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 Perspectiveson July 20, 2012.
The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which would be approximately equivalent to sevenIQpoints 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.”
Indeed, the following video interviewing National Research Council scientists, a Nobel laureate in medicine, a professor of dentistry and other professionals summarizes the evidence fairly succinctly … and makes the case that our understanding of the damage fluoride can cause to our brains is like our growing understanding in the 1970s of the dangers of lead:
[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.