Scaremongering and chemophobia

This poster/internet meme is making the rounds at the moment. A “true believer” asked for my comments on it as he seemed to think its arguments amounted to “gospel truth.”

So here are some comments:

“Natural” vs “man-made”

They are comparing  crystals found in nature with a processed chemical here. But if CaF₂ (the ore fluorite) was meant be used for water treatment it would have to be processed to remove impurities (the natural ore is far from pure). The most effective way of removing contaminants is conversion to hydrofluoric acid and precipitation of calcium fluoride (CaF₂). Ending up with a “man-made” product!

Some anti-fluoride campaigners seem to argue that fluoridation would be OK if the fluoridating agent used was CaF₂. The contaminants present and need for purification are only two of the flaws in their argument. The low solubility of CaF₂ is another flaw.

Incidentally, fluorosilicic acid is effectively purified in its manufacture because of the differing melting and boiling points of heavy metal fluorides and silicon tetrafluoride.

“Safe to hold” vs corrosive

True, concentrated fluorosilicic acid is much more corrosive than CaF₂. But so what – this is an issue for those manufacturing, transporting and handling the source material. It is not an issue for consumers as drinking water does not contain either CaF₂ or fluorosilicic acid.

By the way, the material safety data sheet for CaF₂ says this:

“Potential Acute Health Effects: Hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation. Corrosive to eyes and skin. The amount of tissue damage depends on length of contact. Eye contact can result in corneal damage or blindness. Skin contact can produce inflammation and blistering. Inhalation of dust will produce irritation to gastro-intestinal or respiratory tract, characterized by burning, sneezing and coughing. Severe over-exposure can produce lung damage, choking, unconsciousness or death.”

And:

“Precautions: Keep locked up.. Keep container dry. Do not ingest. Do not breathe dust. Never add water to this product. Wear suitable protective clothing. In case of insufficient ventilation, wear suitable respiratory equipment. If ingested, seek medical advice immediately and show the container or the label. Avoid contact with skin and eyes.”

So the advice to those manufacturing, handling and transporting CaF₂ is that it is not safe to hold  with bare hands!

Sparingly soluble in water

This is one of the disadvantages of CaF₂ as a fluoridating agent as a saturated solution has a fluoride concentration of about 7.5 ppm. Just imagine the size of the container required to hold the quantities of CaF₂ solution required for addition to a reservoir!

The high concentration of fluoride in liquid fluorosilicic acid (and the fact that it rapidly decomposes to produce the hydrated fluoride anion on dilution with water) provides a big advantage to it as a fluoridating agent.

Fluoride toxicity reduced by calcium

Yes, high concentrations of fluoride are toxic – although the concentration in community fluoridated water (CWF) (0.7 ppm) is quite safe. The toxicity of ingested fluoride at high concentrations can be reduced by the presence of calcium – because of the low solubility of CaF₂.

But let’s be realistic, in the absence of other factors the addition of the appropriate amount of calcium would reduce the fluoride concentration to about 8 ppm. Far higher than the regulated maximum for CWF.

As for some other speculated protective action the calcium in CaF₂ could provide – the calcium concentration in a saturated CaF₂ solution is only about 7.5 ppm – and at the fluoride concentration used for fluoridated water CaF₂ would support a calcium concentration of about 0.8 ppm. Any calcium from added calcium fluoride would be irrelevant compared with the natural calcium concentrations in drinking water. The graph compares these figures for several treatment stations in New Zealand –  see Calcium fluoride and the “soft” water anti-fluoridation myth for further information.

“Man-made waste product”

I have discussed the “man-made” fallacy above. Anti-fluoride campaigners love to describe fluorosilicic acid as a “waste product.”  But Wikipedia defines a waste product as:

“unwanted or unusable materials. Waste is any substance which is discarded after primary use, or it is worthless, defective and of no use”

By definition, then, the fluorosilicic acid used in CWF is not a waste product. It would be if it were disposed of without use – then so is food.

