- Ahmed I, Ghuman F, Salman S, Fatima I - "Does drinking water with raised fluoride content affect the thyroid hormone status: A study from Tharparker Pakistan" J Pak Med Ass 72(2):228 -230 (2022)
https://jpma.org.pk/article-details/11089
This was the first study published in 2022 on fluoride effects on thyroid function. The study was conducted by a group of Pakistani dentists on humans >12 years old, predominantly men. Mean age was 33 years. The study was published in the Journal of the Pakistan Medical Association (JPMA).
Unfortunately, several concerns arise regarding the reliability of this study. There are so many errors and discrepancies in this paper, that one wonders if there was any peer review at all.
There are inconsistencies in the way results are reported for fluoride concentrations, as well as thyroid hormone measurements.
Fluoride Concentrations
The fluoride in water concentration is given as 0.3 mg/L for the unexposed area, and 6-8 mg/dL for the exposed area. It is unclear if this use of different units is a mistake, or intentional. A 6-8 mg/dL values would mean a fluoride concentration of 60 to 80 ppm which is very unlikely.
It is unclear, therefore, if the authors meant 6 to 8 ug/dl, or 6 to 8 mg/L. Considering what we know about fluoride effects on thyroid hormone metabolism, we are presuming that the authors meant 0.6-0.8 mg/L. In this context, the findings on thyroid hormone effects appear similar to those by Kheradpisheh et al. (2018).
However, many areas in Pakistan have high fluoride amounts in the water, comparable to 6-8 mg/L, so it is possible that the exposed area has indeed such a water fluoride level. If that were the case, it is likely that the unexposed area has also high fluoride exposure.
Exposed vs Unexposed
The authors claim that fluoride levels were only 0.3 ppm in the water supply in the "unexposed" control village of Gadap Town. However, previous investigations have identified Gadap Town as an "endemic fluorosis" area, with more than half of the population afflicted with dental fluorosis (Mohsin et al., 2014). Thus, one cannot possibly consider this population "unexposed".
No serum or urinary fluoride levels were measured to determine actual fluoride intake, nor were any iodine measurements made.
Free T4 and Free T3
- For Free T4, the reference range is presented as 4.5-12.5 ug/dL. This, again, is not possible. A normal reference range for Free T4 would be a range from 0.8–1.8 ng/dl. Converted to ug/dL, this would be 800–1800 ng/dL. It appears that TOTAL T4 was measured, results of which are usually presented as micrograms per deciliter (ug/dl), with a reference similar to the one described (i.e. 5–12 ug/dl in US labs).
- For Free T3, the reference range is given as 1.2 to 2.8 nmol/L --> nanomoles per liter. This is also not plausible and it appears that TOTAL T3 was measured, which is normally presented as nmol/L, or ng/dL, and with comparable reference range (0.9 to 2.8 nmol/L in US labs). Free T3, on the other hand, is normally given either as pg/dL or pmol/L (ref range 2 to 7 pmol/L in US labs).
The study contends that no significant differences exist in TSH and thyroid hormones between the exposed and unexposed groups. However, this is a misleading statement, and not only for the fact that the control area was an endemic fluorosis area itself.
It is a perfect example how data findings can be presented and manipulated to support a particular viewpoint, while ignoring other relevant data that may contradict it.
Similar to the Canadian study by Barberio et al. (2017), subjects were categorized based on lab diagnostic criteria for hypothyroidism or hyperthyroidism. In this case, a serum TSH <0.4 mIU/L was considered hyperthyroid, and a level >4 mIU/L was taken as hypothyroid.
Although there are no significant differences when subjects are grouped according to this diagnostic criteria, a different narrative emerges when examining the limited data provided, comparing TSH, T4, and T3 levels between the two areas.
TABLE 1:
As in study by Kheradpisheh et al., (2018), mean TSH levels rose to 2.58 mIU/L in the "exposed area". The upper limit for TSH in the first trimester of pregnancy is 2.5 mIU/L.
Current understanding acknowledges that even slight variations within the "normal" or "reference" range for TSH are associated with adverse health effects (PFPC, 2023).
REFERENCES
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, Article number: 2674 (2018)
https://www.nature.com/articles/s41598-018-20696-4
http://poisonfluoride.com/phpBB3/viewto ... 1737#p1737
Mohsin A, Hakeem S, Arain AH, Mirza D, Ali T - "Frequency and severity of dental fluorosis among school children in Gadap Town, Karachi" Pakistan Oral & Dental Journal 34(4): (2014)
https://www.researchgate.net/publicatio ... wn_Karachi
PFPC - Adverse health effects associated with TSH levels within the "normal" or "reference" range (2021-2023)
viewtopic.php?f=7&t=2300
UPDATE February 3, 2022
Another study found by the same authors in the same area, this time on dental fluorosis, make similar errors in reporting the fluoride concentrations. In addition, some false statements are made such as:
This is not true. A concentration of 1.5 mg/L is 1.5 ppm (parts-per-million, the same as mg/L)."World Health Organization (WHO) recommends fluoride concentration level in drinking water at 1.5mg/L or it can be documented as 0.8-0.9 ppm."
It is obvious that none of the data presented in either paper can be relied upon.
- Ahmed et al., - "Frequency of Dental Fluorosis in Population Drinking Water with High Fluoride Level in Thar" JPAD 29(4) (2020)
https://www.jpda.com.pk/frequency-of-de ... in-thar-2/
Yet another study was found on the same control area, by the same author, published in the journal "Fluoride". There we learn that mean urinary fluoride levels were 2.38 mg/L, indicative of a much higher intake than a 0.3 ppm area would provide. Hence, intake is comparable to that from an area with a fluoride water content of between 2 and 3 ppm.
https://fluoridealert.org/wp-content/up ... d-2012.pdf
UPDATE 3, Dec 3, 2023
In a new review on fluoride effects on thyroid function (Iamandii et al., 2023), the researchers further confused the "units issue" by presenting data for Free T3 in μg/dL, and for Free T4 as nmol/L, mixing up the units as presented in the original paper.
- Iamandii I, De Pasquale L, Giannone ME, Veneri F, Generali L, Consolo U, Birnbaum LS, Castenmiller J, Halldorsson TI, Filippini T, Vinceti M - "Does fluoride exposure affect thyroid function? A systematic review and dose-response meta-analysis" Environ Res 117759 (2023) doi: 10.1016/j.envres.2023.117759
https://www.sciencedirect.com/science/a ... 512302563X
viewtopic.php?f=7&t=5624
SEE: PFPC Commentary: viewtopic.php?f=7&t=5624&p=6453#p6453