The proposed fluoridation of water supplies in the greater Dunedin area has reawakened debate – with a passion never much below the surface – about adding the chemical to public water supplies.

A vociferous and dedicated group has its teeth into the issue again because of the extensions of city water supplies to northern towns.

City councillors last week were asked to confirm existing fluoridation for 85% of Dunedin’s residents, to agree that other areas supplied by the main treatment plants (Mt Grand and Southern) receive fluoridated water, and that a local referendum apply to areas served by other reservoirs.

This sparked an emotional debate, with Cr Michael Guest saying those opposed were “akin to quacks and snake oil merchants”.

On the other side, Cr Fliss Butcher raised the sceptre of the thalidomide disaster and also of the mass medication featured in Hitler’s gas chambers.

Fluoridation opponents are correct in one way when they use the emotive approach of regularly repeating the words “mass medication”.

Everybody is being dosed with additional quantities of fluoride, whether they need it or not, and individual choice is eliminated (although fluoride filters can be used).

Anti-fluoridation lobbyists are also right in raising questions and concerns about fluoridation – healthy discussion about such matters should be encouraged, providing both sides adopt the principle of disagreeing without being disagreeable.

And it is healthy for the authorities to be regularly challenged and questioned because they are not always right.

It is well to remember, however, that society does, and should, accept occasions when the greater good overrides individual rights, such as, for example, wearing seat belts, or adding iodine to salt and bread.

Each situation has to be judged on its own merits, while beginning from a standpoint of reluctance to interfere with individual choice.

At the same time, a wise application of precautionary principles should prompt a reluctance to add additional chemicals to water supplies unless they are really needed, and only if known side-effects are tiny.

On one side of the argument, the Fluoride Action Network argues the benefits are “at best dubious” and the risk of side-effects “considerable”.

On the other, the Minister of Health and dental authorities state the health benefits are considerable and the risk of harm from side-effects “minimal”.

Because the councillors, like the general public, are unable to disentangle all the claims and counter-claims and properly understand much of the scientific and statistical evidence, who are we all to believe? Who has the most credibility?At this stage, it has to be the line-up of dental and public health experts.

They are almost all emphatic in their views that what they call “topping up” the fluoride already naturally occurring in water makes teeth more resistant to decay.

They present widespread evidence to show how the teeth of children in fluoridated areas are better and they say they have failed to find the alarming side-effects that opponents attribute to the “poison” form of fluoride added to water.

Sensible proponents, despite fluoride being widely used for 50 years in many places, also believe periodic monitoring for possible side-effects is judicious.

Given the pain, misery and cost of dental decay, particularly to children and especially those from less educated and poorer families, the “experts” at present overwhelmingly endorse current practices and so, therefore, should our councillors as community leaders.

Although fluoridation might be unnecessary in an ideal world, the continued seriousness of dental decay and the established effectiveness of fluoridation means the community should forego individual choice in this matter.

A city council committee for now has agreed fluoridation for most of the city will continue until the next round of annual plan and long-term community plan hearings.

At that stage, a final decision on whether to extend reticulation would also be made.

These recommendations will be discussed at the next council meeting on November 3.

Just as in 2006, councillors are showing a willingness to listen to the anti-fluoride lobby, as well as the Ministry of Health. It must be hoped that they again, even if just by a majority, can dispassionately consider the matter devoid of over-the-top emotional claims.

In so doing, they should support and even extend this essential public health measure.

As Prof Murray Thomson, from the University of Otago’s School of Dentistry, has said: “There is a compelling public health case for community water fluoridation.”