Anti-fluoride campaigners also seem to think that a by-product is somehow evil. This is because most fluorosilicic acid is produced as a by-product of phosphate ore processing. But, come on. Surely production and use of by-products is a desirable feature in judging the conservation aspects of a manufacturing process. And would phosphate chemicals be somehow evil if they were produced as a by-product of fluoride chemical manufacturer from phosphate ores?

Toxicity of “co-contaminants”

I discussed the problem of contaminants in “natural” CaF₂ above and added that contaminants in the fluorosilicic acid used for CWF are very low.

But don’t take my word for it. Water treatment chemicals are regulated and the fluorosilicic acid used for CWF must pass rigid tests for the presence of contaminants. The regulations provide for maximum concentrations of contaminants and where a certificate of analysis shows these are exceeded the material is rejected by water treatment plants.

I discussed this in my article Fluoridation – are we dumping toxic metals into our water supplies? where I debunked this claim made by Fluoride Free NZ. I also provided some data on the chemical analysis of fluorosilicic acid samples. In the article Fluoridation: emotionally misrepresenting contamination I compare the real concentration of contaminants recorded in certificates of analysis with the regulated limits. It turns out that the fluorosilicic acid manufactured in Australia and New Zealand is very low in such contaminants – see figure below.

Of course – some opponents like to claim that any amount of contaminants is too much, despite the regulations. Well, if they want to pursue that argument then they must look at all sources of contamination. In many cases, they will find that there is a larger amount of contamination coming from the original water source, natural contamination, than from the water treatment chemicals

I showed this in the article Fluoridation: putting chemical contamination in context where I compared the amount of arsenic from different sources  in the Hamilton City water supply. The figure below from that article shows that natural levels of arsenic in the water source (the Waikato River) are much higher than the recommended levels for drinking water. Even after treatment (which reduces the arsenic levels to below the recommended maximum) the contribution of arsenic from this natural source is still much greater than the calculated contribution from the fluoridating agent used.

Conclusion

This bit of anti-fluoride propaganda is just another example of scaremongering relying on chemophobia and lack of information, even ignorance.

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Declan Waugh’s misinformation on fluorosilicic acid

Declan Waugh argued recently that silica species produced when fluorosilicates are hydrolysed in water cause a whole range of health problems and deaths. A new theory for him – silica is the problem, not fluoride! He is wrong, of course (see An open letter to Declan Waugh – new mechanism for fluoride toxicity?).

Declan had previously argued the exact opposite. That fluorosilicates do not hydrolyse completely in water and it is the remaining fluorosilicate species that are toxic and cause all these effects. He summarised his arguments and evidence for this in his 2012 report Hexafluorosilicic Acid, Raw Materials, Manufacture, Toxicity and Public Health Concerns as an Active Ingredient in Drinking Water.

This report is typical of Waugh’s writings. He distorts or misrepresents the literature and makes unwarranted inferences. He is not the only person doing this – it’s a common feature of the confirmation bias and cherry picking endemic to the anti-fluoridation movement. However, for some reason some people consider he is an authority on the subject (perhaps they have been fooled by his own hubristic claims to be an “environmental scientist and fluoride researcher”) so his reports get used as evidence and are something quote. For example, the Hamilton City Council listed one of his reports first in the “scientific evidence” which convinced them to stop fluoridation last year (see When politicians and bureaucrats decide the science ). Mark Atkin, the science and legal spokesperson for the local anti-fluoridation group is also fond of citing Declan Waugh – maybe because Waugh is the only source he can find to support his own confirmation bias.

A poster prepared by Declan Waugh to advertise the decisive effect of his submission to the Hamilton City Council fluoride tribunal

In this article I consider some of the claims Waugh makes in the above report and show how he uses distortions and misrepresentation of the literature he cites to support them.

Exaggerating toxicity of fluoride

This part of Waugh’s report is confused but he quotes the relative toxicities of CaF₂ and H₂SiF₆ (1 to 25) to apparently argue “that 1 ppm of hexafluorosilicic ingested orally is the equivalent of 25 ppm calcium fluoride.”  He then seems to argue that the regulated  concentration limits for fluoride are really for CaF₂ – implying that since we use fluorosilicic acid for water fluoridation we should introduce a factor of 25. He seems to say that the limits should not be 1.5 ppm F (he says is set for CaF₂) but 1.5/25 = 0.06 ppm! He says:

“The drinking water standards were established for the much less toxic calcium fluoride which is listed as a moderately toxic compound compared to hexafluorosilicic acid, which is categorised as extremely toxic.”

