Tag Archives: arsenic

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%).

Peterson

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.

Similar articles

NASA and old lace

Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic. (Image NASA)

I managed to catch the tail end of the NASA press conference this morning. This  had created quite a flutter on the internet with some speculating that NASA was going to announce the discovery of evidence for extraterrestrial life.

Well, it proved to be a bit more realistic than that – but nevertheless quite exciting. The press conference discussed research indicating the possibility that arsenic can substitute for phosphorus  in a bacteria. Neil deGrasse Tyson explained this in a brief tweet:

“Like Carbon & Silicon in Periodic Table, Phosphorus & Arsenic sit above &b elow one another, making them kindred souls of chemistry.”

Researchers present their findings in the paper A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus.” It has the usual laundry list of authors (12) we have come to expect for significant work. The lead author is Felisa Wolfe-Simon. And here is the abstract:

Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions. Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, which substitutes arsenic for phosphorus to sustain its growth. Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins. Exchange of one of the major bioelements may have profound evolutionary and geochemical significance.

And here is a short video on the work:
Vodpod videos no longer available.
NASA’s Alien Life News: The Real Story from Sci…, posted with vodpod

The scientists at the press conference disagreed on the actual role of the arsenic and how stable such life forms could be. Clearly more work will be done on this and Wolfe-Simon is publishing further results in February.

This is way out of my area of expertise so I won’t comment further on the research. But I was interested to here the scientists and reporters discuss the feelings that often come with significant discoveries. Ryan Anderson from The Martian Chronicles expressed my thoughts exactly with his comment:

I thought it was great to hear Wolfe-Simon say during the question session that there wasn’t a “eureka moment” where they knew what they had found, it was more like “Hey, this isn’t right.” It reminds me of this Isaac Asimov quote:

The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ (I’ve found it!), but ‘That’s funny…’ -Isaac Asimov.

See also:
NASA Scientists Find Microbes With Arsenic DNA
NASA-Funded Research Discovers Life Built With Toxic Chemical
Of Arsenic and Aliens
Living off Toxic Waste—Bacteria Swap Out Phosphorus for Arsenic

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