There are many claims made about the source of fluoride in our water, some examples are:

Is the fluoride added to the water supply produced as an industrial waste product? And does it due to this origin contain any harmful components in significant amounts?

  • 8
    I dislike the pejorative implication of the question. There are plenty of products that are from at least one point of view waste products of other processes. We put chlorine in water to prevent bacterial contamination but chlorine is a waste product from some perspectives. Sausages could be thought of as a waste product of pig breeding. And the soil we grow vegetables in is a waste product of geological weathering of rocks. Are they therefore bad?
    – matt_black
    Commented Dec 20, 2012 at 20:01
  • 6
    @matt_black - The problem I see is that changing the wording to something softer or removing it altogether you literally remove the purpose of the question. Notice that the examples of the claim I provided all use the term 'waste product'. The term does have a certain connotation, but it also carries with it a certain meaning. Maybe your comment is actually part of something which should be an answer if it can be explained that this is just a harmless by-product. But I feel entitled to use the same language as per the claims attached.
    – going
    Commented Jan 5, 2013 at 10:14
  • fluoridealert.org/researchers/health_database good site to understand the issue.
    – user11312
    Commented Jan 30, 2013 at 18:53

4 Answers 4


As a former resident of Queensland, I looked with interest at the third link provided in the question. The claims are extreme, so I believe it is valuable to address their claims directly, line by line.


The three Fluoride chemicals that could be added to Queensland water supplies for fluoridation are Hydrofluorosilicic Acid, Sodium Silicofluoride or Sodium Fluoride.

I am going to take their word for that.

Hydrofluorosilicic Acid and Sodium Silicofluoride are collectively known as the Silicofluorides and are the chemicals used most in other Australian states fluoridation schemes.

I am going to take their word for that.

The two Silicofluorides chemicals used, are waste products of Phosphate fertilizer manufacture.

One of the fundamental concepts of Chemistry - one of the most important ideas that have advanced science - is that everything is made of atoms. It doesn't matter, chemically, where the atoms come from, they still react the same way. So, from a health perspective, that they are waste products of another process is irrelevant. [Reference: Year 8 high school science class.]

From a political standpoint that may be relevant, but that's not being argued here. From an emotional standpoint, we associate "waste" with "bad". If we replaced the emotive term "waste" with "recycled" suddenly it sounds positive!

They are industrial grade, not pharmaceutical grade products and can contain small residues of toxic heavy metals such as cadmium, mercury or lead.

The introduction of the phrase "pharmaceutical grade" here is a red herring. Most items we ingest are not pharmaceutical grade. The sugar you put in your coffee isn't pharmaceutical grade, and nor is the coffee itself. Why should the water be? The standard here should be "food grade", and the water coming from the tap (certainly in first world countries) is rigorously monitored and controlled. (I'd include a reference here, but it is dependent on your local government, so I can't give a universal answer. I have examined the regulations for a number of states here in Australia, and there are a huge number of pollutants tested for, including heavy metals.) Once the chemicals coming in are dissolved to 1 ppm (see other answer), the "small residues" are going to be diluted even further, making the issue of industrial versus food grade inputs irrelevant. It is the output that matters.

The two Silicofluoride compounds used DO NOT EVEN OCCUR IN NATURE, yet fluoridation promoters call fluoride "NATURAL”.

I will take their word for the fact that the compounds don't occur in nature. Not only is the "natural" argument irrelevant (as they later point out themselves), but the reagents used are irrelevant, as the flouride is no longer attached to the rest of the compound once it is in solution. [Reference: Year 11 high school Chemistry class]

I would, however, like citations for where flouridation promoters call it natural. Are they referring to the silicofluorides or to the idea of fluoride being dissolved in fresh water?

No toxicology studies have ever been performed on the Silicofluoride used in water fluoridation schemes. The only toxicology studies ever done, have been done on Pharmaceutical grade Sodium Fluoride as is used in toothpaste.

Toxicology studies have been done on the fluoride dissolved in the drinking water (see other answer), which is where it is relevant.

Currently less than 5% of Queensland's population drinks fluoridated water.

I'll take their word for it, but irrelevant to the argument (except to explain why there is a motivation to start flouridating water.)