All this ignores that the toxic species in CaF₂ is the fluoride anion. This is the same for fluorosilicic acid in drinking water as the fluoride anion is the end product of its hydrolysis when added to water. In fact the relevant species is the fluoride anion whatever the source – NaF, CaF₂ or fluorosilicic acid. So the relative toxicities Waugh quotes for solid CaF₂ and concentrated fluorosilicic acid are irrelevant.

Calcium fluoride is relatively insoluble (about 15 ppm CaF₂ = 7.3 ppm F) so when the solid is ingested there is less dissolved fluoride anion available to exert a toxic effect. That is why it is less toxic than the readily soluble NaF and fluorosilicic acid. But CaF₂ is soluble enough to easily maintain the optimum concentration of fluoride anion required for the beneficial effect (0.7 ppm F). One could use it to fluoridate water – although the mechanics would be difficult as very little dissolves. Whatever the source, NaF, CaF₂ or fluorosilicic acid, the end product in drinking water is the same so introduction of such relative toxicities is misleading.

Claim hydrolysis is incomplete

Waugh says:

“When added to drinking water Hexafluorosilicic acid dissociates into free fluoride ions, it is now accepted that this reaction is not complete with the possibility of some silicofluoride compounds remaining present in drinking water.⁵
It is further known that the following fluorosilicate species may be present in treated water. However current analytical methodologies are not yet available to accurately measure or quantify the level of residual fluorosilicates or fluorosilicon complexes that may be present.”

Strange. He is claiming that we currently do not have the analytical methods to measure or quantify residual fluorosilicates but nevertheless “it is now accepted” and “further known” silica fluoride compounds are present in drinking water. Trouble is neither the table he presents, or the paper he refers to (from which the table is taken) say this. They say the exact opposite!

The table simply lists the different silicofluorides species that have been chemically proposed, reported or inferred in solids, gases or solutions. While some of these may logically exist in water (eg SiF₆^2- and Si(OH)₄) there is certainly no evidence that they all do. His reference 5 (Urbansky, E. T. (2002). Fate of fluorosilicate drinking water additives. Chem. Rev., 102, 2837–2854) concludes:

“that in drinking water supply with a pH of 5 or higher, fluoridated with sodium silicofluoride [hexafluorosilicate] to the extent of 16 ppm or less, all of the silicofluoride is completley hydrolysed to slicic acid, fluoride ion and hydrogen fluoride. There can be no question of toxicity of SiF₄ or SiF₆^2- under these conditions.”

As for rate of hydrolysis Urbansky (2002) clearly says “all the 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.” This “equilibrium” is essentially the complete hydrolysis of the fluorosilicate as Urbansky and Schock (2000) make clear:

“Based on the above information on both the thermodynamics of the hydrolysis reaction and it’s kinetics, we can safely conclude that there is essentially no (<< 1 part in a trillion) hexafluorosilicate remaining in drinking water at equilibrium and that equilibrium is rapidly reached from the combine uncaltalyzed and metal-catalysed reactions.”

Claim reaction of silica with fluoride in stomach and bladder

Waugh claims:

“According to Urbansky, a senior US EPA chemist and expert upon water fluoridation chemicals” such compounds [H₂SiF₆, NaF, Na₂SiF₆ and AlF₃] may exist in artificially fluoridated drinking water as well as in low acidic environments within the human body (i.e. Stomach and bladder) after consumption of fluoridated water.³“

And

“It is also now hypothesized that incomplete dissociated SiF residues may re-associate both at intra-gastric pH and in the bladder which are low ph environments⁹ (thereby exposing the consumer to toxic harm) and during food preparation (low pH soft drinks) producing SiF species including silicon tetrafluoride, (SiF₄), a known toxin. It is also believed that commercial SiFs are likely to be contaminated with fluosiloxanes.”

