A Public Health Triumph—or a Cautionary Tale?
For decades, the story of fluoridation has been told as a triumph of modern science—a simple, inexpensive way to prevent tooth decay. In 1999, the U.S. Centers for Disease Control and Prevention listed community water fluoridation among the “Ten Great Public Health Achievements of the 20th Century.”
But every triumph deserves re-examination. Behind the tidy narrative lies a more complicated story—one that involves corporate influence, incomplete data, and an assumption of safety that may have blinded us to risk.
The Birth of a Chemical Cure
The practice began with H. Trendley Dean, a dentist with the U.S. Public Health Service. In the 1930s and 40s, Dean examined more than 7,000 children in 21 towns across the American West, where natural fluoride levels in drinking water varied widely. He discovered that levels up to one part per million of fluoride reduced tooth decay, while higher levels produced mottled or stained enamel—a condition he called dental fluorosis. It looked like a manageable trade-off: fewer cavities in exchange for a few white spots. And in mid-century America, when tooth decay was rampant, that sounded like progress.
Dean’s findings were published in 1942, and soon fluoride was hailed as a modern miracle. Yet even at the time, there were doubts. In 1944, the editor of the Journal of the American Dental Association, Dr. Pierce Anthony, called fluoridation “speculatively attractive” but warned that “the addition of a highly toxic substance to drinking water” carried potential dangers that had not been studied.
The following year, in 1945, the U.S. Public Health Service launched the first community trials—in Grand Rapids, Michigan (with Muskegon as a control), and in Newburgh, New York (with Kingston as its control). Dr. David Ast, the chief of the New York State Health Department Dental Bureau, assured the public that “special attention will be given to mental development and emotional stability” of exposed children. No such data were ever published; perhaps they were never collected. But they indicate that concerns about the potential impact of fluoride on brain development were recognized.
How a Public Experiment Became Policy
By the early 1950s, fluoridation was spreading rapidly. Following on the heels of DuPont’s massive marketing campaign, the postwar era was infatuated with chemistry as progress—“better living through chemistry”. The American Dental Association and the U.S. Public Health Service became its most enthusiastic promoters.
Tooth decay was a visible public problem; fluoridation offered an elegant, invisible solution. By 1960, over 50 million Americans were drinking fluoridated water.
But the toxicity of fluoride was defined narrowly—as dental fluorosis, not systemic harm. Few questioned whether a substance that could alter enamel formation might also affect other tissues. And no one—despite the assurance of Dr. David Ast—had tested for subtle developmental neurotoxicity.
By 1971, the National Institute for Dental Research launched a national caries-prevention program with fluoridation as its centerpiece. Decay rates did fall—but they also fell in unfluoridated countries such as Sweden, Denmark, and the Netherlands, where improvements in diet, hygiene, and dental care occurred at the same time. That should have prompted a deeper look. It didn’t.
Regulatory Inertia
Under the 1974 Safe Drinking Water Act, the U.S. Environmental Protection Agency was required to set standards for contaminants that may pose health risks. In 1986, the EPA set a maximum contaminant level of 4 mg/L for fluoride—a threshold intended to prevent severe dental fluorosis and skeletal fluorosis.
Two decades later, in 2006, the National Research Council reviewed the evidence and concluded that this standard was too high and failed to protect against bone fractures and other adverse effects. The committee also found “several lines of evidence” suggesting that fluoride may affect the brain, thyroid, and endocrine system. They recommended the EPA to lower its standard for the levels of fluoride in drinking water.
Nearly twenty years later, the agency has not acted.
Rising Fluorosis, Hidden Concerns
By 2010, rates of dental fluorosis in U.S. children had climbed dramatically. One CDC survey found that over 60 percent of adolescents had some degree of fluorosis—visible evidence of overexposure.
In 2015, the U.S. Public Health Service lowered its recommended level for community water systems from 0.7–1.2 ppm to a single value of 0.7 ppm. The official reason was aesthetic: to reduce mottled teeth.
Revisiting the Science We Thought We Knew
For decades, no one studied fluoride’s effects on the developing brain. That silence began to break in the 1990s with a pioneering—if controversial—study by Phyllis Mullenix at the Forsyth Dental Center in Boston. Using laboratory rats, Mullenix found that high concentrations of fluoride accumulated in brain tissue and altered behavior in ways consistent with neurotoxicity. Her study, published in Neurotoxicology and Teratology in 1995, suggested that early-life exposure could impair learning and memory.
The dental establishment dismissed her work, and Mullenix soon lost her position. But in retrospect, her findings foreshadowed what would emerge from human studies decades later.
In the early 2000s, researchers began studying children living in areas of China, India, and Iran with naturally elevated fluoride levels in water. These were simple, cross-sectional studies, often with limited controls and small sample sizes. Still, they pointed in a consistent direction: children exposed to higher fluoride concentrations scored lower on tests of intelligence.
Then, in 2012, Dr. Anna Choi and colleagues at Harvard published a meta-analysis of 27 such studies. Their conclusion was sobering: children in high-fluoride areas had, on average, seven points lower IQ than those in low-fluoride areas. Most of the studies were imperfect—many lacked individual exposure data—but the consistency of results was striking. It should have been a red flag that fluoride, long assumed to be safe, might affect the developing brain.
Recognizing these hints, a new generation of scientists began applying the same rigorous, prospective methods that Herbert Needleman and others had used to uncovered the dangers of lead.
