Rotorua’s council is considering installing a fluoride-free tap amid heated debate over a directive to fluoridate the city’s water.

Speaking at a Rotorua Lakes Council workshop on Monday the Ministry of Health’s head dentist defended fluoridation directives and, in the face of public and councillor criticism, said the ministry kept a watchful eye on any new studies into the safety and effectiveness of fluoride.

The decision on whether public drinking water supplies should be fluoridated was removed from local government jurisdiction in 2021, with the goal of improving poor dental health.

Rotorua was among 14 councils directed to fluoridate some or all water supplies by then-director general of health Sir Ashley Bloomfield.

The city has until March 28 to fluoridate its central and eastern water supplies, after being granted an extension from April 30 last year. Whether it will comply will be decided on March 26.

Non-compliance carries a maximum penalty of $200,000 and up to $10,000 a day for continuing offences.

Chief oral health adviser Dr Riana Clarke’s presentation at Monday’s meeting was almost immediately met with calls of “misinformation” from the public.

During her presentation, Clarke said fluoridation was a well-established public health measure.

This prompted the cry of “misinformation” from the crowd. Mayor Tania Tapsell said anyone unable to observe quietly would be asked to leave.

She later called for a five-minute pause to regain order.

Clarke said fluoride occurred naturally and the directive would top it up to reach between 0.7 to 1 mg per litre (mg/l), and be monitored.

Water flowing at the Karamu Takina springs and water treatment site. Photo / Laura Smith

Bay of Plenty Regional Council data shared at the workshop showed Rotorua’s springs had a natural fluoride level of 0.04 to 0.14 mg/l. Geothermal water was 4 mg/l and sea water was about 1.3 mg/l.

As Clarke detailed how the ministry believed fluoride to be safe in the set range, one man said “I can’t listen to this, sorry” and walked out.

Clarke said evidence was used to determine, and reconfirm, safe use levels. This included its 2024 review of evidence.

She said it helped health equity and reduction of tooth decay, and was important for lower socio-economic areas.

Fluoridation was used in conjunction with other measures, such as free brushes and paste. It had been used in parts of New Zealand since 1954.

Tooth decay remained the most chronic disease. In the year to December 2023, 268 Lakes District 0 to 14-year-olds received in-patient hospital care for preventable dental conditions, 179 of them Māori children.

There was no high-quality evidence of significant harm to health from fluoridation at the levels set in New Zealand, she said.

At the meeting Health New Zealand medical officer of health Dr Phil Shoemack said the fluoride levels took into account people’s diet, different people’s sensitivity and medical conditions.

“No one will come to harm in New Zealand from drinking fluoridated water.”

Rotorua rural ward councillor Karen Barker. Photo / Laura Smith

Councillor Karen Barker, who has a background in pharmacy, referenced studies that “demonstrated negative consequences for children” around neurodevelopment including for prenatal and born babies and a 2024 federal court case in which a US judge found fluoridation of water at 0.7 mg per litre posed an unreasonable risk of reduced IQ in children.

While it did not conclude with certainty fluoridation was injurious to public health, there was enough risk to require the Environmental Protection Agency to “engage with a regulatory response”.

Clarke said most studies were from countries where fluoride naturally occurred in very high levels.

“All of the evidence we’ve been collecting for about 70 years on water fluoridation hasn’t been usurped by these new papers,” Clarke said. “We’ve been watching very carefully.”

Other studies did not meet “normal study protocols”, she said, but were considered in its review.

It would review its policies if anything “significantly alarmed” it.

Councillor Don Paterson asked how it was justified as a medical treatment without individuals' consent.

Rotorua Lakes Councillor Don Paterson. Photo / Laura Smith

Shoemack said adding fluoride to water was not treatment to individuals but to the water, similar to how folate was added to flour or chlorine to water.

Paterson said addressing sugar consumption was a better solution. Shoemack said there were multiple solutions and “we should be doing everything we can”.

Councillor Lani Kereopa voiced concern local iwi and Treaty partners had no decision-making power on the issue.

Clarke said there were opportunities during the legislative changes for views to be heard.

She said councils could provide a fluoride-free source within the funding provided. Rotorua received about $3 million.

Chief executive Andrew Moraes said staff were investigating the possibility of providing such a tap.

The regional council’s science manager, Rob Donald, said there was no unacceptable risk to the environment from fluoridation with controls in place to keep risk low.

A Court of Appeal hearing is scheduled for June relating to whether the High Court was correct to find that the New Zealand Bill of Rights Act created a procedural duty on the Director General to consider the right to refuse medical treatment under the act when issuing each direction.

It will not affect the validity of the directive.

On Tuesday, New Zealand First issued a statement that said it introduced a member’s bill seeking to restore fluoridation decision-making power to local communities.

It aimed to repeal the Health Act changes that allowed the directives and would amend others to mandate local authorities to hold a binding referendum on water fluoridation.