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The Adverse Effect of Fluoride on Children’s Intelligence: A Systematic Review
Helen Cheng and Richard Lynn
Published: 2013/06/01
Abstract
The authors conducted a systematic review on published studies to date to investigate the effect of fluoride exposure on children’s intelligence quotient (IQ) scores. PSYCHINFO, Web of Science, MEDLINE, SCI, and the China National Knowledge Infrastructure (CNKI) search engines were employed for all documents published up to 2012, in English and in Chinese. In total, 38 studies of fluoride exposure and children’s scores on IQ tests were included in this review. The weighted mean effect size (WMES) on children’s IQ scores between higher and lower regions of fluoride exposure was -.46 (CI 95% -.57 to -.35; p<.001) equivalent to 6.9 IQ points. Sensitivity analyses showed that after excluding studies that had other elements contaminations, the adverse effects of fluoride exposure on children’s intelligence remained to be significant. Further, six of the studies reported significant negative correlations between fluoride in the body and intelligence. The evidence suggests that fluoride in drinking water is a serious public health hazard.
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