Fluoridation findings set teeth gnashing

By Jerome Burne
January 27, 2001

How you feel about a hell-fire preacher being caught with his trousers down depends on whether you are a member of his church. For the faithful it's shocking, for outsiders maybe merely amusing. The sight of doctors refusing to take their own medicine evokes similar emotions, which is why health campaigner Edward Baldwin (the Earl Baldwin of Bewdley) and Trevor Sheldon, of the Department of Health Studies at York University, are outraged.

They believe they have clear evidence that top medical organisations have been playing fast and loose with scientific evidence, failing to apply the rigorous standards they require of others to their own pet projects.

"It is particularly worrying that statements that mislead the public . . . have been made by the British Dental Association [and] the British Medical Association," writes Sheldon in a letter to MPs. "Anyone who considers this report a ringing endorsement is either dishonest, a fanatic or scientifically illiterate," says Baldwin.

The report in question is one published last October into the fluoridation of the UK's water supplies. The benefit of putting extra amounts of the mineral fluoride into drinking water has been the subject of an acrimonious and heavily polarised debate for more than 50 years. The first community to do it was Grand Rapids, Michigan, in 1945.

Supporters claim it is a cheap and effective way of improving the quality of a nation's teeth, while opponents declare there is little evidence that it is effective and plenty that it is hazardous.

More than 3,000 studies have been published on various aspects of the debate and both sides can cite numerous ones in their favour, but neither side has been able to deliver the knock-out paper. The big medical and dental associations on both sides of the Atlantic have long been supporters, and for years the British Dental Association, the British Medical Association, and allies such as the British Fluoridation Society have been pushing the UK government to take a more pro-active line.

At the moment, fluoride is added to 10 per cent of UK water, compared with 62 per cent in the US, but recently the government has been considering giving local councils powers to compel water authorities to add it.

The only European country to have a nationwide scheme is Ireland, which also has a vociferous anti-lobby; its most recent coup was the discovery that the fluoride put in Irish water is actually a cocktail of chemicals, including arsenic and lead, that is a by-product of fertiliser manufacture.

Denmark, Finland and Germany have all tried fluoridation and abandoned it, while France has consistently decided against it.

So to handle this contentious issue, in 1999 the government ordered a review of the evidence. The National Health Service Centre for Reviews and Dissemination at York University was charged with answering such basic questions as: Does it work? Is it safe? Does it help to close the dental health gap between rich and poor? Baldwin, a long-time campaigner against fluoridation, was on the advisory committee.

To understand why he and others involved in the review are so outraged at what happened when they produced their report last October, it is necessary to explain just what the committee was doing.

The systematic review is at the heart of modern evidence-based medicine. It's not like a royal commission where you call witnesses and hear evidence. It's designed to do a very specific job - a sort of court of appeal for the medical profession.

The pace of modern research is so fast that no doctor can keep up with all the latest drugs and treatments, and the evidence for and against them. And even if you had time to check through all the research, how do you judge between conflicting findings? The systematic review was devised to solve this problem.

First, a team of researchers trawls through the literature to find any relevant trials and then - and this is the important part - it ranks them in terms of how reliable they are. For instance, the results of carefully controlled trials with a large number of subjects, preferably "blinded" so no one knew who was getting the treatment, get a higher rating than reports of what happened to a few patients. Then the reviewers reach a conclusion - this works, this doesn't, or maybe (the evidence isn't good enough to decide either way).

This is what the National Institute for Clinical Excellence uses to decide if treatments are worth paying for and it is a technique that provides some sort of objective overview of the claims and counter-claims whirling around fluoride. A systematic review isn't just another bit of evidence, it's a carefully considered judgment on the whole topic.

So what happened when the York group reported on its sifting and weighing of the evidence for fluoride?
In a nutshell, the group said it could not come to any definite conclusion about any of the points because the evidence was so poor. As Sheldon commented later: "We were surprised that, in spite of the large number of studies carried out over several decades, there is a dearth of reliable evidence with which to inform policy."

On the question of effectiveness, the report says: "To have clear confidence in the ability to answer the question, the quality of the evidence would have to be higher." And on safety: "Some possible adverse effects may take many years to develop . . . and so the relationship may go un- detected." Does it reduce social inequalities? "The evidence is of insufficient quality to allow confident statements about whether there is an impact on social inequalities."

The one positive conclusion was that more high-quality research was needed to discover the truth.

But anyone reading the press releases issued by the BMA, the BDA and others could be forgiven for not appreciating that message. "The review confirms that water fluoridation is safe and effective," trumpeted the BDA's release, which went on to declare: "The report confirms that fluoridation reduces dental health inequalities."

The BMA was equally gung-ho: "There is no evidence of any adverse risk to human health. Fluoridation is the most effective way to reduce dental health inequalities".

It's easy to see why the review committee members are so aggrieved. The BDA and the BMA had taken their case to an appeal court of their peers, but when it was thrown out for lack of evidence they responded by issuing press releases claiming victory. Calls to both bodies found them unrepentant. "We believe we gave an accurate summary," said the British Fluoridation Society, whose release echoed those of the other two organisations. "We believe the report does support fluoridation. Lord Baldwin has taken our statements out of context."

Ian Wylie, chief executive of the BDA, said fluoridation was one of the best measures for dental health and he wanted to see it go ahead, although he was keen for more research.

It is tempting to giggle at the sight of a trouserless hell-fire preacher explaining how he was wrestling with sin, but there are serious issues here of trust. The public is already sceptical of reassurances on health matters from official bodies. In the long term, such spinning on the contents of an inconvenient review will do nothing to improve that.