While Portland, Oregon, the second-largest city in the country without fluoride in the water, is considering adding fluoride to their water supply, a Harvard study has been published stating that fluoride impacts children’s neurodevelopment.
The objective of the Harvard study was to perform a systematic review and meta-analysis of published studies to investigate the effects of increased fluoride exposure and delayed neurobehavioral development.
The researchers searched the MEDLINE, EMBASE, Water Resources Abstracts, and TOXNET databases through 2011 for eligible studies. They also searched the China National Knowledge Infrastructure (CNKI) database, as many oral health studies on fluoride neurotoxicity have been published in Chinese journals only.
Lead author Anna Choi, research scientist in the Department of Environmental Health at HSPH, states, “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 neurodevelopment.”
In total, the study identified 27 eligible epidemiological studies with high and reference exposures, endpoints of IQ scores or related cognitive function measures with means and variances for the two exposure groups.
The results of their study reveals that the standardized weighted mean difference in IQ score between exposed and reference populations was -0.45 (95% CI -0.56 to -0.35) using a random-effects model. Thus, children in high fluoride 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.
The study reviewed data based on exposure to high water fluoride levels — not levels found in U.S. drinking water, which is less than 1 part per million.
The study was published online in Environmental Health Perspectives on July 20, 2012.
Dentists, do you think there is a relationship between cognitive function and fluoride?