Flouride in drinking water linked to lower IQ in children

A U.S. government agency released a report on Wednesday that linked fluoride in drinking water at twice the recommended limit to lower IQ in children.

The report came from the National Toxicology Program, which is part of the Department of Health and Human Services. The Associated Press (AP) said the report includes information from studies conducted in Canada, China, India, Iran, Mexico and Pakistan.

The report found that drinking water containing more than 1.5 milligrams of fluoride per liter is associated with lower IQs in children. That limit is above the recommended fluoridation level set at 0.7 milligrams per liter of water by federal health officials since 2015. However, the World Health Organization (WHO) set a safe limit for fluoride in drinking water at 1.5, according to the AP.

According to the U.S. Centers for Disease Control and Prevention (CDC), fluoride replaces minerals that are naturally lost and teeth, thus strengthening teeth and reducing the risk of cavities. The AP noted that adding low levels of fluoride to drinking water has been touted as a major public health achievement, though it’s had critics.

Ashley Malin, a University of Florida researcher who has studied higher fluoride levels in pregnant women, told the AP that the National Toxicology Program report “is crucial in our understanding” of the risks of high levels of fluoride.

The AP wrote that the report said approximately 0.6 percent of the population in the United States are currently using water systems that naturally have fluoride levels of 1.5 milligrams or more.

“The findings from this report raise the questions about how these people can be protected and what makes the most sense,” Malin said, per the AP.

However, the American Dental Association (ADA), a staunch supporter of water fluoridation, has been critical of previous studies linking fluoride to neurological effects. According to the AP, the organization is currently reviewing the National Toxicology Program’s findings.

Fluoride’s role in benefiting teeth health has been widely accepted since the mid-20th century, with Grand Rapids, Michigan, being the first U.S. city to add fluoride to tap water in 1945. In addition, federal officials endorsed water fluoridation to prevent tooth decay in 1950 and continued to promote it even after fluoride toothpaste brands hit the market several years later, the AP reported.

Today, drinking water remains the primary source of fluoride exposure for most Americans, according to researchers.

However, in 2015, health officials revised their fluoride recommendations, reducing the levels in drinking water to address fluorosis—a condition causing tooth discoloration that had become increasingly common among children in the United States.

Meanwhile, the Environmental Protection Agency (EPA) has upheld a strict standard, limiting fluoride levels in public water systems to no more than 4 milligrams per liter. This regulation is intended to prevent skeletal fluorosis, a debilitating condition characterized by weakened bones, stiffness and pain.