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Barberio et al., 2017 - Comments

Posted: Thu Jun 18, 2020 7:36 am
by admin
  • Barberio AM, Hosein FS, Quinonez C, McLaren L - "Fluoride exposure and indicators of thyroid
    functioning in the Canadian population: Implications for community water fluoridation" J
    Epidemiol Community Health 71: 1019-1025 (2017)
Hormones investigated: TSH (Reference Range only, no actual data supplied), FT4 (no data provided for FT4).

This is one of the most absurd papers we have yet encountered.


This paper was part of a 2016 Master's thesis by Amanda Marie Barberio (U of Calgary, 2016). The thesis was entitled:
  • "A Canadian Population-based Study of the Relationship between Fluoride Exposure and Indicators of Cognitive and Thyroid Functioning; Implications for Community Water Fluoridation"
Two papers were published out of this work, the thyroid paper and a companion paper on IQ (Barberio et al., 2017, 2017a).

While Barberio is listed as the primary author, it is Lindsay McLaren - a well-known fluoridation promoter in Alberta - who is "accountable for all aspects of the final manuscript" (Barberio Thesis, 2016). It is McLaren who is listed as the contact for this paper, not Barberio. At the time this study was designed, McLaren was President of the Alberta Public Health Association. She is the Chair in Applied Public Health "evaluating fluoridation cessation in Canada" for the Canadian Institutes of Health Research (CIHR) and the Public Health Agency of Canada (PHAC), the funding sources for this project.

McLarens' work was previously shown to be of highly questionable value, as data she had used to claim that fluoridation cessation in Calgary had increased caries was found to be seriously flawed (Neurath et al., 2017).

Before the Baberio papers were even published, the drafts were used in pro-fluoridation efforts in Alberta. A pro-fluoridation dissemination strategy was a part of this thesis. [SEE: Dissemination Strategy viewtopic.php?p=2695#p2695 ]

[Yet, the 2019 NTP Review Draft lists this paper's authors as having "no conflict of interest".]

Problems with this paper

There are many problems with this paper, but for now, we shall discuss the one of greatest concern:

TSH levels

Authors claim:

"There was no statistically significant association between fluoride exposure and abnormal (low or high) TSH levels relative to normal TSH levels."

The 2019 NTP Review Draft echoed:

"Barberio et al. (2017a) evaluated fluoride effects on TSH levels in children and adults combined and found no relationship between fluoride exposure (measures in urine and tap water) and TSH levels."

Did the authors actually compare TSH levels to urinary fluoride levels?


Although the data from Cycle 3 was available for such a direct comparison, TSH values were assigned to three categories instead: low-normal-high.
  • Low: <0.55 mIU/L
    Medium: 0.55 to 4.78 mIU/L
    High: >4.78 mIU/L

By comparing fluoride levels to a TSH reference range, the true impact of fluoride on TSH levels was now being hidden.

Only when the TSH level was above 4.78 mIU/L or below 0.55 mIU/L, was it considered "abnormal".

The upper limit in the “normal” range -> 4.78 mIU/L is so high that fluoride effects would not be apparent in this investigation.

For example, if fluoride increased TSH from 2 mIU/L to 3 mIU/L, it would never be detected now, as such an increase would still be within the "normal" range.

However, for a pregnant woman, this increase could have devastating consequences on the health of the fetus.

Barberio's upper limit of 4.78 mIU/L for the TSH "normal" range does not apply for women during pregnancy, the greatest risk period for damage to IQ and adverse birth events. The upper-level limit guideline is 2.5 mIU/L for the first trimester.

  • NOTE 1: This kind of misleading data interpretation has been a common tactic not just in fluoride/thyroid investigations (i.e. Hosur et al., 2012), but also in other studies on effects of toxins such as lead or cadmium on thyroid hormone metabolism.

    NOTE 2: From the studies cited in this paper, the authors must be presumed to have been fully aware of the findings that an increase in TSH levels is usually correlated to serum fluoride and/or urinary fluoride concentrations. Barberio et al. cite the work of Susheela et al., (2005) and Singh et al. (2014). Both of these studies showed that TSH levels increased WITHIN the TSH reference range used by Barberio et al., causing disturbances in thyroid hormone metabolism.

TSH & IQ - why is this so important?

Worldwide, TSH levels for pregnant women in the first trimester have an upper limit of 2.5 mIU/L, specifically to avoid loss of IQ and other brain damage in the offspring. The same guidelines are used in Alberta (TOP, 2014).

A TSH level of 2.5 mIU/L is just above the mid-point of the "normal” reference range used by Barberio (0.55 to 4.78 mIU/L).

The mean TSH level in Canada - from the Cycle 3 data used by Barberio et al. - was 1.80 mIU/L for women aged 20 to 39. That level is only a short distance to the first trimester upper limit of 2.5 mIU/L.

