A new report once again raises the question of whether there is a link between fluoride in drinking water and lower IQ levels in children.
The research, published in JAMA Pediatrics on Monday, is a review of 74 other studies exploring how the mineral may affect children’s IQ levels.
The analysis found a statistically significant association between higher fluoride exposure and lower children’s IQ scores. It showed that “the more fluoride a child is exposed to, the more likely that child’s IQ will be lower than if they were not exposed,” Kyla Taylor, author of the study and a health scientist at the National Institute of Environmental Health Studies at the National Institutes of Health, wrote in an email. Taylor was not available for an interview.
For every small increase of fluoride found in kids’ urine, Taylor wrote, “there is a decrease of 1.63 IQ points in children.”
The researchers did not suggest that fluoride should be removed from drinking water. According to the study authors, most of the 74 studies they reviewed were low-quality ones. All were done in countries other than the United States, such as China, where researchers analyzed fluoride levels in water and in urine. Fluoride levels in China and other countries tend to be much higher than in the U.S., the researchers noted.
Fluoride has been added to public water supplies in the U.S. for decades. No studies in the U.S. have flagged any measurable decreases in children’s cognitive development since fluoride was introduced.