In 1931, the probable cause of "mottled teeth" was found in the tap water of afflicted districts by a chemist of the research laboratories of the Aluminum Company of America (ALCOA). The Company became interested when "mottled teeth" were reported among residents of a small mining town: Bauxite, Arkansas, named after the ore mined there.

"Bauxite" is the name of a mineral which is essential for the production of the light metal aluminium. By purification (e.g. by the Bayer Process), the bauxite ore becomes alumina (aluminium oxide) which is mixed with a so-called "flux", a specially prepared sodium fluoroaluminate (derived from natural or synthetic cryolite plus sodium fluoride), and the molten mass is then subjected to an electric current which releases the aluminum metal. In the U.S.A. this process was patented by Charles Martin Hall who thus laid the foundation for the "Pittsburgh Reduction Company" which later was renamed "Aluminum Company of America" (ALCOA). For construction and expansion, the Pittsburgh Reduction Company won the financial support of several businessmen, among them banker Andrew W. Mellon, who gave a bank credit in exchange for a majority in the shares of the new company (1). In the 1920´s said Andrew Mellon was appointed Secretary of the Treasury under President Warren G. Harding, whose successful election campaign had had Mellon´s financial aid. Until he stepped back early in 1932, Mellon in his new position also headed the U. S. Public Health Service, which was -for historic reasons- still under the jurisdiction of the Treasury Department. In this period the "aluminum crusade" raged throughout the United States, and Mellon´s appointment led to a conflict of interest. When the U.S.P.H.S. left the Treasury during a reorganization in 1939, a review revealed that on one occasion "there was a tendency to suppress certain scientific reports of importance to the public health on the grounds that certain commercial interests might be offended" (2) .

The Aluminum Crusade

At the time of Mellon´s appointment, claims of toxic effects of aluminium and its compounds had already a long history. Problems apparently arose with the use of sodium aluminum sulphate ("alum") in medicine (3) and as a component of baking powders (4). According to McCollum et al. (4), President Roosevelt appointed in 1907 "the Referee Board of Consulting Scientific Experts to examine into the alleged health hazard of aluminum. The Board reported in 1914 the conclusion that aluminum compounds, when used in the form of baking powders in foods, were not found to affect injuriously their nutritive value... The Board reported that the aluminum itself has not been found to exert any deleterious action injurious to health beyond the production of occasional colic when very large amounts have been ingested. ... With the advent of aluminum cooking utensils the trade war has been largely shifted to this field." Discussing this latter topic, McCollum and coworkers put much weight to the fact that "there are numerous expressions of opinions by eminent medical authorities that there is no health hazard in respect to aluminum" and that "similar statements from responsible scientific men and eminent medical authorities in England, Germany, and France could be cited". To support their statements the authors then refer any interested reader to a report - of the Mellon Institute of Industrial Research (Bulletin No. 3 of 1923). In 1928 McCollum and his group presented evidence that aluminum is only poorly absorbed and that their spectrographic method allowed for a far more reliable quantitative determination than other methods then in use (5). Yet the battle continued in England, where it had the support of Leo Spira, a physician whose related articles were rejected by editors of medical journals (6), as well as in the United States of America, where it was led by dentist Charles T. Betts, of Toledo, who mostly used the "Watchtower" as an apparently effective publication medium (7). That "one of our own profession" opposed the use of aluminum was hard to accept for the one or the other dentist who defended or propagated aluminum base dentures at that time (8,9).

Suppression of reports:   Mottled teeth in Bauxite, Arkansas

General toxic effects ascribed to aluminum poisoning offered no specific symptoms that could not also be related to other causes. But the occurrence of a clearly visible defect, such as "mottled teeth", would add oil to the fire of the aluminum crusaders if a causal relationship to aluminum uptake could be proven. That the endemic occurrence of mottled teeth had been reported in the Pikes Peak area (Colorado), the only large cryolite deposit in the United States, did already point in this direction. In the late 1920´s new fears emerged that undesired attention could be directed to a bauxite mining community, where a subsidiary of ALCOA was at work: mottled teeth had become endemic among people living in Bauxite, Arkansas, a city appropriately named after the aluminum ore mined there.

