Major studies clearly show the neurological damage of fluoride

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In an effort to protect their unsubstantiated claims, proponents of water fluoridation consistently and irresponsibly refuse to acknowledge the clear and now indisputable fact: fluoridation chemicals damage the developing brain of our young. This article provides a summary of numerous major recent studies clearly showing the neurological damage caused by fluoride.
“The hypothesis that fluoride is a neurodevelopmental toxicant must now be given serious consideration…Exposure to fluoride has increased substantially in recent decades…If the effect sizes reported by Green et al and others are valid, the total cognitive loss at the population level that might be associated with children’s prenatal exposure to fluoride could be substantial.”
Harvard Professor David C. Bellinger
Download a summary here

As of December 2019, 64 studies have associated exposure to fluoridation chemicals with IQ loss in humans, while more than 60 studies have found that fluoride exposure impairs the learning and/or memory capacity of animals. Of the human studies, 62 were based on IQ assessments of 23,773 children, and two studies involved the IQ assessments of 245 adults. These studies provide compelling if not overwhelming evidence that fluoride exposure during the early years of life can damage a child’s developing brain.

Among this steady stream of science over 20 years, there have been five Mother-Offspring studies showing the relationship between maternal fluoride ingestion and subsequent lowered IQ in their children. However, the Green study (2019) is the first to compare fluoridated vs non-fluoridated cities in Canada, where fluoride-water levels are lower than in Australia. Other studies listed show the link between fluoride and ADHD, thyroid disorders, lowered IQ in formula-fed babies, and sleep disorders.

The five Mother-Offspring studies

1. Li et al., 2004; Effects of high fluoride level on neonatal neurobehavioral development. Published in the Chinese Journal of Endemiology in 2004; 23(5):463-5. Translated and republished in 2008 in Fluoride 41(2): 165-170.

The results showed that the urinary fluoride levels of mothers from the high fluoride group were higher than those of the control group. There were significant differences in the neonatal behavioural neurological assessment score and neonatal behavioural score between the subjects in the endemic fluoride areas and the control group. There were also significant differences in the non-biological visual orientation reaction and biological visual and auditory orientation reaction between the two groups.

“It is concluded that fluoride is toxic to neurodevelopment and that excessive fluoride intake during pregnancy can cause adverse effects on neonatal neurobehavioral development.”

2. Valdez Jiménez et al., 2017. In utero exposure to fluoride and cognitive development delay in infants. Published in Neurotoxicology Mar;59:65-70.

This study, involving 65 mother-offspring pairs in Mexico, showed lower IQ in the children between the ages of 3 to 15 months.

After adjusting for potential confounding factors (gestational age, age of child, marginalization index and type of water for consumption), the MDI [Mental Development Index] showed an inverse association with F levels in maternal urine for the first and second trimester.

“Our data suggests that cognitive alterations in children born from mothers exposed to F could start in early prenatal stages of life.”

3. Bashash et al., 2017; Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6–12 years of age in Mexico. Published in Environmental Health Perspectives on 19 September 2017.

 This multi-million-dollar study is the longest fluoride-IQ study conducted so far, with 299 mother-offspring pairs in Mexico. The study showed lower IQ in children 4 and 6 to 12 years of age.

The researchers measured urinary fluoride levels of pregnant women. The study found a strong correlation between total fluoride exposure to women during pregnancy and lowered IQ in their offspring at aged 4 years, and again at 6–12 years. In fact, the study reported that for every 0.5 mg/L increase of fluoride in the urine of the mothers there was a statistically significant decrease in average IQ of the children of about 3 IQ points. A fluoride level in urine of 1 mg/L could result in a loss of 5–6 IQ points.

“This is a very rigorous epidemiology study. You just can’t deny it. It’s directly related to whether fluoride is a risk for the neurodevelopment of children. So, to say it has no relevance to the folks in the U.S. seems disingenuous…”; Dr. Howard Hu, Professor of Environmental Health, Epidemiology and Global Health at the Dalla Lana School of Public Health, University of Toronto, and the study’s principal investigator.

4. Thomas et al., 2018; Prenatal fluoride exposure and neurobehavior among children 1–3 years of age in Mexico. Only the abstract of this study has been published in Occupational & Environmental Medicine, 18 March 2018;75:A10.

This study was based on 401 mother-offspring pairs in Mexico and measured urinary fluoride during pregnancy and its association with subsequent child neurobehavioral outcomes at ages 1, 2 and 3 years. The analysis controlled for maternal age, education, marital status, ‘ELEMENT’ cohort, child’s sex, and child’s age.

The study concluded; “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.”

5. Green et al., 2019; Association between maternal fluoride exposure during pregnancy and IQ scores in offspring in Canada. Published in JAMA Pediatrics, 19 August 2019.

