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 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. All were done in countries other than the U.S., 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.
There has been a growing pushback against fluoridated water in a number of communities across the country. Some have already voted to remove fluoride from public water supplies.
Dentists worry the findings will be potentially damaging to public health.
“What we have seen, though, in areas where fluoride has been removed, is that dental decay rates have increased dramatically,” said Dr. Erica Caffrey, a pediatric dentist and chair of the American Academy of Pediatric Dentistry’s Council on Clinical Affairs.
Despite fluoride’s proven benefits in preventing tooth decay, some experts say any possible link to neurotoxicity in kids should be studied further.
“At a minimum, we need urgently to have an independent scientific panel come together to review the evidence,” said Dr. Bruce Lanphear, a professor of health sciences at Simon Fraser University in Canada.
The U.S. Public Health Service recommends a fluoride concentration of 0.7 mg/L of drinking water. NIH’s Taylor said there was not enough data to determine whether that level has any impact on kids’ IQs in the U.S.
Dr. Courtney Peterson, a pediatric dentist in private practice in Buffalo, New York, is concerned about the movement against the fluoride.
“I think people are going to freak out,” she said. “People are going to look at the headline and say high levels of fluoride will lead to a whole bunch (of problems) without actually looking into it.”
Still, the battle over fluoride is likely to strengthen under President-elect Donald Trump’s next term. His pick to lead the Department of Health and Human Services, Robert F. Kennedy, Jr., previously said without credible evidence that fluoride is “an industrial waste associated with arthritis, bone fractures, bone cancer, IQ loss,” and other problems. Kennedy later told NBC News that “fluoride is on the way out.”
A major sticking point in the debate of fluoride is that there’s never been a double-blinded, randomized, controlled clinical trial to examine how fluoride might affect children.
Researchers at the University of North Carolina, Chapel Hill, however, have begun a study of families with babies under 6 months old who use either fluoridated or nonfluoridated bottled water in their formula and drinking water. The plan is to follow the children for four years.