An advert, paid for by an anti-fluoride organisation, appeared in the New Zealand Herald yesterday claiming there is a connection between consuming fluoride during pregnancy and lower IQs in offspring.
The advert, placed by Fluoride Free NZ, cites a Canadian study published in the American Medical Association's journal, JAMA Pediatrics.
As well as claiming fluoride is unsafe for women during pregnancy, the advert also states "there are now 54 human studies out of 61 that have found fluoride adversely affects brain development".
Professor Allan Blackman from Auckland University of Technology appeared on Seven Sharp to give his expert opinion on the issue.
"My opinion is that - the study referenced in the advert – shouldn't change people's opinion on fluoride, but it probably will," he said.
"What will happen is all the ant-fluoride people will take this as vindication that fluoride is bad, while all the pro-fluoride people will point to deficiencies in the study."
Mr Blackman warns that just because the study is published in a "good journal" doesn't mean it's "beyond reproach".
"There have been lots of replies to this particular paper pointing out certain deficiencies in its methodologies," he said.
He believes it isn't responsible for the advert relying on a single study to have been placed by Fluoride Free NZ.
"You can't go around saying fluoride lowers your kid's IQ - that's just not right."