His reference 3 is to Urbansky (2002) and 9 is to Ciavatta, L., Iulianno, M., & Porto, R. (1988). Fluorosilicate Equilibria in Acid Solutions. Polyhedron, 7(18), 1773–7779.

The falseness of his claim that Urbansky provided evidence of the existence of fluorosilicates in drinking water was discussed above. Urbansky and Schock (2000) actually put the theoretical proportion of silica present as fluorosilicate in the “most acidic gastric conditions” at less 0.0002%. As for Ciavatta et al (1988) – their work has no relevance to the stomach or bladder. They studied the reaction of silicic acid and fluoride in 3 Molar Lithium perchlorate with an acidity between 0.3 and 3 Molar. An ideal solution for the laboratory investigate of chemical equilibria but more extreme than conditions in our stomach and bladder.

So again, Waugh has misrepresented the literature and distorted its relevance to the situation in drinking water and our body.

Nevertheless, Waugh get cited as evidence for incomplete fluorosilicate hydrolysis and for recombination in the stomach. For example Mark Atkin relied on this report of Waugh’s in defending this erroneous claim before the NZ Advertising Standards Authority (see Anti-fluoridation advertising deceptive).

Finney et al (2006) is also often used by anti-fluoridationists to claim recombination in the stomach because they showed presence of an intermediate SiF species at pH values below 3.5 (SiF₅^–). Again this is a laboratory study with higher F concentrations and no interfering species. In the real world drinking water (and especially the stomach content) has all sorts of chemical species, many of which react with F, Si(OH)₄ or both. These will displace any theoretically derived equilibria. I have not seen any reports of detection of silicofluorides species in the stomach or bladder. Nor have I seen anything to suggest that these would be any more toxic than fluoride itself – or any of the other chemical species present in the stomach.

Conclusion

Readers having read my comments here and those on Waugh’s theory about silica toxicity (An open letter to Declan Waugh – new mechanism for fluoride toxicity?) might see a pattern:

• Citation of scientific literature to given credibility to Waugh’s claims;
• Misrepresentation of the cited literature – often claiming they report the exact opposite of what they in fact do;
• Confirmation and cherry picking which is very clear to any intelligent reader;
• Attempt to establish himself as a “scientific authority” on fluoridation which can be used by anti-fluoridation activists to support their own claims.

I guess you can fool some of the people some of the time. But it does show that  such material should always be approached critically and intelligently.

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PS: I would of course welcome Declan Waugh’s response to this article. After all, I might be completely wrong – but I won’t know that without some sort of exchange with him.

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False balance and straw clutching on fluoridation

The alignment of the poster above with a “balanced” duo of opinion pieces on fluoridation in the recent issue of the Journal of primary healthcare is just too good not to comment on.

The articles are:

• New Zealand drinking water should be fluoridated – Yes by W Murray Thomson BSc, BDS, MA, MComDent, PhD Professor of Dental Epidemiology and Public Health, Sir John Walsh Research Institute, University of Otago, Dunedin, New Zealand, and
• New Zealand drinking water should be fluoridated – No by G Mark Atkin  BSc, LLB(Hons) Science and Legal Advisor, New Zealand Fluoridation Information Service, PO Box 9804, Wellington, New Zealand.

Looks a bit uneven, doesn’t it? A Professor of  Dental Epidemiology and Public Health “balanced” against a political  activist? Worse, Atkin’s organisation is an astroturf one set up by the Fluoride Action Network of NZ (FANNZ). Rather clumsily, I add, as they use the same office address! (See Anti-fluoridationist astro-turfing and media manipulation).

Still, I want to comment on the chemical arguments used by Atkin. He is effectively clutching at straws, using very naive interpretations of the chemistry of fluorosilicates and fluoride. As a chemist I find such opportunist distortion of chemistry offensive. Problem is, his and similar arguments are often presented by anti-fluoridation activists and lapped up by their supporters.

