A recent report from the National Toxicology Program (NTP) has linked high levels of fluoride exposure to reduced IQ in children, sparking renewed debate about the safety of water fluoridation. The report, released on August 21, reviewed 72 studies on fluoride’s impact on cognition and found that 64 of them showed a consistent association between high fluoride exposure and lower IQ scores.

The NTP report highlights fluoride concentrations above 1.5 mg/L as posing the greatest risk, a threshold set by the World Health Organization (WHO). In contrast, the United States has varied limits, with the EPA allowing up to 2 mg/L in drinking water and the FDA recommending a lower threshold of 0.7 mg/L. An estimated 1.9 million Americans are currently exposed to drinking water with fluoride levels above 1.5 mg/L, putting many children at risk for cognitive impairment, according to the report.

Fluoride has been added to public drinking water since 1945 as a measure to prevent tooth decay. While the practice has been widely praised for its dental benefits, growing concerns about its neurodevelopmental impact have sparked calls for change. The NTP report also noted potential links between fluoride and other cognitive issues, though the evidence was less conclusive.

In May, another study suggested that prenatal fluoride exposure could lead to neurobehavioral problems in children, further fueling concerns. However, the American Dental Association (ADA) continues to endorse water fluoridation, citing its long-standing effectiveness in reducing cavities.

As health experts debate the merits and risks of fluoride, the new report may prompt public health officials to reevaluate fluoridation practices, especially in communities with naturally high fluoride levels.