FLUORIDE MESSAGE: Professor Paul Connett speaks at a meeting in New Plymouth last night.

New Plymouth will have fewer geniuses and more "mentally handicapped" people if the town keeps fluoride in its water supply.

Those are the findings of Cambridge University graduate professor of chemistry Paul Connett, a director of the international Fluoride Action Network.

He has travelled the world spreading his message that fluoridation of water supplies is ineffective, dangerous to health and lowers IQ.

Last night, he spoke to more than 80 people at the Plymouth International Hotel as part of his nationwide book promotion tour.

His visit comes as the New Plymouth District Council starts consultation to decide how much fluoride should be in its water supply.

Some people may regard Professor Connett as a conspiracy theorist but that did not stop a New Plymouth dentist, Dr Chris Taylor, from listening to what the man had to say.

Dr Taylor said health industry leaders should pay close attention to Professor Connett's case.

"I respect somebody as notable and dedicated as this and the profession needs to listen," Dr Taylor said.

The dental industry promoted the use of fluoride as a cost effective health measure to reduce tooth decay but it also needed to be open to advice, he said.

"You can't just close your ears the whole time," Dr Taylor said.

He would take a good look at studies Professor Connett referred to. "It's generating a lot of interest."

In an interview before the meeting, Professor Connett, who is the executive director of the American Environmental Health Studies Project, spoke to the Taranaki Daily News about what he called the ineffectiveness of fluoridation and its "wildly exaggerated" benefits.

"It's a poison, it's a pesticide," Professor Connett said.

There had been a number of studies indicating water fluoridation decreased IQ and increased the number of intellectually disabled people in populations, he said. "We will see a decrease in the number of geniuses and an increase in the number of handicapped."

Regulating bodies had known about the ineffectiveness of fluoridation for a long time but would not admit it out of fear of losing credibility, he said.

"If you lose credibility you lose the people's trust."

New Zealand was one of only eight countries which had 50 per cent of the population drinking fluoridated water, he said. "It's an insane thing to do, especially if the benefits are so small."

Fluoride was used in a range of potent toxins ranging from chemical weapons to life-saving pharmaceuticals.

About 50 per cent of fluoride ingested was excreted through the kidneys, while the rest accumulated in the body, he said.

Most accumulated in the bones making them brittle, with similar effects to arthritis.

"It's not reversible."

In countries where fluoridation had been discontinued tooth decay had decreased, he said.

Professor Connett gained honours in a Bachelor of Art in natural sciences from Cambridge University.

He also has a PhD in Chemistry.

New Plymouth mayor Harry Duynhoven was asked by supporters of Professor Connett if he could present before council.

The request was declined because the council was not ready to hear submissions until August, he said.

"I haven't blocked anybody," Mr Dunyhoven said.

The council was only at the stage of debating the fluoridation consultation process, not the issue of whether it should be used or not, he said.

Following last night's meeting more than a dozen supporters of Prof Connett's findings rallied to form a New Plymouth against fluoride group.

The aim of the group is to put pressure on the council to stop treating the water supply with fluoride.