Keeping fluoridating NZ water despite bombshell study

Peter Griffin : 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 non-fluoridated areas.

We put fluoride in over 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 game-changer. This is one observational study that doesn't establish cause and effect. It doesn't take into account all of the 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.

What should pregnant mothers do in the meantime?

"I would advise them to drink bottled water or filtered water because it is not a particularly odious thing to do and actually does reduce the risk," said JAMA Pediatrics editor Dimitri Christakis.

Fine, do so as a precaution. 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.