Developmental fluoride neurotoxicity: an updated review

This latest review includes 14 scientific studies conducted subsequent to the review performed by the Harvard School of Public Health in 2012 and confirms the cognitive damage of fluoridation chemicals.
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"The recent epidemiological results support the notion that elevated fluoride intake during early development can result in IQ deficits that may be considerable. Given that developmental neurotoxicity is considered to cause permanent adverse effects, the next generation’s brain health presents a crucial issue in the risk-benefit assessment for fluoride exposure.”
Philippe Grandjean
Head of the Environmental Medicine Research Unit at the University of Southern Denmark and Adjunct Professor of Environmental Health at the Harvard School of Public Health, Boston, USA

In 2012, a team of scientists in the Department of Environmental Health at the Harvard School of Public Health, Boston, Massachusetts, performed a systematic review and meta-analysis of published studies to investigate the effects of increased fluoride exposure and delayed neurobehavioral development.1

In total, the team identified 27 eligible epidemiological studies showing that children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas and supported the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.

This latest review2, (published 19 December 2019) was conducted by Philippe Grandjean, head of the Environmental Medicine Research Unit at the University of Southern Denmark and Adjunct Professor of Environmental Health at the Harvard School of Public Health, USA. The aim of this review was to conduct an integrated literature review on fluoride exposure and intellectual disability, focussing on studies on children published subsequent to the 2012 meta-analysis.

The review commenced by emphasising two important issues: “First, topical fluoride application in the oral cavity appears to be a more direct and appropriate means of preventing caries. Second, systemic fluoride uptake is suspected of causing adverse effects, in particular neurotoxicity during early development. The latter is supported by experimental neurotoxicity findings and toxicokinetic evidence of fluoride passing into the brain.”

The review included 14 recent cross-sectional studies from endemic areas with naturally high fluoride concentrations in groundwater, which supported the previous findings of cognitive deficits in children with elevated fluoride exposures. Three recent prospective studies from Mexico and Canada with individual exposure data showed that early-life exposures were negatively associated with children’s performance on cognitive tests. Neurotoxicity appeared to be dose-dependent, and tentative benchmark dose calculations suggest that safe exposures are likely to be below currently accepted or recommended fluoride concentrations in drinking water.

“The recent epidemiological results support the notion that elevated fluoride intake during early development can result in IQ deficits that may be considerable. Recognition of neurotoxic risks is necessary when determining the safety of fluoride-contaminated drinking water and fluoride uses for preventive dentistry purposes.

“Given that developmental neurotoxicity is considered to cause permanent adverse effects , the next generation’s brain health presents a crucial issue in the risk-benefit assessment for fluoride exposure.”

Peer reviewer reports and the author’s subsequent comments are available here.

  1. Developmental fluoride neurotoxicity: a systematic review and meta-analysis.
    Choi AL (a), Sun G, Zhang Y, Grandjean P. Environ Health Perspect. 2012 Oct;120(10):1362-8. doi: 10.1289/ehp.1104912. Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts.
  2. Developmental fluoride neurotoxicity: an updated review
    Philippe Grandjean; Environmental Health volume 18, Article number: 110 (19 December 2019)