Fluoride is a neurotoxin

64 studies show fluoridation chemicals reduce children’s IQ
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One of the greatest investments we can make in Australia’s future is to nurture our young by reducing neurotoxic substances as much as possible. This article examines the neurological damage that fluoride can cause to the individual and to our society as a whole.
  • The parallels between the history and toxicology of lead and fluoride are remarkable. And fluoride is just as toxic or even slightly more toxic than lead;
  • Cigarettes are another interesting parallel;
  • The neurotoxicity of fluoride has been known since the 1930s;
  • A stream of scientific studies since then have confirmed the damage fluoridation chemicals cause to our brain;
  • In 2006, the US NRC said “it is apparent that fluorides have the ability to interfere with the functions of the brain.”
  • The most significant studies regarding the neurotixicity of fluoride are Green et al 2019, Bashash et al, 2017 and 2018; Thomas et al, 2018; Valdez Jiménez et al. 2017; Li et al, 2004;
  • There are numerous other studies supporting this claim and also demonstrating other neurological damage;
  • These neurotoxicity studies alone are enough for any responsible government to suspend fluoridation immediately, even before examining other studies showing further damage caused by fluoridation chemicals;
  • The precautionary principle is consistently ignored;
  • The neurotoxic effects on an entire population are extremely important and should not be overlooked by any society.
Interesting parallels

For each individual or for an entire nation, our minds are our most important asset. Therefore, for the benefit of our entire society, reducing neurotoxic substances should be a priority and indeed an investment in our nation’s future. But unfortunately, science has been slow to recognise potential neurotoxins, especially when they are supported by vested commercial interests, highly-biased and irrational political protection and an obstinate inability for health professionals to admit they have been wrong for so long.

Lead is a good example. For about as long as fluoride has been added to drinking water, Australia and other nations worldwide breathed hundreds of thousands of tonnes of this neurotoxic substance that was emitted into the atmosphere from leaded petrol.

This toxic air was imposed on our children, undoubtedly contributing to neurological damage and learning difficulties.

In “The Secret History of Lead”1, Jamie Kitman referred to a 1988 report to Congress on childhood lead poisoning in America. From that report, written by the US Agency for Toxic Substances and Disease Registry, Kitman states that “one can conservatively estimate that a total of about 68 million young children had toxic exposure to lead from gasoline from 1927 to 1987”. That’s just in the United States.

And yet the battle to have lead acknowledged as a neurotoxin and eventually removed from our fuel was a multi-decade marathon. In their study titled “The politics of lead toxicology and the devastating consequences for children”2, authors Rosner and Markowitz summed it up quite well:

“At virtually every step in the history of the uncovering of lead’s toxic qualities, resistance was shown by a variety of industrial interests to the association of lead and toxicity. During the first half of the last century, three primary means were used to undermine the growing body of evidence: first, the lead industry sought to control lead research by sponsoring and funding university research.
A second way was to shape our understanding of lead itself, portraying it as an indispensable and healthful element essential for all modern life. Lead was portrayed as safe for children to use, be around, and even touch.
The third way that lead was exempted from the normal public health measures and regulatory apparatus that had largely controlled phosphorus poisoning, poor quality food and meats and other potential public health hazards was more insidious and involved directly influencing the scientific integrity of the clinical observations and research. Throughout the past century tremendous pressure by the lead industry itself was brought to bear to quiet, even intimidate, researchers and clinicians who reported on or identified lead as a hazard.”

The parallels between the history and toxicology of lead and fluoride are remarkable. And it is even more disturbing given that fluoride is just as toxic or even slightly more toxic than lead.

Although nicotine may not be classed as an official neurotoxin, tobacco is another obvious example of heavily-biased commercial influence that protected the multi-billion-dollar cigarette industry, along with a pig-headed attitude from health professionals who failed to recognize or acknowledge the dangers of smoking for decades. Looking back now, it is astounding that from the early 1930s through to the 1950s, doctors and dentists publicly endorsed and promoted smoking with such brazen confidence, often featuring in cigarette advertising.

