A study published in Science Advances has found that children exposed to recommended levels of fluoride in drinking water show better cognitive performance in adolescence, contradicting recent concerns about fluoride’s potential neurodevelopmental risks.

The research, led by Dr. John Robert Warren from the University of Minnesota, analyzed data from nearly 27,000 Americans tracked from high school in 1980 through age 60, making it the first large-scale U.S. study to examine fluoride exposure at levels actually encountered through community water fluoridation.

Students consistently exposed to fluoride at the recommended level of 0.7 milligrams per liter throughout childhood performed modestly better on standardized tests of mathematics, reading, and vocabulary in high school compared to peers without fluoride exposure. The cognitive advantage measured approximately 7% of a standard deviation—small but statistically significant and consistent across all three academic measures.

​The research utilized data from the High School and Beyond cohort study, which began tracking a nationally representative sample of U.S. high school students in 1980. Researchers characterized fluoride exposure by examining historical records of municipal water fluoridation practices and naturally occurring fluoride levels in groundwater from the U.S. Department of Health and Human Services and U.S. Geological Survey.​

Participants were categorized into three groups: those consistently exposed to sufficient fluoride levels (at or above 0.7 mg/L) throughout childhood, those with partial exposure due to changes in local fluoridation policies, and those never exposed to recommended levels. 

Importantly, fluoride exposure showed no negative effects on cognitive function when participants were reassessed at age 60.

The research is significant given the debate surrounding water fluoridation policy in the United States. Florida and Utah recently became the first states to ban the practice, and Health and Human Services Secretary Robert F. Kennedy Jr. has called fluoride “an industrial waste” and advocated for reducing federal fluoridation recommendations.​

Much of the recent concern stems from a National Toxicology Program report that found associations between high fluoride exposure and reduced IQ in children. However, that analysis examined fluoride concentrations at least twice the recommended U.S. level and lacked sufficient data to evaluate effects at the 0.7 mg/L concentration currently recommended by the Centers for Disease Control and Prevention.​

The National Toxicology Program itself acknowledged that “there were insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ.”

The Warren study’s findings align with other recent research conducted at exposure levels relevant to U.S. policy. A University of Queensland study published in December 2024 found no negative association between early-life fluoride exposure and cognitive neurodevelopment among 357 Australian participants, with those consistently drinking fluoridated water scoring slightly higher on IQ tests.

The research team noted that their observational study cannot definitively establish causality, but their results provide strong evidence that exposure to fluoride benefits adolescent cognition and is not harmful to later-life cognitive functioning.