1 Grandjean P

Landrigan PJ Neurobehavioral effects of developmental toxicity. The American Association for Community Dental Programs' primary goal is to support the efforts of those serving the oral health needs of vulnerable populations at the community level. In view of our commitment to preventing oral diseases and improving access to services for the public, we read with interest Grandjean and Landrigan's Review on neurobehavioral effects of developmental toxicity.

2 Choi AL

Sun G

Zhang Y

Grandjean P Developmental fluoride neurotoxicity: a systematic review and meta-analysis. In their Review, Grandjean and Landrigan claim that fluoride might cause neurodevelopmental harm, a claim based on only one paper,of which Grandjean is a coauthor. The study methodology contains several flaws that undermine its credibility and calls into question its applicability to the community water fluoridation programme in the USA.

2 Choi AL

Sun G

Zhang Y

Grandjean P Developmental fluoride neurotoxicity: a systematic review and meta-analysis. The studyis a meta-analysis of 27 cross-sectional studies done in poor, rural communities in China, Mongolia, and Iran, countries where the drinking water contains high levels of naturally occurring fluoride. The 27 original studies did not adequately control for a variety of intervening and confounding variables that could have affected intelligence quotient (IQ) scores, such as parents' education and socioeconomic status and air and water pollution. It is unfortunate that Grandjean and Landrigan did not mention these limitations.

2 Choi AL

Sun G

Zhang Y

Grandjean P Developmental fluoride neurotoxicity: a systematic review and meta-analysis. Additionally, they did not clearly state that the reference groups in their articleuse water fluoridated at about the recommended level. Thus, another interpretation of their analysis could be that communities fluoridated at the recommended level have a higher IQ.

3 Whitford GM

Whitford JL

Hobbs SH Appetitive-based learning in rats: Lack of effect of chronic exposure to fluoride. 4 Shannon FT

Fergusson DM

Horwood LJ Exposure to fluoridated public water supplies and child health and behaviour. 5 Bazian Ltd

Independent critical appraisal of selected studies reporting an association between fluoride in drinking water and IQ: a report for South Central Strategic Health Authority. London, UK. , 6 European Union Scientific Committee on Health and Environmental Risks (SCHER)

Opinion on critical review of any new evidence on the hazard profile, health effects, and human exposure to fluoride and the fluoridating agents of drinking water. 6 European Union Scientific Committee on Health and Environmental Risks (SCHER)

Opinion on critical review of any new evidence on the hazard profile, health effects, and human exposure to fluoride and the fluoridating agents of drinking water. No credible scientific studies show a relation between fluoride consumption and IQ levels; however, several have shown that fluoride ingested at recommended levels is not harmful. Grandjean and Landrigan did not acknowledge the animal studythat showed no evidence of a neurotoxic effect of fluoride, even at levels up to 230 times the recommended concentration; an earlier study showing that fluoride causes no harm to children;two formal reviews that delineate weaknesses in the Chinese fluoride and IQ studies;and the conclusion by one of these sets of investigatorsthat biological plausibility for a link between fluoridated water and IQ has not been established.

Unfortunately, Grandjean and Landrigan's Review has been aggressively and improperly used by antifluoridationists to frighten the public about the effects of fluoridation, a well-established public health measure that has been shown to be cost-effective and safe. As a result, the public's oral health, especially that of the most vulnerable people, is put in jeopardy.

As advocates for better oral health and for serving the public's best interest, we are pleased that The Lancet Neurology is providing a forum for credible experts and organisations to reaffirm the safety and cost-effectiveness of fluoridation—a proven public health measure.

A statement from Grandjean and Landrigan clearly stating that their addition of fluoride to their list of neurotoxins does not apply to fluoridation at the recommended levels of 0·7–1·2 ppm would clarify our concerns on the misuse and misinterpretation of their paper.

We declare no no competing interests.