Probably the earliest means of artificial water fluoridation was the uncontrolled release of industrial fluoride waste into rivers and streams from where many communities get their drinking water. Furthermore, late in the 19th century patents were filed on processes to purify and soften water by addition of fluorides which were claimed to precipitate the minerals responsible for water hardness. No one of the applicants apparently considered any toxic effects of their proposed additions.

In 1931, "natural" fluoride was found to be the cause of "mottled teeth" in humans. Whether indeed natural -taken up by the water from certain rock formations- or merely pollution, - analyses, carried out by Harry V. Churchill, chief chemist of ALCOA´s New Kensington plant, proved its presence in the water of afflicted districts. When in June of that same year the Superintendent of the Filtration Division, Bureau of Water, City of Pittsburgh, wrote to Churchill (1):  

"Several months ago, the Sanitary Water Board found that an industrial plant not far from New Kensington had been discharging fluorine into the Allegheny River. The officials of that plant discontinued such discharge when requested",

he received the following reply (2) [remember, this was written in 1931 !]:

"Tap water from both New Kensington and Pittsburgh shows that the fluorine content is variable in both waters. In no case have we found the amount to be greater than 1 part per million. Fluorine in this amount is probably not harmful and on the other hand may be positively beneficial. ... The presence of fluorine in water is apparently not necessarily proof of industrial contamination since it occurs in small amounts in so many water supplies."

The war production program of the 1940´s increased the problem, as reported in a book edited by William Gafafer, senior statistician of the U.S. Public Health Service (3):

"The sanitation problems resulting from stream pollution by industrial wastes have been greatly increased by the war production program. Industry should and does expect the community to provide a pure water supply. The dumping of industrial wastes into our rivers and streams is an unjustifiable although time-honored practice which should be discontinued. But, we must face the fact that the practice will not and probably cannot be eliminated at this time".

Meanwhile, more inventive spirits realized that instead of dumping fluoride waste directly into rivers, additional income could be earned by other more subtle means of disposal:

"Some of the waste products of industrial processes -fluorine among them- are not only recoverable but valuable. It seems that a major cause of delay in handling problems of this kind may be the lack of machinery for coördination between industry, the public health services, a number of government departments, and those research-workers who by their individual or collective initiative disclose evils we must all desire to abolish" (4).

Yet this type of "machinery" was no longer lacking. Government funds -provided as an outcome of the Social Security Act of 1935- at their hands which they formerly didn´t know how to spend properly (5), Walter J. Pelton and H. Trendley Dean, both of the U.S.P.H.S., had conferred late in October 1942 with H. W. Streeter of the U.S.P.H.S. Stream Pollution Investigation Station, Cincinnati, Ohio, to get assured that the artificial fluoridation of a water supply would not pose any major technical difficulties and to estimate the costs for introducing fluorine into a water supply for a city of about 30,000 (6, 7, 8). 

While Dean´s and Pelton´s source of the fluoride is not mentioned in any of the history books or articles, Wisconsin dentists apparently knew well of the Aluminum Company of America´s interest in selling sodium fluoride, as a letter from dentist John G. Frisch  to ALCOA reveals (9):

"Dear Sirs:

It is our understanding that the Aluminum Company of America is one of the largest producers of sodium fluoride. The demand for this material will soon reach astronomical proportions ... P.S.: The attached list of cities is only a starter and it will catch fire in other states very soon."

ALCOA, for its part, ran several advertisements in the Journal of the American Water Works Association (10) offering sodium fluoride for fluoridation:

"ALCOA sodium fluoride is particularly suitable for the fluoridation of water supplies. ... If your community is fluoridating its water supply  -or is considering doing so- let us show you how ALCOA sodium fluoride can do the job for you"

When the argument was raised that ALCOA´s sodium fluoride is a waste product of their aluminum production, the Journal of the American Dental Association was quick to publish a denial presented by ALCOA´s Chemical Sales Manager H. P. Bonebrake in 1955 (11): 

"DENIES SODIUM FLUORIDE IS INDUSTRY´S WASTE PRODUCT

The Aluminum Company of America last month denied that sodium fluoride is a waste product of aluminum manufacture. ... ´We make no direct sales of sodium fluoride, all of our production being handled through chemical distributors´. ... The letter pointed out also that a high percentage of sodium fluoride is obtained from phosphate rock. ´We have no operations involving phosphate rock,´ the letter stated."  

