Abstract
Objective Does water fluoridation have negative effects? This objective was broken down into four sections: fluorosis, bone fracture and bone development effects, cancer and other possible adverse effects.
Data sources See page 37.
Study selection Thirty-two studies of other possible negative effects were included. These examined various outcomes, including Down's syndrome, mortality, senile dementia, goitre and IQ. All were of evidence level C with a mean validity score 2.7 (range, 1.5–4.5) out of 8. Although 22 studies mentioned potential confounding factors, only six used an analysis that controlled for them.
Data extraction and synthesis See page 37.
Results Three of the studies found significant effects. One found a significant negative effect of water fluoride on Alzheimer's disease (increased incidence) and a significant positive effect on impaired mental functioning (decreased incidence). Another found a significant positive association with congenital malformations in one of two sets of data. A third study found that the combination of low iodine and high fluoride concentrations was associated with goitre and learning difficulties. Because of the varying outcome measures the results could not be formally pooled.
Conclusions Interpreting the results of the other possible negative effects is very difficult because of the small number of studies that met inclusion criteria on each specific outcome, because of the study designs used, and also the low quality of the studies. Overall, the studies examining other possible negative effects provide insufficient evidence on any particular outcome to reach conclusions.
McDonagh M, Whiting P, Bradley M, Cooper J, Sutton A, Chestnutt I, et al. A Systematic Review of Public Water Fluoridation. York: Publications Office, NHS Centre for Reviews and Dissemination, University of York. ISBN 1 900640 16 3; 2000
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Thomas, D. Poor quality studies give insufficient evidence on other possible negative effects of fluoridation. Evid Based Dent 3, 49 (2002). https://doi.org/10.1038/sj.ebd.6400111
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DOI: https://doi.org/10.1038/sj.ebd.6400111