A paper published in 1938 by Trendley Dean and Frederick McKay gives the following details about how officials became aware of the situation: "Apparently the first to report endemic mottled enamel at Bauxite was Dr. F. L. Robertson, a practicing dentist of Benton, a city about 5 miles from Bauxite. His report was made to the Arkansas State Board of Health, and in March 1926 the state health officer asked the United States Public Health Service to make a study of mottled enamel in Bauxite." The authors refer to an "official request for a survey of Bauxite from the State Health Officer, C. W. Garrison, addressed to the Surgeon General, United States Public Health Service, dated March 16, 1926" (10). As there was apparently no response from the USPHS in the meantime, the superintendent of the bauxite mining company, Luther Branting, established contact with McKay in September 1927, who in turn brought the matter to the attention of the Bureau of Child Hygiene in Washington, and urged that a personal examination of the field be made prior to a change of the water supply that the company was already contemplating (10, 11). Grover Kempf, of the Bureau of Child Hygiene, and McKay as a USPHS special consultant conducted that survey in February 1928 (12). McKay mentioned this survey, without details, at an IADR meeting in 1928 (12), but even two years later, in 1930, the Public Health Service -under the direction of Andrew Mellon- had not published any results nor issued a notice. Although McKay assured Branting in March 1928 "that in whatever reports we make, every care will be taken to avoid direct reference to the community" (13), he had lost his patience by March 1930.  In a paper he read at a meeting of the New York Section of the International Association for Dental Research, he referred explicitly to the "examination of the town of Bauxite" that was made "under the auspices of the Department of Public Health of the U. S. Government, two or three years ago, the results of which have not yet been published. Briefly this community was found to be suffering from a 100 per cent affliction." He also told his audience that immediately after the examination, the community abandoned the use of the water and substituted water from an entirely different source, the nearby Saline River, exclusively because of this dental condition (14). Now that the news was out, the Public Health Service released the story in the November 28, 1930, issue of Public Health Reports (15). Due to a release by "Science Service" an article referring to the town of Bauxite also appeared in the Pittsburgh Press, to the surprise of some ALCOA chemists (16), since McKay wrote in an earlier letter to Branting that he would avoid direct reference to the community.

ALCOA´s research efforts

In the meantime ALCOA had started its own research. Since 1926 there was in operation at the Mellon Institute of Industrial Research, Pittsburgh, Pa., a "Utensil fellowship" that investigated searchingly the effects of aluminium on foods - and produced results showing the "perfect safety" of the metal (17). In 1928, another chemist, Gerald Judy Cox, was hired to this fellowship to investigate the effects of aluminium salts on the metabolism of calcium and phosphorus, the main minerals of bones and teeth. These experiments had been initiated by ALCOA after Francis Cowles Frary, one of the chemists of the Aluminium Research Laboratories, visited the Bauxite  mines and heard from Luther Branting about the strange tooth problem (18). Late in 1930 Cox´s results were in and in December of that year Frary wrote to Branting: "In the meantime, we have been experimenting with aluminum salts at the Mellon Institute, and have found that the presence of a very large excess of aluminum salts in the diet can cause the removal of lime from the bones, and presumably from the teeth. This is for the reason that  the deposition of this lime in the body depends upon the presence of adequate amount of phosphorus in the form of phosphoric acid. An excess of soluble salts of either iron or aluminum will eliminate this phosphorus, combining with the phosphorus in the foods to form insoluble phosphates, which are excreted. It would therefore appear rather probable that the presence of large amounts of aluminum salts in drinking water might be connected with the difficulties you mentioned" (18). The corresponding report of the experiments done in rats was presented by Cox et al. in April 1931 at the annual meeting of the American Society of Biological Chemists (19).

