The American Fluoridation Society & Kheradpisheh, Singh and Peckham

How public health authorities in Calgary and fluoride "experts" are manipulating and misrepresenting the science on fluoride toxicity
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The American Fluoridation Society & Kheradpisheh, Singh and Peckham

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October 14, 2021

Whenever a news article on fluoridation in Calgary was published in the last 5 to 10 years, members of the American Fluoridation Society (AFS) flooded the comments sections with misinformation on the "safety" and harmlessness of fluoridation. The scientific literature was - and continues to be - regularly and knowingly misrepresented.

Here are three examples:

EXAMPLE 1: Kheradpisheh et al., 2018

In 2019, in its "Response to Critique by Fluoridation Opponents of the 2019 CADTH Report on Fluoridation"(1), the AFS wrote the following about the 2018 study by Kheradpisheh et al., which had documented that fluoride caused increased TSH levels at very low levels:
The 2018 Kheradpisheh et al. study was performed in Iran, one of the areas with the highest levels of environmental fluoride pollution in the world. As stated in the study: “The main source of drinking water in Yazd city is surface water and well resources in different seasons; thus, differences in fluoride concentration are bound to exist.”

Therefore, it was of the impact of exposure to excessive amounts of environmental fluoride, not of the minuscule amount of fluoride in highly controlled optimally fluoridated water systems.

The AFS "experts" provided no supporting reference for their statement concerning these "highest levels of environmental fluoride in the world" nor could show that there were any such amounts found in the areas investigated in the study, or that they were responsible for the effects observed.


1) The changes in TSH were directly correlated to the fluoride water concentrations, as documented by the authors. In fact, the authors published another paper specifically on this high correlation and the methods used (2).

2) Regarding the differences in well water fluoride concentrations: this was exactly the reason why the areas were chosen - because it enabled the researchers to compare TSH levels to different fluoride water concentrations. This is clearly explained in the paper.

3) The authors were also very clear about their findings that fluoride effects were observed at those AFS-called "minuscule" concentrations, even BELOW those levels used for water fluoridation. At fluoride water concentrations from 0.3 to 0.5 ppm, TSH was increased by 0.5 mIU/L, compared to the area with 0 to 0.3 ppm. In this study, fluoride resulted in a TSH increase from 2.2 mIU/L to 2.8 mIU/L in subjects with normal thyroid function. (2.8 mIU/L is above the recommended TSH upper limit of 2.5 mIU/L for the first trimester of pregnancy - set specifically to avoid loss of IQ and adverse birth events such as low birth weight, premature birth, etc.)

STUDY: "It was found that fluoride has impacts on TSH, T3 hormones even in the standard concentration of less than 0.5 mg/L."

  • Read the study here: Kheradpisheh Z, Mirzaei M, Mahvi AH, Mokhtari M, Azizi R, Fallahzadeh H, Ehrampoush MH - "Impact of Drinking Water Fluoride on Human Thyroid Hormones: A Case-Control Study" Scientific Reports Volume 8:2674 (2018)

EXAMPLE 2: Singh et al., 2014

In the same statement, the AFS wrote the following about the 2014 study by Singh et al., which had found serum fluoride levels directly correlated to serum TSH levels:
"Singh, et al. 2014: A study of the effects of exposure to excessive levels of fluoride in India, another area with the highest level of environmental fluoridation in the world. The water fluoride levels of this study ranged from 2.6 mg/liter - 5.1 mg/liter, levels of no relevance to the 0.7 mg/liter at which water is fluoridated."
Again, a complete misrepresentation. Note once again, the "highest level of environmental fluoridation in the world." AFS provided no reference.


1) Singh et al. reported that fluoride levels in serum were directly correlated to changes in TSH, even at water fluoride concentrations of 1 ppm. Of course, this dose-response relationship is of great relevance to water fluoridation programs. As shown by Kheradpisheh, a mere change from 0.3 ppm to 0.5. ppm fluoride produced a rise in TSH of 0.6 mIU/L.

2) The authors further reported that TOTAL fluoride had to be considered for toxicity assessments, not just fluoride in water, as even in areas with low fluoride there were elevated fluoride levels in serum, pointing to other sources of fluoride intake from food and beverages.

