Tag Archives: Water Treatment

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

Hamilton – the water is the problem, not the fluoride!

Saw this on Facebook the other night – together with the comment:

“If Hamilton don’t want fluoride in the water, how about we replace the water”


Yes, that would be convenient, wouldn’t it. Instead of Hot and Cold taps, why not Red and White?

However, there is an element of truth in the joke. To some extent, the Waikato water is the problem, rather than fluoride added during fluoridation. Anti-fluoridationists are concentrating on the “evils” of the fluoridation agent, fluorosilicic acid, without realising that the source for our water supply in Hamilton introduces more contamination than the fluoridation chemicals.

Have a look at this graphic showing the levels of arsenic (As) in the Waikato River. Through almost the entire length of the river As levels are several times higher than the recommended maximum concentration for human consumption which is 0.01 parts per million (ppm).

The source water for the Hamilton water treatment plant is 2 or 3 times that recommended maximum As concentration.

Fortunately the treatment process remove about 80% of the As.

Let’s compare that with the contamination introduced by fluoridation chemicals.

A typical concentration of As in fluorosilicic acid is 2 ppm (see Fluoridation – are we dumping toxic metals into our water supplies?  and Water treatment chemicals – why pick on fluoride?). There is a large amount of dilution of the fluorosilicic acid when added to water at the recommended dose (0.7 – 1.0 ppm). The final concentration in our drinking water is 0.0001 ppm As. Several orders of magnitude lower than the maximum recommended concentration for human consumption.

In reality, even after removal of 80% of As from the source water the major contribution to any As contamination in Hamilton’s public water supply is the Waikato River itself – not the fluoridation chemicals. By several orders of magnitude.

  Original Arsenic (ppm As) Dilution Contribution to finished water (ppm)
Recommended maximum As (ppm)     0.01
Waikato River water ~0.025 None ~0.005
Fluorosilicic acid 2* ~200,000 ~0.0001

* see Fluoridation – are we dumping toxic metals into our water supplies?  and Water treatment chemicals – why pick on fluoride?

Haven’t the Hamilton anti-fluoridation campaigners got their priorities wrong when they complain about contamination of the fluoridation chemicals used?

See also:

Making sense of fluoride Facebook page
Other Fluoridation articles

Water treatment chemicals – why pick on fluoride?

Almost every person arguing against fluoridation makes the claim that the fluoridation chemicals used are toxic and corrosive. They also claim they contain toxic heavy metals which contaminate our drinking water.

But this is simply fear mongering – relying on chemophobia, because most concentrated chemicals are toxic and often corrosive. And such claims could also be made of the other chemicals used in drinking water treatment. But the anti-fluoridation activists don’t – why pick on fluoride?

Actually, the fluoridation chemicals used are not the main source of possible toxic contamination of our water supply – yet these other chemicals are ignored by anti-fluoridationists. When we consider fluoridation in the context of the water treatment process and analytical data for the chemicals used we find the anti-fluoridation arguments baseless.

The water treatment process

The figure below provides a context for considering the chemicals used in public drinking water treatment and the stages where they are added. It’s a diagrammatic outline of Hamilton City’s water treatment plant (it still include fluoride addition – I guess they are holding off changing the diagram until after the referendum). You can see further details in  A Guide to Hamilton’s Water Supply : River to the Tap.


This is only a typical example. Different treatment plants use different chemicals depending on the plant size, the water source and the availability and cost of chemicals. I consider just a few  representative chemicals below with information on their safety, corrosive nature and chemical contaminants.

Information sources used

The safety information is from safety data sheets produced by the manufacturer or seller. Many of these are in the Orica Chemicals SDS database.

Information on contaminating heavy elements and other contaminants is from Brown et al. (2004). Trace contaminants in water treatment chemicals: sources and fate, American Water Works Association, Journal. 96: 12, 111-125.

Extra information on contaminants in fluoridation chemicals is from the NSF Fact Sheet on Fluoridation Products (2013) and the  NZ Water and Wastes Association Standard for “Water Treatment Grade” fluoride, 1997.

miscellaneous chemicals

A number of chemicals like lime, soda ash, carbon dioxide, potassium permanganate and other acids and alkalis are used, sometimes or commonly. This could be for initial treatment to remove biological matter and in pH control and sedimentation. Adjustment of pH is also necessary to prevent corrosion of pipes.

Coagulation and sedimentation

Aluminium sulphate or alum, is a common coagulant.  Its Safety Data sheet does not classify it as dangerous for transport but does classify it as hazardous – subclasses 6.1 – 9.3.

Under disposal methods it says:  “Refer to local government authority for disposal recommendations. Dispose of contents/container in accordance with local/regional/national/international regulations.”

Possible contaminants (Brown, Cornwall & McPhee, 2004): Coagulant chemicals are the main source of trace metal contamination in water treatment.” However, these together with contaminant trace metals in the source water are generally transferred to the residue stream during sedimentation and filtering so there is little transfer to the finished water.

Soda ash is used for pH control. Its Safety sheet does not classify it as dangerous for transport but does classify it as hazardous – subclasses 6.1 – 6.4.