But Branting felt this was the wrong track. Along with his reply (Dec. 12, 1930), he forwarded copies of his correspondence with McKay to Frary and argued: "As to the particular well water which was causing the damage, this water was from the deep wells and not from the ordinary shallow wells in this section. The water from the ordinary shallow wells even though the well be sunk in bauxite, seems to have no  bad effects. Bauxite children who had used spring water or ordinary shallow-well water instead of the deep-well water have good teeth"  (20). As none of the rather difficult chemical tests for soluble aluminum salts had been performed on either the present or past water supplies (21) a water analysis was in order for which a gallon of water from the former supply was requested from the Bauxite chemist. Frary explained: "We are now very well equipped to do this because we have a quartz spectroscope which will enable us to determine extremely minute elements present" (22). On January 6, 1931, ALCOA chemist  Laudemann reported in an internal communication the first surprising find of fluoride in the sample of the former Bauxite water supply and asked the chemist of the Bauxite works, R. C. Cross, to send another sample of that water to verify the find (23). Cross sent it. He also passed on the information that at the University of Arkansas Experiment Station, Fayetteville, experiments on the effects of fluoride in the diet were being carried out on guinea pigs and rats (24), after deleterious effects on calcification of bones and teeth had been observed in swine as a consequence of feeding raw rock phosphate with a rather high fluoride content (24a). Frary´s reply indicated that "if we check this presence of fluoride in this new sample, we are inclined to write Dr. McKay and tell him  what we have found, and suggest that if he can get us samples of the water of the other communities where this difficulty has also been noted, we will be very glad to check them up and see if they also contain fluorine" (25). Thus, on January 20, 1931, Harry Van Osdall Churchill, of ALCOA´s New Kensington Laboratories, sat down to write a 4-pages-letter to inform Frederick McKay that fluoride might be the long-sought cause of the dental problem (26): "Its presence was revealed when the evaporation residue from this water was spectrographed. The spectrum produced showed the characteristic band spectrum of calcium fluoride. The presence of fluoride was so unexpected in water that a new sample was taken with extreme precautions. Again the characteristic band spectrum of calcium fluoride was obtained. It is worthy of note to recall that the only deposit of cryolite in the United States is found on Pikes Peak. Cryolite is a double fluoride of sodium and aluminum. Fluorides are very often found in the vicinity of volcanic activity and in those localities where hot or warm springs are encountered." As the chemists did not wish to broadcast their findings "since this presence of fluoride may or may not have significance", Churchill asked McKay to arrange to procure water samples from afflicted districts "with a minimum of publicity".

The news about fluoride was exciting to McKay, though he did not know how the ALCOA chemist "got in touch with the situation". When he asked Branting (27), the latter did not explain that he kept the ALCOA people up-to-date about his correspondence with McKay and any developments, but replied: "I believe his attention was drawn to the situation by the publicity our town received in the newspapers through the release recently by ´Science Service´ of an item on the subject" (28).

On March 31, 1931, Churchill announced his find in a short talk before a meeting of the American Chemical Society at Indianapolis, whereupon a notice was issued in a published summary of the meeting. The interest his presentation evoked is reflected in the number of requests he received thereafter for his full report which was, however, only published in September of that year in "Industrial and Engineering Chemistry" (29). As to how he allegedly got in touch with the situation, articles in the "Pittsburgh Press" of May 31, 1931, and in the "Scientific American" of November, 1931, claimed "Churchill had fluorine in mind, as a matter of fact. He had recalled that brewers once used to sterilize beer vats with a calcium fluoride solution, because it killed wild yeast, but that drinkers of the beer became afflicted with peculiar bone troubles, and the dismayed brewers ceased its use" (30, 31).

One p.p.m. is the limit ?

When Churchill submitted his full report on May 19, 1931, for publication, his water analyses for fluoride comprised about 30 samples from different cities "scattered over the United States" (32). The fluoride contents of waters from districts with mottled teeth (Colorado Springs, Oakley, a well near Lidgerwood, a well near Kidder, and the deep well of Bauxite) ranged from 2 to 13.7 parts fluoride per million parts of water (ppm or mg/l) (29, 32), which is in accord with the increasing relative severity of mottled teeth observed by McKay (33). Water samples of non-afflicted areas, where fluoride was found by the spectrographic method, contained in all cases less than 1 ppm (29). However, his quantitative chemical fluoride estimations were made with a modification of a method developed by Fairchild (originally used for fluoride estimation in rock phosphate) which was later criticized for giving far too high values even after further modification (34). It was rash to take the magic limit of 1 ppm literally at this time.

