However, in the end it will be the decision of the respective councils and that would require a clear mandate from the community to do so.

Northland District Health Board chief executive Nick Chamberlain told Parliament’s health select committee on Wednesday they had tried previously to have fluoride introduced. “We have a number of times and I believe we should again and it’s our role to,” Dr Chamberlain said. “We see the significant benefits of fluoride so I’ve talked to my team about us looking at another campaign.”

However, it would require the approval of the board before it went ahead with any campaign.

Northland had probably the worst oral health outcomes in the country, Dr Chamberlain told the committee. The latest figures showed more than 65 per cent of Northland’s 5-year-olds had tooth decay.

Every child in Northland 12 years old or younger had access to an annual oral health check. “Getting the uptake is the challenge, particularly in rural areas,” Dr Chamberlain said.

The DHB had also started varnishing the teeth of 20,000 children with fluoride to help protect them. While it was effective it was also time consuming and expensive, Dr Chamberlain said.

In order for councils to introduce fluoride to the water supply there needed to be a clear mandate from the community. A referendum was held on this issue by the Whangarei District Council in 2002 and 70 per cent of those who responded voted against it. In 2007 the Far North District Council began a two-year fluoridation trial in Kaikohe and Kaitaia. The trial did not continue after 2009 despite NDHB offering to fund it.

Whangarei dentist Lawrie Brett said introducing fluoride to the water supply would be a mistake. “All the research shows that it’s not effective in reducing dental decay,” Dr Brett said.

While most health professional would agree with the DHB’s stance on fluoride, more were going against it, he said.

“There’s no question of it being a health hazard,” Dr Brett said. “It’s a poison.”

Many regions around New Zealand have fluoride in the water supply including most of Auckland, Wellington and Dunedin.