To: Hazel Blears, MP
House of Commons, London, SW1A 0PW.

11 December 2002.

Dear Minister,

We are scientists involved in the systematic review of evidence on the effects of water fluoridation, carried out by the NHS Centre for Reviews and Dissemination at the University of York. As far as we are aware, no other review of this topic is of comparable scientific standard, and we are concerned about some continuing misinterpretations of the evidence which could have implications for public policy. It is not for us to say whether the standard of evidence should be judged sufficient for a public health measure affecting whole populations, but we think it is important that decision makers are aware of what the review really found.

1. Effectiveness of fluoridation in reducing caries.

We could discover no reliable good-quality evidence in the fluoridation literature world-wide. What we found suggested that fluoridation was likely to have a beneficial effect, but in fact the range could be anywhere from a substantial benefit to a slight disbenefit to children's teeth.

2. Effectiveness of fluoridation in reducing inequalities in dental health across social groups.

This evidence is weak, contradictory and unreliable.

3. Safety of fluoridation.

Apart from an increase in dental fluorosis (mottled teeth) we found no clear pattern among the possible negative effects we examined, and we felt that not enough was known because the quality of the evidence is poor.

We append relevant extracts from the report of the review from which the conclusions under 1 and 2 can be substantiated. 3 covers too broad an area to summarise easily.

Since the report was published in September 2000 there has been no other scientifically defensible review that would alter the findings of the York review. As emphasised in the report, only high-quality studies can fill in the gaps in knowledge about these and other aspects of fluoridation. Recourse to other evidence of a similar or lower level than that included in the York review, no matter how copious, cannot do this.

We think these matters are important enough to bring directly to your attention, as well as to the notice of others who have a stake in public health policy.

Yours sincerely,

Professor Jos Kleijnen, Director, NHS Centre for Reviews and Dissemination.
Professor Trevor Sheldon, Head of Department, Department of Health Sciences, University of York.
Sir Iain Chalmers, UK Cochrane Centre.
Professor George Davey-Smith, Department of Social Medicine, University of Bristol.

COPIES TO: Rt Hon Alan Milburn, MP; Sir Liam Donaldson, Chief Medical Officer;
The Lord Hunt of Kings Heath; Sir Anthony Cleaver, Chairman, MRC.