PM’s Science Advisor wades into water fluoridation

The Prime Minister’s Chief Science Advisor, Professor Sir Peter Gluckman, has added his voice to the discussion on the topical issue of water fluoridation and science. He has written a blog post exploring the science of fluoridation and how it can be used – and misused – in the current debate.

An excerpt (read in full here):

What is in the water?

In recent weeks we have seen a revival of the water fluoridation “debate”. Perhaps the question we need to ask is “what is the debate really about?”

The science of fluoride in water is effectively settled. It has been one of the most thoroughly worked questions in public health science over some decades. There is a voluminous scientific and lay literature that needs to be considered.

There is no doubt that the presence of low amounts of fluoride in water (either naturally occurring or adjusted to between 0.7 and 1 mg/litre) reduces the incidence of dental caries and this is even in advanced economies where dental hygiene has been much improved and where fluoride toothpastes are available. In some countries, fluoride need not be added to the water supply because their geology naturally provides water with fluoride in at least these concentrations. But for some decades, in countries such as New Zealand, where fluoride levels are very low in natural water, fluoride has been added to the water supply.

Notably, both the very young and the old benefit from fluoride in the water supply. They develop fewer dental caries and thus have a significant reduction in the downstream effects such as the need for invasive dental surgery associated with problematic dental status. As in all populations the burden of poor dental health is considerably greater for those in less advantaged socioeconomic conditions and it is this population that benefits most from water fluoridation.

In other areas of the world, natural levels of fluoride in water can reach well above 4 mg/litre – this level is considered by authorities to be the level at which water is still determined to be perfectly safe for human consumption. It is absolutely clear that at doses used in New Zealand to adjust the natural level to a level consistent with beneficial health effects (0.7-1.0mg/litre), there is no health risk from fluoride in the water. Like any agent, including salt, sugar and water itself, if you eat or drink enough it can become toxic. At the doses used in New Zealand water, however, one would in all likelihood become very ill or succumb to water intoxication before any toxic effect of fluoride was discernable.

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