Fluorosilicic acid and sodium fluorosilicate are common fluoridating chemicals. When diluted in water the fluorosilicate decomposes to form silica and the fluoride anion. Some anti-fluoridation activists, including Mark Atkin, deny this becuase they wish to deny the relevance of studies showing the safety of fluoride at concentrations used in fluoridating drinking water. So they advance the bogey of  an especially toxic fluorosilicate species. Atkins condenses two of their arguments in this succinct statement:

“Silicofluorides do not fully dissociate to form free fluoride ions in aqueous solution and revert to the silicofluoride ion in acid stomach conditions.”

Hydrolysis of fluorosilicate.

There is some straw clutching going on here in the discussion of the chemistry of fluorosilicates and fluoride which distorts the real chemistry.

The Nuclear Magnetic Resonance work of Finney et al (2006)  (“Reexamination of hexafluorosilicate hydrolysis by 19F NMR and pH measurement”) showed complete decomposition of fluorosilicate species at neutral pH values on dilution. They also showed the presence of surviving fluorosilicate species at low pH values (3 and below) – which is of course irrelevant for water treatment. No one is going to produce drinking water at such acidic values.

Anti-fluoride people are using the observation at low pH values to claim that fluorosilicate species remain in solution at neutral pH values. They sometimes also rely on studies where authors have expressed their results with an indication of precision. For example, Atkin’s activist organisation (the NZ Fluoridation Information Service) claims fluorosilicates:

“do not completely break down into Fluoride ions. This was shown by Crosby in 1969.”

But Crosby (1969) (“Equilibria of fluorosilicate solutions with special reference to the fluoridation of public water supplies”) actually reported:

“sodium fluorosilicate, at the concentration normally present in public water supplies, is dissociated to at least 95%.”

Atkins and his organisation are clutching at a very weak straw there.

Let us be clear – the research indicates that within experimental precision the deocmposition of fluorosilicates is complete and, as expressed by Urbansky (2002), (“Fate of fluorosilicate drinking water additives”):

“equilibrium should have been achieved by the time the water reaches the coinsumer’s tap  if not by the time it leaves the waterworks plant.”

Reversion of fluoride to fluorosilicate?

Atkin’s claim of reversion of fluoride to fluorosilicate “in acid stomach conditions” is also incorrect. He is relying on a simplistic misunderstanding of the nature of “dissociation” of fluorosilicate on dilution.

It is important to recognise the “dissociation” of fluorosilicate species into fluoride and silica at neutral pH values is, in effect, a decomposition. Because of the polymerisation of the silica, and the olation and oxolation reactions involved, the equilibrium is driven to completion – in effect the silica is removed from the reaction. (While it may remain in “solution” or “suspension” for a time it is effectively inert – due to olation – as far as the equilibrium is concerned).

What do I mean by olation? While monomolecular Si(OH)₄ is formed on dissociation of the fluorisilicate it rapidly undergoes reactions which lead to exclusion of water and the transformation of Si-OH bonds to Si-O-Si bonds.

(HO)₃Si-OH + OH-Si(OH)₃

↓ Olation

(HO)₃Si-OH-Si(OH)₃ + OH

↓ Oxolation

(HO)₃Si-O-Si(OH)₃ + H2O

Eventually this leads to formation of colloidal and solid silica. But even while in solution olation and oxolation reduces the reactivity of the silica species.

Just as fluorosilicate species do not reform in your tap water, they do not reform in your stomach. Even if the silica is still in suspension it is no longer present as mono-molecular Si(OH)₄ and is effectively inert. So despite the low pH there is no simple equilibrium. Remember too, your drinking water will contain silica derived from other sources besides fluorosilicate (which is probably a minor contributor).

Sure, one can prepares solutions in the laboratory at pH values of 3 or less that contain fluorosilicate species – but once decompostion (involving loss of silica reactivity) occurs at neutral pH values the reaction  is not easily reversed. Especially considering the time lapsed between decomposition of the fluorosilicate and drinking water entering one’s stomach.

HF in stomach

But Atkin still has a fallback postion – if the fluorosilicate doesn’t get you the hydrofluoric acid will. He aserts:

“that 40% of ingested fluoride is absorbed through the stomach wall as molecular hydrofluoric acid (a known mutagen). This negates the ‘all fluoride ions are the same’ deception.”

