The protective effect of community water fluoridation (CWF) on caries has been well demonstrated and relationships with adverse health outcomes have also been alleged. We have recently completed a study of the association between concentrations of fluoride in public water supplies (PWS) and dental caries indicators, as well as several adverse non-dental health-outcomes in England, using recent available routine surveillance data. The methods and results are presented in more detail in other talks at this meeting. The benefits in terms on reduction of caries from CWF are clearly supported by our results, and there was strong interaction with socio-economic status. For example, comparing children in areas with a fluoridation scheme and >0.7mg/l fluoride to low areas with <0.2mg/l fluoride, there are 17% less with caries in the least deprived areas, rising to 28% in the most deprived areas. For non-dental outcomes, we found some associations between fluoride and fractures (adverse) and bladder cancer (protective). However in both cases the pattern of results, especially the lack of a dose response pattern across exposure, suggested a non-causal association. It was concluded that these findings were consistent with water fluoridation being an effective and safe public health measure, in areas with fluoride concentration up to 1 mg/l, to reduce dental caries and reduce dental health inequalities. In reaching this conclusion, the study team balanced both the magnitude of the dental and non-dental effects, and the strength of evidence in terms of internal coherence and consistency with other evidence. Most studies showing adverse effects are at much higher fluoride concentrations and extrapolation to lower concentrations is very uncertain. Some endpoints such as endocrine (thyroid) and neurological (IQ) for exposure up to 1 mg/l could not be addressed in this study, and still need addressing.
Author affiliations (Abstract number S02.02.34 on page 400 of the 2018 ISEE abstracts):
Tony Fletcher1, Giovanni S. Leonardi1, David Roberts1
1. CEE, Public Health England, Chilton, United Kingdom.
*Abstract online at https://ehp.niehs.nih.gov/doi/10.1289/isesisee.2018.S02.02.34
Note: Also see another abstract on fluoridation presented by Tony Fletcher at the ISEE Conference: Association between Fluoride Concentration in Public Water Supplies and Beneficial and Adverse Health Outcomes in England: An Ecological Study.