First US Study of Fluoride Neurotoxicity Finds Significant Risk To Developing Brain

Government funded study found mothers with higher fluoride exposure had children with double the risk of neurobehavioral problems

When you add this to all the other studies that have been done on this subject…[it] suggests that the impact of fluoride on neurobehavioral development problems is causal.”

— Howard Hu, MD, MPH, ScD

NORTH SUTTON, NEW HAMPSHIRE, U.S.A, May 20, 2024 / — A study published in the Journal of the American Medical Association (JAMA) today found that in fluoridated Los Angeles, the children of mothers with higher fluoride exposures during pregnancy had double the odds of several neurobehavioral problems compared to mothers with lower exposures. This is the first-ever study of fluoride neurotoxicity conducted in the United States. It was funded by the National Institutes of Health (NIH) and the US Environmental Protection Agency (EPA), reports the Fluoride Action Network.

This represents the 10th consecutive NIH-funded study in humans finding adverse effects of fluoride on children’s developing brains. The previous studies were in Canada and Mexico and consistently found lowering of IQ or increased risk of behavioral problems like ADHD associated with early life exposure to fluoridated water or fluoridated salt.

This latest study was conducted by researchers based at the University of Southern California on a cohort of mothers and children called the MADRES cohort.

Fluoride exposures during pregnancy were assessed from measurements of urinary fluoride in the first and third trimesters. The study found that urinary fluoride levels were almost identical to those found in Canadian and Mexican studies where the main source of fluoride was artificial water fluoridation or salt fluoridation, respectively.

Behavioral problems in the children were assessed at 3 years of age with a widely-used method called the Child Behavior Checklist (CBCL). The types of behavioral problems assessed by the CBCL are classified into two types, “internalizing” and “externalizing”:

“Internalizing problems sums the Anxious/depressed, Withdrawn-depressed, and Somatic complaints scores; Externalizing problems combines Rule-breaking and Aggressive behavior. There also is a Total problems score, which is the sum of the scores of all the problem items.”

The MADRES cohort showed a significantly increased risk of total and internalizing problems as fluoride exposure increased. All seven of the CBCL problem sub-scales increased with increasing fluoride exposure, with Somatic Complaints and Emotionally Reactive increasing the most, by 20% and 14%. None decreased.

Similarly, the study adapted CBCL scores to five subscales used in the American Psychiatric Association’s DSM-5 (Diagnostic & Statistical Manual of Mental Disorders) to assess behavioral problems and found all five types of behavior problems increased as fluoride increased. Autism and Anxiety symptom scores increased the most. An increase of maternal urine fluoride during pregnancy of 0.68 mg/L was associated with a significant 19% increase in Autism Spectrum problems.

FAN’s Science Director, Chris Neurath, noted “This is the first rigorous study to look at fluoride and autism symptoms, so it is concerning that it suggests a link. Its findings bolster reports of individuals with autism whose symptoms are made worse when drinking fluoridated water or other sources of fluoride.”

The study controlled for many potentially confounding factors, thereby increasing confidence that fluoride was the cause of the increased behavioral problems. When controlling for prenatal lead exposure, the increased odds of behavior problems went from a doubling to as much as quadrupling.

In a press release, Lead author Dr. Ashley Malin, said: “Our findings are noteworthy, given that the women in this study were exposed to pretty low levels of fluoride—levels that are typical of those living in fluoridated regions within North America. There are no known benefits to the fetus from ingesting fluoride, and yet now we have several studies conducted in North America suggesting that there may be a pretty significant risk to the developing brain during that time.”

Malin’s comments are especially relevant after the publication of two large studies from England, the CATFISH study and the LOTUS study, which found virtually no dental benefit from fluoridated water. Neither found any benefit for those in low socio-economic status groups. (1)(2)

The paper’s authors urged expectant mothers in their release to avoid drinking unfiltered tap water, “This is all critically important for pregnant persons, because…fluoride can cross the placenta and the blood-brain barrier, which can harm the developing brain of the fetus, said Tracy Bastain, Ph.D.” She added, “Eliminating that from drinking water is probably a good practice.”

The published paper emphasized that this is not an isolated study, but the most recent in a large number of studies consistently finding that fluoride harms the developing brain:

“Taken together, the weight of the scientific literature supports an association of prenatal fluoride exposure with adverse child cognitive and neurobehavioral development in North America.”

They cite the National Toxicology Program’s recent systematic review, which has identified over 70 human studies of fluoride and IQ, with 90% of them finding a significant reduction in IQ. Among the 19 highest quality studies—many with exposures in the range found in fluoridated communities—18 found reductions in IQ; a 95% consistency. (3)

FAN’s Executive Director, Stuart Cooper, pointed out that “It’s shameful that it has taken this long for a study of fluoride’s effect on the brain of children to be done here in the US. In other countries studies were being conducted decades ago and they were consistently finding problems. The US is the birthplace of fluoridation and one of the few countries still practicing it, but our government avoided research, perhaps out of fear of what it would find. Fluoridation proponents have even used the absence of a US study to dismiss the findings of the studies from other countries.”

Cooper points out that in FAN’s ongoing lawsuit in federal court against the EPA seeking to prohibit adding fluoride to drinking water, “EPA argued that extrapolating from other countries to the US was not possible. It was never a valid argument, and this new study should put that misinformation to rest.” (4)

Cooper added “A federal ruling in our lawsuit is expected soon. This new study further confirms that parents must not expose a child’s developing brain to fluoride, and the only way this is possible is if policy makers end water fluoridation immediately.”

Large communities like State College (PA), Collier County (FL), and Union County (NC) have recently ended fluoridation.

(4) 17-CV-02162-EMC (KAW) Food & Water Watch, inc. et al. v. EPA, et al.

Stuart Cooper
Fluoride Action Network
[email protected]
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CDC Oral Health Director: We Have No Safety Data on Fluoride and the Brain

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