Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis
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"Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis" is a 2012 study published in Environmental Health Perspectives by four well-qualified researchers (Anna L. Choi,[note 1] Guifan Sun,[note 2] Ying Zhang,[note 3] and Philippe Grandjean[note 4]) that has been mis-cited by anti-fluoridists for years.
In short: They were studying fluoride poisoning in China, and it's irrelevant to any debate over intentional water fluoridation.
In June of 2012, some news organizations transmitted a press release by the "NYS Coalition Opposed to Fluoridation, Inc." which suggested that a 2012 Harvard meta-study on the effects of water fluoridation and child IQs found "significantly lower IQ" in children. What a ghastly thing to see coming from real scientists, doing real science!
However, if you actually read the paper and look at Table 1, the study compared children in areas with recommended levels of fluoride in water — the same levels that are introduced in the process of water fluoridation (0.5 to 1.5 mg/L) — to children in areas with high fluoride levels (above 1.5 mg/L). In other words, and yet again, this paper documents the risks of chronic fluoride toxicity, not water fluoridation.
The authors of the original 2012 meta-analysis published an updated statement on the study in September of that year, underscoring this:
Our study summarized the findings of 27 studies on intelligence tests in fluoride-exposed children; 25 of the studies were carried out in China.
In general, complete information was not available on these 27 studies, and some limitations were identified.
So not only were the studies lacking complete information and were limited in scope (both of which greatly harm scientific replicatability), they were also all conducted in China, a country with severely lacking academic freedom from the state as well as having many places where ground water has exceeded safe amounts for consumption.
Fluoride released into the ground water in China in some cases greatly exceeded levels that are typical in the U.S.
That the fluoride levels in the Chinese studies had at times been elevated directly by industrial spills into the ground water supply means that other compounds could possibly have leaked into the water (that were not even looked for by the fluoride studies) and which may just as well — or better — explain the apparent reduction in IQ.
When considering the risks and benefits of fluoride exposure, the level of intake needs to be considered.
These results do not allow us to make any judgment regarding possible levels of risk at levels of exposure typical for water fluoridation in the U.S. On the other hand, neither can it be concluded that no risk is present.
That is to say, pro-fluoridation science does not recommend massive amounts of fluoride being added to water supplies. As with anything, the dose makes the poison. What is literally concluded by the study authors about their meta-analysis of the Chinese research is that it cannot be used to say anything about U.S. water fluoridation. Neither can it be used to demonstrate the harmful effects (or complete safety, to be fair) of municipal fluoridation as the study is better used to examine the effects of fluoride poisoning. So when this paper is quoted, let the authors of said paper have the last word — it is not relevant to the U.S. or to the supposed dangers of artificial fluoridation.
- Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis, PubMed Central
- Impact of fluoride on neurological development in children, Harvard School of Public Health
- Department of Environmental Health, Harvard School of Public Health, Boston
- School of Public Health, China Medical University, Shenyang
- School of Stomatology, China Medical University, Shenyang
- Institute of Public Health, University of Southern Denmark, Odense
- Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis by Anna L. Choi et al. (2012). Environ. Health Perspect. 120(10): 1362–1368. doi:10.1289/ehp.1104912. Full text of the paper.
- What the fuck is wrong with you, Reuters?(broken link)
- Mercola, J. (January 18, 2013). Harvard Study Confirms Fluoride Reduces Children’s IQ. The Huffington Post. Retrieved March 20, 2017.
- Seriously, even Wikipedia editors are sick of seeing that study and that Lancet one too, since they constantly say "refer to the archives" whenever those studies are brought up.
- Statement on Fluoride Paper by Anna Choi (September 11, 2012).