A U.S. government report has found that fluoride in drinking water at twice the recommended limit is associated with lower IQ in children, marking the first time such a link has been determined “with moderate confidence” by a federal agency.
The report, released by the National Toxicology Program, is based on an analysis of previously published research from multiple countries, including Canada, China, India, Iran, Pakistan and Mexico.
The big picture: Studies reviewed in the report suggest that drinking water containing more than 1.5 milligrams of fluoride per liter is consistently linked with lower IQs in kids, although the report did not quantify the exact number of IQ points lost at different levels of fluoride exposure.
- The federal health officials have recommended a fluoridation level of 0.7 milligrams per liter of water since 2015, and the World Health Organization has set a safe limit for fluoride in drinking water at 1.5 milligrams.
Go deeper: The report highlights that about 0.6% of the U.S. population, approximately 1.9 million people, are on water systems with naturally occurring fluoride levels of 1.5 milligrams or higher, raising questions about how these individuals can be protected.
- The report did not reach a conclusion about the risks of lower levels of fluoride, and it emphasized the need for more research, particularly concerning the impact of high levels of fluoride on adults.
