People who grew up in a town with fluoride in its water can flash their pearlies this week, happy that they are not stupid after all.

Recent research shows fluoride in drinking water does not lower IQ. The University of Otago study followed the health and development of 1000 babies born in 1972 for 40 years. Senior lecturer Dr Jonathan Broadbent said people who had lived in fluoridated areas their whole lives had slightly higher IQs. He said people had been quoting “bad science” to councils that wasn’t accurate.

So fluoride doesn’t make us stupid. But New Zealand legislation covering it seems dumb.

At present, each local government body has its own rules on fluoride. Twenty-two of the nation’s 67 councils add fluoride to their water supply and about half of the population drinks fluoridated water.

Fluoride was taken out of Tauranga’s water supply in 1992 after a referendum in which more than half of the city’s residents voted against its continued use.

But responsibility for fluoride is becoming a major toothache for indebted local councils. On Monday, at the Local Government New Zealand conference in Nelson there was a call for the decision on whether fluoride should be added to the water supply to be made by the Director-General of Health, rather than local authorities.

This call backs last year’s recommendation by a parliamentary health committee to transfer responsibility for fluoride additives to the Ministry of Health and district health boards.

Taking the responsibility for supplying fluoridated water supplies out of the hands of local body politicians makes sense. A local referendum is expensive. Rotorua ratepayers may soon have to pay up to $100,000 for a referendum on whether fluoride should be introduced to the district’s water supplies.

Ratepayers may also have to pay the bill for litigation when – as has been the case in Hamilton and South Taranaki – anti-fluoride campaigners have challenged the councils’ right to add fluoride to water. A judicial review and appeal in South Taranaki have cost about $250,000 so far.

One has only to look at Hamilton to see how the current system can lead to a farcical situation – with fluoride in and out of the water like the hokey cokey.

This month the High Court cleared the way for Hamilton’s water to be fluoridated again. It was previously removed by council 12 months ago but a referendum voted overwhelmingly for its return. Opponent Safe Water New Zealand intend to challenge the decision by a judicial review.

Under the current system, councils must consider submissions by the anti-fluoride lobbyists but councillors are not qualified to do so. Anti-fluoridation groups such as Fluoride Action Network New Zealand have lobbied hard in recent fluoride debates in Hamilton, Hastings, South Taranaki and Whakatane and are poised for action in the upcoming referendum in Rotorua. Fluoride Action Network New Zealand argued that fluoride can be linked to adverse health effects such as arthritis, thyroid dysfunction, hypersensitivity, and lowered IQ.

The latter claim has been disproved by Otago University researchers, but when lobbyists present councils with declared risks as facts, how can local governments be sure of the safety of fluoride?

The answer is simple – central government has already declared it so. The Ministry of Health strongly supports water fluoridation as a “safe, effective and affordable way to prevent and reduce tooth decay across the whole population”.

“A very large body of scientific literature supports fluoridation as a safe means of reducing rates of tooth decay,” the ministry website says.

According to the Ministry of Health and Toi Te Ora Public Health, numerous large scientific reviews over the past 60 years and on-going monitoring of all new, relevant scientific studies continue to confirm that water fluoridation is effective and safe – and not linked to any health risks.

The World Health Organisation, Public Health Commission, Ministry of Health and Environmental Science and Research have all supported its safety. About 370 million people in 27 countries have fluoridated water supplies. Other countries use fluoridated salt or milk.

At Ministry of Health recommended levels of between 0.7 and one milligram of fluoride per litre, it would be impossible to experience fluoride toxicity from drinking water.

One would have to drink more than 5000 glasses of fluoridated water in one sitting.

Anything is toxic if you have too much of it, even water without fluoride.

Nor does water fluoridation intend to replace brushing teeth, regular dental check-ups or a low-sugar diet. Not everyone is brushing their teeth twice daily with the right toothpaste or forgoing the fizz. The 2009 New Zealand Oral Health survey found only about 65 per cent of people brushed twice a day using fluoride toothpaste, slightly less for children.

Last year Bernadette Drummond, of Otago University’s dentistry faculty said that more than 40 per cent of New Zealand 5-year-olds get dental decay and of those, about a third of those will have significant problems.

According to the Ministry of Health, studies have also shown that when communities stop fluoridation, there is a reversal of the benefits, an increase in decay rates and a large increase in the number of baby teeth extracted. Most recent studies continue to show that the difference between fluoridated and non-fluoridated areas continues to be significant throughout life. Fluoride tablets don’t provide constant small doses through the day and are more expensive over time than water fluoridation.

The parliamentary health committee which last year recommended that responsibility for fluoride be handed to the DHBs noted that oral disease was among the most prevalent chronic diseases in New Zealand and among the most preventable.

“Oral diseases and their consequences, such as embarrassment, pain, and self-consciousness, can have a profound effect on a person’s quality of life and ability to gain employment … Caries can also affect children’s development, school performance, and behaviour, and thus families and society in general.”

The committee noted that children appeared to have better oral health in areas with a fluoridated water supply.

“The scientific evidence was clear that when fluoride is added to the water supply in appropriate monitored doses there is a reduction of dental caries in children, particularly children living in low socio-economic families.”

So with such body of clear scientific evidence, already backed by central government, it seems absurd that we leave the decision to local councils to set their own rules for each community.

Why not just make one rule for all New Zealanders?

This is the view presented by Kapiti Mayor Ross Church in one of our sister community papers, Kapiti News. Kapiti this year voted to continue with fluoride in the water. Mr Church wants the decision on fluoridation to rest with Government.

“The Ministry of Health has clear guidelines on fluoride. What the LGNZ needs is for these to become directives. There is consistency in this. Already, Government sets the standards for every other aspect of drinking-water quality. Government also sets the standards for the quality of our waterways through the new National Policy Statement for Freshwater. Buildings and waterways may not be owned by Government, but Government sets the standards. Now is the time for Government to do the same with fluoridation of our water.”

Important health issues should not be made on a public vote at community level. We are not medical experts and should not be advised on health issues by councils, as evidenced when Hamilton Council sent out a leaflet last year to explain its controversial decision to remove fluoride. The content was slammed by dental authorities with the University of Otago’s Dr Jonathan Broadbent, calling it “wrong, unscientific and misleading” and telling residents to disregard it.

Councils should not have to grapple with submissions on fluoride from all manner of bodies, from lobby groups to lone paranoids. Nor should ratepayers foot the bill for legislative action.

Putting the decision in the hands of central government is still democratic. The government is still accountable to voters. But this should be a nationwide public health directive, not a battle about individual rights. Returning the fluoride decision to the government makes better sense, better consistency for all New Zealanders and better teeth.