- Over 100 animal studies showing that prolonged exposure to varying levels of fluoride can damage the brain, particularly when coupled with an iodine deficiency, or aluminum excess;
- 41 human studies linking moderately high fluoride exposures with reduced intelligence;
- 30 animal studies reporting that mice or rats ingesting fluoride have an impaired capacity to learn and/or remember;
- 12 studies (7 human, 5 animal) linking fluoride with neurobehavioral deficits (e.g., impaired visual-spatial organization);
- 3 human studies linking fluoride exposure with impaired fetal brain development.
Based on this accumulating body of research, several prestigious reviews — including a report authored by the U.S. National Research Council and a meta-analysis published by a team of Harvard scientists – have raised red flags about the potential for low levels of fluoride to harm brain development in some members of the population.
The NRC Review (2006)
In 2006, the National Research Council (NRC) stated that “it is apparent that fluorides have the ability to interfere with the functions of the brain.” In addition to calling for U.S.-based research on fluoride’s IQ effects, the NRC expressed concern about fluoride’s possible contribution to dementia. According to the NRC:
“Studies of populations exposed to different concentrations of fluoride should be undertaken to evaluate neurochemical changes that may be associated with dementia. Consideration should be given to assessing effects from chronic exposure, effects that might be delayed or occur late-in-life, and individual susceptibility.”
EPA’s Neurotoxicology Division Review (2007)
In 2007, scientists from the Neurotoxicology Division of the U.S. Environmental Protection Agency identified fluoride as having “substantial evidence” of “developmental neurotoxicity.” A developmental neurotoxin is a chemical that can damage the young, developing brain.
The EPA scientists based their conclusion on studies showing that fluoride exposure during pregnancy can damage the brain of the offspring. Consistent with EPA’s assessment, three studies from China have found that the brain of the human fetus can be significantly damaged by the mother’s high fluoride intake. While the safe dose for preventing this effect is not yet known, some adults in western countries have higher urinary fluoride levels of fluoride than the mothers in the Chinese studies (=4.3 ppm). (Mansfield 1999; Yu 1996; Dong 1993).
Harvard Review (2012)
In July of 2012, a team of Harvard researchers published a “meta-analysis” of 27 studies that have investigated the relationship between fluoride and human intelligence. (Choi 2012) The overwhelming majority of these studies found that fluoride exposure was associated with reduced IQ in children. In fact, 26 of the 27 studies that met the Harvard team’s inclusion criteria found a relationship between elevated fluoride and reduced IQ. The Harvard team thus concluded that fluoride’s effect on the developing brain of children should be a “high research priority” in countries like the U.S. where, despite mass fluoridation programs, no studies have yet been conducted to investigate the issue.
As noted by Dr. Philippe Grandjean, an environmental health scientist at the Harvard School of Public Health:
“Fluoride seems to fit in with lead, mercury, and other poisons that cause chemical brain drain. 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.”
Harvard Scientist Criticizes Wichita Paper’s Whitewash of Fluoride/IQ Study
Dr. Philippe Grandjean, the senior scientist on the Harvard team, has criticized the Wichita Eagle for deceptively attributing its own conclusions on fluoridation to the Harvard scientists. Fluoridation’s potential to produce “chemical brain drain,” Grandjean writes, is an issue that “definitely deserves concern.”
Decrease of Iodine Intake Found in Americans
The iodine status of Americans has changed significantly over the past 20 years, according to a Centers for Disease Control and Prevention (CDC) study published in October’s Journal of Clinical Endocrinology and Metabolism. While there were concerns in the 1970’s and 1980’s about possible high iodine intake, a laboratory indicator
The Facts About Fluoride & Human Intelligence
Ingestion of fluoride has been linked to reduced intelligence in 37 studies of human populations. Despite calls by the National Research Council and a team of Harvard scientists to take these findings seriously, American fluoridation proponents are cavalierly dismissing the warnings based on misleading, and even demonstrably false, claims.
NRC (2006): Fluoride’s Neurotoxicity and Neurobehavioral Effects
The NRC’s analysis on fluoride and the brain.
Fluoride’s Direct Effects on Brain: Animal Studies
The possibility that fluoride ingestion may impair intelligence and other indices of neurological function is supported by a vast body of animal research, including over 40 studies that have investigated fluoride’s effects on brain quality in animals. As discussed by the National Research Council, the studies have consistently demonstrated that fluoride, at widely varying concentrations, is toxic to the brain.
Fluoride Affects Learning & Memory in Animals
An association between elevated fluoride exposure and reduced intelligence has now been observed in over 30 studies of human populations. Although a link between fluoride and intelligence might initially seem surprising or random, it is actually consistent with a large body of animal research. This animal research includes the following 30
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Fluoride & the Brain: An Interview with Dr. Phyllis Mullenix
The following interview with Phyllis Mullenix took place on October 18, 1997. The interviewer is Paul Connett. I. ACADEMIC BACKGROUND Connett: We’re talking with Dr. Phyllis Mullenix, who in 1995, published a very important work on the neurotoxic effects of fluoride in rat studies. And Phyllis would you begin by telling us your