A long-term US study shows water fluoridation at recommended levels doesn’t reduce cognitive ability, with kids who drank such water doing slightly better in school tests. “The paper is entirely consistent with the information that has been gathered over many, many, many years of studying the fluoride supplementation of the domestic water supply,” says a New Zealand practising dentist Dr Justin Wall
Whereas earlier US studies looked at exposure to very high levels of fluoride, far beyond recommended standards, a new paper in Science Advances looks at more representative water fluoridation levels.
Researchers looked at language and maths test results from tens of thousands of US high schoolers in 1980, and the water fluoride levels they were exposed to since conception. After accounting for other factors, kids exposed to at least 0.7 mg/L of water fluoride had better results.
A follow up with a subset of participants until around age 60 showed that, although this cognitive edge became insignificant, growing up with recommended water fluoride levels didn’t contribute to cognitive decline.
“I think that the research itself can be applied internationally. It’s not something that’s simply restricted to the environment in 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,” says Dr Wall
“Furthermore, the health system, as we know, is under pressure, and any measure that can be taken to reduce the pressure on the health system, across the board, needs to be supported. And without a doubt that is the case with fluoridation.”
However, some other studies have found associations between fluoride and cognitive issues, generally at higher concentrations than used in fluoridation programmes, according to University of Otago Professor of Dental Epidemiology and Public Health Jonathan Broadbent.
“There has been limited recent New Zealand research on community water fluoridation. With new fluoridation programmes being launched in New Zealand ongoing research is greatly needed; this is a necessary part of stewardship in running public health interventions such as fluoridation.
“New fluoridation programmes in New Zealand have been focused on areas with higher proportions of deprived New Zealanders and so should have good benefits for oral health, which tends to be worse in areas with greater deprivation,” says Professor Broadbent. “On the other hand, other health issues occur at greater rates in deprived areas so spurious associations could be found. It is essential that the outcomes of these new programmes are monitored carefully.”
