at this level, it would have been obligated to state so and recommend accordingly. It did not.
Additionally, the 2006 NRC Committee on Fluoride made no recommendation to lower the secondary MCL for fluoride, 2.0 ppm. Water is fluoridated at 0.7 ppm, one third the level this Committee made no recommendation to lower.
In 2013, Dr. John Doull, highly respected toxicologist, and Chair of the 2006 NRC Committee on Fluoride, stated:
"I do not believe there is any valid, scientific reason for fearing adverse health conditions from the consumption of water fluoridated at the optimal level"
---John Doull, MD, PhD, Chair of the National Academy of Sciences, National Research Council 2006 Committee Report on Fluoride in Drinking Water
Steven D. Slott, DDS
In regard to thyroid and fluoridated water:
Delete"Studies conducted in areas of endemic fluorosis suggest that excess fluoride may be associated with thyroid disturbances similar to those observed in iodine deficiency (e.g.goitre), and that high fluoride intake could exacerbate the effects of iodine deficiency. A review of the literature to 1984, including well-controlled studies in large populations exposed to fluoride over long periods, found no convincing evidence of a link between human goitre and fluoride intake."
"Both the NHS/York (2000) and the SCHER (2011) reviews concluded that neither animal or human studies to date support a role for fluoride-induced thyroid perturbations in humans in the absence of iodine deficiency."
--------Health effects of water fluoridation:
A review of the scientific evidence
A report on behalf of the Royal Society of New Zealand
and the Office of the Prime Minister’s Chief Science Advisor
August 2014
"The available medical and scientific evidence suggests an absence of an association between water fluoridation and thyroid disorders.
Many major reviews of the relevant scientific literature around the world support this conclusion. Of particular importance are:
* an exhaustive review conducted in 1976 by an expert scientific committee of the Royal College of Physicians of England;
* a systematic review in 2000 by the NHS Centre for Reviews and Dissemination at the University of York; and,
* a 2002 review by an international group of experts for the International Programme on Chemical Safety (IPCS), under the joint sponsorship of the World Health Organisation (WHO), the United Nations Environment Programme (UNEP), and the International Labour Organisation (ILO).
None has found any credible evidence of an association between water fluoridation and any disorder of the thyroid."
------BRITISH FLUORIDATION SOCIETY STATEMENT (January 2006) on the absence of an association between water fluoridation and thyroid disorders.
This statement has been reviewed and endorsed by the British Thyroid Association (BTA); however, the BTA would recommend that appropriate monitoring of thyroid status should be considered in areas where fluoridation is introduced to enable an ongoing epidemiological evidence base for thyroid status with fluoridation to be created.
http://www.bfsweb.org/facts/sof_effects/statementofflo.htm
" In the literature reviewed, doses appropriate for caries reduction were not shown to negatively impact thyroid function. Studies in which humans received doses significantly higher than the optimum fluoride intake for long periods of time showed no negative impact on thyroid function."
-----Fluoridation Technical Study Group City of Fort Collins, Col orado. Report of the Fort Collins Fluoride Technical Study Group. 2003. .
Steven D. Slott, DDS
Nothing like having a bunch of like minded peers reviewing your work. just because so called respected professionals advocate some thing doesn't make it right, just look at eugenics. if you want other well respected peers who advocate differently, there are 13 Nobel prize winners who are against adding fluoride in the water.
DeleteSome one who has an overactive thyroid is treated with fluoride, so that seems to me that there is something going on, now I'm not saying that thyroid problems are caused by fluoride, there are more problematic reasons for not taking fluoride, like disruption of the DNA, the immune system, and duming down of the brain as shown in about 41 studies as of late.
ReplyDeleteWhat doctor would prescribe medication to a 200 lb. man and then give the same amount to a 20 lb baby, and on top of that he knows neither of their medical history's, talk about unethical practice.