Whatever ALCOA´s policy may have been when this denial was published, it sure changed from time to time (12):

"Your reference to an advertisement of January 1950 indicates that you are delving considerably into past history on a subject that is moving rather rapidly. ALCOA´s policy may change from time to time; for a number of years we have sold sodium fluoride exclusively through distributors. We are now selling direct and we may sell to municipalities or anyone who wants to buy sodium fluoride. We manufacture sodium fluoride for sale. Anyone who wants to use it can buy it from us (or from a number of other sources), providing our production facilities enable us to supply it and our prices enable us to secure the business."

In the meantime, chemical companies like Blockson, of Joliet, Il., had sponsored year-long surveys "to develop new uses for sodium fluosilicate" (13), the waste product of the phosphate fertilizer industry:

"Almost all of the sodium fluosilicate produced today is a by-product of the phosphate industry and is derived from the calcium fluoride and fluorapatite in phosphate rock. ... The data reveal that the demand for this salt is only a fraction of the potential production and also shows why the phosphate fertilizer plants have to dispose of silicon tetrafluoride and hydrofluosilicic acid as wastes. At the present time it is uneconomical to convert these chemicals to hydrofluoric acid or some other fluorine compound."

It was, therefore, not far off to suggest its use for water fluoridation, nor was it a big surprise that someone of the National Institutes of Health, namely biochemist Frank James McClure, made the actual proposal in 1950 (14):

"As additional data are obtained, particularly with reference to dental caries effects, conclusions may be warranted regarding the possibility of substituting sodium fluosilicate for sodium fluoride as a water fluoridizing agent."

One of the technical advantages would be that instead of 19 pounds of sodium fluoride for one million gallons of water, only 14 pounds of sodium silicofluoride (another name for fluosilicate) would be required (15). No toxicological tests had yet been performed with this product. A "Technical Service Release No. 6" from E. I. Du Pont de Nemours & Co., Grasselli Chemicals Department, Wilmington, Delaware, claimed to provide toxicity information - but that was only for those handling the stuff in the water works:

"Sodium silicofluoride like sodium fluoride and other water soluble fluorides, is toxic. Packages carry a warning label against swallowing or inhaling. Handling precautions should be such as to avoid prolonged contact of sodium silicofluoride or its solutions with the skin which may result in dermatitis.  ... Precautions should also be taken against breathing the dust and inhaling spray mist from solutions. It is recommended that a toxic dust respirator be worn when loading feed hoppers in that if inhaled to excess, the mucous membranes may be affected, resulting in nose bleeds." 

As if "nose bleeds" would be the only effect on mucous membranes after inhalation.

The switching from sodium fluoride to sodium fluosilicate (and hexafluosilicic acid), as well as other sources of fluoride, was facilitated after a talk by Francis Bull, Dental Director of the Wisconsin State Board of Health, at a meeting of the State Dental Directors in June 1951 (16). He recommended never to refer to "sodium fluoride" as the agent used for water fluoridation, for most people know it as a trademark of rat poison and insecticide (e.g. McKesson´s "Sodium Fluoride"):

"Now, in regard to toxicity - I noticed that Dr. Bain used the term ´adding sodium fluoride´. We never do that. That is rat poison. You add fluorides. Never mind that sodium fluoride business, because in most instances we are not adding sodium fluoride anyhow. All of those things give the opposition something to pick at, and they have got enough to pick at without our giving them any more."

Clearly, this argument served others to advance their ideas of other fluoridation compounds, e.g. "Flural" developed by Wayne E. White, a former ALCOA chemist, then with Ozark-Mahoning Company (17):

"It seems certain that a principal reason for the initial reluctance of public health officials to endorse fluoridation and for the disinterest, until recently, of the public in this easy way to better dental health has been the association of fluoride with rat and roach poison. It is an understandable frame of mind which provokes the statement, ´Sodium fluoride in our drinking water? No, Sir, I don´t want my children to drink rat poison, better that their teeth drop out. Sodium fluoride is the stuff that gets into pies sometimes and kills a bunch of people.´"

With the growth in fluoridation programs, sodium fluosilicate, like sodium fluoride, was in short supply already in 1951, and prices went higher (18):

"Further impetus to fluoridation of community water supplies was given late in August when Office of Price Stabilization granted higher price ceilings to manufactureres of sodium silicofluoride ... ´Sodium silicofluoride has gained in importance recently,´ said the OPS order, in part ´because of the large growth in water fluoridation programs embarked upon by public authorities.´ ... Information received from the U. S. Public Health Service shows that the failure to expand production of sodium silicofluoride is a deterrent to the expansion of the water fluoridation programs."

