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Hypothyroidism and Reduced Intelligence

Fluoride's effects on the thyroid and on intelligence

The Thyroid Gland

An interesting article on self-help for people with Hashimoto's disease

Not for one moment are we implying that fluoride causes Hashimoto's disease.  However, anything which can help sufferers need to publicised widely.  Here is a very helpful article from Dr. Izabella Wentz dated 3rd February 2015:  LINK

Kent University publishes research into the prevalence of hypothyroidism in the fluoridated areas of England

February 2015
.  A team of researchers at Kent University (UK) published a piece of observational research on hypothyroidism.  The researchers concluded, after having collected and analysed absolute data relating to patients with hypothyroidism who were diagnosed by every GP surgery in England, that you are almost twice as likely if you are a post-menopausal woman living in the West Midlands to experience hypothyroidism than if you lived in Greater Manchester.   The difference is believed to be due to Birmingham residents being fluoridated whilst Manchester residents are not.  The correlation between fluoride and hypothyroidism is statistically significant.

This report was initially commented on briefly by proponents of fluoridation who promised to produce research which would refute the findings.  Things have gone remarkably quiet though. Perhaps it has proven impossible to contradict the findings?  Instead, the pro-fluoridation tactic now seems to be to deny the existence of the research and to instead quote earlier research which states no harm proven (perhaps because there hasn't been any other establishment research into the incidence of hypothyroidism?)

We've paired the Kent Research with a piece of research which dates back to the 1930's.  An Austrian Physician called Viktor Gorlitzer von Mundy who had many patients with hyperthyroidism experimented on himself using a concentrated solution of hydrofluoric acid.  He recognised that fluoride was anti-thyroid and reasoned that a non-dissociated fluoride compound would be more easily absorbed via the skin than fluoride which would normally exist in a dissociated state when in water.  He carefully measured the volume and temperature of bath water and added a precise amount of the hydrofluoric acid compound before asking his patients to bathe in the water.  The treatment was almost 100% successful.  In the early days while he was establishing the protocol, some of his patients had too many baths and developed hypothyroidism.

The hot water fluoride treatment was discontinued in the 1960s when more manageable and standardised medicines were developed.

WMAF was remarkably fortunate to be able to have the 1932 research translated from archaic Austro-German into English during 2015 otherwise we would never have known that it was hydrofluoric acid which dampened down the thyroid via hot bath water.

A small percentage (1.5%) of the fluoridating acid contains hydrofluoric acid.  Those people who enjoy hot baths when living in a fluoridated area are in double jeopardy.  Not only is their health threatened when they drink fluoridated water but the damage is compounded if they absorb fluoride through their skin.

And where is the Department of Health in all this?  Nowhere - absolutely nowhere.  No research has been done since the publication of Kent University's research in order to establish or refute causation now that we have established such a strong correlation.  Further research is undoubtedly overdue but neither the DH nor Public Health England have seen fit to spend part of their budget on interviewing women living in fluoridated and non-fluoridated areas to see whether they have lived most of their lives in that area and to find out if they enjoy hot baths.  This is such a simple way of establishing causation or otherwise.  But no - the DH and PHE can't be asked!

LINK to the Gorlitzer 1932 research       LINK to the Kent University research

Click on this LINK to see the original paper in Austro-German. Note that thyrotoxicosis is the same as hyperthyroidism.

Fluoridation proponents try to muddy the waters

The text below has been copied, unedited, from an email sent on 7th March 2015 to international members of Fluoride Action Network (USA).  

ADA Spokesperson Makes False Statements About NRC Study of Thyroid

A spokesperson for the American Dental Association made an inaccurate statement in the media recently while criticizing the latest study from Kent University (Peckham et al, 2015) showing hypothyroidism’s link to fluoridation.   

Dr. Edmond Hewlett, ADA spokesman and a professor at the UCLA School of Dentistry has been quoted by numerous publications discounting the study, stating that other studies have not uncovered a link between fluoridated water and thyroid problems, saying: 

“the 2006 report by the U.S. National Research Council (NRC) found no adverse effects on the thyroid even at levels more than four times greater than that used in fluoridation."

The quote appeared in a number of articles including those by the Chicago Tribune,HealthDay, and WebMD.  It’s an absolutely false statement, as FAN’s NRC Thyroid webpage makes very clear.  What isn’t clear is whether Dr. Hewlett intentionally lied when making the statement, or if he just lacked the knowledge to make an accurate statement on the matter. 

