Tag Archives: NZ Sciblogs

Another defeat for anti-fuoridation claims about arsenic

Anti-fluoride campaigners make a song and dance about contaminants, particularly arsenic, in fluoridation chemicals. However, a new study shows there is actually nothing to worry about – and, in fact, these campaigners should be more concerned with natural sources of arsenic, than with fluoridation chemicals.

The study is:

Peterson, E., Shapiro, H., Li, Y., Minnery, J. G., & Copes, R. (2015). Arsenic from community water fluoridation: quantifying the effect. Journal of Water and Health.

Past studies estimated the arsenic contribution to drinking water from fluoridation using the arsenic concentration of the fluoridation additives. This new study went further and compared the actual arsenic concentrations of  1329 paired raw water and treated drinking water samples. The samples were taken from 121 drinking water systems in Ontario, Canada.

The graph below compares the mean values of arsenic concentrations in raw water and treated water for both fluoridated (49%) and unfluoridated systems (51%).


The data shows that even after treatment the concentration of arsenic due to natural sources is about 0.44 ppb. Fluoridation added a mere 0.07 ppb to this! (ppb = parts per billion = micrograms/litre = μg/L).

The authors concluded that fluoridation is associated with an extra 0.078 ppb compared with non-fluoridated systems when controlling for other factors (raw water concentrations, treatment processes and water source).

Let’s put these figures in context. The maximum acceptable value (MAV) for arsenic in drinking water is 10 ppb. So even the raw water mean concentration of 0.69 ppb (0.44 ppb after treatment) is safe. And the extra arsenic in fluoridated water is only 0.7% of the MAV!

Surely the sensible person will worry about natural sources of arsenic long before getting their knickers in a twist over the contribution from fluoridation.

I drew a similar conclusion from some New Zealand (Hamilton City) data in my article Fluoridation: putting chemical contamination in context. In that case, the contribution for arsenic from natural sources was much higher (around 30 ppb in the raw water – 3 times the MAV, and about 3 ppb in the treated water – a third of the MAV ).

New paper confirms previous studies

This new study confirms previous work based on the measured concentration of arsenic in fluoridating chemicals. That work produced regulations defining maximum permissible levels of contamination in water treatment chemicals. These are based on a maximum contribution of 1 ppb – 10% of the MAV.

Peterson et al., (2015) indicates the extra arsenic resulting from fluoridation is less that 10% of these standards. This is likely to be much less in Australia and New Zealand as the actual arsenic concentrations in the major fluoridating agent used, fluorosilicic acid, are much lower than those used in North America.

So – my message to anti-fluoridation campaigners is stop worrying about arsenic due to fluoridation. If you must worry then check out the concentration  of arsenic in your drinking water, and the raw water source, due to natural sources.

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Journeys to the Ice – New SciBlogsNZ blogger

Welcome to Matt Woods, who is now blogging at sciblogsNZ. Matt spent some time working in Antarctica on an ice coring reconnaissance expedition. His blog, Journeys to the Ice, will cover Antarctica and Antarctic science.

Matt has also started a podcast. So go to his blog and have a look. perhaps subscribe to the podcast.

SciblogsNZ must now have about 30 bloggers. Its launch a few months ago represented a big step in science communication in New Zealand. I have certainly noticed a large increase in the activity of local science bloggers – and this must be a good thing.

Inevitably it’s led to a few attacks on science blogging by local conspiracy theorists (eg. Poneke and Ian Wishart). Another sign of effective communication, I say.

And Sciblogs NZ is certainly getting attention from others on the internet. It is currently the 5th ranking blog on the NZ blog ranking survey based on sitemeter statistics (see NZ blogs sitemeter ranking – January ‘10).

Update: This post was interpreted by Poneke as another conspiracy (see Taxpayer-funded Science Media Centre gets a curious ratings boost from global warming). Interesting though there seems to be a bit of a battle between sciblogs and Poneke on the rankings. (At the moment Sciblogs is in 4th and Poneke 5th).


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NZ scientists twittering

sciblogsWho would have thought it. Certainly not me.

NZ Sciblogs is now twittering. Go to Sciblogsnz if you want to follow.

Looks like the NZ Sciblogs platform is only weeks away.

See also: NZ science bloggers – new opportunity