A meta-analysis assessing the relationship between children’s IQ and fluoride exposure revealed that increased fluoride exposure in pregnant women and young children correlates with a greater reduction in the children’s IQ.
This meta-analysis included 74 epidemiological studies and found a consistent pattern where increased fluoride exposure in pregnant women and young children correlates with lower IQ levels in children.
Published today in JAMA Pediatrics, the study was carried out by scientists from the National Institutes of Health’s (NIH) National Toxicology Program (NTP).
Accompanying the study, a commentary described this statistical meta-analysis as the most extensive and rigorous examination of fluoride’s impact to date, urging a reevaluation of systemic fluoride exposure.
The researchers globally reviewed studies, evaluating their quality and controlling for variables such as age, gender, fluoride concentrations, cognitive test types, methods of fluoride measurement, and study locations.
Their analysis identified a significant inverse relationship between fluoride exposure and children’s IQ scores, meaning that higher fluoride exposure during pregnancy or early childhood is associated with lower IQ scores.
Moreover, the study indicated that this negative effect is significant at both higher and lower levels of fluoride exposure across studies deemed to be of high quality.
Data were categorized into subgroups based on fluoride concentrations less than 4 milligrams/liter (mg/L), less than 2 mg/L, and less than 1.5 mg/L in both drinking water and urinary fluoride—which estimates total fluoride exposure.
For every 1 mg/L increase in urinary fluoride, a 1.63-point reduction in children’s IQ was observed, according to the study.
The findings were less definitive at lower exposure levels due to challenges in distinguishing exposure contrasts, the researchers noted.
The U.S. Public Health Service currently recommends a fluoride concentration of 0.7 mg/L in community water systems, a decrease from the previous range of 0.7-1.2 mg/L set in 2015.
In the U.S., an estimated 40-70% of fluoride intake derives from fluoridated water.
However, water fluoride levels alone likely underestimate total fluoride exposure, as individual behaviors such as water, coffee, or tea consumption, processed food intake, infant feeding choices, and use of fluoridated products like toothpaste or mouthwash also play significant roles.
This JAMA meta-analysis is part of ongoing research by NTP scientists that began in 2015, exploring the association between fluoride exposure and reduced IQ in children. The team published a monograph in August, and today’s meta-analysis provides comprehensive data on fluoride’s neurotoxic effects on brain development.
NTP’s publications emerged amid considerable opposition from fluoride advocacy groups, including the American Dental Association (ADA) and public health officials, who attempted to obstruct publication and influence the study’s conclusions.
This research underwent an unprecedented level of peer review, driven by political influences, as stated by the former head of the NTP.
The study’s results “may inform future comprehensive public health risk-benefit assessments of fluoride,” the authors concluded.
Amidst ongoing debates over water fluoridation, JAMA Pediatrics released the meta-analysis.
For decades, public health officials and dental advocates have promoted water fluoridation as a major public health success, dismissing skeptics as conspiracy theorists. However, as scientific knowledge about fluoride’s toxic impacts, particularly on children’s cognitive development, has advanced, the practice’s safety has been questioned. Originally, public health recommendations to add fluoride to water nearly 70 years ago did not account for these toxic effects.
Current guidelines for water fluoridation primarily address dental fluorosis risks—a discoloration condition caused by excessive fluoride exposure in childhood—impacting approximately 23% of the U.S. population. No guidelines or limits based on potential neurocognitive effects currently exist.
Yet, recent findings, including the NTP’s 2024 monograph, link higher fluoride levels in drinking water to lower IQ in children. Additionally, a May study in JAMA Network Open reported neurobehavioral issues in children born to mothers who drank fluoridated water in Los Angeles during pregnancy.
In September 2024, a landmark legal decision found that water fluoridation at current levels in the U.S. poses an “unreasonable risk” of lowering children’s IQ, prompting a federal judge to order the Environmental Protection Agency (EPA) to take regulatory action. This ruling concluded a prolonged lawsuit initiated by environmental and consumer groups and individual families advocating to stop water fluoridation.
