I’m currently reading through the background information prepared for Hamilton City councillors ahead of the meeting they had yesterday, at which they decided to end the fluoridation of Hamilton’s water supply. Right now I’m beginning to think that those of us who are science educators & communicators have done something very wrong, because in the summary of ‘views against’ I see things like this (emphasis in the original):
A key sub-theme that emerged within this topic was the view that fluoride is a chemical or poison.
Yes, fluoride is a chemical. So are table salt & dihydrogen monoxide**. So often we see the term ‘chemical’ used in a pejorative sense, ignoring the fact that everything on the planet, ourselves included, is at some level a concatenation of chemicals. Incidentally, in the right – or should that be wrong? – quantities all are toxic: drinking too much water can be fatal.
The source of fluoride used in water fluoridation is hydrofluorosilicic acid (HFA).
Several submitters attached copies of the Material Safety Data Sheets…. which includes various warnings such as "Avoid contact with skin and eyes", "Repeated or prolonged exposure may result in fluorosis" and "Avoid contaminating waterways".
And indeed, there would be major risks in allowing concentrated HFA to come into contact with skin or eyes. But somewhere along the track people seem to have lost track of the fact that people drinking fluoridated water are not exposed to these risks, for the HFA is highly diluted upon being added to the water supply. As above, the dose makes the poison.
One of the papers submitted in support of dropping fluoridation is summarised here (it’s sometimes referred to as the ‘Harvard study’). The paper itself can be read at this link. It’s a meta-analysis of data from China, "where fluoride generally occurs in drinking water as anatural contaminant". Reasonably large areas of China have groundwater with more than 1.5mg/L of naturally-occurring fluoride – above recommended levels. The study found that
children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas
and concluded that
[t]he results support the possibility of an adverse effect of high fluoride exposure on children’s neurodevelopment.
While I’m sure that this was viewed as significant support for stopping fluoridation, there’s something missing:the ‘high-exposure’ groups were receiving naturally-high levels of fluoride in their water, or were drinking water contaminated by industrial wastes. Levels of fluoride in these groups reached more than 30mg/L. The ‘low’ groups (also called the ‘reference’ groups in the study) were getting less than 1mg/L – the same levels found in treated drinking water in New Zealand.
In other words, this study does not demonstrate that the up-till-now-current levels of fluoride in our water represent a danger to children’s intellectual development. (Did those citing it in support of removing fluoride from our water, actually read it?)
Science education: we can do better. Much better.
** You can demonise most things if you try hard enough.