THURSDAY, Aug. 22, 2024 (HealthDay News) — High levels of fluoride in drinking water may harm children’s intelligence, a new U.S. government report shows.

The potentially controversial report is based on analysis of published research and is the first time a U.S. federal agency has found a link between twice the recommended amount of fluoride and lower IQ in children.

“Since 1945, the use of fluoride has been a successful public health initiative to reduce tooth decay and improve overall oral health in adults and children,” the report said. “However, there is concern that some pregnant women and children may be consuming more fluoride than they need because they now obtain fluoride from many sources, including treated tap water, water-fortified foods and beverages, tea, toothpaste, dental floss, and mouthwash, and the total combined intake of fluoride may exceed safe levels.”

Importantly, “the finding of lower IQs in children was based primarily on epidemiological studies in countries outside the United States, such as Canada, China, India, Iran, Pakistan, and Mexico, where some pregnant women, infants, and children were exposed to total fluoride exposures exceeding 1.5 mg fluoride/L of drinking water,” the report’s authors explained. “The U.S. Public Health Service currently recommends 0.7 mg/L, and the World Health Organization has established a safe limit for fluoride in drinking water of 1.5 mg/L.”

One expert welcomed the results.

“I think this (report) is critical to our understanding” of that risk, said Ashley Malin, a researcher at the University of Florida who recently published a study on the effects of higher fluoride levels in pregnant women on their children, the Related Press.

The report did not attempt to quantify exactly how many IQ points might be lost with different levels of fluoride exposure, but some of the studies examined in the report suggested that IQ was 2 to 5 points lower in children exposed to higher levels of fluoride.

The report found that about 0.6% of the U.S. population — about 1.9 million people — are connected to water systems that naturally contain 1.5 milligrams or more of fluoride.

“The findings of this report raise the question of how these people can be protected and what makes the most sense,” said Malin.

The American Dental Association, which advocates water fluoridation, told the AP that the organization’s experts were still reviewing the report.

Fluoride is a mineral that occurs naturally in water and soil. Although it can come from a number of sources, drinking water is the primary source for Americans, the researchers said.

In 2015, U.S. authorities lowered their recommendation for fluoride levels in drinking water to counteract a dental disease called fluorosis, which can cause stains on teeth and is becoming increasingly common among American children. AP reported.

However, recent research has pointed to another problem: It suggests a link between higher fluoride levels and brain development. Animal studies showed that fluoride can impair cell function in brain regions responsible for learning, memory, executive functions and behavior. AP reported.

After further research continued to raise questions, the National Toxicology Program began an evaluation of available studies in 2016 in the hope that this could shed light on whether new measures to limit fluoride levels were needed.

“Because fluoride is such an important issue for the public and health authorities, it was imperative that we make every effort to accurately present the science,” Rick Woychik, director of the National Toxicology Program, told the AP in explaining the time required to complete the report.

More information

The National Institutes of Health has more information on fluoride.

SOURCE: National Toxicology Program, report, August 22, 2024; Related Press