Activists peddle chemical misinformation for fluoridation referenda

The propaganda produced by anti-fluoridation activists reminds me of this cartoon.


There are just so many examples of this in a flyer produced by the Fluoride Action Network of NZ (FANNZ) for the upcoming fluoridation referenda in Hamilton, Whakatane and Hastings. Here is just one small section describing the fluoridating chemicals used in New Zealand.


They are, of course, referring to the most commonly used fluoridating, chemicals –  fluorosilicic acid and sodium fluorosilicate. I have written about these chemicals, and the FANNZ misinformation on them before – see Fluoridation – are we dumping toxic metals into our water supplies?,  Water treatment chemicals – why pick on fluoride?  and Hamilton – the water is the problem, not the fluoride! .

The claims on the flyer are just misleading, if not outright lies. Just in the extract above (only a small part of the flyer):

1: Fluorosilicic acid is a by-product of the fertiliser industry in New Zealand. There is a market for that chemical (if only a relatively small one in New Zealand because we don’t have a fluoride industry) so it is not waste.  Sure, in its concentrated form it is corrosive and toxic – as are all such chemicals. Including those used in water treatment like chlorine, sodium hydroxide, aluminium sulphate, etc. (see Water treatment chemicals – why pick on fluoride? ).

2: No, it is not food grade, neither is the chlorine, sodium hydroxide and alum used in water treatment. Because they aren’t used in foods – especially at those concnetrations.

3: Contamination with “mercury, arsenic, lead, cadmium and other heavy metals” is extremely small (see Fluoridation – are we dumping toxic metals into our water supplies?,  Water treatment chemicals – why pick on fluoride?  and Hamilton – the water is the problem, not the fluoride! ). Regulations define permissible levels of contaminants in our water supply and the chemicals used to treat it. They are based on known health risks of such chemicals and include large safety factors.  Suppliers must fulfill these requirements, and provide certificates of analysis from independent laboratories, or the material is rejected.

Here is an example of the data from a Certificate of Analysis for a batch of fluorosilicic acid supplied to the Hamilton City council earlier this year:


Those levels of heavy metals are extremely low. FANNZ has access to this information – a copy of this certificate was supplied to the local FANNZ representative by the Hamilton City Council. So why do they persist with this lie about contamination with toxic heavy metals?

4: No, it is not the same as naturally occurring calcium fluoride (CaF2). But when diluted in water fluorosilicic acid and the fluorosilicate anion decomposes to form the fluoride anion (F) and silica.


The reaction is driven to completion by removal of SiO2 from solution. The fluoride anion is exactly the same as that in calcium fluoride and a solution of dissolved CaF2. It is the F species which provides the beneficial action to teeth and bones.

5: No it has never been tested for human safety at the low concentrations used in water fluoridation – for a very good reason. You can’t prepare a solution of fluorosilicic acid at these low concentrations because of its decomposition (see equation above). But, because it is hydrolysed to form F, safety studies carried out with fluoride solutions prepared from chemicals like sodium fluoride and CaF2 are completely relevant. Remember, the fluoride anion is the fluoride anion, whatever its origin.

Chemical confabulation

Anti-fluoridation activists are nothing if not faithful to their story. They perform all sorts of difficult mental gymnastics when confronted with the facts above. Some of them will invent anything to deny these facts. For example:

Claim 1: The fluorosilicate does not decompose completely – it still gets into your drinking water and body. They will even quote Crosby et al (1969) who reported “that sodium fluorosilicate, at the concentration normally present in public water supplies, is dissociated to at least 95%.” The activists choose to interpret “at least 95%” to mean they have 5% to point to, and not representing any margin of error in the data.

There have been a number of studies specifically for checking the completion of hydrolysis of fluorosilicate anion at low concentrations. Although equilibrium measurements indicate complete hydrolysis it was necessary to make sure that kinetic factors did not inhibit the reaction.

Most of these studies were reviewed by Urbansky 2002, in his paper “Fate of Fluorosilicate Drinking Water Additives.” He concluded that all the chemical “rate data suggest that equilibrium should have been achieved by the time the water reaches the consumer’s tap if not by the time it leaves the waterworks plant.”

Similarly, Finney et al (2006) investigated fluorosilicate hydrolysis using 19F NMR and reported their results agreed with “previous findings that at pH ~ 7 and at typical drinking water formal fluoride concentration, hexafluorosilicate dissociation to produce free fluoride ions will be essentially complete.”

Claim 2: Fluoride in natural CaF2 is bound tightly to Ca and the extra Ca acts as “a partial antidote to fluoride toxicity, so, obviously, the statement ‘fluoride is fluoride is fluoride’ is misleading.”

As a chemist I find this confused but several anti-fluoridation activists have made that claim to me. Fluoride exists in solution as the hydrated F anion – not directly connected to a cation as in the solid crystal. Effectively it is independent of the cations in solution. Sure, if there is excessive Ca2+ then CaF2 crystals will precipitate. And other ions could also promote removal of other insoluble products. But in solution fluoride is fluoride is fluoride. It is not influenced by its origin.

Really, this sort of gobbledygook is just an attempt to avoid reality. It is not science.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
New Zealanders for fluoridation Facebook page

8 responses to “Activists peddle chemical misinformation for fluoridation referenda

  1. Hey Ken.. just a quick (and possibly stupid) question about flouride in water.
    Does a person still get the benifits if the water is used in something else and not drunk directly… for instance if the water is used to make some soup, or a jug of coffee, or a loaf of bread?


  2. Ken, you obviously don’t know what you are talking about.

    Of course alum is used in food… as a food additive

    of course sodium hydroxide is used in food.

    Also, of course HFA is a waste product of fertiliser production… the fact that some of it can be used else where does not decry the claim it is a waste product. That’s like saying the organic waste we put in our bin isn’t waste because it’s converted into compost.



  3. rrrr… Ken does not say that alum is not used in food. He says that the alum used in water is not the same as that used in food.. ie. not food quality I assume – same goes for socium hyroxide.,

    Just as an interesting aside for New Zealanders who who live through the marmite drought…. the nations favorite spread is actually a “waste product” of another process (or was originally)… just a thought…. our industrial processes are complex.


  4. Yes, Max. Drinking or eating food means that F concentrations in saliva can be maintained at effective levels. This helps to limit enamel mineralisation from acid attack which caused decay. Also, F in the ingested food will have a beneficial effect on bones.


  5. Ron, I have amended the text a little to clarify. But, it is a stupid argument as the regulations specify the pourity of the chemcials used by maximum levels of contaminants – not by grade.

    As for waste product – I suppose you consider the phosphate produced as a by product of the fluoride industry when apatite ores are used a waste products too? The word is only being used for emotional effect in this flyer. It is dishonest.


  6. <i.As for waste product (…) The word is only being used for emotional effect in this flyer. It is dishonest.

    Why can’t Ron just use a dictionary? I’ve provided him with the definitions of waste and by-product in an earlier post.
    Ron appears rather challenged in this regard, perhaps he has some sort of learning disability.


  7. Ron, I’d have hoped you were a little more environmentally concious. After all, isn’t the principle behind recycling that something need only become waste if it cannot be somehow used or converted efficiently to something usable? So many things we use everyday use recycled materials. By your argument, we should get rid of them all, purely because they are made from recycled materials. Is that not absurd?


  8. I love it when the antis hit me with the its a byproduct of the fertilizer industry
    My reply is, the fertilizer industry started in 1843, so explain to me how all that fluoride in china and India got into the groundwater in 150 years. and all the fluoride in the world has been produced since 1843


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