  • Read the study here:
    Singh N, Verma KG, Verma P, Sidhu GK, Sachdeva S - "A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas" Springerplus 3:7 (2014) doi: 10.1186/2193-1801-3-7. eCollection 2013 Jan 3. PubMed PMID: 24455464.

EXAMPLE 3: Peckham et al., 2015

Again, from the same 2019 statement by the AFS, the following misinformation can be read about the findings by Peckham et al. that fluoridation was related to an increase in hypothyroidism:
"2015 Peckham: This study has been widely discredited within the scientific literature for its inadequate control for confounders, poor methodology, and reaching a conclusion not supported by the scientific literature."


1) The only "scientific literature" aimed to discredit the study was written by pro-fluoridationists. We have seen some incredible ignorant reviews, such as one by Newton et al. from the UK's Public Health office (3).

2) Hypothyroidism is diagnosed by elevated TSH levels. Fluoride increases TSH levels, as can be clearly observed in the two studies discussed above.

3) As far as the conclusions "not being supported by the scientific literature" - there are hundreds and hundreds of studies going back more than 150 years documenting fluoride effects on thyroid hormone metabolism, 250 of which have been published in the last 20 years alone (4). The supporting evidence is outright overwhelming.
  • Read the study here:
    Peckham S, Lowery D, Spencer S - "Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water" J Epidemiol Community Health 69(7):619 (2015)
    doi:10.1136/jech-2014-204971 ... 4971.short

The American Fluoridation Society simply lies. Why?

Wendy Small
PFPC Canada


(1) American Fluoridation Society (AFS) - "Response to Critique by Fluoridation Opponents of the 2019 CADTH Report on Fluoridation" (July 2019) ... -91819.pdf ... -91819.pdf

(2) Kheradpisheh Z, Mahvi AH, Mirzaei M, Mokhtari M, Azizi R, Fallahzadeh H, Ehrampoush MH - "Correlation between drinking water fluoride and TSH hormone by ANNs and ANFIS" J Environ Health Sci Eng 16(1):11-18 (2018)

(3) Newton J et al. - 'Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water': Comments on the authors' response to earlier criticism. Journal of Epidemiology and Community Health 69(4):jech-2016-208649 (2017)
Available from:
  • Authors state:
    "We were fascinated to discover that the direction of association between deprivation and hypothyroidism switched direction in their model after adjustment for proportion aged over 40 years (OR changed from 0.49 to 1.7). Although good to know that it was not an error, discovery of such a statistical quirk in the model (which we believe is an extreme example of Simpson’s paradox6) raises more questions than it provides answers about the relevance and validity of the model for the hypothesis being examined."
    Here we can see what happens when "experts" completely ignorant about thyroid disorders or the endocrine system review a paper of this nature. Had they possessed any knowledge on thyroid function they would have known that thyroid hormone metabolism changes at around the age of 40 years (i.e. Strich et al., 2016).

    Strich D, Karavani G, Edri S, Gillis D. - "TSH enhancement of FT4 to FT3 conversion is age dependent" Eur J Endocrinol 175(1):49-54 (2016) ... 5/1/49.xml
    "As TSH levels increase, FT3/FT4 ratios increase until age 40, but this differential increase does not occur in older age groups."
(4) PFPC Canada - Recent Research - 250+ papers on the effects fluoride on thyroid hormones (2001 - 2021)

Further notes re: Peckham

See also:

Grimes DR - "Commentary on “Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water” Journal of Epidemiology and Community Health 69(7):616–616 (2015)

Warren JJ, Saraiva MCP - "No Evidence Supports the Claim That Water Fluoridation Causes Hypothyroidism" Journal of Evidence Based Dental Practice 15(3):137–139 (2015)

Newton JN, Young N, Verne J, Morris J - "Water fluoridation and hypothyroidism: results of this study need much more cautious interpretation" Journal of Epidemiology and Community Health 69(7):617–618 (2015)
"In addition, some 20–30% of these patients will be receiving levothyroxine because of previous thyroid ablation by surgery or
radiation therapy to treat hyperthyroidism,7 which is even less likely to be in any way related to fluoride ingestion....The approach used is notoriously unreliable as a way of identifying independent associations and the lack of a clearly established prior hypothesis make it very unconvincing as evidence of a causal relationship."

FACT: The pharmacological efficacy of fluoride as an anti-iodine/anti-thyroid agent has been established since the 1930s. Fluoride's relationship with iodine is firmly established in other countries of the world.
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