Fluoride at twice the recommended limit is linked to lower IQ in kids, US government report says

FILE-A father and daughter drink from a water fountain. (Photo by Jeffrey Greenberg/Universal Images Group via Getty Images)

The federal government released a recent report stating that fluoride in drinking water at twice the recommended limit is linked to lower IQ in children. 

In a report from the National Toxicology Program, part of the Department of Human Services, the agency provides a summary of previously reviewed studies in Canada, China, India, Iran, Pakistan, and Mexico, finding that drinking water containing more than 1.5 milligrams of fluoride per liter is connected with lower IQs in kids, the Associated Press reported. 

RELATED: Drinking fluoridated water during pregnancy may lower children's IQs, study suggests

The report did not attempt to measure the amount of IQ points lost with varying levels of fluoride exposure. However, several studies evaluated in the report imply that IQ was 2 to 5 points lower in kids who had higher exposures to fluoride.

According to the AP, the 324-page report did not determine the dangers of lower levels of fluoride, explaining that more research is needed. The report also did not state what impact prominent levels of fluoride could have on adults.

In 2016, the National Toxicology Program began working on a review of studies that offered input on a need for fluoride-limiting guidance.

What is fluoride?

Fluoride is a mineral that exists naturally in water and soil. It also strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, the AP reported citing the Centers for Disease Control and Prevention.