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Southern District Health Board dental public health specialist Tim Mackay yesterday responded to a Canadian study that concluded maternal exposure to higher levels of fluoride during pregnancy was associated with lower IQ scores in children aged 3 to 4 years.
The issue arose after a Fluoride Free NZ billboard that said fluoridated water ''lowers kids' IQ'' was removed from outside Dunedin Airport.
The airport told the advertising company that put it there it was not comfortable with that message on its land.
The billboard referred to the Canadian study.
Asked to respond to the issue, Dr Mackay said he was aware of the study.
But there had been a lot of work done recently in New Zealand on fluoride as part of the Health (Fluoridation of Drinking Water) Amendment Bill.
The Bill, if passed, would allow health boards to make decisions about the fluoridation of local government drinking water supplies in their areas.
He said the result of that work was the conclusion fluoride was ''safe and effective''.
However, Dr Mackay said health specialists were prepared to look at new evidence as it came along.
When a new study like the Canadian one came out, the Ministry of Health or university researchers needed to consider it, and discover, for instance, whether there was cause and effect in associations found between fluoride and children's IQ, and whether issues such as socio-economic status were taken into account.
For scientific issues it was important not to become ''stuck in a dogma''.
Good studies on a large scale could shift scientific thinking.
However, at the moment, there were no good, published studies that had shifted the balance of thought, Dr Mackay said.