But no doubt the problem would quickly be solved (19):

"Even though a recent survey indicates that both sodium fluoride and sodium silicofluoride are presently in short supply, this is unquestionably a temporary condition. For example, the fluoride present in the tonnage of phosphate rock processed annually in Florida alone, if all recovered, is sufficient to fluoridate every public water supply in the United States. ... A fourth chemical, hydrofluosilicic acid, has attractive possibilities if and when it becomes available in sufficient quantity. In the form of a 30 percent solution it could be fed from the rubber-lined drum in which it was shipped directly into the water supply."

Why the shortage?

"Since only a limited number of fertilizer manufacturers recover fluosilicic acid for sale to municipalities, when any one of these halts or decreases production a major source of supply is affected. ... This limited extent of recovery facilities is the key to the problem, since there is no real shortage of fluorides. Annual production of phosphate rock exceeds 40 million tons, and most forecasts estimate 1970 production at about 50 million tons. Phosphate rock contains about 4 per cent fluorine, and if even a small fraction of the total amount available were recovered and processed, there would be ample quantities for water fluoridation as well as for other uses. The increased demand for fluoride compounds, plus the pressure exerted by anti-pollution agencies, should encourage more phosphate rock processors to install or enlarge recovery facilities and thus ensure ample availability of fluorides in the future." (20) 

How it is produced (20):

"The recovery of hydrofluosilicic acid involves essentially the recirculation of scrubbing water until the acid concentration reaches a marketable value, which may vary from 20 to 30 per cent, but usually is about 23 per cent. Sodium silicofluoride is manufactured by adding soda ash to dilute hydrofluosilicic acid and filtering off the resultant precipitate."

Sodium fluosilicate and (hydro)fluosilicic acid are not the only compounds used for water fluoridation without prior toxicological testing. Late in the 1950´s, Franz J. Maier and Ervin Bellack, of the U.S.P.H.S., developed a "fluorspar dissolver" (21, 22) that yields a concoction very similar to Wayne White´s "Flural":

"The use of solutions containing aluminum compounds is considerably more practical, in that one of the chemicals routinely employed in water plants as a coagulant is alum (aluminum sulfate) and it has been found that by varying the concentration of alum in solution, any desired quantity of fluoride can be obtained from fluorspar."  

The authors claim in their patent (21):

"A continuous process for fluoridation of drinking water comprising:

- continuously feeding and stirring an aqueous solution of an aluminum sulfate salt into a bed of comminuted fluorspar, whereby a water-soluble reaction product containing aluminum ions and fluoride ions is formed as an aqueous solution, and a substantially water-insoluble calcium sulfate sludge is formed as a byproduct;

- continuously supplying measured amounts of said aluminum ions and fluoride ions containing aqueous solution of said reaction product together with calcium sulfate sludge to a supply of drinking water, said amounts being adequate to provide sufficient fluoride ions to meet dental health standards and to provide at least part of the aluminum ions necessary to effect coagulation of the impurities in said drinking water, and said calcium sulfate sludge assisting in the purification of said drinking water by flocculation of the impurities contained in said drinking water ..." 

This device did not exist just on paper, but was really installed in a few communities, the people there being used as guinea pigs living on an unapproved concoction of fluoroaluminate complexes.

"In order to prove its practicability, the dissolver was installed in the filtration plant at Bel Air, Md., on July 6, 1956, and has been running almost continuously since then. Arrangements were made with the owners of the plant and the Maryland State Department of Health to install the dissolver in place of a sodium fluoride solution feeder" (23).

Finally,

"an opportunity to build, install and test an installation for larger plants was afforded by a leading producer of fluorspar, who contributed the apparatus to the water utility serving Rosiclare and Elizabethtown, Il., and sufficient fluorspar to fluoridate the supply for the next five years" (22).

In 1970, Maier reported (24):

"This process is particularly advantageous in countries where fluorspar is mined and where manufactured fluoride compounds must be imported. Brazil, where this situation occurs, now has more plants using fluorspar for water fluoridation than the rest of the world combined." 