Sodium Fluoride is a waste product of Aluminium smelting and is the fluoridation chemical used in Queensland in Dalby, Mareeba, Moranbah and Townsville/ Thuringowah.

Again, the source of the chemical is irrelevant from a chemical/health perspective.

Freedom of Information reveals that water supply of Bamaga is fluoridated with a Silicofluoride and that Sodium Fluoride used in other Queensland areas is imported from China.

It would appear that most of the Queenslanders that are currently drinking fluoridated water are drinking water fluoridated with imported Chinese industry waste products, probably sourced as a waste product of the Chinese Aluminium smelting industry.

Certainly the source country is irrelevant for health effects. It is only relevant to trigger emotive patriotic and political concerns. Similarly, it doesn't matter how the information was obtained - citing "Freedom of Information" strikes an emotive chord that the government may be trying to otherwise hide something. I would like to see a cite of the request and the resulting data, to ensure we aren't being exploited by people putting in FoI requests where a regular request (or even web search!) would get the same information.

Water from rivers, creeks or dams does contain small amounts of natural fluoride. Levels of fluoride in SE Qld surface waters are usually only about 0.1 parts per million, or nine times less the amount of the Fluoride that Queensland Government plans on adding to Brisbane's water supply.

Okay, I'll take their word for that.

Fluoride occurs naturally in water when water flows though or over rocks and abrades rocks that contain Fluorspar, or Calcium Fluoride (Ca F2). Calcium fluoride is very insoluble. Water that contains natural Fluoride from abraded Fluorspar containing rocks also contains Calcium which can offer some protection from Fluoride. Fluoride binds with Calcium readily and Calcium is given as a treatment for Fluoride poisoning.

Most of this sounds plausible, and I confirmed that Calcium Flouride is very insoluble on Wikipedia, so no disagreements here. Note: they are straying awfully close to the "natural is good" fallacy that they themselves later attack.

Calcium Fluoride (the natural form of Fluoride) is not permitted to be added to any Australian water supply.

I would like a cite for that. I note that it has been approved for food by the EU. If there is such a restriction, is it just to avoid unnecessary mining? (5 Billion kg mined annually [Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5., via Wikipedia]) Or concerns that there is a cost of extracting the Flouride with concentrated Sulphuric Acid (Wikipedia) before adding it to the water, thus defeating the purpose of using a "natural" source.

Groundwater as in bore water or well water can contain very high levels of "natural" fluoride and in parts of China, India and the Rift Valley, natural Fluoride has led to devastating health effects such as crippling Skeletal Fluorosis for millions of people. Arsenic, Lead and Mercury are also "natural". Natural does not necessarily mean good or desirable.

I believe all of this to be true. If anyone proposed to set flouride levels to the point they could trigger skeletal fluorosis, that would be terrible. Fortunately, I have seen no proposals to exceed the World Health Organization recommended maximum fluoride value at which fluorosis should be minimal [ref: Fawell J, Bailey K, Chilton J, Dahi E, Fewtrell L, Magara Y. Fluoride in Drinking-water [PDF]. World Health Organization; 2006. ISBN 92-4-156319-2. Guidelines and standards. p. 37–9. via Wikipedia].

The Silicofluoride compounds used for water fluoridation are very acidic and addition to water often entails addition of other chemicals such as soda ash to neutralize the acidity to prevent corrosion of water reticulation equipment. Appendix one of the 1999 NHMRC Review of water fluoridation was a questionaire for Councils which fluoridate and included a request for any evidence for Fluoride incompatibilities, such as enhanced corrosion or breakdown of gaskets or seals, in the water distribution network.

Okay. Someone asked a question. And?

The Queensland Government has said they would pay the setting up costs of fluoridation, but will not be paying for any recurrent and on going costs. Any Fluoride caused corrosion problems in water treatment plants or water reticulation systems would be to the future cost of Councils and ratepayers.

The Queensland Government is funded by tax-payers. The local council is funded by tax-payers. This isn't a health argument, it is an argument about which bucket of tax-payer money should be used within a political system, and therefore is not subject to scientific scrutiny.

In conclusion: there are a number of emotive arguments here, but no references, and some half-truths. I would look elsewhere for evidence that flouridation contains harmful components. It may be right that that the flouride is extracted from the output of other industrial processes, but that is both irrelevant (from a consumer health and safety perspective) and claimed without evidence here.

