A long-term study published in the Proceedings of the National Academy of Sciences reveals that exposure to community water fluoridation during childhood has no impact on intelligence or brain function in later life.
Researchers analyzed data from the Wisconsin Longitudinal Study, which has tracked 10,317 participants since 1957. The study compared cognitive test results at ages 16, 53, 64, 72, and 80 between those raised with fluoridated water and those who were not.
Rob Warren, a sociologist and population health expert at the University of Minnesota, led the research. He sought to determine if early-life fluoride exposure could lead to long-term cognitive consequences.
"I was curious about the short-term effects on adolescent cognition," Warren said, "but also cognitive functioning later in life."
Countering claims of neurotoxicity
The findings directly contradict recent assertions by U.S. Health Secretary Robert F. Kennedy Jr., who has described fluoride as "industrial waste" linked to decreased IQ.
Dr. Scott Tomar, head of the department of population oral health at the University of Iceland in Chicago, called the research "quite significant."
"I think that the public can be assured," Tomar said. "There is no association with community water fluoridation and any measure of IQ or neurodevelopment."
Opponents of fluoridation have cited smaller studies from China and other nations with much higher fluoride concentrations than the 0.7 milligrams per liter recommended by the CDC. These concerns have led to fluoride bans in Utah and Florida, with similar legislation pending in Kentucky, Louisiana, Missouri, and Oklahoma.
While the study provides robust evidence for the U.S. population, some experts noted limitations in the methodology. Dr. Bruce Lanphear, a professor at Simon Fraser University, noted that the researchers inferred exposure based on residence rather than measuring individual intake from toothpaste or diet.
"If you don’t measure individual exposure, you risk missing the real signal," Lanphear wrote in an email.