While some people are strongly in favor of adding fluoride to water to prevent tooth decay, others argue clearly against. An article in the British Medical Journal (BMJ) wonders whether it is possible for people to take part in consultations on an informed bases as evidence is often misrepresented and uncertainties glossed over.

Approximately nearly 6% of global water supplies contain fluoride to around 1mg/l, according to Sir Iain Chalmers and team. In England and Wales approximately 9-10% of water supplies contain 0.5-1mg/l fluoride – this is either added or is present naturally.

The subject of water fluoridation is a contentious one. Identifying the benefits and harms, deciding on whether fluoride is a medicine, and the ethics of mass intervention, are all controversial topics.

The UK Department of Health, in 1999, commissioned the Centre for Reviews and Disseminations at York to carry out a systematic evaluation of the potential harms and benefits of fluoridating water. The researchers identified 3,200 papers. However, they were surprised to find that the quality of the evidence (either way) was mediocre.

The authors stress that an absolute certainty on the safety of anything does not exist. However, as far as the fluoridation of water is concerned, people should be aware of the limitations of evidence about its potential harm. The majority of studies are not designed well enough and they are not large enough to identify small but important risks, especially in the case of chronic conditions, after fluoride is introduced into water supplies.

The writers also stress that the evidence for finding other ways of preventing tooth decay, such as adding fluoride to toothpaste, is strong. However, relying on toothpaste introduces a degree of inequality as it depends on individual behavior.

Is adding fluoride to water supplies an example of mass medication? Some people think it is. One has to decide whether fluoride is a medicine. Some argue that fluoride occurs naturally at levels comparable to those in artificially-fluoridated water supplies – which does not make it a medicine (they say).

If fluoride is deemed to be a medicine, then it should be subjected to the stipulations and standards of proof required of drugs, write the authors. If it is used as a mass preventive measure for healthy people, the evidence should be strong that the net benefit is larger than needed to treat illness. Surprisingly, there have not been any randomized trials of water fluoridation.

What about the ethics of water fluoridation, ask the authors. Individual have the right to refuse a drug treatment or some other intervention. The following factors have to be taken into account:

— The potential benefit(s) must be weighed against uncertainty about harms.
— The fact that generally there is less tooth decay today than a few decades ago.
— What other effective methods of prevention are there?
— People’s right to choose.

The authors say it is crucial that the dissemination of evidence be trustworthy (people must believe it). Opposers of fluoridation argue that it does not reduce tooth decay, while at the same time they overstate the evidence on harm. However, the Department of Health’s objectivity is not squeaky clean – the British Fluoridation Society is funded by it, it also used the findings of the review selectively in order to give an overoptimistic assessment of the evidence supporting fluoridation.

“Against this backdrop of one sided handling of the evidence, public distrust in the information it receives is understandable. We hope this article helps provide professionals and the public with a framework for engaging constructively in public consultations,” the authors conclude.

Rod Griffiths, Regional Director of Public Health, West Midlands, England, in a Personal View article, believes that when you weigh everything up the fluoridation of water supplies is beneficial. Birmingham, he explains, has among the best dental health in England and has had fluoride in its water for 40 years – obesity, heart disease and life expectancy in Birmingham are far from best. Griffiths wonders why there is so much passion about fluoride, when there are so many other chemicals we should be concerned about.

“Adding fluoride to water supplies”
BMJ Volume 335, pp 699-702
“Personal View: Fluoride: a whiter than white reputation?”
BMJ Volume 335, p 723


Written by: Christian Nordqvist