  • 4
    "It doesn't matter, chemically, where the atoms come from" Carbon from the atmosphere has a higher proportion of radioactive isotopes than carbon atoms that have been buried for a very long time, which is how carbon dating works. While they might be largely the same from a chemistry perspective, there can be important differences. Mind you, it probably doesn't affect the debate on fluoride, but it's worth mentioning... Commented Feb 3, 2012 at 1:55
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    @HighlyIrregular: I agree with your clarification: Yes, the isotope ratio may be theoretically different based on the source, and, yes, that makes no difference to the chemistry involved in the fluoride debate.
    – Oddthinking
    Commented Feb 3, 2012 at 2:48
  • Perhaps this answer could be marginally improved by changing the reference from "food safe" to an accepted food standard of Generally recognized as safe (GRAS) or other applicable standards. Just a thought! :) Commented Jan 30, 2013 at 20:17
  • @Brian: I haven't the money to check the Food Chemicals Codex. I am a bit uncomfortable in general with this being the accepted answer. A fisking of one of the three sources provided isn't quite the same as an answer to the question.
    – Oddthinking
    Commented Jan 30, 2013 at 21:21
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    @Oddthinking: I added a few points (particularly on fluoride and chemical industry), though as an own answer as it got too long for comments. I also came accross arguments for Basel, Switzerland stopping their fluorination, and human health concerns were at most an indirect concern. Commented Jan 31, 2013 at 0:41

My answer will focus on water fluoridation.

Virtually all water contains some amount of fluoride.

Water fluoridation is the process of adding fluoride to the water supply so that the level reaches approximately 1 part fluoride per million parts water (ppm) or 1 milligram fluoride per liter of water (mg/L); this is the optimal level for preventing tooth decay. [Source]

From the World Health Organization:

Research on the oral health effects of fluoride started around 100 years ago;
The focus has been on the link between water and fluorides and dental caries and fluorosis, topical fluoride applications, fluoride toothpastes, and salt and milk fluoridation.

WHO recommends for public health that every effort must be made to develop affordable fluoridated toothpastes for use in developing countries.

Water fluoridation, where technically feasible and culturally acceptable, has substantial advantages in public health;

Alternatively, fluoridation of salt and milk fluoridation schemes may be considered for prevention of dental caries.

From History of Water Fluoridation:

Water fluoridation has been described by the Centre for Disease Control (CDC) as one of the ten most important public health advances of the 20th Century.

Currently, some 40 countries have artificial water fluoridation schemes in existence. ... it is estimated that 400 million people have access to fluoridated water worldwide.

e.g. (numbers are from 2004)

  • USA (64%)
  • Canada (43%)
  • Panama (18%)
  • Republic of Ireland (73%)
  • Australia (61%)
  • New Zealand (61%)
  • Israel (75%)
  • Malaysia (70%)
  • United Kingdom (10%)
  • Singapore (100%)
  • Brazil (41%)
  • Argentina (21%)
  • Chile (40%)
  • Spain (10%)
  • Columbia (80%).

Water fluoridation Source

If you live in the USA, the CDC lists fluoridation levels by state.

Safety of Water Fluoridation:

The question of the safety of water fluoridation has been investigated time and time again by a variety of national and international commissions, most notably in recent times by the NHS Centre for Reviews and Dissemination in 2000 (the York Review).

York's main conclusion was that there was no clear evidence of any adverse effect from water fluoridation other than staining of enamel (dental fluorosis).

The York Review has been followed up in the United Kingdom by the Medical Research Council (MRC).
The MRC's view is that there is very little cause for concern on any potential general health issue in relation to water fluoridation.

From The National Cancer Institute:

In one of the studies reviewed for the Public Health Service (PHS) report, scientists at the National Cancer Institute evaluated the relationship between the fluoridation of drinking water and the number of deaths due to cancer in the United States during a 36-year period, and the relationship between water fluoridation and number of new cases of cancer during a 15-year period.

After examining more than 2.2 million cancer death records and 125,000 cancer case records in counties using fluoridated water, the researchers found no indication of increased cancer risk associated with fluoridated drinking water.

