A major new U.S. study suggests that children exposed to the amount of fluoride typically added to public water may actually perform slightly better on cognitive tests in adolescence — contradicting Florida’s recent decision to ban fluoridation statewide.
The study, published in Science Advances, looked at a large group of U.S. students and checked how much fluoride they drank from birth through high school. They then compared this to how the students did on math, reading and vocabulary tests.
Kids who drank the amount of fluoride typically added to public water (about 0.7 milligrams per liter) scored a little better than those who drank less.
The cognitive advantage was smaller by age 60 and not statistically significant, but researchers found no evidence of long-term harm, showing that fluoride at recommended levels is safe.
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The study, which was funded by the National Institutes of Health, used student data originally sampled in 1980, with a cognitive follow-up conducted around 2021, when many participants were about 60 years old.
Researchers analyzed 57,960 students for adolescent cognitive outcomes and followed 13,260 of them around age 60 to assess midlife cognition.
The researchers took into account factors such as family income, race, where students lived, and whether they lived in urban or rural areas. Researchers used records of municipal water fluoridation and naturally occurring fluoride in groundwater to classify children as consistently exposed, partially exposed or unexposed to fluoridated water.
“Our results cast doubt on the idea that typical fluoride exposure reduces cognitive performance and suggest it may even have modest benefits during adolescence,” said the study's lead author, John R. Warren, of the Minnesota Population Center at the University of Minnesota.
Florida lawmakers cited concerns over neurodevelopmental risks when deciding to remove fluoride from all public water systems. The law went into effect on July 1. Studies cited by state Surgeon General Dr. Joseph Ladapo, including one from the National Toxicology Program, warned that fluoride could harm IQ and behavior in children and fetuses.
Calling fluoridation "forced medication," Gov. Ron DeSantis emphasized families still had the choice to get fluoride through toothpaste, mouthwash, dental visits and elsewhere.
Critics of the ban argue that much of the research cited by Florida officials focuses on fluoride levels far above those typically found in U.S. water. Public health experts warn that eliminating fluoride could reverse decades of progress in preventing tooth decay.
While Florida’s ban reflects caution over potential toxicity, the new evidence suggests those concerns may not apply to the levels Americans have historically received. The study highlights the importance of basing public health policy on research grounded in the exposure levels people actually experience.
“This research contradicts the rationale for the Florida ban,” Warren wrote. “Typical levels of fluoride in U.S. water are safe for children and may support academic achievement.”
