Disputed review claims link between fluoride levels, childhood IQ loss

New study links fluoride in water to lower IQ in children, sparking debate over safety and benefits.

A divisive new study out on January 6 in a US medical journal could reignite debate over fluoride’s safety in water, linking higher exposure levels to lower IQ in children.

Published in the Journal of the American Medical Association (JAMA) Pediatrics, it has sparked pushback from some scientists who criticise the study’s methods, defend the mineral’s proven dental benefits, and warn the findings may not directly apply to typical US water fluoridation levels.

Its release comes as President-elect Donald Trump prepares to take office. His health secretary nominee, Robert F. Kennedy Jr., is a vocal critic of fluoridated water, which currently serves nearly two-thirds of the population.

Researchers from the National Institute of Environmental Health Sciences (NIEHS) reviewed 74 studies on fluoride exposure and children’s IQ conducted in 10 countries including Canada, China, and India.

The same scientists helped formulate an official government recommendation in August that there is “moderate confidence” that higher levels of fluoride are linked to lower IQ scores.

Now, the team led by Kyla Taylor said the new analysis found a “statistically significant association” between fluoride exposure and reduced IQ scores.

Specifically, the study estimates that for every 1 mg per litre increase in urinary fluoride — a marker of overall exposure — children’s IQ drops by 1.63 points.