A Fortunate Experiment?

 Keith Rankin, 29 March 2001

To fluoridate or not to fluoridate the local spring water? That was the question that the people of Onehunga had to decide. Their will prevailed. The Auckland City Council voted 10-9 to retain the status quo, but not before passions were raised by both supporters and opponents of fluoridation.

A referendum of sorts was held among Onehunga residents. In a turnout that was about as high as you can ever expect to get for a stand-alone postal ballot (about one-third of ballots were returned) there was a two-to-one rejection of the fluoridation proposal. That means only one-sixth of the population supported change.

A majority of members of the Maungakiekie Community Board and various commentators (most specifically the NZ Herald's Brian Rudman) believed that the residents' poll should have been overridden on the grounds that the evidence in favour of fluoridation is "irrefutable", and on the claim that many fluoridation supporters for one reason or another forgot to return their ballots. To undermine the referendum, Community Board proponents even produced the results of a secret 5-month-old telephone survey that appeared to contradict the referendum result. To get such a different result, the persons sampled by telephone were almost certainly asked leading questions that virtually obliged agreement.

As a political economist - and as an Onehunga resident who is equally happy to drink fluoridated or unfluoridated water - these kinds of anti-democratic rationalisations worry me.

The referendum non-response rate was most likely due to a combination of public ignorance and indifference. Most people had no opinion.

Of those Onehunga residents who did have an opinion, the weight of opinion was clearly and substantially against fluoridation. In this regard, the Onehunga poll was almost certainly more reliable than the referendums held with the general election in 1999. In those polls, many people who would not have chosen to participate felt obliged to fill in ballot papers that they were not expecting to receive. Such voters responded to the leading questions asked of them in an entirely predictable manner.

The Onehunga poll however was a proper referendum. The public was asked to either support or reject a specific proposal that had been sanctioned by public health experts.

The opposition to fluoride is not simply the ravings of conspiracy theorists, as fluoridation proponents insinuate. The legitimate fear is that public health technocrats do not actually know all that there is to know about fluoride, and that unintended harm may result from excess fluoride. The question then becomes one of whether the gains from having fluoride in the water exceed the risk of harm. The gains from having fluoride in water have not yet been presented to the public in an unambiguous way.

The main beneficiaries of fluoridation are children. But we need to consider children of different ages. Few would doubt that 10-year old children who don't clean their teeth are better off with fluoride in the water. But are there any fluoridation benefits to a 2-year old child who swallows substantial amounts of fluoride toothpaste twice a day?

The information we have seems to come from interested parties. Fluoridation proponents assert that children in Onehunga have 50 percent more tooth decay than other Auckland children. But maybe the children of Glen Innes also have 50% more tooth decay? We need to compare dental health statistics on a suburb by suburb basis.

How do the residents of Onehunga West compare with their middle-class neighbours in Hillsborough and Three Kings? How do children from the low income Maori and Pacific families of Onehunga East compare with comparable families in neighbouring Mangere and Otahuhu?

Herald readers would be well served by a clear unbiased presentation of the evidence of children's dental health in different parts of the cities of Auckland. Simple statistical techniques are available to determine whether bad dental health in Onehunga is caused by a lack of fluoridated water or by other causes.

It is my view that all of Auckland benefits if one part of Auckland has unfluoridated water. Call it an experiment. Keeping Onehunga unfluoridated means that researchers will be able to study the effects of water fluoridation over the long term. Onehunga serves as the study's control group.

A continuance of the status quo means that both supporters and opponents of fluoridation can choose to reside in a place that suits their preference. As economists say, "the customer is always right". That maxim applies to public goods like water as much as it applies to pizzas and meat pies.

We need expertise in public health, just as we do in economics, statistics and other branches of science. But we also need humility from our experts. According to one claim advanced in the "Catching the Knowledge Wave" project, the world's knowledge now doubles every seven years. Who knows what this exponential growth of future knowledge will reveal about fluoride?

The more we know, the more we upwardly revise our estimates of what we don't know. A future 'knowledge society' will be less certain about what is true and what is not true than our society of the 20th century was. Last century, too many of our decision-makers believed they knew everything that there was to know.

Fluoridation is a small matter that raises big questions.

published in the Herald at

© 2001   Keith Rankin

Rankin File | 2001 titles