Under disposal methods it says:  Refer to local government authority for disposal recommendations. Dispose of material through a licensed waste contractor.”


Chlorine is commonly used. Its Safety data Sheet classifies it as a class S7 dangerous poison which “must be stored, maintained and used in accordance with the relevant regulations.”

Under disposal methods it says: “Refer to Waste Management Authority. Dispose of material through a licensed waste contractor. Contact supplier for advice.”

Possible contaminants (Brown, Cornwall & McPhee, 2004)Carbon tetrachloride (used to clean storage containers)


Fluorosilicic acid is the most common fluoridating chemical. Its Safety data sheet describes it as a class S7 dangerous poison.

Under disposal methods it says: “Refer to Waste Management Authority. Dispose of  material through a licensed waste contractor. Decontamination and destruction of containers should be considered.”

Possible contaminants (Brown, Cornwall & McPhee, 2004): Arsenic was the only trace metal contaminant found above detection levels in just a few samples, and then in small amounts.

This year’s NSF Fact sheet on fluoridation  also confirmed this picture. saying:

“In summary, the majority of fluoridation products as a class, based on NSF test results, do not contribute measurable amounts of arsenic, lead, other heavy metals, radionuclides, to the drinking water.”

(NSF International is a global independent public health and environmental organization that provides standards development, product certification, testing, auditing, education and risk management services for public health and the environment.)

The  NZ Water and Wastes Association Standard for “Water Treatment Grade” fluoride, 1997 says:

“Commercially available hydrofluorosilicic acid, sodium fluoride and sodium silicofluoride are not known to contribute significant quantities of contaminants that adversely affect the potability of drinking water.”

I discussed the question of the level of toxic metal contamination in fluorosilicic acid in my article Fluoridation – are we dumping toxic metals into our water supplies? This mentions the requirement of suppliers to provide certificates of analysis to make sure their product is suitable for water treatment. A number of certificates of analysis for fluorosilicic acid are available on line which confirm the very low levels of contaminant heavy metals. For typical fluorosilicic acid certificates see Incitec 09, Incitec 08 and Hamilton City.

The table below also shows typical analytical results for fluorosilicic acid.

General conclusions

According to Brown, Cornwall & McPhee, 2004:

“Except for occasional contamination from bromate in sodium hypochlorite and carbon tetrachloride in chlorine., drinking water treatment chemicals were not typically shown to be significant sources of most contaminants of regulatory concern (including lead, copper, arsenic, and other trace metals) in finished water. This was becausc of the low occurrence of contaminants in drinking water treatment chemicals and the partitioning of most contaminants into the residuals streams when they were present in raw water or treatment chemicals.”

The recovery of sediment and sludge after coagulant treatment removes most of the toxic contaminants coming from the source water and the treatment chemicals (mainly the coagulant). No significant contamination comes from the chlorine or fluoridation chemicals added towards the end of the treatment. The table below confirms this.

The real amounts of contaminant toxic metals in fluorsilicic acid are far lower than the amounts allowed by the water treatment standards.  The regulated impurity levels are calculated from the maximum acceptable values of an impurity (taken from the Drinking Water Standards for New Zealand 1995) and the dilution when the material is added to drinking water to achieve a concentration of 0.7 – 1.0 ppm F. It incorporates a safety factor of 10. The data for the fluorosilicic acid is from my research but confirms figures in certificates of analysis. And the last column shows that there is no detectable contamination of toxic heavy metals in the final drinking water

Final drinking water quality

Toxic Element Impurity limits FSA Drinking water
As (ppm) 132 2 <0.002
Cd (ppm) 40 <1 <0.001
Cr (ppm) 660 5 <0.001
Hg (ppm) 26 < 0.1 <0.001
Ni (ppm) 264 < 1 <0.001
Pb (ppm) 132 0.3 <0.001
Cu (ppm)   < 0.2 <0.013
Zn (ppm)   2.1 <0.013

Impurity limits – calculated from maximum acceptable values in drinking water and a safety factor of 10. See NZ Water and Wastes Association Standard for “Water Treatment Grade” fluoride, 1997.
FSA – typical analytical data for fluorosilicic acid used in fluoridating New Zealand water supplies.
Drinking water – actual levels of toxic elements in your drinking water (Wellington region) – all below the limit of detection of the standard analytical procedure.

The “proof of the pudding is in the drinking” – one could say. The antifluoridation activists have been simply scare mongering with their claims that fluoridation amounts to putting toxic elements into our drinking water. The fluoridation chemicals are not even the main possible source of such contaminants.

See also
Fluoride in our water facebook page
Debunking the anti-fluoridation myths
From Australia – debunking anti-fluoridation arguments

For other articles on fluoridation see Fluoridation page.

Tactics and common arguments of the anti-fluoridationists

Anti-fluoridation activists have celebrated their recent win in Hamilton (see Hamilton City Council reverses referendum fluoridation decision) and are moving on with their plans for similar victories in other New Zealand communities. While most of the newspaper and TV polls show a clear majority support for fluoridation these activists managed to achieve a victory in Hamilton by relying on a raft of arguments which misrepresent or distort the science. They used the facade of science to attack the reality of science.

