Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal

NEW YORK, July 24, 2012 /PRNewswire-USNewswire/ -- Harvard University researchers' rev...

Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal

NEW YORK, July 24, 2012 /PRNewswire-USNewswire/ -- Harvard University researchers' review of fluoride/brain studies concludes "our results support the possibility of adverse effects of fluoride exposures on children's neurodevelopment." It was published online July 20 in Environmental Health Perspectives, a US National Institute of Environmental Health Sciences' journal (1), reports the NYS Coalition Opposed to Fluoridation, Inc. (NYSCOF)

"The children in high fluoride areas had significantly lower IQ than those who lived in low fluoride areas," write Choi et al.

Further, the EPA says fluoride is a chemical "with substantial evidence of developmental neurotoxicity."

Fluoride (fluosilicic acid) is added to US water supplies at approximately 1 part per million attempting to reduce tooth decay.

Water was the only fluoride source in the studies reviewed and was based on high water fluoride levels. However, they point out research by Ding (2011) suggested that low water fluoride levels had significant negative associations with children's intelligence.

Choi et al. write, "Although fluoride may cause neurotoxicity in animal models and acute fluoride poisoning causes neurotoxicity in adults, very little is known of its effects on children's neurodevelopment. They recommend more brain/fluoride research on children and at individual-level doses.

"It's senseless to keep subjecting our children to this ongoing fluoridation experiment to satisfy the political agenda of special-interest groups," says attorney Paul Beeber, NYSCOF President. "Even if fluoridation reduced cavities, is tooth health more important than brain health? It's time to put politics aside and stop artificial fluoridation everywhere," says Beeber.

After reviewing fluoride toxicological data, the NRC reported in 2006, "It's apparent that fluorides have the ability to interfere with the functions of the brain."

Choi's team writes, "Fluoride readily crosses the placenta. Fluoride exposure to the developing brain, which is much more susceptible to injury caused by toxicants than is the mature brain, may possibly lead to damage of a permanent nature."

Fluoride accumulates in the body. Even low doses are harmful to babies, the thyroid, kidney patients and heavy water-drinkers. There are even doubts about fluoridation's effectiveness (2). New York City Legislationis pending to stop fluoridation. Many communities have already stopped.

Infant formula when mixed with fluoridated water delivers 100-200 times more fluoride than breastmilk. (3)


Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal

As of May 2013, a total of 43 studies have investigated the relationship between fluoride and human intelligence, and a total of 19 studies have investigated the relationship fluoride andlearning/memory in animals. Of these investigations, 37 of the 43 human studies have found that elevated fluoride exposure is associated with reduced IQ, while 19 of the 20 animal studies have found that fluoride exposure impairs the learning and memory capacity of animals. The human studies, which are based on IQ examinations of over 11,000 children, provide compelling evidence that fluoride exposure during the early years of life can damage a child’s developing brain.

After reviewing 27 of these studies, a team of Harvard scientists concluded that fluoride’s effect on the young brain should now be a “high research priority.” (Choi, et al 2012). Other reviewers have reached similar conclusions, including the prestigiousNational Research Council (NRC), and scientists in the Neurotoxicology Divisionof the Environmental Protection Agency (Mundy, et al).

Quick Facts About the 37 Studies:
  • Location of Studies: China (28), India (5), Iran (3), and Mexico (1).
  • Sources of Fluoride Exposure: 31 of the 37 IQ studies involved communities where the predominant source of fluoride exposure was water; six studies investigated fluoride exposure from coal burning.
  • Fluoride Levels in Water: IQ reductions have been significantly associated with fluoride levels of just 0.88 mg/L among children with iodine deficiency. (Lin 1991) Other studies have found IQ reductions at 1.8 ppm (Xu 1994); 1.9 ppm (Xiang 2003a,b); 0.3-3.0 ppm (Ding 2011); 2.0 ppm (Yao 1996, 1997); 2.1-3.2 ppm (An 1992); 2.3 ppm (Trivedi 2012); 2.38 ppm (Poureslami 2011); 2.45 ppm (Eswar 2011); 2.5 ppm (Seraj 2006); 2.85 ppm (Hong 2001); 2.97 ppm (Wang 2001, Yang 1994); 3.1 ppm (Seraj 2012); 3.15 ppm (Lu 2000); and 4.12 ppm (Zhao 1996).
  • Fluoride Levels in Urine: 12 of the 37 IQ studies have provided data on the level of fluoride in the children’s urine. 8 of these 12 studies reported that the average urine fluoride level was below 4 mg/l, and 6 reported average fluoride levels below 3 mg/L. To put these levels in perspective, a study from England found that 5.6% of the adult population in fluoridated areas have urinary fluoride levels exceeding 3 mg/L, and 1.1% have levels exceeding 4 mg/L. (Mansfield 1999) Although there is an appalling absence of urinary fluoride data among children in the United States, the excess ingestion of fluoride toothpaste among some young children is almost certain to produce urinary fluoride levels that exceed 2 ppm in a portion of the child population.
Harvard Study Finds Fluoride Lowers IQ - Published in Federal Gov't Journal

Methodological Limitations

As both the NRC and Harvard reviews have correctly pointed out, many of the fluoride/IQ studies have used relatively simple designs and have failed to adequately control for all of the factors that can impact a child’s intelligence (e.g., parental education, socioeconomic status, lead and arsenic exposure). For several reasons, however, it is extremely unlikely that these limitations can explain the association between fluoride and IQ.

First, some of the fluoride/IQ studies have controlled for the key relevant factors, and significant associations between fluoride and reduced IQ were still observed. This fact was confirmed in the Harvard review, which reported that the association between fluoride and IQ remains significant when considering only those studies that controlled for certain key factors (e.g., arsenic, iodine, etc). Indeed, the two studies that controlled for the largest number of factors (Rocha Amador 2007; Xiang 2003a,b) reported some of the largest associations between fluoride and IQ to date.

Second, the association between fluoride and reduced IQ in children is predicted by, and entirely consistent with, a large body of other evidence. Other human studies, for example, have found associations between fluoride and neurobehavior in ways consistent with fluoride being a neurotoxin. In addition, animal studies have repeatedly found that fluoride impairs the learning and memory capacity of rats under carefully controlled laboratory conditions. An even larger body of animal research has found that fluoride can directly damage the brain, a finding that has been confirmed in studies of aborted human fetuses from high-fluoride areas.

Finally, it is worth considering that before any of the studies finding reduced IQ in humans were known in the western world, a team of U.S. scientists at a Harvard-affiliated research center predicted (based on behavioral effects they observed in fluoride-treated animals) that fluoride might be capable of reducing IQ in humans. (Mullenix 1995)


When considering their consistency with numerous animal studies, it is very unlikely that the 37 human studies finding associations between fluoride and reduced IQ can allbe a random fluke. The question today, therefore, is less whether fluoride reduces IQ, but at what dose, at what time, and how this dose and time varies based on an individual’s nutritional status, health status, and exposure to other contaminants (e.g., aluminum, arsenic, lead, etc). Of particular concern is fluoride’s effect on children born to women with suboptimal iodine intake during the time of pregnancy, and/or fluoride’s effects on infants and toddlers with suboptimal iodine intake themselves. According to the U.S. Centers for Disease Control, approximately 12% of the U.S. population has deficient exposure to iodine.


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