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17h ago

Largest U.S. Study Finds No Cognitive Harm From Fluoridated Water, Notes Small Gains in Teen Achievement

A U.S. cohort study of nearly 27,000 people links policy-level exposure to modest gains in adolescent test scores without detecting cognitive harm in later life.

File photo: a public water tap (left) and U.S. Secretary of Health and Human Services (HHS) Robert F. Kennedy, Jr (right).
A new study found that young people exposed to fluoride at recommended levels performed better on cognitive tests than peers who did not have fluoride in drinking water.
Image
© SrideeStudio via Shutterstock

Overview

  • Published in Science Advances, the analysis matched High School and Beyond test results to historical fluoridation records and U.S. Geological Survey well data to estimate childhood exposure.
  • Students with full childhood exposure to recommended levels (about 0.7 mg/L) scored slightly higher in math, reading, and vocabulary, with effects around 7% of a standard deviation.
  • Follow-ups through 2021 found no statistically significant association between childhood exposure and global cognition around age 60.
  • The findings address earlier National Toxicology Program conclusions that linked higher exposures (at or above roughly 1.5 mg/L) to lower IQ while noting insufficient evidence at typical U.S. levels.
  • Researchers note limits such as inferred exposure from school location and test-score proxies for IQ, and they plan follow-up work using direct IQ measures; public-health bodies continue to endorse fluoridation as some states, including Utah and Florida, have banned it.