In essence this is the same as the “sciency” sounding tactics of the climate change and evolution science denial movements. These tactics of the anti-fluoridationists were analysed by Jason M Armfield in his 2007 paper When public action undermines public health: a critical examination of  antifluoridationist literature. Tactics like:

  • Selective reporting of studies and results,
  • Downplaying or ignoring the evidence,
  • Ignoring ecological factors in comparing communities,
  • Fear mongering,
  • Misrepresentation of evidence,
  • Using half-truths and “The Big Lie,”
  • Innuendo,
  • Follow the leader arguments.

In short – bamboozling with science.

The paper provides a clear and well documented description of the anti-fluoridationist tactics. It does briefly give examples and citations to show how the science gets distorted, although detailed discussion of the science is not the main purpose of the paper. It’s a useful resource for anyone trying to come to grips with the “Gish galloping” claims made by these activists.

One of the tables in the paper provides a handy list of common arguments used together with brief rejoinders. It’s a handy summary and I have reproduced the content below – the fluoridationist claim, followed by the real situation:

Water fluoridation confers no oral health benefit:

Numerous systematic literature reviews from a number of countries have found water fluoridation to provide a significant caries preventive effect.

Water fluoridation causes hip fractures, cancers, Alzheimer’s, reduced intelligence in children, etc.:

Research finding associations between water fluoridation and various diseases offer no proof, as causality cannot be established in these studies. Water fluoridation opponents handpick studies and may misrepresent the results so as to support their views. Large-scale systematic reviews have not confirmed any associations between water fluoridation and the large list of diseases linked to it by opponents of water fluoridation.

Fluoride is a toxic poison:

Fluorine is a naturally occurring element that, like many other natural substances, can be toxic if consumed in excess. Water fluoridation ensures ingestion of fluoride well below any toxic level, both for adults and children. Fluoride is used in rat poison and other dangerous substances. It is dose that determines the level of toxicity. Many essential and commonly occurring elements form poisonous or toxic substances.

Numerous other countries have rejected water fluoridation:

Some other countries have elected not to introduce water fluoridation because they prefer, or already have, other approaches to improving dental health. Nonetheless, many countries do have water fluoridation and benefits are conferred to all people, including those at high risk who may not effectively use individual fluoride exposures.

Water fluoridation is supported only by ‘shoddy’ science:

Decades of research and hundreds of scientific articles published in peer-reviewed journals support water fluoridation. This research is so convincing that almost all major dental and health authorities support it.

There should be a public plebiscite. It is undemocratic to have water fluoridation forced upon us:

In almost all democratic systems representatives of a population are elected to make decisions on behalf of the population. Plebiscites or public referendums are not required to pass legislation that is compatible with the constitution or charter under which the country operates. Water fluoridation fits within a government’s duty of care to the country’s citizens.

Tooth decay has declined in countries with and those without water fluoridation. Water fluoridation makes no difference:

Declines in tooth decay have occurred as a result of changing exposures to fluoride and dietary changes. Regardless, water fluoridation reduces tooth decay above and beyond these other effects. Ecological comparisons of some countries with others offer no support for or against water fluoridation as many other factors may account for differences in disease experience from one country to the next. Water fluoridation does make a difference.

Most people do not want water fluoridation:

Independent research in most places where water fluoridation is being considered shows that people support water fluoridation. Generally, the more knowledge people have the more likely they are to support it.

Water fluoridation is costly and not economically viable:

Research has previously found water fluoridation to be cost-effective. Newer technologies have made water fluoridation cost-effective for increasingly smaller populations. In addition to being cost-effective, it is also necessary to keep in mind the reduction in dental disease and therefore the pain and suffering reduced as a result of water fluoridation.

Water fluoridation infringes freedom of choice and individual rights and is unconstitutional:

Adding fluoride to water is just one of many instances where a chemical or nutrient is added to a food or beverage for public health benefits. It already occurs in water with the addition of chlorine, which aids greatly in eliminating water borne disease, as well as in several foodstuffs. Water fluoridation sets no precedent.

Water fluoridation is being pushed on us as a result of ‘big business’ interests:

The scientists researching the effectiveness of water fluoridation as well as health officials and dentists do not receive money from sugar, aluminium or any other companies for their research or opinions.

There is more caries in fluoridated X than in non-fluoridated Y. This proves water fluoridation does not work:

Ecological comparisons involving the arbitrary selection of fluoridated and non-fluoridated communities or areas do not provide credible evidence of the effectiveness or otherwise of water fluoridation as any differences may be the result of other factors which are linked to tooth decay but differ across the areas. Scientific research has found water fluoridation to be effective.

We should wait until water fluoridation is proved to be safe:

Water fluoridation has been implemented in some places for more than half a century – long enough that any dangers would be apparent if they existed. The weight of evidence strongly indicates that water fluoridation is safe.

I think this list provides a good starting point for sensible discussion.

Thanks to Jason M Armfield (2007): When public action undermines public health: a critical examination of  antifluoridationist literature. Australia and New Zealand Health Policy 2007, 4:25

See also: Fluoridation

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