Fluoride at twice recommended limit linked to lower IQ in kids: U.S. report

A U.S. government report expected to stir debate concluded that fluoride in drinking water at twice the recommended limit is linked with lower IQ in children.

A U.S. government report expected to stir debate concluded that fluoride in drinking water at twice the recommended limit is linked with lower IQ in children.

The report, based on an analysis of previously published research, marks the first time a federal agency has determined — “with moderate confidence” — that there is a link between higher levels of fluoride exposure and lower IQ in kids. While the report was not designed to evaluate the health effects of fluoride in drinking water alone, it is a striking acknowledgment of a potential neurological risk from high levels of fluoride.

Fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the U.S. Centers for Disease Control and Prevention. The addition of low levels of fluoride to drinking water has long been considered one of the greatest public health achievements of the last century.

“I think this (report) is crucial in our understanding” of this risk, said Ashley Malin, a University of Florida researcher who has studied the effect of higher fluoride levels in pregnant women on their children. She called it the most rigorously conducted report of its kind.

The long-awaited report released Wednesday comes from the National Toxicology Program, part of the Department of Health and Human Services. It summarizes a review of studies, conducted in Canada, China, India, Iran, Pakistan, and Mexico, that concludes that drinking water containing more than 1.5 milligrams of fluoride per liter is consistently associated with lower IQs in kids.

The report did not try to quantify exactly how many IQ points might be lost at different levels of fluoride exposure. But some of the studies reviewed in the report suggested IQ was two to five points lower in children who’d had higher exposures.

Since 2015, federal health officials have recommended a fluoridation level of 0.7 milligrams per liter of water, and for five decades before the recommended upper range was 1.2. The World Health Organization has set a safe limit for fluoride in drinking water of 1.5.

The report said that about 0.6 per cent of the U.S. population — about 1.9 million people — are on water systems with naturally occurring fluoride levels of 1.5 milligrams or higher.