A 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 results also suggested that fluoride exposure also did not contribute to cognitive decline as they aged.
The study, which was funded by the National Institutes of Health, used data from about 27,000 students originally sampled in 1980, with a cognitive follow-up conducted around 2021, when most were about 60 years old.
Researchers found no evidence of long-term harm, showing that fluoride at recommended levels is safe.
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The study 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 assertion that exposure to recommended levels of fluoride reduce academic achievement or cognitive functioning," the study's authors wrote.
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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 researchers cited "strong evidence that exposure to fluoride — at levels ordinarily seen in the United States and of relevance to policy debates about municipal water fluoridation — has benefits for adolescent cognition and is, at worst, not harmful for later-life cognitive functioning."
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