Fluoridation of the municipal water supply is either an oddball and unethical medical practice with close to zero benefits and significant health risks – or one of our greatest public health achievements.

It all depends on who you believed at a Hamilton City Council workshop yesterday, where touring US professor Paul Connett presented the case against Hamilton continuing with fluoridation, and Waikato medical officer of health Felicity Dumble responded with an equally staunch summary of the health benefits of the practice.

Soaking up the unfiltered addresses were eight councillors and about 40 members of the public – none of whom appeared to leave with opinions significantly altered after further examination of the city’s most debated public health intervention.

Hamilton’s water supply has been fluoridated since 1966, while councillor workshops have examined the issue in 2003 and 2005, with a 2006 referendum attracting 70 per cent public support for continuation.

But Dr Connett, co-author of the recently published book The Case Against Fluoride, said it was the only example of New Zealand using the public water supply to deliver medicine.

“That is an absolutely stupid thing to do because you can’t control the dose when people drink different amounts of water,” he said.

“Everybody gets it. There is no individual doctor oversight, no health agency is monitoring the side effects, and there are virtually no primary health studies conducted in New Zealand.”

He described fluoride as “an industrial grade waste product” and “known toxic substance”, with New Zealand’s average treatment rate of 0.85 parts per million being over 200 times the level found in mother’s milk.

“You have to ask yourself, who knows more about what the baby needs, evolution which took millions of years to develop or a bunch of dentists in the US in the 1940s.”

While mainstream views of PCBs, lead and asbestos had been significantly modified over the years, “no other pollutant in the world has got such generous treatment as fluoride”.

He noted fluoride worked on the outside surface of the tooth rather than from the inside of the body.

“It makes as much sense to swallow fluoride as it does to swallow sun tan lotion.”

And with 96 per cent of New Zealand toothpaste contained fluoride, he questioned the need to have people drinking water containing it.

Dr Connett said potential harmful effects of fluoride included bone damage, brain damage, lower thyroid function and accumulations in the pineal gland.

“We might actually be killing our people with this practice.”

He pointed to 24 published studies which suggested exposure could lower intelligence quotients.

“What parent in their right mind would put their children’s teeth above their brains?”

He said the fact so many dentists supported fluoride only reflected historic teachings based on “junk science” which did not stand up to scrutiny. And the health bureaucracy was simply trained to “promote policy rather than question it”.

But Dr Dumble rejected almost all his points, including the idea that fluoride was mass medication.

“It is topping up something that is already in the water,” she said, noting fluoride was the 13th most common element on earth and found in all water – including the Waikato River in amounts varying from 0.2-0.6PPM.

She estimated the council’s investment of $40,000 a year in fluoridating the water supply saved over $1 million in dental treatment costs.

“There is a role for local government in protecting public health.”

She said fluoride worked better at preventing tooth decay at a mass level than “personal practice” because it could affect broad sections of the community, including the most vulnerable.

“It is safe, easy to use and cost-effective.”

Waikato data showed less tooth decay among children in Tokoroa – which has fluoridation – than in Cambridge, which doesn’t have it.

Since the 2006 referendum she said there had been no new evidence to prompt a change of policy.

“If you are thinking about reversing the policy, you have to look at whether there has been any new reliable evidence that would suggest previous decisions were wrong.