From somone named <Anonymous> on G+ i saw a link to a blogpost from a doctor about the dangers of fouride. that sounded interesting but potentially nutty (conspiracy nuts like such ideas). from reading the discussion at varius sites it was still unclear what i shud believe. so i downloaded the actual study cited and read it. its a pretty decent correlational systematic review. causation can be difficult to establish here, but ther shud be som natural experiments that can be used. for instance, som areas currently have high levels of flouride in the water for natural reasons. we can test the children of those areas, and then fix the drinking water by lessening flouride levels to those used in western countries, so about 1mg/L. then wait som years, like 10, and test som other children. if flouride is causing lowered IQ scores, they shud hav gone up by now. apply som stats to get rid of any potential Flynn effect. shud be somwhat easy to make this experiment in developing countries.
Ba c k g r o u n d: Although fluoride may cause neurotoxicity in animal models and acute fluoride
poisoning causes neurotoxicity in adults, very little is known of its effects on children’s neuro
oBj e c t i v e: We performed a systematic review and metaanalysis of published studies to investigate
the effects of increased fluoride exposure and delayed neurobehavioral development.
Me t h o d s: We searched the MEDLINE, EMBASE, Water Resources Abstracts, and TOXNET
databases through 2011 for eligible studies. We also searched the China National Knowledge
Infrastructure (CNKI) database, because many studies on fluoride neurotoxicity have been pub
lished in Chinese journals only. In total, we identified 27 eligible epidemiological studies with high
and reference exposures, end points of IQ scores, or related cognitive function measures with means
and variances for the two exposure groups. Using randomeffects models, we estimated the stan
dardized mean difference between exposed and reference groups across all studies. We conducted
sensitivity analyses restricted to studies using the same outcome assessment and having drinking
water fluoride as the only exposure. We performed the Cochran test for heterogeneity between stud
ies, Begg’s funnel plot, and Egger test to assess publication bias, and conducted metaregressions to
explore sources of variation in mean differences among the studies.
re s u l t s: The standardized weighted mean difference in IQ score between exposed and reference
populations was –0.45 (95% confidence interval: –0.56, –0.35) using a randomeffects model.
Thus, children in highfluoride areas had significantly lower IQ scores than those who lived in low
fluoride areas. Subgroup and sensitivity analyses also indicated inverse associations, although the
substantial heterogeneity did not appear to decrease.
co n c l u s i o n s: The results support the possibility of an adverse effect of high fluoride exposure on
children’s neurodevelopment. Future research should include detailed individuallevel information
on prenatal exposure, neurobehavioral performance, and covariates for adjustment.
ke y w o r d s: fluoride, intelligence, neurotoxicity. Environ Health Perspect 120:1362–1368
(2012). dx.doi.org/10.1289/ehp.1104912 [Online 20 July 2012]