Community water fluoridation and intelligence quotient: systematic review and meta-analysis of observational studies

The aim is to assess the current level of evidence of the association between community water fluoridation and intelligence. The method used for the study was a systematic review and meta-analysis of observational studies, to evaluate evidence of an association between exposure to community water fluoridation and intelligence using intelligence quotient (IQ) tests. Indexed databases PubMed/Medline, Embase, Scopus, Web of Science and reference lists of included articles were used. A meta-analysis with random effects models was performed and beta coefficients and pooled standardized mean differences (SMDs) and 95% confidence intervals of IQ scores were estimated in relation to water fluoridation. Of the 941 studies identified by the database search, three studies were included in the meta-analysis that used adjusted beta linear regression coefficients. There is no meta-analysis for adults because there is only one study for them. In the joint analysis, there was no association between exposure to fluoride in the water supply and IQ, for a linear regression coefficient (called β) of 1.01. Heterogeneity between studies was low. This meta-analysis underlines the safety of community water fluoridation concerning IQ's intelligence assessment.