The historical evidence of fluoride’s neurotoxicity

Before examining the impact that a neurotoxin such as fluoride can possibly have on an entire population we should review several relevant studies.

It has long been suspected that fluoride may have the potential to damage the central nervous system and today the neurotoxicology of fluoride is one of the most active areas of fluoride research, although no studies of this kind have ever been conducted in Australia, New Zealand or even the United States. However more than 300 studies conducted elsewhere have confirmed that fluoride is a neurotoxin.

Kaj Roholm was a Danish scientist and researcher best known for his study of fluorine and fluoride toxicity. In 1937 he published Fluorine Intoxication: A Clinical and Hygienic Study, documenting the progression of fluorine poisoning in humans and animals including gastrointestinal upsets, bleeding gums, advanced cases of skeletal fluorosis, crippling arthritis and more importantly neurological disorders. As a result, Roholm was a strong opponent of water fluoridation. Even Henry Dean, dental researcher and one of the pioneers of water fluoridation hailed Roholm’s study as the “most outstanding contribution to the literature of fluorine.”

In the 1940s, Harold Hodge, a well-known toxicologist and first president of the US Society of Toxicology, conducted a study – the results of which were not released for 50 years – showing that fluoride had an adverse impact on an animal’s central nervous system. Hodge played a key role in promoting water fluoridation in the US, stating emphatically that it was safe, however he later admitted that his safety figures were wrong.

In 1978, George Waldbott et al published their paper; “Fluoride: The Great Dilemma”, where they highlighted a long list of fluoride sensitivity symptoms, including loss of mental acuity and ability to concentrate; depression, excessive nervousness, dizziness, tendency to lose balance and visual disturbances – all signs of the neurotoxicity of fluoride. The paper concludes with the quote; “Laymen, including those concerned with decisions on fluoridation, will be impressed by what seems to be the reasonableness of the case, oblivious to the omissions and obsolete presuppositions upon which much of it is based.”

Laymen, including those concerned with decisions on fluoridation, will be impressed by what seems to be the reasonableness of the case, oblivious to the omissions and obsolete presuppositions upon which much of it is based."

George Waldbott et al, "Fluoride: The Great Dilemma”

In the late 1980s, Chinese researchers began a series of studies that would continue to show the neurotoxic effect of fluoride, manifesting as reduced IQ in children living in villages with high levels of natural fluoride in the water.

In 1994, New Zealand doctor Bruce Spittle, who specialised in psychiatric medicine, published an article titled, “Psychopharmacology of Fluoride: A Review”3. In this paper Spittle suggested that chronic exposure to fluoride may be associated with cerebral impairment affecting particularly concentration and memory. He listed several possible mechanisms whereby fluoride could affect brain functioning, including “influencing calcium currents, altering enzyme configurations, inhibiting adenyl cyclase activity and increasing phosphoinositide hydrolysis.”

In 1995, Phyllis Mullinex, a leading toxicologist, was asked by the Forsyth Dental Centre in Massachusetts to examine the neurotoxic effects of several chemicals used in dentistry. Because of her work examining the toxic effects of drugs used to treat cancer in children and previous work in neurotoxicology, Mullinex was appointed chairperson of the first toxicology department in a dental school in the United States.

Mullinex led a team of researchers from several other US medical research institutions and they conducted extensive and rigorous animal studies, showing that fluoride fed to mother rats resulted in offspring that suffered from either malaise or ADHD-like symptoms, depending on whether the mother was given fluoride before or after birth. The studies also showed that fluoride accumulates in rat brains. Surprised by the results the tests were repeated and the findings were confirmed. Mullinex and her team concluded, “A generic behavioural pattern disruption as found in the rat study can be indicative of a potential for motor dysfunction, IQ deficits and/or learning disabilities in humans.”