Yes, in the acid conditions of your stomach F anions will exist in equilibrium with the protonated HF species.

H⁺ + F^– ↔ HF

This is also true for other weakly acidic anions – even sulphate – that is just simple chemistry. But, the real danger of the solution in your stomach is that it is very acid, it has a low pH – a very high concentration of hydrogen ions. It is the hydrogen ions that are corrosive. (If anything, the presence of weakly acidic anions like fluoride will actually lower the acidity by removing some of the hydrogen ions). One does not put one’s hand, or any other sensitive tissues, into acidic solution like this. However the stomach is built to handle these conditions.

I understand the molecular species involved in the transfer of fluoride across the stomach wall cells into the blood stream is HF. (Once in the blood HF will convert to fluoride because of the higher pH). So clearly the low pH assists in uptake of F by the body. Don’t forget the concentrations of fluoride, and therefore HF, is actually very low. The protonated species in your stomach solution are not equivalent to the HF (or HCl and H₂SO₄) chemicals we are used to in their concentrated forms in the laboratory.

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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

Anti-fluoridation study flawed – petition rejected

A recent research paper claiming a signficant cost/benefit advantage in banning the use of fluorosilicic acid as a fluoridating agent in public water treatment, and replacing it with sodium fluoride, has been found flawed. This was revealed as a result of the rejection by the US Environmental protection Agency (EPA) of a petition by the author

Dr William Hirzy testifies for an anti-fluoridation group

The original paper by Hirzy et al. (2013) is on-line – full details are Hirzy, J.W., Carton, R.J., Bonanni, C.D., Montanero, C.M., Nagle, M.F. (2013) Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis  J Environmental Science and Policy Volume 29, May 2013, Pages 81–86.

Briefly the authors had used data (arsenic (As) concentrations in a number of samples of fluorosilicic acid and sodium fluoride) and a model for the predicted incidence of cancers resulting from As contamination in water supplies. Their cost/benefit analysis claimed “the U.S. could save $1 billion to more than $5 billion/year” by using pharmaceutical grade sodium fluoride instead of fluorosilicic acid.

Consequently Hirzy petitioned the EPA to ban use of fluorosilicic acid, using his study as supporting evidence. The EPA responded officially on August 6 and, despite some of the legalese, their notice is worth reading for anyone interested in the fluoridation controversy.

A calculation error for arsenic

When I first read Hirzy’s paper I was concerned that the quoted values for As in the fluorosilicic acid samples he considered were higher than found in New Zealand. (As concentrations in local fluorosilicic acid for water treatment are about the same as for the pharmaceutical garde sodium fluoride he used). I wondered if his data was out of date, or he had used commercial grade samples and not water treatment samples. However, the EPA found a more basic fault – Hirzy’s calculations were wrong! They had “failed to convert their estimates of lifetime cancer risk to estimates of annual cancer risk for the purpose of calculating annual net benefits.” When corrected the cost benefit analysis favoured fluorosilicic acid “(-$81M/year to -$8M/year, respectively) rather than pharmaceutical grade NaF over HFSA:”

