More fluoride should be put into Britain’s drinking water, according to health secretary Alan Johnson. Money has been earmarked for health boards wishing to do so. In some parts of the UK, fluoride occurs naturally in the water supply; in others, such as the Midlands, it is already added to water supplies.
To Johnson, there is not much debate. “All the facts are in favour of greater fluoridation,” he said in parliament. “There is absolutely no clinical evidence whatsoever that links fluoridation with anything other than fluorosis. Fluorosis is a discolouration of the teeth, and there are perfectly simple ways to deal with it.”
The British government is quite rightly concerned with reducing inequalities in health. Tooth decay seems a good place to intervene: there is widespread agreement that lower social class is a higher risk for tooth decay in children. Fluoride, the theory goes, protects teeth against decay and by adding it to the water, there is no need to rely only on the more difficult task of changing behaviour (tooth-brushing or better diets) that help to prevent dental problems.
Certain things are guaranteed to divide medical opinion; adding fluoride to tap water is one of them. Some believe that offering only fluoridated public water supplies is mass medication by another name and unfair to those who wish to have freedom of choice. They are concerned with potential harms, such as bone thinning and cancer. Others believe that fluoride is safe, well-tested and represents a real opportunity to improve dental health and reduce the misery of treatment.
Who is right? Although I have serious reservations about disallowing choice, if there is little in the way of harm and a lot of potential benefit, then pragmatic acceptance of the least bad scenario seems the most sensible position. The ability to judge harms and benefits, however, rests on an evaluation of the evidence. And in the case of fluoride, it is not clear the evidence is there.
The York Review, a systematic review of all the research relating to water fluoridation, was published in the British Medical Journal in 2000. The researchers were interested in tooth decay, missing teeth and dental fillings. They wanted to assess the changes in dental health caused by fluoridation in the UK and to examine the adverse effects reported.
They found that the quality of the overall evidence was poor and inconclusive but suggested that while adding fluoride to water did reduce the number of children with tooth decay, it also increased the amount of dental fluorosis. The study was followed by “Water Fluoridation and Health”, a report from the Medical Research Council published in 2002. This fully recognised the York Review and recommended quality research on, among other things, biological uptake of fluoride and the effects of water fluoridation in children using toothpaste containing fluoride.
The MRC also wanted further research to be done into the amount of fluorosis in fluoridated and non-fluoridated areas and to examine the effects of fluoridated water on bone health, if further biological testing indicated it was necessary. The other main concern raised about fluoride is that it could be a potential carcinogen and the MRC suggested that there should be an analysis of water fluoridation in relation to cancer rates.
I am not much of a conspiracy theorist, as some anti-fluoride campaigners seem to be. But neither am I completely sold on the idea that fluoride in the water is the most important factor in preventing tooth decay – a recent paper in the BMJ showed that rates of dental decay in the EU are falling, whether or not water is fluoridated. There are many public health interventions I am happy to comply with, where there is evidence to support them – for example, immunisation against measles, mumps and rubella. But rather than politicans simply recommending we add fluoride to water, we should do the research first.
Margaret McCartney is a GP in Glasgow