- 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)
https://pubmed.ncbi.nlm.nih.gov/28839078/
This is one of the most absurd papers we have yet encountered.
Background
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"
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=4435#p4435
After publication, dental organizations were quick to pronounce how valuable this study was and how it had contributed to the "vast amount of research" showing how safe water fluoridation was. SEE: https://ilikemyteeth.org/adding-researc ... -exposure/
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?
No.
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: <0.55mIU/L
Medium: 0.55 to 4.78 mIU/L
High: >4.78mIU/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.
- SEE Table Cycle 3: https://poisonfluoride.com/Science/NTP_ ... _data.html
(Data available on-line at https://www150.statcan.gc.ca/t1/tbl1/en ... 1310033401
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 narrower range.
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 of 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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