But there are concerns about water fluoridation:

Some recent studies suggest that overconsumption of fluoride can raise the risks of disorders affecting teeth, bones, the brain and the thyroid gland.

The WHO acknowledges this:

Fluoride is one of the very few chemicals that has been shown to cause significant effects in people through drinking-water.

Fluoride has beneficial effects on teeth at low concentrations in drinking-water, but excessive exposure to fluoride in drinking-water, or in combination with exposure to fluoride from other sources, can give rise to a number of adverse effects.

What is used for Water Fluoridation?

From the CDC - Water Fluoridation Manual:

There are several practical considerations involved in selecting compounds:

  • the compound must have sufficient solubility to permit its use in routine water plant practice.
  • the cation to which the fluoride ion is attached must not have any undesirable charasteristics
  • the material should be relatively inexpensive and readily available in grades of size and purity suitable for their intended use.

Sodium Fluoride
The first fluoride compound used in water fluoridation. It was selected on the basis of the above
criteria and also because its toxicity and physiological effects had been so thoroughly studied.

Sodium Silicofluoride
As with most silicofluorides, it is generally obtained as a by product from manufacture of phosphorus fertilizers.
Once it was shown that ... there is no difference in the physiological effect, silicofluorides (and hydrofluosilic acid) were rapidly accepted for water fluoridation, and in many cases, have displaced the use of sodium fluoride.

Other Fluoride Chemicals
Hydrofluoric acid (not hydrofluosilici acid), although low in cost, presents too much safety and
corrosion hazard to be acceptable for water fluoridation.

Note: A "by product" isn't automatically a "bad" thing. It just means it's not the primary product.

More Sources:

  • This answer covers way more than the initial scope of the question, which is whether added fluoride is a waste product.
    – dwjohnston
    Commented Jun 21, 2015 at 23:53

Some additonal points:

Is fluoride in water an industry waste product?

  • it is an "industry waste product" of the fertilizer industry just as platinum, gold and silver are industrial waste products from copper electro refining they are by-products in the anode sludge. (Not all industrial "waste" is bad!)

    • Main product:

      • copper (15.8 million t/a or ca. 125 billion US$)
    • By-products:

      • gold (2700 t/a (total production world wide - not only from anode sludges) or ca. 145 billion US$), ( silver (22500 t/a total or ca. 23 billion US$)

Source: Wikipedia and today'ss gold/silver prices

  • Yes, fertilizer production slurries are used for CaF2 production. [Source: a paper suggesting utilization of old waste. Note that the paper puts the annual need of Poland to 4000 - 5000 t. Note also that the CaF2 needed in metallurgy (not alumninum production) does not need to be as pure as for other uses.]

  • No, F⁻ is not a waste product in chemical industry. In fact, huge amounts of CaF2 are mined for their fluoride. I didn't see world wide numbers, but here's a USGS report which states the:

apparent consumption of fluorspar [CaF2 mineral] (excluding fluorspar equivalents of fluorosilicic acid, hydrofluoric acid, and cryolite) in the United States was 601,000 metric tons in 2000.

  • In aluminum production, F⁻ may be lost from the process if SiO2 is present (the reverse of the hydrolysis below takes place, there is no water around). The aluminum works usually do call this a waste of fluoride: they either have to buy new fluorite, or recover the F⁻ from the fluorosilicate (difficult, expensive). Source: lectures in inorganic and technical chemistry.

  • A quick glance through the Internet suggests that you pay something in the order of magnitude of several hundred US$ / t (varies of course a lot depending on how many tons you are willing to buy, and the purity).

Why not add Calcium fluoride to drinking water?

Because is is insoluble: it would be inefficient. The solubility product of CaF2 is 3.9 x 10⁻¹¹, meaning that even if no other Ca²⁺ is around, you don't get above 6.5 mg/l. This is technically not feasible: you'd need to leave one-sixth of the total drinking water in contact with CaF2 long enough to reach equilibrium and then mix it with the remaining five parts. Instead, you need higher concentrated stock solutions of which small parts are dosed into the drinking water.

On the other hand, this also means that if appreciable amounts of Ca²⁺ is present in the drinking water, your F⁻ uptake will basically be zero.

The "natural" form of Fluoride

  • CaF2 (fluorite) is the most important F⁻ mineral since the kryolith reserves were finished (in the 1980s). This is because CaF2 is very insoluble, and Ca²⁺ is common.