The management of Forsyth Dental and no doubt other influential fluoride supporters did not expect or like the neurotoxic link that Mullinex discovered. Soon after her 1995 paper “Neurotoxicity of Sodium Fluoride in Rats”4 was accepted for publication, she was told that her work was “no longer relevant to dentistry” and she was sacked from Forsyth Dental. To this day, Australia’s National Health and Medical Council (NHMRC) still dismisses the studies by Phyllis Mullinex because they were conducted on rats. In fact all fluoride studies conducted on animals have been dismissed by NHMRC.

In 1998, a chemist and two psychologists (led by Julie A. Varner at Binghamton University, New York) and a neurotoxicologist from the Environmental Protection Agency, fed rats for one year using 1ppm sodium fluoride or 0.5ppm aluminium fluoride. The team discovered the rats had kidney damage, brain damage, elevated aluminium levels in the brain and increased deposits of ß-amyloid protein in the brain, similar to those seen in humans with Alzheimer’s disease.5

In 2004, Guan et al6 showed that fluoride inhibited nicotinic acetylcholine receptors (nAChRs) in the brain (in laboratory rats) – a crucial part of the nervous system. The association with Central Nervous System disorders has been researched by Dr. Agneta Nordberg, a Swedish neurotoxicologist and expert on nAChRs: “The [nAChRs] in the brain are important for functional processes, including cognitive and memory functions… The nAChRs are found to be involved in a complex range of central nervous system disorders including Alzheimer’s disease (AD), Parkinson’s disease, schizophrenia, Tourette’s syndrome, anxiety, depression, and epilepsy.”

In 2006, the US National Research Council (NRC) published the result of its major review of fluoride7 and stated, “it is apparent that fluorides have the ability to interfere with the functions of the brain.” In addition to calling for US-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.”

In 2007 the prestigious Lancet Neurology medical journal described fluoride as “an emerging neurotoxin” in this context, and as being “an obvious candidate” for being so.8

In 2008 a Scientific Consensus Statement9 identified that the developing brain is much more susceptible to neurotoxins than the adult brain. This is particularly so before six months of age, as the blood-brain barrier is not fully formed until that age. This places bottle-fed infants at particular risk if their formula is reconstituted with fluoridated water.

In 2011, a review on the neurotoxicity of fluoride titled, “Effects of fluoride on the central nervous system”10 was published. Lead author Luis Valdez-Jiménez concludes:

“Fluoride can accumulate in the body, and it has been shown that continuous exposure to it causes damaging effects on body tissues, particularly the nervous system directly without any previous physical malformations.”
“Several clinical and experimental studies have reported that the F induces changes in cerebral morphology and biochemistry that affect the neurological development of individuals as well as cognitive processes, such as learning and memory. F can be toxic by ingesting one part per million (ppm), and the effects are not immediate, as they can take 20 years or more to become evident.
The prolonged ingestion of F may cause significant damage to health and particularly to the nervous system. Therefore, it is important to be aware of this serious problem and avoid the use of toothpaste and items that contain F, particularly in children as they are more susceptible to the toxic effects of F.”

New Zealand doctor and researcher Bruce Spittle also conducted a review of the neurotoxicity of fluoride in 201111 and concluded; “there is no threshold for fluoride neurotoxicity in drinking water, and the only assuredly safe level is zero.”

A total of 33 fluoride-IQ studies have been conducted in China and they all identified a lowering of IQ with increasing fluoride exposure in children. Australia’s National Health and Medical Research Council have dismissed all of these studies because all except two of these studies involved water fluoride levels greater than the normal fluoride levels in Australia. The two exceptions were a study by Lin (1991)12 involving children with an iodine deficiency and another by Xiang (2003)13 which had a range from 0.57 milligrams per litre but a mean of 2.54 mg/L.