This is the largest study conducted with 512 mother-offspring pairs, showing lower IQ in children 3–4 years of age.

The scientists assessed fluoride exposure in two ways. They measured fluoride in women’s urine samples during pregnancy. They also calculated fluoride consumption based on how much is in a city’s water supply and how much women recalled drinking. They found that a 1 mg/L increase in concentration of fluoride in mothers’ urine was associated with a 4.5 point decrease in IQ among boys, though not girls. However, when the researchers measured fluoride exposure based on the women’s fluid intake, they found lower IQs in both boys and girls: A 1 mg increase per day was associated with a 3.7-point IQ deficit in both genders.

The editors of JAMA Pediatrics admitted this study reversed their previous misconception that fluoridation was perfectly safe and only crazy people claimed it could be neurotoxic. The editor-in-chief said if his wife were pregnant he would advise her to avoid fluoridated water. Several experts equated the harm found from fluoride to that from childhood lead poisoning.

“The hypothesis that fluoride is a neurodevelopmental toxicant must now be given serious consideration…It is instructive to recall that the hypothesis that subclinical lead exposures pose a neurodevelopmental hazard was bitterly contested in the 1980s and 1990s, and it was only the weight of evidence that eventually accumulated that led to the now widely held consensus that no level of lead exposure is safe…If the hypothesis is true, the implications are worrisome. Exposure to fluoride has increased substantially in recent decades…If the effect sizes reported by Green et al and others are valid, the total cognitive loss at the population level that might be associated with children’s prenatal exposure to fluoride could be substantial.” Editorial by Harvard Professor David C. Bellinger, PhD, MSc.

Criticisms of the Green study are largely unfounded. For a response to criticisms of this study, click HERE.

Several studies link fluoride exposure to ADHD and thyroid problems and point to drinking water as the major source of exposure

6. Malin and Till, 2015; Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association. Published in Environmental Health, 2015.

This study involved data on ADHD prevalence among 4-17 year olds collected in 2003, 2007 and 2011 as part of the National Survey of Children’s Health, and state water fluoridation prevalence from the Centers for Disease Control and Prevention (CDC) collected between 1992 and 2008.

The study showed that each 1% increase in the prevalence of artificial fluoridation in 1992 was associated with approximately 67,000 to 131,000 additional ADHD diagnoses from 2003 to 2011.

“Parents reported higher rates of medically-diagnosed ADHD in their children in states in which a greater proportion of people receive fluoridated water from public water supplies. The relationship between fluoride exposure and ADHD warrants future study.”

7. Bashash et al., 2018; Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico City. Environ Int. 2018 Dec;121(Pt 1):658-666.

This study, funded by the US National Institute of Health and conducted by 14 researches from various universities in Canada, US and Mexico, found that mothers in Mexico with higher fluoride exposure during pregnancy were more likely to have children with symptoms of ADHD. This study was published in the journal Environmental International.

“Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention as measured by the CRS-R in the offspring.”

8. Till C, et al, 2018; Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada. Environmental Health Perspectives. 2018 Oct;126(10):107001.

Among 1,566 pregnant women in Canada, those living in fluoridated regions had almost double the fluoride levels in their urine compared with women in non-fluoridated regions.

“Community water fluoridation is a major source of fluoride exposure for pregnant women living in Canada.”

Findings from the above two studies suggest that the Bashash 2017 results from Mexico City can confidently be applied to Canada, the US and Australia, namely that pre-natal exposure to fluoride has the potential to lower IQ in children and emphasises the completely erroneous response from the American Dental Association that the Bashash 2017 study was not relevant to the US.

9. Malin et al., 2018; Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status. Published in Environment International; October 2018.

This large study is particularly relevant to Australia because it showed that Canadian adults who are iodine deficient and have higher fluoride exposure are at an increased risk of hypothyroidism.

The study involved health records of 6.9 million adults between the ages of 18 and 79 years. Adults who were diagnosed with a thyroid disorder, or who were on thyroid medication, as well as pregnant women, were excluded.

The study found that adults who are iodine deficient and have higher levels of fluoride in their system have a greater risk of an underactive thyroid. In fact 18 per cent of the 6.9 million adults they studied were iodine deficient. That’s potentially around 1.2 million people at risk of an underactive thyroid due to fluoride exposure. Hypothyroidism in pregnant women is known to lower IQ in their children.

“Prior studies investigating fluoride exposure and thyroid function among adults did not consider iodine status – an important modifying factor,” said lead author, Ashley Malin, post-doctoral fellow at the Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai in New York. “It was particularly important that we considered iodine status in this study because iodine deficiency is relatively common among adults in Canada.”

“I have grave concerns about the health effects of fluoride exposure. And not just from my study but the other studies that have come out in recent years,” said Malin.

10. Riddell et al., 2019; Association of water fluoride and urinary fluoride concentrations with attention deficit hyperactivity disorder in Canadian youth. Environment International; Oct 22, 2019.

