Shock study needs work

I’m a strong advocate for putting fluoride in the public water supply. The evidence from here and abroad suggests that children who live in areas with fluoridated water have much lower rates of dental decay than those who live in nonfluoridated areas.

We put fluoride in more than half of the country’s water supply because it doesn’t naturally exist in sufficient quantities to offer our teeth protection.

So what do we make then of the bombshell scientific paper that appeared last week, suggesting that kids exposed to more fluoride at a very young age have lower IQ?

The study appeared in the highly-credible journal JAMA Pediatrics and has caused a stir globally. The editors agonised over whether to publish it, knowing the impact it could have on public health.

The research followed mother and child pairs living in fluoridated and non-fluoridated areas of big Canadian cities. The scientists took urine samples from 512 pregnant mothers and had them complete questionnaires about their fluoride intake. Later, at age 3 and 4, their children were given IQ tests.

The key result showed that a 1 milligram per litre increase in maternal urinary fluoride concentration was associated with a 4.5-point lower score on the IQ test – for boys only. Girls did about the same with greater exposure to fluoride.

The finding is surprising, but it isn’t a gamechanger. This is one observational study that doesn’t establish cause and effect. It doesn’t take into account other factors that could be at play. The differing results between boys and girls aren’t explained and have puzzled scientists.

IQ tests are well established but are subject to degrees of error.

The results need to be replicated in other large cohorts before anyone can say that exposure to fluoride during pregnancy has an impact on children’s brain development.

That hasn’t stopped New Zealand anti-fluoride campaigners from claiming the study results justify a ‘‘moratorium on fluoridation’’.

They don’t. But I’d like to see more research. But the fact remains that once born, kids need exposure to low levels of fluoride to protect their growing teeth.

Community fluoridation is the best way to safely give them that.

The fact remains that once born, kids need exposure to low levels of fluoride to protect their growing teeth.