A U.S. government report has concluded, for the first time, that there is a link between fluoride in drinking water at levels twice the recommended limit and lower IQ in children. The National Toxicology Program’s report, released Wednesday, is based on an analysis of existing research and represents a significant acknowledgement of the potential neurological risks associated with high levels of fluoride exposure.
The report, which evaluated studies conducted in countries such as Canada, China, India, Iran, Pakistan, and Mexico, found that drinking water containing more than 1.5 milligrams of fluoride per litre is consistently associated with lower IQs in children. While the report did not quantify the exact impact on IQ, some studies suggested that children exposed to higher fluoride levels had IQs that were 2 to 5 points lower.
Fluoride is a mineral that strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the U.S. Centers for Disease Control and Prevention (CDC). For decades, the addition of low levels of fluoride to drinking water has been considered a major public health achievement, helping to prevent tooth decay across the population.
However, concerns have been growing over the potential impact of fluoride on brain development, particularly in fetuses and young children. Research has increasingly suggested that higher levels of fluoride exposure may affect neurochemistry and cell function in brain regions responsible for learning, memory, and behaviour. This has led some experts, like Ashley Malin, a University of Florida researcher, to suggest that pregnant women might want to reduce their fluoride intake from sources like water and certain teas.
The report has sparked renewed debate over the appropriate levels of fluoride in drinking water. Currently, federal health officials recommend a fluoridation level of 0.7 milligrams per litre, with the World Health Organization (WHO) setting a safe limit at 1.5 milligrams per litre. The U.S. Environmental Protection Agency (EPA) has a separate requirement that water systems should not exceed 4 milligrams of fluoride per litre to prevent skeletal fluorosis, a condition that weakens bones and causes pain.
The American Dental Association, which supports water fluoridation for its dental health benefits, has been critical of earlier drafts of the report and is still reviewing the latest findings. The report suggests that more research is needed to fully understand the impact of lower levels of fluoride on children’s development and to determine appropriate policy measures for managing fluoride exposure.