  • However, sea water contains approx. 1 mg/l F⁻ - that is much more in total, so after all, one may argue that the "natural" form or F⁻ is in the sea...

Hydrofluorosilicic Acid and Sodium Silicofluoride do not occur in nature

... because they immediately hydrolyze when in contact with water:

SiF6²⁻ + 2 H2O → 6 F⁻ + SiO2 + 4 H⁺ (hydrofluorosilicic acid is this plus 2 H⁺ on each side of the equation, sodium siliciofluoride instead has 2 Na⁺ on each side)

SiO2 is silica (as in quartz sand or produced by algae)

The 4 H⁺ react acidic, but remember that it is just about 0.04 mg/l (H: 1 g/mol, F: 19 g/mol) and the pH may be adjusted anyway.

Amount of F⁻ in drinking water

I missed in the discussion so far the levels of F⁻ in drinking water that are recommended for fluoridation and that are the upper allowed limit.

Here's another link to very detailed explanations from CDC

  • CDC recommendation is ca. 1 mg/l F⁻ (there are corrections according to how much water people drink per day in warmer or cooler regions)
  • The EPA sets an upper level of 4 mg/l, and a "secondary limit" (should be below, but isn't legally required) at 2 mg/l.

Basel (Switzerland) stopped drinking water fluoridation in 2003.

Here's a German language pdf from a lab report controlling F⁻ levels afterwards that cites the Neue Zürcher Zeitung.
The arguments are interesting,

  • they had an insular position, no one around had drinking water fluoridation any longer
    (meaning also, that if everyone around gets appropriate levels of F⁻ e.g. from fluorinated table salt and tooth paste, the Basel population may run a risk of overdoses as they probably also use fluorinated salt and tooth paste)
  • waste of F⁻: only 1 % of the water actually gets drunken (meaning that the remaining 99% are technically an environmental pollutant)
  • lack of evidence that fluoridation of drinking water is more efficient than the widespread use of fluorinated table salt (which is nowadays available everywhere) This point is a nice example of how different statements about the same thing can leave very different impressions: This other news article just speaks of "lack of evidence of efficiency", not mentioning that "over other measures like use of fluoridated table salt". (more below)

  • The second article also mentions that fluoridation did cost 120000 SFR per year (the article ends saying that several voters asked that this money should be directly put into caries prophylactic measures).

Efficiency of drinking water fluoridation

The CDC documentation gives further insight, which may also help to judge point 3 of the Basel list.

  • they cite that "80% of the dental caries in permanent teeth of U.S. children aged 5--17 years occurs among 25% of those children", and it is associated with low socio-economic status.

  • Judging from the abstract (pay-wall) this article argues that drinking water fluorination is not necessary any more in many regions as oral hygiene habits (including use of fluorinated toothpaste) are good.

  • However the CDC estimates that every $ for drinking water fluoridation saved something around at least $ 5 (they say typically for larger communities $ 38) of caries treatment (about $ 0,5 - 3 per person and year for fluoridation vs. $ 15 for avoided caries repair, they link studies).

  • CDC also states, that the effects seem to get lower, but attribute it to the fact that fluorinated water is also consumed by people living outside fluoridating communities (e.g. beverages shipped, ...)


Clearly there are harmful components, otherwise studies such as this wouldn't exist:

Comparison of hydrofluorosilicic acid and pharmaceutical sodium fluoride as fluoridating agents—A cost–benefit analysis


From the abstract:

"The U.S. could save $1 billion to more than $5 billion/year by using USP NaF in place of HFSA while simultaneously mitigating the pain and suffering of citizens that result from use of the technical grade fluoridating agents."

I do realise though that this study postdated the question!

  • I think this reference could be the base of a good answer, but worded quite differently. Rather than using the existence of the paper as a proof of something nebulous, why not quote from the paper itself about what the alleged pain and suffering is?
    – Oddthinking
    Commented Feb 12, 2014 at 3:37
  • 3
    your first assertion, that the only reason something is studied is because it is harmful, is wrong. There's many studies that are done for other reasons, or because something is thought to be harmful but the study shows it's not.
    – jwenting
    Commented Feb 13, 2014 at 14:32

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