In a large study undertaken by Zohreh Kheradpisheh from the Environmental Science and Technology Research Center in Iran, it was found that fluoride water concentrations of 0.3 to 0.5 ppm increased the TSH level by 0.6 mIU/L, compared to an area with 0 to 0.29 ppm fluoride. This resulted in a TSH increase from 2.2 mIU/L to 2.8 mIU/L - above the first-trimester upper limit of 2.5 mIU/L - thereby placing pregnant women and their offspring at risk (Kheradpisheh et al 2018). Increases were even more pronounced in people suffering from hypothyroidism, as reported previously by Lin et al. (1991).

Findings like these should be enough to question all fluoride supplementation programs:
  • - A 0.5 ppm increase of fluoride in water has been shown to increase TSH by 0.6 mIU/L (Kheradpisheh et al., 2018).

    - An 1.3 ppm increase of fluoride in the water supply/urinary fluoride increases the serum TSH level by 1.9 mIU/L (Bachinskii et al, 1985).

    - In areas of iodine-deficiency or under hypothyroid conditions, a 0.5 ppm increase of fluoride in the water supply can raise the TSH level manyfold (Lin FF et al, 1991; 1992; Kheradpisheh et al., 2018).

Here, in this study on thyroid and IQ, the authors EXCLUDED pregnant women, as “pregnancy has a profound impact on the thyroid gland and thyroid function” (Barberio thesis, 2016).

Absurd is the word.

How can a study on fluoride effects on thyroid, TSH and IQ not consider TSH levels and their upper limits during pregnancy? And, if the TSH data was available, why weren't those actual levels compared to the urinary fluoride levels?

When the Cycle 3 data is sorted by gender for the age group most stable for this kind of investigation (20-39 yrs), an obvious association is seen across the percentiles - as urinary fluoride levels rise, so do the TSH levels while FT4 levels decrease. Assigning people to a TSH reference range of 0.55 to 4.78 mIU/L would never show this relationship.

A few last words about TSH levels within a "normal" range...

The TSH "normal range" for adults has been very controversial for many years and is now commonly set at 0.4 - 4 mIU/L, although many are advocating for a much lower upper limit.

Over 70 major studies in the last 20 years have shown significant associations of TSH levels in the upper range of "normal" with many adverse health conditions.

A higher TSH level within the reference range in pregnant women is associated with an increased pregnancy loss rate (Negro et al., 2010), pre-term birth (Korevaar et al., 2019); and overall adverse pregnancy outcome (Arbib et al., 2017).

Increases in TSH concentration within normal ranges were adversely associated with cognitive function and ADHD symptoms in children (Alvarez-Pedrerol et al. 2007; Endendijk et al., 2017; Pérez-Lobato et al., 2015; Freire et al., 2010). Others have identified elevated TSH "within the normal range" as an independent risk factor for non-alcoholic fatty liver disease (Tahara et al., 2019; Kim et al., 2020), the Metabolic Syndrome (Li et al., 2020; Ruhla et al., 2010; Boggio et al., 2014), or thyroid cancer (Zirilli et al., 2019; Polyzos et al., 2008; Ye et al., 2013; Kim et al., 2013; Boi et al., 2013).

This is an urgent and important issue.

In these times of COVID-19, the public has a right to accurate information from the authorities on matters affecting public health. This includes accurate information on the toxicity of fluoride.

Under no circumstances should this paper by Barberio, McLaren et al. be allowed to further influence public health policy in Canada.

Wendy Small
PFPC Canada, June 2020


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"Statistically significant differences were observed in the highest quartiles of TSH, suggesting a need for re-evaluation of the upper limit of the normal TSH range."

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Barberio AM - "A Canadian Population-based Study of the Relationship between Fluoride Exposure and Indicators of Cognitive and Thyroid Functioning; Implications for Community Water Fluoridation" Master's Thesis, University of Calgary (2016)

Barberio AM, Hosein FS, Quinonez C, McLaren L - "Fluoride exposure and indicators of thyroid functioning in the Canadian population: Implications for community water fluoridation" J Epidemiol Community Health 71: 1019-1025 (2017)

Barberio AM, Quinonez C, Hosein FS, McLaren L - "Fluoride exposure and reported learning disability diagnosis among Canadian children: Implications for community water fluoridation" Can J Public Health 108: 229-239 (2017a)

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Freire C, Ramos R, Amaya E, Fernández MF, Santiago-Fernández P, Lopez-Espinosa MJ, Arrebola JP, Olea N - "Newborn TSH concentration and its association with cognitive development in healthy boys" Eur J Endocrinol 163(6):901-9 (2010)

