We investigate associations between community water fluoridation (CWF), adolescent IQ, and cognition across the life course using representative data from the US state of Wisconsin. Exposure is inferred from historical records on community water fluoridation; adolescent IQ is ascertained from state testing records; and cognition in later life is assessed as part of the Wisconsin Longitudinal Study P. Herd et al. , Int. J. Epidemiol. 43 , 34–41 (2014).. In contrast to studies cited in recent decisions to end CWF in Utah, Florida, and elsewhere, we find no evidence that CWF is negatively associated with adolescent IQ or adult cognitive functioning.
Warren et al. (2026) studied this question.