But as usual, NHMRC focuses on fluoride concentration and avoids this most relevant issue of daily dose. In this respect it is worth examining Xiang’s study further. While this study had a mean of 2.54 mg/L, the range was 0.57 to 4.5 mg/L and the lower end of this concentration range showed that a daily dose of 1.4mg per day is enough to lower IQ in children by a significant 5 points. Other studies have revealed that it’s easy for children in Australia and New Zealand to exceed 1.4mg/L of fluoride per day considering all the sources of fluoride.

It is astounding that NHMRC dismissed Xiang’s study above and refuses to consider any study not originally published in English. It is equally astounding that they also refuse to consider any animal studies, even though such studies are required by government regulatory agencies such as the US’s EPA and FDA. Animal studies are an essential component of a “weight of evidence” evaluation of the toxicity of a chemical substance or medical intervention. For more details, see our article: Can the NHMRC be trusted?

In July 2012, a team of 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.14 In fact 26 of the 27 studies, involving more than 8,000 school children, 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 US where, despite mass fluoridation programs, no studies have yet been conducted to investigate the issue. The authors also said that this risk should not be ignored, and that more research on fluoride’s impact on the developing brain is warranted.

The average loss in IQ was reported as a standardized weighted mean difference of 0.45, which is approximately equivalent to seven IQ points for commonly used IQ scores.

It is worth noting that children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas, with some studies suggesting that even slightly increased fluoride exposure could be toxic to the brain. The researchers suggested that any toxic effect on brain development may have occurred earlier, and that the brain may not be fully capable of compensating for the toxicity.

The review found a correlation between fluoride exposure and lowered IQ independent of other potential causes such as arsenic and low iodine. It further found that, from the geographical distribution of the studies and the local mineral content, it was unlikely that the effect was due to neurotoxicants other than fluoride.

“Although the studies were generally of insufficient quality, the consistency of their findings adds support to existing evidence of fluoride-associated cognitive deficits, and suggests that potential developmental neurotoxicity of fluoride should be a high priority for research.”

In March 2014, the prestigious Lancet Neurology journal published a review titled “Neurobehavioural effects of developmental toxicity”15 which concluded that fluoride is one of only 11 chemicals that is known to damage the developing brain. Developmental neurotoxins are capable of causing widespread brain disorders such as autism, attention deficit hyperactivity disorder, learning disabilities, and other cognitive impairments.  The harm is often untreatable and permanent.

“Our very great concern is that children worldwide are being exposed to unrecognized toxic chemicals that are silently eroding intelligence, disrupting behaviours, truncating future achievements, and damaging societies, perhaps most seriously in developing countries,” wrote Philippe Grandjea, author of the Lancet review.
“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,” said Grandjea.

In March 2017, the results of the first mother-infant pair study were released. Titled “In utero exposure to fluoride and cognitive development delay in infants”16, this study involved 65 pregnant women living in areas of high naturally occurring fluoride in the drinking water. Most of the fluoride levels were higher than Australian or New Zealand levels, nevertheless 33.8% of the births were pre-term and the authors noted that “cognitive alterations in children born from exposed mothers to fluoride could start in early prenatal stages of life.”

In September 2017, the results of the “Bashash” study17, a major 12-year, multi-million dollar study were published in the prestigious journal Environmental Health Perspectives. Titled “Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6–12 Years of Age in Mexico”, followed up to 299 mother-offspring pairs in Mexico over 12 years and reported that the fluoride levels in the urine of the pregnant women was the factor for a loss of 5 to 6 IQ points in the offspring at ages 4 and 6-12 years of age. The fluoride levels in the urine of the pregnant women are similar to what is found in adults in fluoridated communities in the US, Australia and New Zealand. This study and the following study by Thomas et al., was funded by the US National Institutes of Health, the US Environmental Protection Agency, and the US National Institute of Environmental Health Sciences. See our article: Fluoride and reduced IQ.