The presence of fluoride in the water was not regarded by Churchill as proof that mottled enamel is actually caused by it. But, as he wrote to McKay, "the whole study despite its brevity has many interesting implications and might well be the subject of a paper to be presented say to the Water Division of the American Chemical Society" (32). The defect, he wrote to an American Chemical Society representative, "would be mentioned only as the stimulus for our work. It seems to me that this discovery is interesting and naturally we want to reach those who are interested in water quality" (35).

One of the "many interesting implications", especially related to water quality, was revealed in Churchill´s correspondence with C. F. Drake of the Water Filtration Plant of the City of Pittsburgh´s Department of Public Works. Drake had heard Churchill speaking at the American Water Works Association convention on May 26, 1931, and wrote him on June 1, 1931: "Naturally the reference to Pittsburgh tap water and its spasmodic fluorine content which appears to have had no explanation, came to our attention. 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" (36). Drake´s request for information concerning the time of occurrence of fluorine in Pittsburgh tap water was answered by Churchill on June 3: "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..." (37). Fortunately, the day when Drake´s original request arrived, Churchill´s mail also contained a letter from a local dentist, L. Ockner (38), who drew his attention to fluoride´s "beneficial effects" by mentioning earlier European work (Hempel, Jodlbauer, Denninger, Brissemoret) as cited in a book by Hermann Prinz of Philadelphia. (Prinz, who was born in Germany in 1868 and emigrated to the U.S.A. about 1890, took up dentistry at the University of Michigan, where he graduated in 1896. Since about 1913 he was Professor of dental materia medica at the University of Pennsylvania (39) and mentioned the early fluoride work in his book "Dental materia medica and therapeutics").

Another "interesting implication" concerned ALCOA´s Massena plant. The occurrence of mottled teeth in Massena was stated by three local dentists, but they were not able to say whether a greater or lesser percentage than elsewhere were treated for that condition, as they had no sufficient experience elsewhere (40). The water analysis revealed no fluorine, at least not at the time or at the point the sample had been taken (41).

References:

