A major new study has put one of the most widely circulated health fears of recent years to rest, finding that exposure to fluoride in drinking water during childhood has no effect on IQ or cognitive function at any point in life. Researchers from the University of Minnesota, the University of Wisconsin, and the University of Michigan examined community water fluoridation levels in Wisconsin going back to the 1940s and tracked the outcomes of more than 10,000 residents, following their test scores through school and then administering multiple cognitive assessments when participants were between 53 and 80 years old. The team found no difference in cognitive performance between people who grew up drinking fluoridated water and those who did not. The study was published in the Proceedings of the National Academy of Sciences, one of the most respected scientific journals in the world.
The findings arrive at a particularly timely moment, as several states have recently enacted bans on fluoride in public water supplies amid widespread public concern about its safety. The lead researcher said he was motivated to conduct the study specifically because he was disappointed by the quality of evidence being cited to support the claims linking fluoride to lower IQ, and he wanted to answer the question properly. His results, which align with a separate large study published the previous year that also found no connection, suggest that decades of water fluoridation at levels used in the United States have not harmed cognitive development. Fluoride has long been recognized as one of the most effective public health tools ever deployed, credited with dramatically reducing tooth decay across the population and named by the CDC as one of the ten greatest public health interventions of the 20th century.
