Comment by JoshGG | Hacker News Reader

Comment by JoshGG | Hacker News Reader

Developmental fluoride neurotoxicity: an updated review

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923889/

Conclusion

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.

Environ Health. 2019; 18: 110. Published online 2019 Dec 19. doi: 10.1186/s12940-019-0551-x PMCID: PMC6923889PMID: 31856837 Developmental fluoride neurotoxicity: an updated review

Philippe Grandjeancorresponding author1,2 Author information Article notes Copyright and License information PMC Disclaimer 1Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115 USA 2Department of Public Health, University of Southern Denmark, Odense, Denmark Philippe Grandjean, Email: kd.uds.htlaeh@naejdnargp. corresponding authorCorresponding author

With the usual caveat that in G20 countries, fluoridation is recommended at a concentration of 0.7 mg/L .. ie only added if levels are below that.

Fluoride meta studies, such as the one above, look at areas with extremely high levels of natural fluoridation, starting at least at one and half times the recommended dose and looking at areas with double, triple, and more that level.

There are issues in areas with high fluoridation levels, the fluoride and the other high metals levels in these regions in China and Mexico ...

But not basis for back propagating issues at high doses in multi metals areas to infer issues at the lower recommended dose rates.

Note that the association is for levels far higher than those used in drinking water. An updated meta-review (https://www.nature.com/articles/s41598-021-99688-w) also suggests an association between high fluoride intake and lower IQ, but notes that the quality of evidence is very low. It suggests that there is no evidence that low-to-moderate levels, like those used in drinking water, pose any neurotoxic effect; if there are effects, they may only be present at levels 3-10x higher than recommended fluoridation levels.

> Results

> Fourteen recent cross-sectional studies from endemic areas with naturally high fluoride concentrations in groundwater 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.

Having said that, the linked paper also notes that the benifits of flouridated water do not seem to be significant (likely do to the widespread use of flouridated toothpaste).

Reply on news.ycombinator.com