Federal Report: Too Much Fluoride Can Lower Kids' IQs

The National Toxicology Program says it has determined—"with moderate confidence"—that there is a link between high levels of fluoride exposure and lower IQs in children. The report from the NTP, part of the Department of Health and Human Services, found that drinking water with more than 1.5 milligrams of fluoride per liter was associated with lower IQs in kids, the Hill reports. That's more than twice the current recommended maximum. The maximum recommended level was lowered from 1.2 to 0.7 in 2015 due to separate concerns about fluorosis, a cosmetic condition that causes splotches on teeth.

The AP calls the long-awaited report a "striking acknowledgment of a potential neurological risk from high levels of fluoride." The NTP reviewed studies from other countries, including Canada, China, and Iran. It said that out of 19 studies considered "high quality," 18 "reported an inverse association between estimated fluoride exposure and IQ in children." The report didn't say how many IQ points could be lost as a result of high exposure, but some of the studies involved said it could be between 2 and 5. According to the report, which did not address the effects of high fluoride levels in adults, around 0.6% of Americans, almost 2 million people, live in areas where naturally occurring fluoride levels in community water systems are higher than 1.5 milligrams.

Fluoride has long been added to water in many parts of the US to reduce tooth decay. "Many substances are healthy and beneficial when taken in small doses but may cause harm at high doses," NTP Director Rick Woychik said in a statement about the report. "More research is needed to better understand if there are health risks associated with low fluoride exposures." The report could influence a federal judge's upcoming ruling in the long-running Food and Water Watch vs. EPA case. In the case, Senior Judge Edward M. Chen "has to make a decision without deference to the EPA about whether fluoride poses an unreasonable risk to human health," Bloomberg Law reports. (More fluoride stories.)