In March 2018, a study by Thomas et al titled “Prenatal fluoride exposure and neurobehavior among children 1–3 years of age in Mexico”18, reported that pregnant women’s fluoride exposure is linked to lower IQ in their children aged one to three years. The authors of this study said that their findings “suggest higher in utero exposure to fluoride has an adverse impact on offspring cognitive development that can be detected earlier, in the first three years of life.”

In October 2018 a study by Till et all19, found that pregnant women in “optimally” fluoridated Canada have significantly higher levels of fluoride in their urine than women in non-fluoridated communities. This study also showed that pregnant Canadians had fluoride urinary levels similar to those that reduced IQ in offspring from last year’s Bashash et al, 2017 NIH-funded study by 5 to 6 IQ points. These findings suggest that the Bashash results from Mexico City may be applied to Canada, and probably the U.S., namely that pre-natal exposure to fluoride has the potential to lower IQ in children.

In total, more than 100 animal studies have shown that prolonged exposure to varying levels of fluoride can damage the brain, particularly when coupled with an iodine deficiency, or an excess of aluminium, while 45 animal studies reported that mice or rats ingesting fluoride have an impaired capacity to learn and/or remember. A total of 53 human studies have linked moderately high fluoride exposures with reduced intelligence. Another 12 studies (seven human and five animal) linked fluoride with neurobehavioral deficits (eg, impaired visual-spatial organization). A further three human studies have linked fluoride exposure with impaired foetal brain development.

“there is no threshold for fluoride neurotoxicity in drinking water, and the only assuredly safe level is zero.”

Dr. Bruce Spittle, MB, ChB with distinction, DPM and author.
The neurotoxic effects of fluoride on an entire population

Human intelligence is often measured using “intelligence quotient” or “IQ” – a total score derived from several standardized tests. The abbreviation “IQ” was coined by the psychologist William Stern in 1912 from the German term Intelligenzquotient, for a scoring method for intelligence tests conducted at the University of Breslau.

When a population’s IQ scores are plotted on a chart, they invariably form a ‘bell curve’ distribution. This means that a population normally has an average IQ of 100 (the top of the bell curve) and around 70 per cent of the population scores between 85 and 115 – i.e. plus and minus one standard deviation of 15 points. At either extremes about 2.5 per cent of the population scores above 130, and 2.5 per cent below 70.

According to Achieve Australia, “Categories of mild, moderate, severe and profound levels of intellectual impairment are defined on the basis of IQ scores. A person is classified as having an intellectual disability if their IQ falls below 70”.

With an average IQ of 100, a drop in IQ of 5 or 6 points – the fall in IQ revealed in the Bashash study (5 or 6 six per cent of the average) – doesn’t seem like much. But for a whole population this is significant.

Why? Because this fall would effectively move the whole bell curve to the left, which means the average IQ would become 94 or 95 points. For the great majority of Australians this is not of major significance. A teacher for example, would not be able to identify the difference between a student with an IQ of 100, compared to a student with an IQ of 95. However, it is the extremes of the bell curve that will have major consequences for a society. Such a reduction across a population of 5 or 6 IQ points will halve the number of intellectually gifted people and increase by nearly 60 per cent the number of intellectually impaired people. What society can afford this consequence – even before considering all the other potential adverse health effects from fluoride?

This bell curve shows the influence of fluoride on a whole population with the halving of intellectually gifted children and increase by nearly 60% the number of intellectually impaired children.

History shows that we have been slow to recognise and acknowledge a number of neurotoxic substances, while advancements in science continue to reveal how sensitive the foetus, infant and child are to chemicals– especially effecting the development of the brain. It took decades for the science and medical communities to admit that lead could damage our health and yet scientists and doctors fought aggressively not to have it removed from widespread use.

