What is it about?
There have recently been high-profile claims that being exposed to fluoride harms children's IQ. However, the evidence used to support that claim has generally been of very low quality; has not come from representative samples in the United States; and has often considered dosages of fluoride far exceeding what is relevant for public policy debates. Using data on 10,000+ members of the Wisconsin high school class of 1957, we find no evidence that fluoride exposure --- at levels relevant for decision-making about community water fluoridation --- has any relationship to adolescent IQ or adult cognition.
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Why is it important?
Ours is the first U.S.-based study to use population representative data to examine a very important question: Is it true, as some have claimed, that exposing children to fluoride through community water fluoridation harms their IQ? If so, that would have to be weighed against the benefits of the practice (e.g., improved dental health). However, we find no evidence that adolescent fluoride exposure harms IQ or longer-term cognition.
Perspectives
I came to this study agnostic about what we would find. I was surprised by the poor quality of existing evidence on the question, and was curious to see what we'd learn from better data.
John Warren
University of Minnesota Twin Cities
Read the Original
This page is a summary of: Municipal water fluoridation, adolescent IQ, and cognition across the life course: Evidence from the Wisconsin Longitudinal Study, Proceedings of the National Academy of Sciences, April 2026, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2536005123.
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