1. Arsenic. EPA evaluated the cost-benefit analysis submitted by the petitioners and determined that the petitioners miscalculated net benefits for pharmaceutical grade NaF compared to HFSA. Specifically, it appears that the petitioners failed to convert their estimates of lifetime cancer risk to estimates of annual cancer risk for the purpose of calculating annual net benefits. This error alone results in a 70-fold overestimation of the number of annual cancer cases due to arsenic. That is, for the analysis in which the petitioners evaluate arsenic concentrations of 0.078 parts per billion (ppb) due to HFSA and 0.00084 ppb due to pharmaceutical grade NaF, the estimated numbers of cancer cases, when corrected, decrease from 320 to 4.6 per year for HFSA and from 3.4 to 0.05 per year for pharmaceutical grade NaF (Refs. 2 and 9). Similarly, for the analysis in which the petitioners evaluate an arsenic concentration of 0.43 ppb due to HFSA and 0.00084 due to pharmaceutical grade NaF, the estimated numbers of cancer cases,  when 8 corrected, decrease from 1,800 to 25 per year for HFSA and from 3.4 to 0.05 per year for pharmaceutical grade NaF (Refs. 2 and 9). After making the correction (i.e., annualizing the lifetime cancer risk), and retaining all other assumptions of the petitioners analysis, the analysis actually indicates that the cost-benefit ratio is in favor of using HFSA over pharmaceutical grade NaF (-$81M/year to -$8M/year, respectively) rather than pharmaceutical grade NaF over HFSA (Ref. 9). As a result, the information submitted by petitioners does not support the petitioners’ claim that there are net benefits in switching from HFSA to pharmaceutical grade NaF. Given that the petition is based upon the premise that the benefits of using pharmaceutical grade NaF as a fluoridation agent significantly exceed the costs relative to the use of HFSA as a fluoridation agent, EPA concludes that petitioners have not set forth sufficient facts to establish that HFSA presents or will present an unreasonable risk of injury to health or the environment with respect to arsenic or that it is necessary to initiate a TSCA section 6(a) rulemaking to protect adequately against such risk.

Lead risk not proved

The EPA similarly found that Hirzy’s claim that fluorosilicic acid caused leaching of lead from pipes in the water supply system was similarly unproved”

2. Lead. Petitioners assert that HFSA contains lead but provided no data to support this assertion. Petitioners also assert that the use of HFSA in lead-containing water piping systems results in leaching of lead from lead-containing water piping systems into water (Ref. 5), and that when chloramine is used in conjunction with silicofluorides greatly enhanced leaching of lead into water occurs (Ref. 3). . . . .  Based on the available evidence, EPA cannot conclude that the use of HFSA, with or without the presence of chloramine, results in enhanced leaching of lead.

Radioactive contaminants

Again the EPA found that Hirzy’s claims about radionuclide contamination were not supported:

4. Radionuclides. Although the petitioners mention “concern” about radionuclides, the petitioners present limited information to support a claim that HFSA presents or will present and unreasonable risk with respect to radionuclides. NSF compiled data from initial and annual monitoring tests for fluoridation products that NSF certified to NSF/ANSI 60 between 2007 and 2011 (216 samples) and between 2000 and 2006 (245 samples). Alpha emitters (type of radioactive decay in which an atomic nucleus emits an alpha particle) were detected in less than 1% of the 216 samples analyzed between 2007 and 2011. The mean (non-detects were estimated at ½ the detection limit) and maximum values were less than the MCL of 15 picoCuries per liter (pCi/L) and were less than the NSF/ANSI 60 SPAC of 1.5 pCi/L (Ref. 15). Beta photon emitters (another type of radioactive decay in which an atomic nucleus emits a beta particle) also were detected in less than 1% of the 216 samples analyzed between 2007 and 2011. The mean (non-detects were estimated at ½ the detection limit) and maximum values were less than the MCL of 4 millirems per year (mrem/y) and were less than the NSF/ANSI 60 SPAC of 0.4 mrem/y (Ref. 15). Radionuclides (alpha or beta) were not detected in any (0%) of the 245 samples analyzed between 2000 and 2006 (Ref. 11). The concentrations reported represent contaminant levels expected when the fluoridation products are dosed into water at the allowable maximum use levels for NSF/ANSI 60- 2012 (see Refs. 14 and 15). NSF notes that lower product use levels would produce proportionately lower contaminant concentrations. Thus, the petition has failed to present facts that establish that HFSA presents or will present an unreasonable risk of injury to health or the environment with respect to radionuclides, or that it is necessary to issue a TSCA section 6 rulemaking to protect health and the environment from such risk.

So, it would be nice if anti-fluoridationists would stop using Hirzy’s paper to “prove” that use of fluorosilicic acid causes cancer when used as a fluoridating agent. Or better still, stop promoting the lie that such fluoridating agents contaminate our drinking water with toxic heavy metals and radioactive elements.

But, going by past practice I am not going to hold my breath.

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