Nowadays, fluoroaluminate complexes are extensively used in biochemical studies for their known effects on the so-called "G-Proteins" whereby they cause considerable toxic effects (25). (Will it make a difference whether the aluminum and the fluoride are ingested separately (with food and drink) and meet under the favorable conditions for complex formation in the stomach?)

What surprise will be brought to light with a thorough investigation into low-dose chronic fluorosilicate (=silicofluoride) toxicity which is still pending (26) ? 

References:

(1) C. F. Drake to H. V. Churchill, June 1, 1931; in the ALCOA papers, State Historical Society of Wisconsin (SHSW), Madison, Wisconsin; (2) H. V. Churchill to C. F. Drake, June 3, 1931; in the ALCOA papers, SHSW; (3) Gafafer W. M.: "Manual of industrial hygiene and medical service in war industries", W.B. Saunders Company, Philadelphia, 1943, p. 338; (4) "Fluorosis - endemic and man-made", The Lancet II (Dec. 7, 1946) 835; (5) Editorial: "Federal Aid in Public Health Dentistry", JADA 30 (April 1943) 577; Pelton W. J.: "Federal Aid in Public Health Dentistry", read before the Oral Hygiene Group of the American Public Health Association, Oct. 28, 1942, publ. JADA 30 (April 1943) 570; (6) H. T. Dean to H. W. Streeter, July 16, 1945; in the Ruth Roy Harris Papers, History of Medicine Division, National Library of Medicine (NLM), Bethesda, Md.; (7) H. W. Streeter to H. T. Dean, August 6, 1945; in the Ruth Roy Harris Papers, NLM; (8) McClure F. J.: "Water Fluoridation. The search and the victory", NIDR, Bethesda, Md., 1970, p. 113; (9) John G. Frisch to Aluminum Company of America, June 27, 1949; in the Frisch papers, SHSW; (10) JAWWA 43:6 (1950); (11) "Denies sodium fluoride is industry´s waste product", J. Am. Dent. Assoc. 51 (Sept. 1955) 373; (12) H. P. Bonebrake to C. A. Barden, July 10, 1957;    (13) Hampel C.A.: "Sodium fluosilicate - a neglected chemical", Chem. Eng. News 27 (1949) 2420; (14) McClure F. J.: "Availability of fluorine in sodium fluoride vs. sodium fluosilicate", Public Health Reports 65 (1950) 1175; (15) E. I. Du Pont de Nemours & Co., Grasselli Chemicals Department, Wilmington, Delaware: "Sodium Silicofluoride in water fluoridation", Technical Service Release No. 6, Feb. 6, 1950; (16) Proceedings of the fourth annual conference of State Dental Directors with the Public Health Service and the Children´s Bureau, June 6 - 8, 1951, Federal Security Building, Washington D.C., p. 12; copy in the Ruth Roy Harris papers, NLM; (17) Wayne E. White, of Ozark-Mahoning Company: "Flural - a new flocculating-fluoridating agent for municipal water treatment",  undated manuscript, in the J.G. Frisch papers, SHSW; (18) "Water Fluoridation", J. Am. Dent. Assoc. 43 (1951) 499; (19) Black A. P.: The chemist looks at fluoridation", J. Am. Dent. Assoc. 44 (1952) 137; (20) Bellack E., Baker R. J.: "Fluoridation Chemicals - The Supply Picture", J. Am. Water Works Assoc. 62 (1970) 223; (21) Maier F.J., Bellack E.: "Fluoridation of Drinking Water", US Patent 3,078,225; filed Oct. 29, 1957; patented Feb. 19, 1963; (22) Maier F. J.: "Advances in the use of fluorspar for fluoridation", J. Am. Water Works Assoc. 52 (1960) 97; (23) Maier F. J., Bellack E.: "Fluorspar for fluoridation", J. Am. Water Works Assoc. 49 (1957) 34; (24) Maier F.J.: "25 years of fluoridation", J. Am. Water Works Assoc. 62 (1970) 3; (25) Strunecka A., Patocka J.: "Pharmacological and toxicological effects of aluminofluoride complexes", Fluoride 32:4 (1999) 230; (26) Masters R.D., Coplan M.J., Hone B.T., and Dykes; "Association of Silicofluoride Treated Water with Elevated Blood Lead"; NeuroToxicology 21:6 (2000) 1091-1100;  Coplan M. J., Masters R.D.: "Silicofluorides and fluoridation", Fluoride 34:3 (2001) 161 

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