MRC report estimates of fluorosis prevalence in fluoridated and non-fluoridated areas (2002)

After the York review of water fluoridation was published in 2000, the Department of Health asked the Medical Research Council (MRC) to consider its findings and make recommendations on priorities for further research. (1)

Prevalence higher in areas with natural fluoridation that in areas served by community water fluoridation schemes

With regard to dental fluorosis, the MRC asked the York team to undertake further analysis to compare prevalence rates for naturally and artificially fluoridated areas.  This work revealed that the risk of cosmetically significant fluorosis was greater in naturally fluoridated areas than in artificially fluoridated areas, even when the fluoride concentrations in water were exactly the same.

York estimates based on combined data from naturally and artificially fluoridated areas

York’s original estimates had suggested that there might be a 12% prevalence of fluorosis of aesthetic concern in artificially fluoridated areas.  However, these calculations had combined data from both naturally and artificially fluoridated areas.

MRC focus on results of European studies

Many of the studies of naturally fluoridated areas that were reviewed by the York team had taken place in countries with hotter climates than the UK and where water intake is typically higher and the risk of fluorosis correspondingly greater at any given fluoride concentration. The relevance of the York figures was therefore called into question.

This led the MRC to look specifically at data from European sources, including the study illustrated on this page.  Taking account of such information, the MRC suggested that a more realistic prevalence figure for fluorosis of aesthetic concern would be around 3% to 4% in artificially fluoridated areas and around 1% in non-fluoridated areas.

  1. Medical Research Council (2002): Working group report: Water fluoridation and health.