Vol. 121, No. 3 CorrespondenceOpen AccessDevelopmental Fluoride Neurotoxicity: Clinical Importance versus Statistical Significance Siamak Sabour and Zahra Ghorbani Siamak Sabour Search for more papers by this author and Zahra Ghorbani Search for more papers by this author Published:1 March 2013https://doi.org/10.1289/ehp.1206192Cited by:2AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit We were interested to read the article by Choi et al. (2012), who investigated the effects of increased fluoride exposure and delayed neurobehavioral development by reviewing published studies and performing a meta-analysis. Of the 39 studies identified, the authors considered 27 to be eligible. Choi et al. reported a mean difference in IQ (intelligence quotient) score between exposed and reference populations of –0.4 (95% confidence interval: –0.5, –0.3) using a random-effects model. Thus, children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.Even if we ignore the weaknesses of the study (Choi et al. 2012), including a lack of individual-level information and the high probability of confounding because the authors did not adjust for covariates, a difference of 0.4 in mean IQ is clinically negligible (Jeckel et al. 2007; Rothman et al. 2008; Szklo and Nieto 2007) even though it was statistically significant. In general, clinical importance takes priority over statistical significance. The p-value can easily change from significant to nonsignificant because of sample size or the mean difference and standard deviation of the variable in the study population (Jeckel et al. 2007; Rothman et al. 2008; Szklo and Nieto 2007). As Choi et al. (2012) pointed out in their conclusion, there is a “possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.” Such a conclusion can be considered an ecological fallacy, which can easily lead to misinterpretation of the results. It is important to know that statistics cannot provide a simple substitute for clinical judgment (Jeckel et al. 2007; Rothman et al. 2008; Szklo and Nieto 2007).The authors declare they have no actual or potential competing financial interests.ReferencesChoi AL, Sun G, Zhang Y, Grandjean P. 2012. Developmental fluoride neurotoxicity: a systematic review and meta-analysis.Environ Health Perspect 120:1362-136822820538. Link, Google ScholarJeckel JF, Katz DL, Elmore JG, Wild DMG. 2007. Epidemiology, Biostatistics, and Preventive Medicine. 3rd ed. Philadelphia:Saunders/Elsevier. Google ScholarRothman JK, Greenland S, Lash TL. 2008. Modern Epidemiology. 3rd ed. Philadelphia:Wolters Kluwer/Lippincott Williams & Wilkins. Google ScholarSzklo M, Nieto FJ. 2007. Epidemiology; Beyond the Basics. 2nd ed. Sudbury, MA:Jones and Bartlett. Google ScholarFiguresReferencesRelatedDetailsCited by Yu X, Chen J, Li Y, Liu H, Hou C, Zeng Q, Cui Y, Zhao L, Li P, Zhou Z, Pang S, Tang S, Tian K, Zhao Q, Dong L, Xu C, Zhang X, Zhang S, Liu L and Wang A (2018) Threshold effects of moderately excessive fluoride exposure on children's health: A potential association between dental fluorosis and loss of excellent intelligence, Environment International, 10.1016/j.envint.2018.05.042, 118, (116-124), Online publication date: 1-Sep-2018. Garbin C, Santos L, Garbin A, Moimaz S and Saliba O (2017) Fluoretação da água de abastecimento público: abordagem bioética, legal e política, Revista Bioética, 10.1590/1983-80422017252193, 25:2, (328-337), Online publication date: 1-Aug-2017. Vol. 121, No. 3 March 2013Metrics About Article Metrics Publication History Originally published1 March 2013Published in print1 March 2013 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.