There is already sufficient evidence to show the neurological impact of fluoride on the developing brain, even before the application of the precautionary principle. To continue defending fluoridation chemicals as safe and effective while arrogantly dismissing any study that shows the consequences to our society is, at best, highly irresponsible and certainly not an investment in our nation’s future.

“Right now we have 1 in 6 children in the U.S. with neurodevelopmental brain disease, including ADHD, Autism Spectrum Disorders, low IQ and behavioral disorders, and 1 in 8 women who will develop thyroid disease. These two epidemics tell us that chemicals like fluoride and lead, both developmental neurotoxins and endocrine disruptors, have no place in our public water."

Angela Hind MD

Reference notes:

  1. “The secret history of lead”, Jamie Lincoln Kitman. Part 1, published in The Nation, 20 March 2000. Available here.
  2. “The politics of lead toxicology and the devastating consequences for children”, Rosner and Markowitz, 2007. Abstract available here.
  3. “Psychopharmacology of Fluoride: A Review”, Dr. Bruce Spittle, February 1994. Available here.
  4. “Neurotoxicity of Sodium Fluoride in Rats”, Mullenix P.J. et al, March 1994. Abstract available here.
  5. “Chronic administration of aluminium-fluoride or sodium-fluoride on rats in drinking water: alterations neuronal and cardiovascular integrity.”, Varner, J.A. et al, February 1998, Brain Research 784, no.1-2. Abstract available here.
  6. “Decreased nicotinic receptors in PC12 cells and rat brains influenced by fluoride toxicity – a mechanism relating to a damage at the level in post-transcription of the receptor genes.” Guan, Z., et al, August 2004. Abstract available here.
  7. “Fluoride in Drinking Water: A Scientific Review of EPA’s Standards” (2006); Committee on Fluoride in Drinking Water, Board on Environmental Studies and Toxicology, US National Research Council. PDF available here.
  8. “Neurobehavioural effects of developmental toxicity,” Dr Philippe Grandjean, MD, Philip J Landrigan, MD, February2014, The Lancet Neurology. Available here.
  9. “Policy Implications Based on the Scientific Consensus Statement on Environmental Agents Associated with Neurodevelopmental Disorders” From the Learning and Developmental Disabilities Initiative, July 2008. Drafted and edited by: Steven G. Gilbert, PhD, DABT, Institute of Neurotoxicology and Neurological Disorders; Elise Miller, MEd, Institute for Children’s Environmental Health and the Collaborative on Health and the Environment’s Learning and Developmental Disabilities Initiative . PDF available here.
  10. “Effects of the fluoride on the central nervous system,” Neurologia, June 2011, Valdez-Jiménez L, et al. Abstract available here.
  11. “Neurotoxic effects of fluoride”, Dr Bruce Spittle, July 2011. Available here.
  12. “The relationship of a low-iodine and high-fluoride environment to subclinical cretinism in Xinjiang,” Lin F, et al 1991. PDF available here.
  13. “Effect of fluoride in drinking water on children’s intelligence,” Xiang et al, March 2003. Available here.
  14. “Developmental Fluoride Neurotoxicity: A Systematic Review and Meta-Analysis,” Anna L. Choi , Guifan Sun , Ying Zhang , and Philippe Grandjean. October 2012, Environmental Health Perspectives. Available here.
  15. “Neurobehavioural effects of developmental toxicity,” Grandjean, Philippe, and Philip J Landrigan. March 2014. PDF available here.
  16. “In utero exposure to fluoride and cognitive development delay in infants,” Valdez Jiménez et al, March 2017. Abstract available here.
  17. “Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6-12 Years of Age in Mexico,” Bashash M et al, Environmental Health Perspectives, September 2017. Available here.
  18. “Prenatal fluoride exposure and neurobehavior among children 1–3 years of age in Mexico,” Deena Thomas et al, March 2018, BMJ Occupational and Environmental Medicine. Abstract available here.
  19. “Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada,” Christine Till et al, October 2018, Environmental Health Perspectives. Available here.