Intended for healthcare professionals

Analysis Controversy

Adding fluoride to water supplies

BMJ 2007; 335 doi: (Published 04 October 2007) Cite this as: BMJ 2007;335:699
  1. K K Cheng, professor of epidemiology1,
  2. Iain Chalmers, editor2,
  3. Trevor A Sheldon, professor and pro-vice chancellor3
  1. 1Public Health Building, University of Birmingham, Edgbaston, Birmingham B15 2TT
  2. 2James Lind Library, Oxford OX2 7LG
  3. 3Health Services Research, University of York, York YO10 5DD
  1. Correspondence to: K K Cheng k.k.cheng{at}
  • Accepted 15 July 2007

Adding fluoride to water supplies to prevent dental caries is controversial. K K Cheng, Iain Chalmers, and Trevor A Sheldon identify the issues it raises in the hope of furthering constructive public consultation and debate

Several countries add fluoride to water supplies to prevent dental caries (boxes 1 and 2). Since the 2003 Water Act, water companies are required to add fluoride to supplies when requested—after public consultation—by a health authority in England or the Welsh Assembly in Wales.1

Summary points

  • Water fluoridation is highly controversial

  • Evidence is often misused or misinterpreted and uncertainties glossed over in polarised debates

  • Problems include identifying benefits and harms, whether fluoride is a medicine, and the ethical implications

  • This article provides professionals and the public with a framework for constructive public consultations

Box 1 Dental caries

What is dental caries?

Dental caries is a process of demineralisation of dental hard tissue caused by acids formed from bacterial fermentation of sugars in the diet. Demineralisation is countered by the deposit of minerals in the saliva—remineralisation. Remineralisation is a slow process, however, which has to compete with factors that cause demineralisation. If remineralisation can effectively compete the enamel is repaired. If demineralisation exceeds remineralisation a carious cavity finally forms. Fluoride prevents caries by enhancing remineralisation.

How common is caries?

The figure shows the average numbers of decayed, missing, and filled teeth in 12 year old children for several European countries. In most countries this number is around 1.5 and 50% of children have no caries. Although the prevalence of caries varies between countries, levels everywhere have fallen greatly in the past three decades, and national rates of caries are now universally low. This trend has occurred regardless of the concentration of fluoride in water or the use of fluoridated salt, and it probably reflects use of fluoridated toothpastes and other factors, including perhaps aspects of nutrition.

Tooth decay …

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