This study, also conducted in Canada, found that higher tap water fluoride levels and fluoridation of municipal water supplies were associated with a higher risk of an ADHD diagnosis as well as increased symptoms of hyperactivity and inattention among children and teenagers but especially among adolescents. The study found that children living in areas with fluoridated water had almost triple the risk of having a diagnosis of ADHD as those who lived in non-fluoridated areas. This study confirmed previous studies linking fluoride to ADHD from Mexico and the USA [Malin 2015 and Bashash 2018].

“These findings, which point to a potential cumulative effect of fluoride exposure, highlight the need for further investigation of the potential for fluoride-mediated developmental neurotoxicity in populations with water fluoridation,” said the study’s lead researcher.

Formula-fed babies and lower IQ

11. Till, C et al., 2019; Fluoride exposure from infant formula and child IQ in a Canadian birth cohort. Environment International, Volume 134, January 2020, 105315 (available online on 16 November 2019).

This Canadian study showed that formula-fed babies in fluoridated areas averaged 4 IQ points lower compared with formula-fed babies in non-fluoridated areas. Typically, formula is reconstituted with tap water. Tests of non-verbal IQ showed even more dramatic effects, with an average loss of 9 points in the non-verbal component of IQ tests.

The average water fluoridation level in Canada is 0.6 mg/L, while the current average in the USA is 0.7mg/L. The average for Australia is around 0.8mg/L with a range of 0.6–1.1mg/L. When translated to typical water fluoridation levels in the USA of 0.7 mg/L, these findings suggest a loss of non-verbal IQ of 13 points for infants in fluoridated areas compared to those with low levels of fluoride in the water, so the IQ loss for Australia is probably higher.

“This study shows that not just pregnant women should be advised to avoid fluoridated water, their children should as well.”

Sleep disorders

12. Malin, A et al., Fluoride exposure and sleep patterns among older adolescents in the United States: a cross-sectional study of NHANES 2015–2016. Environmental Health volume 18, Article number: 106 (2019)

This study found that in adolescents aged 16-19 years living with fluoridated water, there was a doubling of symptoms indicative of sleep apnoea, compared with those with low fluoride water. There were also significantly later bed times and waking times in the adolescents with higher water fluoride levels.

The link between fluoride and sleep disturbances may be through fluoride’s effect on the pineal gland. This gland, situated in the brain, regulates sleep-wake cycles through the hormone melatonin. The pineal gland accumulates high levels of fluoride. Previous studies in animals suggested fluoride may alter melatonin levels [Luke 1997]. Alteration of sleep patterns may be a neurotoxic effect of fluoride separate from the loss of IQ and increased risk of ADHD due to earlier life exposures.

“Chronic low-level fluoride exposure may contribute to changes in sleep cycle regulation and sleep behaviours among older adolescents in the US.” Ashley J Malin


The scientific evidence that fluoridation chemicals are a neurotoxic hazard, especially for our young, is now overwhelming. If this surprises many Australian and New Zealand health professionals it is because they are not aware of the numerous studies and blindly accept and repeat the long-held, archaic, erroneous view that fluoridation is “safe and effective”. To continue to ignore or dismiss each accumulating piece of evidence can amount to negligence because the science is now undeniable.

Numerous experts now acknowledge that fluoride poses a similar risk for the developing brain as lead poisoning. In fact, around 30 years ago when leading researchers first started voicing concern that “low-level” lead was causing neurobehavioral harm in children, the existing scientific evidence to support that concern was weaker than science now available for fluoride. It took more than two decades for the CDC to finally respond to the evidence on “low-level” lead and reduce the “level of concern” to the 5 ug/dL blood lead level it currently stands at. How long will it take Australian health officials to realise that, for the sake of our children, fluoride does not belong in our water?

The accompanying podcast associated with the Green et al study (2019) contained the following exchange between Dimitri Christakis, MD, MPH, Editor in Chief, JAMA Paediatrics, and Frederick Rivara, MD, MPH, Editor in Chief of JAMA Network Open, for the August 19, 2019 issue:

Dimitri Christakis, MD, MPH, Editor in Chief JAMA Paediatrics
Frederick rivara
Frederick Rivara, MD, MPH, Editor in Chief of JAMA Network Open

DC: …in the meantime we are left with the challenge of how to advise pregnant women.
FR: So if mothers come into their doctor’s offices and ask the pediatrician what to do, what are you going to say?
DC: I think I would advise them to drink bottled water or filtered water because it’s not a particularly odious thing to do and it potentially does reduce the risk.
FR: Yeah. You know the other thing is that some people may not be able to afford bottled water – could be a financial burden to some low-income families and we need to think about that as well.

Listen to the entire JAMA Pediatrics Editors’ Summary here…