In 2017, Dr. Morteza Bashash and colleagues found that higher prenatal fluoride exposure, measured in maternal urine, was associated with lower IQ in their children—affecting both boys and girls. Importantly, the urinary fluoride concentrations in Mexican mothers were later shown to be comparable to those of women living in fluoridated communities in North America.
Two years later, in 2019, our team published data from the Maternal-Infant Research on Environmental Chemicals (MIREC) study in Canada. Importantly, our studied was conducted in communities with and without optimally-fluoridated drinking water. We found that each 1 mg/L increase in maternal urinary fluoride—a measure of exposure during pregnancy—was associated with a 4.5-point decrease in IQ in boys. The pattern held when we looked at municipal water data: children whose mothers drank water with higher fluoride concentrations scored significantly lower on IQ tests than those whose mothers consumed less-fluoridated water.
In 2025, Taranbir Singh and his team in Bangladesh reported similar findings in a large, well-controlled study: children exposed to prenatal fluoride levels—often lower than those found in many fluoridated communities—showed measurable reductions in IQ.
By now, the evidence had become impossible to ignore. More than 75 human studies have examined the relationship between early-life fluoride exposure and IQ scores. Most—though not all—found an inverse association.
The Evidence That Changed the Equation
To clarify the growing debate, Dr. Kyla Taylor and colleagues at the National Toxicology Program conducted a systematic review of 74 studies from ten countries. After a series of rigorous external reviews, the draft report reached a clear conclusion: fluoride exposure is consistently associated with lower IQ scores in children. In the highest-quality studies, each 1 mg/L increase in urinary fluoride corresponded to an average 1.1-point decrease in IQ.
A one-point loss might sound trivial. It isn’t. As with lead, small shifts in the population mean have large social consequences: fewer gifted children, more needing special education, and a measurable reduction in lifetime earnings and national productivity. The EPA Science Advisory Board has acknowledged that a 1–2 point shift in average IQ can have profound public-health implications.
Then, in September 2024, federal judge Edward M. Chen reviewed the accumulated evidence in Food & Water Watch et al. v. U.S. Environmental Protection Agency, a case brought under the Toxic Substances Control Act. After hearing expert testimony and reviewing the NTP’s findings, he ruled that fluoridation of public water at 0.7 mg/L—the level considered “optimal” in the United States—“poses an unreasonable risk of reduced IQ in children.”
It was a historic decision—the first U.S. court ruling to recognize developmental neurotoxicity from community water fluoridation—and a turning point in a debate that had been frozen in certainty for seventy years.
The Hidden Inequity of Fluoridation
Fluoridation was promoted as an egalitarian measure—a way to protect poor children’s teeth. Yet it now appears that its burdens fall most heavily on the same families it was meant to help.
Formula-fed infants in fluoridated communities can receive up to 70 times more fluoride than breastfed infants, because breast milk naturally contains almost none. Wealthier families can avoid exposure by using filters or bottled water. Low-income families cannot.
A policy intended to narrow health disparities may instead be widening them.
The Science Caught in Time
The scientific foundation of fluoridation has not kept pace with modern knowledge. The 1954 National Academy of Sciences report assumed that water was the only major source of fluoride exposure. It did not account for fluoride in toothpaste, processed foods, tea, or pesticide residues—all of which now contribute to total intake. Nor did it consider effects on the brain.
We also know much more about fluoride’s mechanism. Its cavity-fighting benefit is mainly topical—from contact with tooth enamel—not from ingestion.
Numerous randomized controlled trials show that brushing with fluoride toothpaste reduces decay. But a RCT of systemic fluoride supplements given to pregnant women found no benefit for their children’s teeth. Swallowing fluoride does not appear to prevent cavities.
In 2024, a Cochrane Collaboration review of post-1975 studies—after widespread use of fluoride toothpaste—found that community water fluoridation was associated with only a 3–4 percent reduction in dental caries, a difference that was not statistically significant.
The Principle of Consent
British epidemiologist Geoffrey Rose once drew an important distinction:
“The situation is different where individuals have no choice to reject a preventive measure. They can buy toothpaste with or without added fluoride, but if fluoride is added to drinking water, they can hardly avoid imbibing it. We should expect a higher level of scientific evidence and popular acceptability for measures such as water fluoridation which are imposed and not chosen by the recipients.”
Exactly. When a measure is imposed on everyone, the burden of proof must be higher—not lower.
The Lesson We Keep Ignoring
The focus on fluoridation has diverted attention from other important determinants of dental health. Lead exposure, poor nutrition, and deficiencies in vitamin D also influence enamel formation. Promising alternatives—such as hydroxyapatite, the mineral that makes up tooth enamel—has been shown to reduce caries.
But for decades, fluoride was treated as the only tool we needed. Other paths were neglected.
Public health has a history of holding on too long. We minimized the risks of lead poisoning. Now we are doing the same with fluoride.
The evidence has shifted. The benefits of drinking fluoridated water are smaller than we once believed. The risks—especially to the developing brain—are now impossible to ignore.
Anyone who insists otherwise either hasn’t read the new research or chooses not to.
It’s time for a re-evaluation.
Coming Next
In the next part of this series, I’ll dive into the debate over the cohort studies and the National Toxicology Program’s review of fluoride and IQ—and explore why policy has lagged behind what the science now shows.
Original article online at: https://blanphear.substack.com/p/what-if-fluoride-was-never-safe