Photo: AFP
A New Zealand dental surgeon says a 40-year study shows water fluoridation does not hinder brain development in children and those who drank it did slightly better in tests.
Researchers in the US surveyed tens-of-thousands of people on maths and language skills from teenagerhood until the age of 60.
While earlier studies looked at exposure to very high levels of fluoride, far beyond recommended standards, a paper in Science Advances, looked at more representative fluoridation levels.
Researchers looked at language and maths test results of high schoolers in 1980, and the fluoride levels they were exposed to since being born. They found after accounting for other factors, children exposed to at least 0.7mg/L of water fluoride had better results.
A follow up with participants until about the age of 60 showed that although the cognitive edge became insignificant, growing up with recommended water fluoride levels didn't contribute to cognitive decline.
"The discussion has been that fluoridation of domestic water supply has been associated with cognitive impairment in young people," dentist Dr Justin Wall said.
"The good thing with this new study is it's a much larger group of people, and they are followed right through until age 60."
Dr Wall said the study clearly shows fluoridation was safe for people of all ages.
He said fluoridation was particularly vital in protecting the oral care of New Zealand's ageing population.
Dr Wall believed although the research was done in the US it could be applied internationally and was not restricted to America.
"It is something that is well and truly applicable to New Zealand, and this research should go all the way to reassure the public of New Zealand and the municipal authorities who are being charged with implementing the fluoridation of the water supply that this is a safe and effective means of protecting the health of all New Zealanders.
New Zealand's health system was under pressure, Dr Wall said, and any measure to reduce the pressure on it needed to be supported.
"Without a doubt that is the case with fluoridation."
Limited research in New Zealand
Professor of dental epidemiology at the University of Otago, Jonathan Broadbent, said the US study result was reassuring, but there had been limited recent New Zealand research on community water fluoridation.
"With new programmes being launched in New Zealand ongoing research is greatly needed."
Broadbent said the programmes were focused on areas with higher proportions of deprived New Zealanders and so should have good benefits for oral health, which tended to be worse in areas with greater deprivation.
But he said it was essential the outcomes of the new programmes were monitored carefully.
In an interview with Midday Report, lead author of the US research, Professor Rob Warren from the University of Minnesota, said based on 40 years' worth of data, it showed children who grew up drinking water with recommended levels of fluoride actually did slightly better in school tests.
The results appeared to contradict an earlier study looking at exposure to very high levels of fluoride in children, which found it lowered cognitive ability.
"But their fluoride exposure was many times recommended levels," Warren said.
The findings should give authorities and the public confidence when it came to making policy decisions on water fluoridation, he said.
"If you're weighing the pros and cons, a big concern has been impact on cognition. And this study shows that we don't need to worry about the potential for that negative effect."
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