(1) Holbrook S.: "Mr. Mellon", p. 253 of "Cäsaren der Wirtschaft" (The age of the Moguls), 1954; (2) Hampton B.C.: "The Public Health Service leaves the Treasury Department", Publ. Health Rep. 54 (June 30, 1939) 1133; (3) Schulz H.: "Wirkung und Anwendung der unorganischen Arzneistoffe", 3rd edition, Haug Verlag Berlin, 1920, p. 245; (4) McCollum E.V, Orent-Keiles E., Day Harry G.: "The newer knowledge of nutrition", 5th edition, MacMillan Company, New York 1939, p. 275-278); (5) McCollum E.V., Rask O.S., Becker E.J.: "A study of the possible role of aluminum compounds in animal and plant physiology", J. Biol. Chem. 77:2 (1928) 753; (6) c.f. Spira L.: "The drama of fluorine. Arch enemy of mankind", Milwaukee 1953; (7) Bergman J.: "Aluminum: Satan´s metal and killer of millions? The Watchtower´s incredible crusade against aluminum", http://www.premier1.net/~raines/aluminum.html (last access Dec. 1998); (8) Campbell D.D.: "The cast swaged aluminum base denture", J. Am. Dent. Assoc. 22 (Dec. 1935) 2082; (9) Campbell D. D.: "The cast-aluminum base denture", J. Am. Dent. Assoc. 23 (July 1936) 1264; (10) Dean H.T., McKay F.S., Elvove E.: "Mottled enamel survey of Bauxite, Ark., 10 years after a change in the common water supply", Publ. Health Rep. 53 (Sept. 30, 1938) 1736; (11)  L. R. Branting to F.S. McKay, Sept. 14 & Oct. 7, 1927; McKay to Branting, Oct. 17, 1927, in the ALCOA papers, State Historical Society of Wisconsin, Madison, Wi.; (12) McKay F. S., Kempf G. A.: "Review of the most recent research on mottled enamel", J. dent. Res. 8 (1928) 416; (13) F. S. McKay  to L. R. Branting, March 12, 1928, in the ALCOA papers; (14) McKay F. S.: "The present status of the investigation of the cause, and of the geographical distribution, of mottled enamel, including a complete bibliography on mottled enamel", J. dent. Res. 10:5 (1930) 561; (15) Kempf G.A., McKay F.S.: "Mottled enamel in a segregated population", Publ. Health Rep. 45 (Nov. 28, 1930) 2923; J. dent. Res. 12 (1932) 117; (16)  F. C. Frary to L. Branting, Jan. 17, 1931, in the ALCOA papers; (17) Weidlein E. R.: "Various results of being researchful", Science 82 (Dec. 13, 1935) 553; (18) F.C. Frary to L. Branting, Dec. 9, 1930, in the ALCOA papers; (19) Cox G.J., Dodds M.L., Wigman H.B., Murphy F.J.: "The effects of high doses of aluminum and iron on phosphorus metabolism", J. Biol. Chem. 92 (1931) XI; (20) L. R. Branting to F.C. Frary, Dec. 12, 1930, in the ALCOA papers; (21) H. M. Laudemann to R.C. Cross, Dec. 9, 1930; R. C. Cross to H. M. Laudemann, Dec. 15, 1930; H. M. Laudemann to R.C. Cross, Dec. 19, 1930, in the ALCOA papers; (22) F. C. Frary to L. R. Branting, Dec. 16, 1930, in the ALCOA papers; (23) H. M. Laudemann to R. C. Cross, Jan. 6, 1931, in the ALCOA papers; (24) R.C. Cross to H. M. Laudemann, Jan. 12, 1931, in the ALCOA papers; (24a) "Effects of fluorine on bone formation", Bulletin of the Agricultural Experiment Station, University of Arkansas, Fayetteville, Arkansas, No. 215, (Nov. 1926) 23-27; (25) F.C. Frary to L. R. Branting, Jan. 17, 1931, in the ALCOA papers; (26)  H. V. Churchill to F. S. McKay, Jan. 20, 1931, in the ALCOA papers; (27) F. S. McKay to L. R. Branting, Feb. 2, 1931, in the ALCOA papers; (28) L. R. Branting to F. S. McKay, Feb. 9, 1931, in the ALCOA papers; (29)  Churchill H. V.: "Occurrence of fluorides in some waters of the United States", Ind. Eng. Chem. 23:9 (Sept. 1931) 996; (30) "Scientist here finds ´secret poison´ which blackens teeth of children", Pittsburgh Press, May 31, 1931; (31) "Disfigurement of children´s teeth", Scientific American 145 (Nov. 1931) 350; (32) H. V. Churchill to F. S. McKay, March 5, 1931, in the ALCOA papers;  (33) F. S. McKay to H. V. Churchill, March 9, 1931, in the ALCOA papers;  (34) Boruff C. S., Abbott G. B.: "Determination of fluorides in Illinois Waters", Ind. Eng. Chem. 5 (1933) 236; (35) H. V. Churchill to Edward Bartow, March 6, 1931, in the ALCOA papers; (36) C. F. Drake to H. V. Churchill, June 1, 1931, in the ALCOA papers; (37) H. V. Churchill to C. F. Drake, June 3, 1931, in the ALCOA papers; (38) L. Ockner to H. V. Churchill, June 1, 1931, in the ALCOA papers; (39) Denton G.B.: "Some interrelations between German and American Dentistry, 1800 - 1914", J. Am. Dent. Assoc. 61 (Nov. 1960) 587; (40) V. C. Dorschuk to H. V. Churchill, June 4 and June 11, 1931, in the ALCOA papers; (41) Spectrographic analysis by H. V. Churchill, June 18, 1931, in the ALCOA papers;