Harvard Study – Published in National Institute of Health Journal – Finds Fluoride Lowers Children’s IQ

Yet Another Government Report Finds that Fluoride Lowers IQ in Kids

The Harvard School for Public Health reports:

For years health experts have been unable to agree on whether fluoride in the drinking water may be toxic to the developing human brain. Extremely high levels of fluoride are known to cause neurotoxicity in adults, and negative impacts on memory and learning have been reported in rodent studies, but little is known about the substance’s impact on children’s neurodevelopment. 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 may adversely affect 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 [click for abstract] was published online in Environmental Health Perspectives on July 20, 2012.

Environmental Health Perspectives is a publication of the United States National Institutes of Health’s National Institute of Environmental Health Sciences.

Harvard’s announcement continues:

The researchers conducted a systematic review of studies, almost all of which are from China where risks from fluoride are well-established. Fluoride is a naturally occurring substance in groundwater, and exposures to the chemical are increased in some parts of China. 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.


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 but one study suggested that high fluoride content in water may negatively affect 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 suggested that even slightly increased 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. The children studied were up to 14 years of age, but the investigators speculate that any toxic effect on brain development may have happened earlier, and that the brain may not be fully capable of compensating for the toxicity.

“Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain,” Grandjean says. “The effect of each toxicant may seem small, but the combined damage on a population scale can be serious, especially because the brain power of the next generation is crucial to all of us.”

Numerous other government reports have shown fluoride’s adverse impacts on intelligence:

[A] 2006 National Academy of Science [report ] reviews the scientific studies which have been performed on fluoride, and concludes:

It is apparent that fluorides have the ability to interfere with the functions of the brain and the body by direct and indirect means. (bottom of page 222).

The NAS report also notes that fluoride may actually impair intelligence, and that more testing should be done in this regard.

Indeed, studies from around the world continue to find that exposure to sodium fluoride – especially in the very young – lowers IQ. See this and this. The same is true for rats exposed to fluoride. See this and this. And see the studies listed here.

Dr. Vyvyan Howard – a PhD fetal pathologist, who is a professor of developmental toxico-pathology at the University of Liverpool and University of Ulster, president of the International Society of Doctors for the Environment and former president of the Royal Microscopical Society and the International Society for Stereology, and general editor of the Journal of Microscopy – said in a 2008 Canadian television interview (short, worthwhile video at the link) that studies done in several countries show that children’s IQ are likely to be lower in high natural water fluoride areas.

He said that these studies are plausible because fluoride is known to affect the thyroid hormone which affects intelligence and fluoride is also a known neurotoxicant. Such studies have not been conducted in countries that artificially fluoridate the water such as the US, UK and Canada, but should be, he said.

And as the International Business Times noted last month on the newest Chinese study on fluoride:

Exposure to fluoride may lower children’s intelligence, says a study published in Environmental Health Perspectives, a publication of the National Institute of Environmental Health Sciences. Fluoride is added to 70 percent of U.S. public drinking water supplies.


About 28 percent of the children in the low-fluoride area scored as bright, normal or higher intelligence compared to only 8 percent in the “high” fluoride area of Wamaio.

In the high-fluoride city, 15 percent had scores indicating mental retardation and only 6 percent in the low-fluoride city. The authors of the study eliminated both lead exposure and iodine deficiency as possible causes for the lowered IQs.

One scientist – Jennifer Luke – alleged in a 2001 scientific article that fluoride accumulates in the brain (specifically, in the structure of the pineal gland) more than it accumulates in our bones. In other words, she implies that fluoride may accumulate more in the brain than in the teeth, doing more harm than good (here’s Luke’s 1997 PhD dissertation on the topic.)

The 2006 National Academy of Sciences report corroborates some of Luke’s allegations:

As with other calcifying tissues, the pineal gland can accumulate fluoride (Luke 1997, 2001). Fluoride has been shown to be present in the pineal glands of older people (14-875 mg of fluoride per kg of gland in persons aged 72-100 years), with the fluoride concentrations being positively related to the calcium concentrations in the pineal gland, but not to the bone fluoride, suggesting that pineal fluoride is not necessarily a function of cumulative fluoride exposure of the individual (Luke 1997, 2001). Fluoride has not been measured in the pineal glands of children or young adults, nor has there been any investigation of the relationship between pineal fluoride concentrations and either recent or cumulative fluoride intakes.

Donald Miller – cardiac surgeon and Professor of Surgery at the University of Washington – alleges:

Fluoride … inhibits the enzyme acetylcholinesterase in the brain, which is involved in transmitting signals along nerve cells.


Fluoride also damages the brain, both directly and indirectly. Rats given fluoridated water at a dose of 4 ppm develop symptoms resembling attention deficit-hyperactivity disorder. High concentrations of fluoride accumulate in the pineal gland, which produces serotonin and melatonin.