Garg A, Vanderpump MP - "Subclinical thyroid disease" Br Med Bull (2013) 107:101-16. doi: 10.1093/bmb/ldt024. Epub 2013 Aug 6. PMID: 23919951

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

Kim D, Vazquez-Montesino LM, Escober JA, Fernandes CT, Cholankeril G, Loomba R, Harrison SA, Younossi ZM, Ahmed A - "Low Thyroid Function in Nonalcoholic Fatty Liver Disease Is an Independent Predictor of All-Cause and Cardiovascular Mortality" Am J Gastroenterol (2020)

Kim HK, Yoon JH, Kim SJ, Cho JS, Kweon SS, Kang HC - "Higher TSH level is a risk factor for differentiated thyroid cancer" Clin Endocrinol (Oxf) 78(3):472-7 (2013)

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Li M, Zhang X, Zhou X, Han X, Zhang R, Fu Z, Wang L, Gao Y, Li Y, Ji L - "The Association Between Serum Thyrotropin Within the Reference Range and Metabolic Syndrome in a Community-Based Chinese Population" Diabetes Metab Syndr Obes 13:2001-2011 (2020) ... /32606859/

Negro R, Schwartz A, Gismondi R, Tinelli A, Mangieri T, Stagnaro-Green A - "Increased pregnancy loss rate in thyroid antibody negative women with TSH levels between 2.5 and 5.0 in the first trimester of pregnancy" J Clin Endocrinol Metab 95(9):E44-8 (2010)

Neurath C, Beck JS, Limeback H, Sprules WG, Connett M, Osmunson B, Davis DR - "Limitations of fluoridation effectiveness studies: Lessons from Alberta, Canada" Community Dent Oral Epidemiol 45(6):496-502 (2017)


Pérez-Lobato R, Ramos R, Arrebola JP, et al. - "Thyroid status and its association with cognitive functioning in healthy boys at 10 years of age"Eur J Endocrinol 172(2):129-139 (2015)
"Higher TSH slightly but significantly increased the risk of a lower score in certain neuropsychological tests."

PFPC - "The problems with TSH level within a 'normal' range" (2020)

Polyzos SA, Kita M, Efstathiadou Z, Poulakos P, Slavakis A, Sofianou D, Flaris N, Leontsini M, Kourtis A, Avramidis A - "Serum thyrotropin concentration as a biochemical predictor of thyroid malignancy in patients presenting with thyroid nodules" J Cancer Res Clin Oncol 134(9):953-60 (2008)

Ruhla S, Weickert MO, Arafat AM, Osterhoff M, Isken F, Spranger J, Schöfl C, Pfeiffer AF, Möhlig M - "A high normal TSH is associated with the metabolic syndrome" Clin Endocrinol (Oxf) May;72(5):696-701 (2010)

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.

Statistics Canada - Hormone measures of the household population ... 5B0%5D=5.1

Statistics Canada - Canadian Health Measures Survey (CHMS) Data User Guide: Cycle 3. Ottawa, ON (2015)

Susheela AK, Bhatnagar M, Vig K, Mondal AK - "Excess fluoride ingestion and thyroid hormone derangements in children living in Delhi, India” Fluoride 38(2):151-161 (2005)

Tahara K, Akahane T, Namisaki T, Moriya K, Kawaratani H, Kaji K, Takaya H, Sawada Y, Shimozato N, Sato S, Saikawa S, Nakanishi K, Kubo T, Fujinaga Y, Furukawa M, Kitagawa K, Ozutsumi T, Tsuji Y, Kaya D, Ogawa H, Takagi H, Ishida K, Mitoro A, Yoshiji H - "Thyroid-stimulating hormone is an independent risk factor of non-alcoholic fatty liver disease" JGH Open 4(3):400-404 (2019) doi: 10.1002/jgh3.12264. PMID: 32514444; PMCID: PMC7273701

TOP Alberta - Clinical Practice Gudielines - Thyroid (2014) ... deline.pdf

U of Calgary - Profile McLaren - (2020)

Wang M, Liu L, Li H, Li Y, Liu H, Hou C, Zeng Q, Li P, Zhao Q, Dong L, Zhou G, Yu X, Liu L, Guan Q, Zhang S, Wang A - "Thyroid function, intelligence, and low-moderate fluoride exposure among Chinese school-age children" Environ Int 134:105229 (2020) doi: 10.1016/j.envint.2019.105229. Epub 2019 Nov 4. PMID: 31698198
"We detected a significant modification effect by TSH on the association between urinary fluoride and IQ scores, without mediation by THs."

