A new government report links high fluoride exposure in drinking water to lower IQ in children.
The report, published by the Department of Health and Human Services’s National Toxicology Program, examined previously published research and found that drinking water containing more than 1.5 milligrams of fluoride per liter is associated with the lower IQs.
The report noted it was not designed to evaluate the health effects of fluoride in water, but the findings were made with “moderate confidence.”
Fluoride strengthens teeth and reduces cavities by adding minerals back into a person’s mouth that are lost during normal activity, according to the Centers for Disease Control and Prevention.
Low levels of fluoride added to drinking water has been considered one of the greatest public health achievements over the last 100 years, The Associated Press reported.
The report determined children have lower IQs after being exposed to high levels of fluoride after reviewing epidemiology studies in Canada, China, India, Iran, Pakistan and Mexico.
In those countries, some pregnant women, infants and children were exposed to fluoride higher than 1.5 milligrams per liter of drinking water.
The report didn’t say how many IQ points could be lost for being exposed to higher fluoride levels, but some studies suggested IQ can be 2 to 5 points lower in children who were exposed to high levels, the AP noted.
The U.S. Public Health Service currently recommends 0.7 milligrams per liter. About 0.6 percent of the U.S. population is on water systems that have 1.5 milligrams per liter, the report noted.
The report said it did not find high fluoride exposure to have an impact on adult cognition. It also said there is “insufficient data” to determine whether the United States’s 0.7 recommendation causes negative impacts on children.
“Many substances are healthy and beneficial when taken in small doses but may cause harm at high doses,” the report said. “More research is needed to better understand if there are health risks associated with low fluoride exposures.”
The report said its findings may be able to help provide information to regulatory agencies that set standards on the safety of fluoride.