People with Alzheimer’s disease have high levels of aluminum in their brains. Fluoride combines with aluminum in drinking water and takes it through the blood-brain barrier into the brain. Dr. Russell Blaylock, MD, a neurosurgeon, spells out in chilling detail the danger fluoride poses to one’s brain and health in general in his book Health and Nutrition Secrets that can Save Your Life (2002).

Hat tip:  Paul Beeber.

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  • Eric B.

    See Fluoridation: The Battle of Darkness & Light, an exposure of the dangers of fluoride in drinking water which was published in 2003 (or earlier). It has links to 116 documents on the web (perhaps some now gone) providing supporting evidence. Of course, nothing has ever been done in the U.S. about these dangers, because of the well-known phenomenon of the “revolving door”, where industry officials regularly change places with government regulators, a.k.a. corruption. In 2006 the National Research Council of the National Academies published a report entitled Fluoride in Drinking Water (which may or may not be one of the reports cited in the article) which cited a Chinese study which reported that “the average IQ scores were lower in the more highly exposed [to fluoride in drinking water] children. This was due to fewer children in the high IQ range”, and said (on p.352): In light of the collective evidence on various health end points and total exposure to fluoride, the committee concludes that EPA’s MCLG [the Environmental Protection Agency’s maximum contaminant level goal] of 4 mg/L should be lowered. Did the EPA do anything? Or did the government regulators prefer to keep receiving the gestures of appreciation for good work provided by industry representatives?

  • Angus MacPherson

    One thing the Article does not mention is that Naturally Occurring Fluoride is Calcium Fluoride. The industrial waste chemicals that are forced on the American public are NOT Calcium Fluoride and are instead many times more toxic than natural sources. Plus these chemicals contain mercury, lead and has been shown recently, radioactive particles.

    Industrial Waste Fluoride is a Soft Kill Bioweapon against the American Public. Don’t believe me?
    Just TRY and have it removed from your town. They will ignore you, they will set you up, they will have detectives come to your door..and if you go into any local businesses to try and warn them or even ask how they filter their water, the police will be called on you (personal experience). In short, those in power will fight TOOTH AND NAIL to keep these chemicals in your water… to a degree that goes WAY beyond caring about kids teeth…
    It’s Eugenics, pure and simple.. Again, this is easy to see. Just TRY and have your city stop dumping this in the drinking water and see what Hell you will go through. Proof they are trying to kill us. Period.

  • John B.

    Even I find the topic interesting, I don´t see it can be as dangerous as for example Unhealthiest Fast Food Picks with tons of calories and chemical supplements. The problem is maybe the matter of choice. We can decide what we are gonna eat but we can´t do it with our drinking water. And I´m against buying the bottled drinking water since it fails in comparison with drinking water from tap.

  • tal

    Professor at Harvard is Being Investigated
    Federal investigators and Harvard University officials are probing whether a Harvard professor buried research suggesting a link between fluoridated tap water and bone cancer in adolescent boys

  • Bud

    If anyone thinks the article above or this site is merely a purveyor of ‘spooky fringe’ topics, check out all their disclaimers to the right of the comments section, National Security and Copyright Notices. They don’t list all of that for reader edification; each of these statements has a substantive legal purpose. Speaks volumes on our country, doesn’t it. The decline is no longer gradual…

  • Peter Davidson

    You claim that the studies only found a loss of an average “half an IQ point” caught my attention.
    I am informed by a medical scientist that this is not correct – that the measure used does not give results in IQ points, but uses a scale of “standardised, weighted mean difference”, in which one point equals 15 IQ points. The difference of 0.45 on this scale therefore equated to SEVEN IQ points.
    Could you please verify this claim and, if correct, amend your article accordingly?
    Many thanks,
    Peter Davidson

    • R. Weitz

      This article inaccurately reports the findings in an updated version of the article. The link posted above leads to an article that reads: “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.*

      * This sentence was updated on September 5, 2012.

  • christie9999

    I have 4 kids. When they were small ALL they drank was Kool Ade made with tap water, or plain old tap water. I think most families keep a fair amount of pop or juice in the house. We didn’t. I preferred fresh fruits or veggies to juice and never would buy pop. 3 of my 4 children have been in gifted classes throughout their school careers. My oldest daughter is a Senior in H.S. and the 1st time she took the ACT she scored a 29 without even going over practice tests. This is my same daughter that has fluorosis (an actual problem from excessive amounts of fluoride). My youngest said his goal this school year was to get straight A+’s in school (he’s always gotten straight A’s) and. so far he is succeeding, and in Advanced 7th grade classes mind you. My third