Ye ZQ, Gu DN, Hu HY, Zhou YL, Hu XQ, Zhang XH - "Hashimoto's thyroiditis, microcalcification and raised thyrotropin levels within normal range are associated with thyroid cancer" World J Surg Oncol. 11:56 (2013)

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Barberio - Dissemination strategy

Posted: Wed Jul 01, 2020 8:59 am
by admin
6.5 Dissemination strategy
(from Master Thesis: A Canadian Population-based Study of the Relationship between Fluoride Exposure and Indicators of Cognitive and Thyroid Functioning; Implications for Community Water Fluoridation by Amanda Marie Barberio, U of Calgary, 2016)

Dissemination of these results to the scientific and health professional communities will occur via:

1) two oral presentations at the Canadian Association for Public Health Dentistry Annual Conference in Edmonton, Alberta from September 30th to October 1st 2016, and

2) submission of both manuscripts to scientific peer-reviewed journals. Other possible modes of dissemination include formal presentations to dental health professionals (e.g., hygienists and dentists) and Calgary City Council.

In anticipation that non-scientific audiences such as decision makers and the general public will be interested in the findings of this research, we have prepared a point-form version of a plain language summary (presented below).

What did we do?
  • We examined the relationship between fluoride exposure and measures of cognitive and thyroid functioning, among Canadians.
Why did we do it?
  • *The mineral fluoride can be added to public drinking water supplies to prevent tooth decay. This practice is called community water fluoridation (CWF).]

    *Experts in Canada determined an ‘optimal concentration’ of fluoride to add to drinking water that they believe is safe.

    *However, some people still worry about the safety of CWF. It is important that safety concerns are carefully studied.

    *We used new, high quality data from the Cycles 2 and 3 of the Canadian Health Measures Survey. This is a national survey that is led by Statistics Canada. People who participated in the survey gave samples of their urine and tap water that were tested for fluoride. Other information collected during the survey helped us measure participants’ cognitive and thyroid functioning.
What did we find?
  • *We did not find any relationship between fluoride and poor thyroid functioning.

    *We did not find any relationship between fluoride and having a learning disability.

    *Participants with higher fluoride in their urine were more likely to report having ‘some’ cognitive problems than ‘no’ cognitive problems. However, this relationship was very weak. This relationship completely disappeared when we focused on people who were getting fluoride from CWF.

    *Participants with higher fluoride in their urine were not more likely to report having ‘high’ cognitive problems than ‘no’ cognitive problems.
Why does this matter?
  • *Overall, our results suggest that the amount of fluoride people are consuming is safe.

    *These results will be helpful to people who make decisions about adding fluoride to drinking water.

About Hosur et al.

Posted: Thu Jul 23, 2020 12:34 am
by wendy
Barberio et al. make reference to the study done by Hosur et al., in 2012.

They state:

"Conversely, a study by Hosur et al (2012) did not detect altered levels of thyroid hormones (free T3, free T4 and TSH) in 65 individuals living in India with dental fluorosis (used as a proxy for high fluoride exposure), with the exception of one individual whose serum levels of TSH were elevated."

This is incorrect.

1) Altered hormone levels were certainly observed, regardless as to what Hosur et al. state in their conclusion. The levels did not go outside a very wide "normal" range - even wider than in this study by Barberio et al. - hence were not considered "abnormal".

As Hosur et al. state:

"FT3 levels were significantly different between mild and moderate, as well as between mild and severe fluorosis groups...a significant difference was found between TSH levels of moderate and severe fluorosis groups."

The table speaks volumes: ... /Hosur.png


Re: "dental fluorosis used as a proxy for high fluoride exposure":

Dental fluorosis (DF) can't be used as a proxy for current fluoride intake in children and adolescents of this age. DF can only occur from fluoride exposure during crucial times of development - in utero to about 30 months of age for deciduous teeth and permanent incisors - esthetically the most important teeth. The dental defects seen in DF stem from thyroid hormone disturbances during that particular time period, when thyroid hormone levels are vastly different than in later years. The permanent incisors themselves don't erupt until about age 7. When thyroid hormones are measured they can only reflect the thyroid status at the time of the investigation. Likewise, when fluoride is measured in serum/urine, it reflects the current intake. The children in the study by Hosur et al. are between 10 and 18 years old.

Hosur et al. compared children with and without dental fluorosis from areas with different fluoride concentrations in the water. Unfortunately, the majority of the children in the study group had less fluoride in the water than the control group, making that comparison useless. Urinary fluoride or serum fluoride levels were not measured.

Re: The "one individual whose serum levels of TSH were elevated": there was one individual from the study group, but also one from the control group with elevated TSH (Of course many children had elevated TSH levels when "normal ranges" were properly applied.)

As Hosur et al. provide individual thyroid hormone data for all children in the paper, one can observe the same hormone disturbances as were documented earlier by Susheela et al. (2005).

See: Comments on Hosur et al., 2012: viewtopic.php?f=7&t=2389