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latest information

(05/01/16) A summary of 'Cochrane Collaboration systematic review of water fluoridation 2015' has been posted in Reports.
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(16/04/14) A critique of 'One in a Million: The Facts' has been posted in Reports.
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(16/04/14) 'Fluoridation: Popularity' has been posted in the Archive.
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(18/04/10) New fluoridation scheme for Southampton


(18/04/10) The Reports and Archive sections have been updated with further documents and links


(11/07/09) A critique of Prof. Newton's report to South Central SHA has been posted in Reports.
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(28/09/08) A critique of the South Central Strategic Health Authority Consultation Paper on Water Fluoridation in Southampton, has been posted in Reports.
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(07/09/08) A response to the Chief Dental Officer's 'Dear Colleague' letter of guidance for new schemes, endorsed by scientists from the York review, has been posted in Reports.
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(23/06/08) Isle of Man has announced on 12th June that it will not be fluoridating its water supply
Read more.

Letter to Lord Darzi

3rd June 2008

Dear Lord Darzi,

We are running into problems with Written Answers to my Questions about water fluoridation. I had to put down a second Question recently because my original Question in three parts had not been addressed (1 April 2008, WA 155; 1 May WA 32-33). Even now one of my Questions has not been answered.

There is a history of non-answers on this topic going back to the days of Margaret Jay at Health, which have needed further Questions, correspondence, and meetings with Ministers and officials which have been wasteful of the Department's time and mine. I would like to avoid more of this by bringing it to your attention now. In my experience this has been unique to fluoridation. With other health matters that I have addressed in the past 10 - 15 years there have been no such difficulties.

These points need to be made about Answers given since March this year:

1. As background, the Department set up the 'York review' to bring clarity and good science to the evidence base on fluoridation, following my prompting during 1997 - 99 when I was supported by Sir Iain Chalmers of the UK Cochrane Centre. Because this was a systematic review it was the best and most reliable exercise that there has been in this field - in the words of Sir Iain and Professor Sheldon from York, "the only scientifically defensible assessment of the evidence worldwide". I served on the review's advisory board.

2. Your Answer WA 155 on 1 April did not respond satisfactorily to my Questions. Because of York's quality and status, and your Department's sponsorship of it, it is puzzling that you see nothing improper in the British Fluoridation Society ignoring it when seeking figures for fluorosis of aesthetic concern. On any question addressed by York, this would surely be the first authority that a competent unbiased commentator would cite.

3. The BFS, in contrast to York, plays a promotional role in fluoridation (Lord Hunt of Kings Heath, 31 January 2001, WA 66). Its website confirms its campaigning activities together with many other organisations. It is not a neutral body, which makes it even less understandable that your Answer of 1 April does not suggest that York's assessment might be more reliable than that of the BFS.

4. You did not deal with my Question (1 April) how York's assessment differed from the sources that the BFS chose to cite. The answer is that the BFS estimates for the prevalence of fluorosis of aesthetic concern were 4% at the highest: York's figure was three times this, at 12.5%. Such a finding from a systematic scientific review is likely to be the most accurate available; the BFS's sources are of unknown reliability. York based its conclusion on 70+ studies; the BFS has cited 5.

5. The disparity in figures is not affected by the low quality (York's 'level C') of fluorosis studies in the world literature, which you refer to, since this might be thought to provide all the more reason to be guided by the highest-quality review. Contrary to your Answer of 1 May, no BFS-cited study pre-2000 was of a standard to meet York's inclusion criteria, and these can safely be discarded as reliable evidence. The likelihood of the post-York BFS-cited studies being of an acceptable level, given the known standards in fluoridation research, is not high. Therefore the likelihood of the evidence adduced by the BFS overturning York's expert assessment of over 70 studies must be small.

6. The same considerations apply to the MRC's estimate of fluorosis of aesthetic concern which you referred to on 1 May (WA 32). The MRC's was not a systematic review, with the care to minimise bias that that entails; and its reasons for preferring a lower fluorosis incidence figure than York were based explicitly (MRC 4.2; 4.2.1) on pre-2001 studies, which York would have taken account of or rejected, and on a misreading of York's analyses of figures for hot climates which is clear both from the body of York's text, and from the lead reviewer's letter to the BMJ soon after the York report was published which explained why climate had shown no significant influence. This oversight by the MRC, taken together with its lesser rigour and status as a review, must reduce any grounds for confidence in its estimate that prevalence is "probably lower" than York reported. The Department has itself acknowledged its acceptance of the York review in Written Answers.

7. You are also incorrect in your Answer of 1 April that the York reviewers were referring to fluorosis of aesthetic concern when they said that "the precision of these rough estimates is low". I put down a Question on this, but your Answer of 1 May did not address it. Despite the somewhat clumsy phrasing of the relevant paragraph in York's Executive Summary, the respective 95% confidence intervals in York Tables 7.7 & 7.8 show that it was a comparison of water fluoride levels of 0.4 ppm v. 1.0 ppm that was imprecise ("the confidence limits around this value include infinity"), while the 12.5% figure for fluorosis of aesthetic concern at 1 ppm was more robust. When it is noted that the lowest figure in York's confidence interval gave a prevalence of 7%, and that the figures were based on a transparent examination of all the relevant admissible studies by a world-class review, to prefer the view of the BFS or MRC could be deemed scientifically eccentric.

My complaint is that there is too little rigour and too many errors here by a Department that ought to pay more careful attention to what the systematic review, which to its credit it set up, actually reported. My complaint is also that we seem to be slipping again into a position where some of my less welcome Questions are simply not answered, causing extra time and effort for all of us.

The bottom line has been evident for some years, not least to the independent scientists from the York review. It was expressed in a paper last October in the BMJ by Professors K.K. Cheng and Trevor Sheldon and Sir Iain Chalmers when they wrote of the Department's "questionable" objectivity and its "overoptimistic assessment of the evidence in favour of fluoridation". If it had not been important to play down a likely figure of 1 person in 8 with serious dental fluorosis, there would have been no need to have recourse to low-level evidence from an organisation that campaigns for fluoridation, which also attracted criticism for its partiality from the Nuffield Council on Bioethics in its report Public health: ethical issues last November. When all is said and done, it is the systemic unwillingness within the Department to believe that the evidence for fluoridation might not be as rosy as was once believed that is most regrettable, and it is not conducive to the advancement of good science.

Yours sincerely,

The Lord Darzi

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