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A new study suggests that drinking water fluoride levels during pregnancy — even below WHO and EPA limits — may be associated with lower fluid cognition scores in children. Researchers found a notable drop in scores once fluoride concentrations exceeded 0.675 mg/L, well below the EPA's 4 mg/L maximum. The findings are sparking debate about whether current safety thresholds need a closer look.
A study published in the American Journal of Epidemiology found that prenatal exposure to fluoride in public drinking water — even at concentrations below WHO and EPA limits — is nonlinearly associated with lower fluid cognition scores in children. Researchers from Columbia University analyzed data from over 690,000 fluoride measurements and 2,514 children across 23 U.S. states, finding that cognitive scores dipped once fluoride levels exceeded 0.675 mg/L, a threshold just below the U.S. Public Health Service's recommended optimal level of 0.7 mg/L.
The effects appeared strongest in younger children (under age 7) and in boys, suggesting that early neurodevelopment may be a particularly sensitive window. Some experts are calling for a reassessment of the EPA's maximum contaminant level and potential fluoride mitigation at high-concentration sites — though others note that no effects were observed below the 0.7 mg/L recommended threshold, and that the dental benefits of fluoridation remain significant.
By the Numbers:
Why it matters: With tens of millions of Americans drinking water above the optimal fluoride threshold, these findings could inform public health guidance on water fluoridation. Experts emphasize that any policy reconsideration must carefully weigh potential neurodevelopmental risks against the well-established dental health benefits of fluoride.
