This article details the difference in intelligence between those with higher exposures to fluoride compared with those with smaller exposures. Additionally, I've been drinking well water for most of my life. I've noticed my city folk counter-parts who are part of the 77% of U.S. citizens who drink fluoridated water became dumber over the decades. The effect is very noticeable especially in the area of critical thinking skills; the difference is profound.
‘Impact of fluoride on neurological development in children’ ~ An article by Marge Dwyer published to Harvard T.H. Chan School for Public Health newsletter on July 25, 2012
In a meta-analysis, researchers from Harvard School of Public Health (HSPH) and China Medical University in Shenyang for the first time combined 27 studies and found strong indications that fluoride adversely affects cognitive development in children. Based on the findings, the authors say that this risk should not be ignored, and that more research on fluoride’s impact on the developing brain is warranted.
The study was published online in Environmental Health Perspectives on July 20, 2012.
The researchers conducted a systematic review of studies, almost all of which are from China where risks from fluoride are well-established. Virtually no human studies in this field have been conducted in the U.S., said lead author Anna Choi, research scientist in the Department of Environmental Health at HSPH.
Even though many of the studies on children in China differed in many ways or were incomplete, the authors consider the data compilation and joint analysis an important first step in evaluating the potential risk. “For the first time we have been able to do a comprehensive meta-analysis that has the potential for helping us plan better studies. We want to make sure that cognitive development is considered as a possible target for fluoride toxicity,” Choi said.
Choi and senior author Philippe Grandjean, adjunct professor of environmental health at HSPH, and their colleagues collated the epidemiological studies of children exposed to fluoride from drinking water. The China National Knowledge Infrastructure database also was included to locate studies published in Chinese journals. They then analyzed possible associations with IQ measures in more than 8,000 children of school age; all studies suggested that fluoride content in water negatively affects cognitive development.
The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which would be approximately equivalent to seven IQ points for commonly used IQ scores with a standard deviation of 15. Some studies found that even slight fluoride exposure could be toxic to the brain. Thus, children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.
“Fluoride fits in with lead, mercury, and other poisons that cause chemical brain drain,” Grandjean says. “The effect of each toxicant in minute exposures may seem small by itself, but the combined damage of typical exposures on a population scale has proven serious, especially because the brain power of the next generation is crucial to all of us.”
Read a September 2012 statement by the authors.
Learn more about the IQ measurements by HSPH’s Anna L. Choi and Philippe Grandjean in response to a letter to the journal published in the March 2013 (Vol. 121, No. 3) Environmental Health Perspectives.
Follow-up Fluoride Study Published
December 19, 2014 — As a follow-up, Philippe Grandjean, adjunct professor of environmental health at Harvard School of Public Health (HSPH), Anna Choi, research scientist in the Department of Environmental Health, and colleagues have published a pilot study of cognitive functions in Chinese children exposed to different levels of fluoride from drinking water.
The new paper, entitled “Association of lifetime exposure to fluoride and cognitive functions in Chinese children: A pilot study,” has been published online and in the January-February 2015 issue of Neuro-toxicology and Teratology.
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