Kathleen Thiessen, Ph.D., who was one of the authors of the 2006 NRC report on fluoride, responded to the inaccurate statement with the following letter to the author of the HealthDay article that quoted Dr. Hewlett:

Regarding a recent HealthDay article by Alan Mozes, which has been used by the Chicago Tribune, WebMD, and probably others: 

The article on fluoride and underactive thyroid, reporting on a recent publication by Stephen Peckham et al., quotes a representative of the American Dental Association as saying that "the 2006 report by the U.S. National Research Council found no adverse effects on the thyroid even at levels more than four times greater than that used in fluoridation."  This statement by the ADA spokesman is demonstrably inaccurate.  

From the NRC report:

pp. 262-263: Fluoride exposure in humans is associated with elevated TSH concentrations, increased goiter prevalence, and altered T4 and T3 concentrations. . .  In humans, effects on thyroid function were associated with fluoride exposures of 0.05-0.13 mg/kg/day when iodine intake was adequate and 0.01-0.03 mg/kg/day when iodine intake was inadequate.  

p. 260: The major endocrine effects of fluoride exposures reported in humans include elevated TSH with altered concentrations of T3 and T4. . . .  These effects are summarized in Tables 8-1 and 8-2, together with the approximate intakes or physiological fluoride concentrations that have been typically associated with them thus far.  Table 8-2 shows that several of the effects are associated with average or typical fluoride intakes of 0.05-0.1 mg/kg/day (0.03 with iodine deficiency). . . . A comparison with Chapter 2 (Tables 2-13, 2-14, and 2-15) will show that the 0.03-0.1 mg/kg/day range will be reached by persons with average exposures at fluoride concentrations of 1-4 mg/L in drinking water, especially the children.  The highest intakes (>0.1 mg/kg/d) will be reached by some individuals with high water intakes at 1 mg/L. . . . 


p. 266:  Fluoride is therefore an endocrine disruptor.

p. 234:  Thus, several lines of information indicate an effect of fluoride exposure on thyroid function.

(Note: Kathleen Theissen says "I was one of the authors of the 2006 NRC report.  The NRC report is available at

Kathleen Thiessen, Ph.D.

Oak Ridge Center for Risk Analysis, Inc. 

Comment by WMAF (UK)

(1)           The disease states of hyperthyroidism and hypothyroidism are ranged on a continuum with the normal euthyroid state lying somewhere in the middle: 

Hyperthyroidism         >              Euthyroid state          >            Hypothyroidism 

For a chronology for fluoride's effect on the thyroid go to LINK            

Fluoride reduces human and animal intelligence

Harvard IQ Researchers Respond to Pro-Fluoridation Criticism

The authors of the 2012 Harvard Meta-analysis that highlighted fluoride’s role as a developmental neurotoxin, Philippe Grandjean, MD, PhD, and Anna Choi, ScD, have written a letter responding to pro-fluoridation criticism  by Dr. Jonathan Broadbent of their work.  Broadbent’s counter-study and Grandjean’s letter in response were both published in the American Journal of Public Health.  In his response Grandjean states,

“We are therefore concerned that the safety of elevated fluoride exposure is being exaggerated in ways similar to those employed by vested interests to misconstrue the scientific evidence of other neurotoxicants, such as lead, mercury, and certain pesticides.  Firm dismissal of fluoride as a potential neurotoxic hazard would seem premature.”

This isn’t the first time Grandjean has responded to pro-fluoridation efforts to downplay the impact fluoride has on IQ.  In December, he challenged the spin being used by fluoridation promoters.  Grandjean’s commentary (Mottled fluoride debate) appears on his website (Chemical Brain Drain) and is printed in full below. Grandjean explained that for the children tested, 

“Their lifetime exposures to fluoride from drinking water covered the full range allowed in the US. Among the findings, children with fluoride-induced mottling of their teeth – even the mildest forms that appears as whitish specks on the enamel – showed lower performance on some neuropsychological tests. This observation runs contrary to popular wisdom that the enamel effects represent a cosmetic problem only and not a sign of toxicity. At least one of five American children has some degree of mottling of their teeth.”

Fluoride Action Network’s entire discussion on this phenomenon is reproduced below. 

As of September 2016, a total of 57 studies have investigated the relationship between fluoride and human intelligence, and over 40 studies have investigated the relationship fluoride and learning/memory in animals. Of these investigations, 50 of the 57 human studies have found that elevated fluoride exposure is associated with reduced IQ, while 45 animal studies have found that fluoride exposure impairs the learning and/or memory capacity of animals. The human studies, which are based on IQ examinations of over 12,000 children, provide compelling evidence that fluoride exposure during the early years of life can damage a child’s developing brain.