Less than two weeks after the September 2024 ruling, Cochrane released an updated review indicating that the dental benefits of adding fluoride to drinking water are minimal, showing little difference from the effects observed 50 years ago.
Following this, numerous U.S. cities and towns have chosen to discontinue water fluoridation. The surgeon general of Florida has recommended that local governments cease the fluoridation of their water supplies, highlighting the neuropsychiatric risks, especially to pregnant women and children.
Robert F. Kennedy Jr., nominated by president-elect Donald Trump to head the U.S. Department of Health and Human Services (HHS), announced via social media that Trump intends to stop water fluoridation on his first day in office.
Kennedy’s statement prompted a series of mainstream media articles in defense of fluoridation, although some commentators admitted that traditional views on fluoride are due for reassessment.
The HHS includes the Centers for Disease Control and Prevention (CDC), which is responsible for setting guidelines on water fluoridation levels.
Two expert opinions clash
Dr. Steven M. Levy, a professor at the University of Iowa and member of the ADA’s National Fluoridation Advisory Committee, penned a harsh critique of the recent JAMA study, accusing its authors of selective research inclusion and analytical methods that “raise substantial concerns regarding the article’s validity and utility.”
Levy’s critique did not address the feedback from peer reviewers or any amendments to the study’s initial conclusions. His criticisms largely stemmed from the pressures he and the ADA committee applied, both publicly and privately, as revealed in documents obtained via Freedom of Information Act (FOIA) requests during the trial.
Levy heavily referenced a meta-analysis by Dr. Jayanth V. Kumar in his response, using it as a primary argument against the NTP’s conclusions. This analysis reported no link between fluoride and reduced IQ at low fluoridation levels.
Levy and Kumar, who are both on the ADA advisory committee, have long collaborated. According to emails exposed through public records requests, their study excluded contrary data and sought to discredit the NTP’s findings.
Michael Connett, the attorney for the plaintiffs in the fluoride case, described the commentary as an “ADA hit job,” suspecting Kumar was the main author, with Levy simply the named signatory, a fact that should have been disclosed, he argued.
Connett’s FOIA efforts revealed the ADA’s influence behind the scenes.
By referring multiple times to Kumar’s analysis without naming him, Levy appeared to be citing an independent authority. However, documents from the court case showed their longstanding partnership aimed at countering the NTP’s research.
Levy concluded that despite some indications of a “potential association” between high fluoride levels in water and IQ, current public health guidelines on fluoride should remain unaffected by these findings.
Dr. Bruce Lanphear, Pamela Den Beston, and Christine Till, who have conducted significant research on fluoride toxicity, contended that the JAMA meta-analysis underscores the need to reevaluate fluoride guidelines.
They noted that although tooth decay has decreased since the inception of water fluoridation in the U.S., similar declines have occurred in nations without fluoridation, likely due to fluoride toothpaste use and sugar reduction efforts—a strategy less emphasized in the U.S.
Their research indicated that fluoride prevents cavities primarily through topical application, not during tooth development as previously believed.
The CDC and ADA often cite studies claiming fluoridated water reduces cavities by 25%. However, the authors pointed out these figures are from older, lower-quality studies and highlighted the Cochrane review’s findings of negligible fluoridation benefits.
Lanphear and colleagues also discovered elevated urinary fluoride levels in pregnant Canadian women consuming fluoridated water.
Proponents argue water fluoridation is essential for protecting low-income children lacking regular dental care. Yet, the authors argue these children are also more susceptible to other neurotoxins like lead, making fluoridation potentially more harmful.
Given that NTP’s analysis linked fluoride exposure to potential cognitive impacts, they concluded, “Health organizations and regulatory bodies must reevaluate fluoride’s risks and benefits, particularly for pregnant women and infants.”
The EPA has until the end of the month to appeal the federal judge’s directive to create new regulations for water fluoridation based on its neurodevelopmental risks to children.