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Cheng et al's article on fluoridation of water supplies provides a welcome opportunity to restate our view that fluoridation has reduced the burden of dental disease and offers the potential to address persistent inequalities in oral health.1 As with other health measures, safety should continue to be monitored and the ethical dimension discussed.
We first address the doubts expressed about the Department of Health's objectivity. The Department of Health, in 1999, commissioned the University of York to undertake a systematic review of fluoridation.2 The York team considered 735 research studies that met their relevance criteria and found no conclusive evidence of a causal relation between fluoridation and systemic illness. Nevertheless, we accepted their primary recommendation—that the evidence base for fluoridation needed strengthening—and responded with a commitment to sponsor further research. In 2001, we asked the Medical Research Council (MRC) to identify and prioritise the research needed to inform public policy on fluoridation.3 In 2003, in accordance with MRC recommendations, we commissioned the University of Newcastle to investigate the bioavailability of fluoride from artificial and natural sources.4
Despite significant improvements in the past 30 years, many people still experience unnecessary pain and discomfort from dental disease, and inequalities still exist across the country. The probability of having decay in primary teeth is about 50% higher in the lowest social group than in the highest.5 Fluoridation mitigates this association, as shown by York's finding that water fluoridation increases the number of children without tooth decay by 15%.2 A meta-analysis found a 27% reduction in dental decay in adults living in fluoridated areas.6
Fluoride toothpaste alone will not reduce inequalities in oral health because its use depends on individual behaviour. Targeted fluoridation schemes offer greater potential because they are population based interventions.
We welcome new research, particularly into the safety of fluoridation. However, as the MRC pointed out,3 research priorities should be determined by plausibility of effect. The study from Taiwan cited by Cheng et al does not fall into this category because its authors say, “Our study found an excess rate of bladder cancer that was restricted to females. It seems biologically implausible for fluoride to affect cancer rates for one sex only.”
The question of whether fluorides added to water should be licensed depends on whether they are categorised as medicines. The Medicines and Healthcare Products Regulatory Agency considers that, for regulatory purposes, drinking water (fluoridated or not) is a “food” and is not subject to the licensing requirements for medicines.
As the authors indicate, the ethical justification for fluoridation depends on the benefit to public health. We are satisfied that the persistence of inequalities in oral health provides this justification. Parliament accepted this argument as recently as 2005, when new requirements for consultations were approved by a large majority in both houses. Strategic health authorities may only make arrangements with a water provider to fluoridate an area if they have conducted open, wide ranging consultations.
The benefits, safety, and ethics have rightly been key issues in previous consultations on water fluoridation and continue to be at the heart of future consultations.
Competing interests: None declared.