A tinfoil hat-wearing posse publicly berated Associate Minister of Health Peter Dunne about his disdain for anti-fluoride activists.

The fluoride campaigners – including Hamilton City Councillor Siggi Henry - wore the hats at a public meeting in Hamilton to protest Dunne's descriptions in Parliament of such activists.

He called them "tinfoil-hat wearing ... UFO-abducted pseudo-scientists".

TOM LEE/STUFF Peter Dunne spoke at National MP Tim Macindoe's monthly forum at Cafe Agora in Hamilton on Friday.

Dunne shrugged off the protest, which occurred on Friday at Hamilton National MP Tim Macindoe's monthly forum at the Agora café.

"If you choose to wear a tin hat on a rainy day, then I think that's your issue," Dunne said.

"I actually quite enjoy the fact that you're wearing hats."

TOM LEE/FAIRFAX NZ Anti-fluoride campaigners were demanding an apology from Peter Dunne after he called them "tin-hat wearing ... UFO-abducted pseudo-scientists". They are, from left, Gareth Vanstone, Christine Norris, Jill Masters and Hamilton City Councillor Siggi Henry.

One of the hat-wearers, Christine Norris, took Dunne to task.

"You seem to be in the habit of calling names. I think you're rude, spiteful and ungentlemanly like,' Norris said.

"I'm going to ask you to do something you're going to have to do very frequently in the future," she said. "I'd like you to apologise to me for calling me those names."

Dunne declined, saying the comments were not intended to be taken personally.

"I think calling people tin hat-wearing is no big deal," Dunne said. "I think it's all in good humour."

As Associative Minister of Health, Dunne is involved in putting through legislation to make it possible for district health boards to mandate the fluoridation of the country's water supplies.

Decisions around fluoridating water currently lie with local body politicians, rather than health boards.

"I'm the target because I'm the one in charge of the legislation and I'm the one pushing for fluoridation," Dunne said. "So, you know, good on them for trying, but we're going to proceed."

Macindoe reminded the audience the event is open and requested they remain considerate as the room heckled the tin-hatted confronters.

"I'd rather this didn't turn into a public meeting on Fluoride," Macindoe said.

Dunne said the decision to fluoridate was based on relevant health experts and Dunne believes it is a good thing.

Fluoride is a natural substance often found naturally in water that is proven to reduce tooth decay.

It is added to New Zealand's water supply to improve Kiwis' oral hygiene.

Henry disagrees, saying it causes bone fractures, a lower IQ and that people who drink unfluoridated water have better teeth than people who drink fluoridated water.

"It actually doesn't touch your teeth when you drink water - it never touches your teeth," she said.

"It is only New Zealand, Australia and the US adding fluoride and the rest of the world are not."

Another member of the tin hat-wearing team, Jill Masters, asked Dunne why he had opposed the proposal to introduce a tax on sugar if oral health was a concern.

"Consumption of sugar in food and drinks is what causes tooth decay … simple as that," Masters said.

"You'd think, if you wanted better oral health in the population, you would be looking at ways to [improve] how people eat and drink," she said.

Dunne said although he thinks New Zealanders need to reduce sugar consumption, government should focus on better food-labelling and oral health education before introducing a sugar tax.

"I'd far rather we take a staged and systematic approach," Dunne said.

"Do I think that a sugar tax at this time is the most effective step we can take in that regard? I remain to be convinced."