Debate
A case against water fluoridation
Not only does fluoridation of water have only a marginal benefit to dental health, it also has health risks and circumvents our right to refuse medication, argues H S Micklem
‘S 40 Scottish Dental magazine
afe and effective’ has long been the mantra of propo- nents of water fluoridation. To
be clear at the outset, I am not discussing here the use of topical fluoride (as in toothpaste, rinses etc), but questioning the mantra over the efficacy, safety – and also propriety – of adding fluoride to the public water supply. In line with nearly all of Europe
and most other countries, we do not fluoridate our water in Scotland, relying instead on the forward- looking Childsmile programme. But occasional voices still call for its reintroduction1 and it is worth considering how inadvisable such a retrograde step would be.
Does it work? Since the early trials, more than 60 years ago, the incidence of caries has declined similarly in fluoridated and non-fluoridated communities2, probably due in part to fluoride toothpaste and, in part, to better diet and living conditions. Today, fluori-
dation may still have some effect, but it is marginal and less than has often been claimed. Such a lukewarm endorsement
may seem surprising when one considers how energetically the practice has been promoted, even described by the US Centers for Disease Control as ‘one of the great public health achievements of the twentieth century’. But any benefit of fluoride is now agreed to be primarily topical and does not, as was long believed, involve incorporation into the enamel of the developing teeth (which results in fluorosis, see below). Thus it does not need to be swal-
lowed. While salivary fluoride is often believed to play a role in caries control, it appears that the concen- tration of fluoride in ductal saliva is too low to exert a significant effect, the residue from toothpaste being a more important source 3,4. None of the largest trials
conducted since the 1980s has demonstrated more than an almost trivial effect. That has not usually been apparent from the abstracts
of the reports, which talk about impressive-sounding reductions in caries of 25 per cent or more. But the use of relative percentage changes can be very misleading when small numbers are involved. For example, a 25 per cent reduction reported for 12 year olds in 19905 turned out to represent just one-sixth of a tooth surface, an absolute reduction of less than 1 per cent. Moreover, even that small reduc-
tion is really only a delay: the number of DMF teeth increases during the teens almost equally in fluoridated and non-fluoridated areas with the former lagging the latter by a few months. This may simply be due to a delay in the eruption of the permanent teeth6. An even smaller effect was seen in Australia7. A recent survey using registry data from Denmark8 provides a curious exception, describing an anti-caries effect of even very low concentra- tions (0.125-0.25 mg/l) of naturally occurring fluoride in drinking water, even where fluoride toothpaste is generally used. Vitamin D status could be a
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