U.S. children exposed to fluoride concentrations typical of community water systems show “modestly better” cognitive performance in secondary school, according to a new national study.
Published Nov. 19 in Science Advances, the study—“Childhood fluoride exposure and cognition across the life course”—examined data from the nationally representative High School and Beyond cohort, which followed 26,820 students from more than 1,000 U.S. high schools. Researchers assessed fluoride exposure from conception through adolescence and compared cognitive outcomes in adolescence and again at around age 60.
“Our results provide 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,” the authors wrote.
While cognitive advantages were not statistically significant at age 60, point estimates remained positive.
The authors stressed that their observational study cannot prove causation, but their findings align with a broader body of research showing no adverse cognitive effects at fluoride levels typical of municipal water fluoridation.
Most earlier studies linking fluoride to lower IQ were conducted in regions of China, India and Iran, where natural fluoride levels are far higher than those in North American drinking water.
Public-health agencies in both Canada and the United States recommend an optimal fluoride concentration of 0.7 mg/L, a level the CDC and Health Canada state is safe and effective for reducing tooth decay.
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Political context
The study arrives amid ongoing political debate over fluoride and other public-health measures. U.S. Health Secretary Robert F. Kennedy Jr. has repeatedly questioned fluoride’s safety, describing it as neurotoxic in some public statements and has cited “gold-standard science” to justify policy reversals. Both Kennedy and President Donald Trump have leaned on preliminary or fringe studies to cast doubt on established evidence, according to scientists interviewed by AP News.
Researchers warn that political decisions have increasingly relied on weak evidence or anecdote, including claims about vaccines, acetaminophen use in pregnancy and water fluoridation.
“Until clear evidence exists that water fluoridation lacks public-health benefit or compelling evidence of harm … it seems foolhardy to interfere with a long-established and well-recognized public-health success,” wrote Dr. David Savitz of Brown University in an accompanying Science Advances editorial.
Public-health authorities continue to describe community water fluoridation as one of the most effective and equitable preventive oral-health measures. The Centers for Disease Control and Prevention names it one of the 10 great public-health achievements of the 20th century.