You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Fluoride does not adversely affect IQ development in children, a Dunedin study just published in an academic journal says.
The study published in the American Journal of Public Health used data from the Dunedin Multidisciplinary Study.
Lead author Dr Jonathan Broadbent, a public health dentistry specialist, said the research focused on fluoride exposure during the first five years. After that age, IQ was relatively stable.
Dr Broadbent compared those who grew up in Dunedin suburbs with and without fluoridated water. Use of fluoride toothpaste and tablets was taken into account, and the study controlled for other factors, such as socioeconomic status.
The researchers examined IQ and other cognitive skills between 7 and 13, and at age 38.
IQ information was available for 992 and 942 study members in childhood and adulthood, respectively.
''Our analysis showed no significant differences in IQ by fluoride exposure, even before controlling for the other factors that might influence scores.
''In line with other studies, we found breast-feeding was associated with higher child IQ, and this was regardless of whether children grew up in fluoridated or non-fluoridated areas.''
Dr Broadbent said studies showing adverse effects from fluoride were poorly designed.
''In comparison, the Dunedin Multidisciplinary Study is world-renowned for the quality of its data and rigour of its analysis.
''Our findings will hopefully help to put another nail in the coffin of the complete canard that fluoridating water is somehow harmful to children's development.
''In reality, the total opposite is true, as it helps reduce the tooth decay blighting the childhood of far too many New Zealanders,'' Dr Broadbent said.
The findings were rubbished by opposition group Fluoride Free NZ yesterday. National co-ordinator Mary Byrne disputed the study's integrity, saying it appeared children taking fluoride tablets were included with those drinking unfluoridated water.
''It appears they have included children taking fluoride tablets in the already much smaller sample of children drinking unfluoridated water. Children taking fluoride tablets would have a similar dose of fluoride than the children drinking fluoridated water.''
Ms Byrne said Dr Broadbent's public advocacy of fluoride's oral health benefits meant the findings carried less weight.
Dr Broadbent rejected Ms Byrne's concern the unfluoridated children included those taking fluoride tablets.
The study controlled for fluoride tablet intake, and also, tablets were found to have no effect on IQ anyway.
He strongly rejected the suggestion he was not sufficiently unbiased to lead the study.
The research team included other dentists, but also psychologists and a statistician, Dr Broadbent said.
Dr Broadbent will speak about his findings to a psychology conference in San Francisco later this week.