After reviewing 27 of the human IQ studies, a team of Harvard scientists concluded that fluoride’s effect on the young brain should now be a “high research priority.” (Choi, et al 2012). Other reviewers have reached similar conclusions, including the prestigious National Research Council (NRC), and scientists in the Neurotoxicology Division of the Environmental Protection Agency (Mundy, et al). In the table below, we summarize the results from the 50 studies that have found associations between fluoride and reduced IQ and provide links to full-text copies of the studies. For a discussion of the 7 studies that did not find an association between fluoride and IQ, click here.

Quick Facts About the 50 Studies:

·         Location of Studies: China (32), India (13), Iran (4), and Mexico (1).

·         Sources of Fluoride Exposure:  41 of the 50 IQ studies involved communities where the predominant source of fluoride exposure was water; seven studies investigated fluoride exposure from coal burning.

·         Fluoride Levels in Water: IQ reductions have been significantly associated with fluoride levels of just 0.7 to 1.2 mg/L (Sudhir 2009); 0.88 mg/L among children with iodine deficiency. (Lin 1991)

Other studies have found IQ reductions at 1.4 ppm (Zhang 2015); 1.8 ppm (Xu 1994); 1.9 ppm (Xiang 2003a,b); 0.3-3.0 ppm (Ding 2011); 2.0 ppm (Yao 1996, 1997); 2.1 ppm (Das 2016); 2.1-3.2 ppm (An 1992); 2.2 ppm (Choi 2015); 2.3 ppm (Trivedi 2012); 2.38 ppm (Poureslami 2011); 2.4-3.5 ppm(Nagarajappa 2013); 2.45 ppm (Eswar 2011); 2.5 ppm (Seraj 2006); 2.5-3.5 ppm(Shivaprakash 2011); 2.85 ppm (Hong 2001); 2.97 ppm (Wang 2001, Yang 1994); 3.1 ppm (Seraj 2012); 3.15 ppm (Lu 2000); 3.94 ppm (Karimzade 2014); and 4.12 ppm(Zhao 1996).

·         Fluoride Levels in Urine: About a quarter of the IQ studies have provided data on the level of fluoride in the children’s urine, with the majority of these studies reporting that the average urine fluoride level was below 3 mg/L. To put this level in perspective, a study from England found that 5.6% of the adult population in fluoridated areas have urinary fluoride levels exceeding 3 mg/L, and 1.1% have levels exceeding 4 mg/L. (Mansfield 1999) Although there is an appalling absence of urinary fluoride data among children in the United States, the excess ingestion of fluoride toothpaste among some young children is almost certain to produce urinary fluoride levels that exceed 2 ppm in a portion of the child population.

Methodological Limitations

As both the NRC and Harvard reviews have correctly pointed out, many of the fluoride/IQ studies have used relatively simple designs and have failed to adequately control for all of the factors that can impact a child’s intelligence (e.g., parental education, socioeconomic status, lead and arsenic exposure). For several reasons, however, it is unlikely that these limitations can explain the association between fluoride and IQ.

First, some of the fluoride/IQ studies have controlled for the key relevant factors, and significant associations between fluoride and reduced IQ were still observed. This fact was confirmed in the Harvard review, which reported that the association between fluoride and IQ remains significant when considering only those studies that controlled for certain key factors (e.g., arsenic, iodine, etc). Indeed, the two studies that controlled for the largest number of factors (Rocha Amador 2007Xiang 2003a,b) reported some of the largest associations between fluoride and IQ to date.

Second, the association between fluoride and reduced IQ in children is predicted by, and entirely consistent with, a large body of other evidence. Other human studies, for example, have found associations between fluoride, cognition, and neurobehavior in ways consistent with fluoride being a neurotoxin.  In addition, animal studies have repeatedly found that fluoride impairs the learning and memory capacity of rats under carefully controlled laboratory conditions. An even larger body of animal research has found that fluoride can directly damage the brain, a finding that has been confirmed in studies of aborted human fetuses from high-fluoride areas.

Finally, it is worth considering that before any of the studies finding reduced IQ in humans were known in the western world, a team of U.S. scientists at a Harvard-affiliated research center predicted (based on behavioral effects they observed in fluoride-treated animals) that fluoride might be capable of reducing IQ in humans. (Mullenix 1995)


When considering their consistency with numerous animal studies, it is very unlikely that the 50 human studies finding associations between fluoride and reduced IQ can all be a random fluke. The question today, therefore, is less whether fluoride reduces IQ, but at what dose, at what time, and how this dose and time varies based on an individual’s nutritional status, health status, and exposure to other contaminants (e.g., aluminum, arsenic, lead, etc). Of particular concern is fluoride’s effect on children born to women with suboptimal iodine intake during the time of pregnancy, and/or fluoride’s effects on infants and toddlers with suboptimal iodine intake themselves. According to the U.S. Centers for Disease Control, approximately 12% of the U.S. population has deficient exposure to iodine.