Caution needed in altering the 'optimum' fluoride concentration in drinking water.

The US Public Health Service has finalized its recommendation relating to community water fluoridation (Federal Panel on Community Water Fluoridation, US Department of Health and Human Services, 2015). It recommends an optimal concentration of 0.7 mg/l F based on their argument that this concentration provides the best balance of protection from dental caries while limiting the risk of dental fluorosis. The rationale for this recommendation can be questioned, particularly given the contrasting etiologies and impact on the community. Uncertainty surrounds the key evidence considered by the panel. This study argues that the panel should have exercised more caution and called for further research before reducing the 'optimal' concentration of fluoride in water supplies. Up-to-date data on caries and fluorosis trend by age group or birth cohort, analyses on attributable risk for fluorosis, data on individual and population impact of caries and fluorosis, water intake over an extended period across the seasons, and the curvilinear relationship of fluoride concentration in water supplies and caries protection would have all been desirable to inform the panel, given the foreshadowing of the recommendation in late 2011. Further, a wider range of policy directions to achieve the best balance of protection from dental caries while limiting the risk of dental fluorosis are available from the international literature. Assessment of these should have been more evident. There is a public health policy responsibility to monitor water fluoridation programs so as to achieve a near maximum reduction in dental caries without unacceptable levels of dental fluorosis. However, recommendations to alter existing policy need to be cognizant of the balancing of risk and protective exposures across the entire population and potentially all ages and to be based on recent data that are purposefully collected, critically analyzed and carefully interpreted.