Document RpDOmjwYrq46Bb1j4EGK89BX7

Fsvim>\MKvrAL kescarch 18,300-314(1979) ty /> / i* *,*** 2 Historical Background to the Asbestos Problem 1 The turmoil and s> practical arts and ma body armor at the si Douglas H. K. Lee*1 and Irving J. Seukoff Environmental Sciences Laboratory, Mount Sinai School of Medicine. Nov York, New York Received June 7, 1978 EARLY BEGINNINGS Asbestos has been known in various forms and used for different purposes since prehistoric times. In Finland, for example, pottery dating from 2500 B.C. has been found i i i I Chinese merchant's Asbestos wicks and the 18th century, anc the establishment of before lapsing for la< known and well-ke| making of threads < paper, cloth, and ev to incorporate asbestos (presumably anthophyQite) fibers, and Busmanoid pottery at 'i* 1806-1807. Tara re! tributed to stone-age times (before the middle of the first century B.C.) has been found containing amphibole in the region ranging from southern Sudan to northern Kenya (70, the labia of female leggings, ropes, bel 93). Finnish peasants are also reported to have used asbestos rock to pack crevices in their O stoves in Corsica. log huts from time immemorial. One of the earliest historical records tells of the use of asbestos wick in a gold lamp for the goddess Athene in the fourth to fifth century B. C. At the tum of that century Theophrastus described the persistence of the wick after the oil was burned off, and Strabo and Plutarch continue the story (28, 44, 84). Herodotus, writing about 456 B.C., remarks on the use of an asbestos cloth for retaining the ashes of O In 1725, shortly W3 Sloane that he had O* made of the stone < k Salamander Cottor N British Museum, b the dead during cremation, and Pliny in the first century A.D. calls it the funeral dress of kings. Such a shroud is reported to have been recovered from a pre-Augustinian tomb to have been Arne Aldini and Cavr (23b, 44,50). Plutarch described other articles into which the material was woven. One form of the Greek word aao-peerros signified "unquenchable;" the perpetuity of until the period 1 banknotes, was sta the flame given by wicks containing asbestos would have justified the appelation. The concept of indestructibility seems to have been added to the connotation later. Some display at a Lond asbestos yams mat confusion has resulted from another form rjaaPcarog of the same word that signified what today we would cal! slaked lime (95). The term "amiantos" and its variations, common in mediterranean countries, also has (17). In 1866, two t title of the Patent that was needed v a confused etymology. Lithos amiantos is said to be the original term, as used by the Greeks to indicate a rock unstained, untainted, or undefiled, referring presumably to the cleansing of asbestos material by fire (19). It has been suggested, however, that the Karpasian flax referred to by Pausanius (second century A.D.) came from a village in Cyprus known as Aniianto, which might be the town of Amiandos near which chrysotile Tlte rediscover South Africa pros followed. has been found in recent times. In England, the term "amianthus" survived until the end Canadian Prodttc of the 19th century, when the word "asbestos" took its place. In France today, "amiantc" is used at least as frequently as "asbeste." The property of being unconsumed and even purified by fire is emphasized in the account given by Marco Polo (ca. 1250 A.D.) of a cloth reputed to be of salamander skin, but actually consisting of "amianto" prepared from rock by a process that persisted well into the nineteenth century (50). Apparently a similar account given some 150 years earlier did not attract antiquarian interest (48). The story of Charlemagne's tablecloth and the impression made on guests when he threw it into the fire has been many times recounted in recent literature (21, 50). 1 Attempts to wo were unsuccessfu rediscovered by ' (21,23a,49,50,5 who transported established the subsequent disill cial ventures we rapid developme 1 Present address: Nazareth 5-1, Deer Hill Rd., St. Thomas 00801, U.S. Virgin Islands. increased to sev 0013-9351/79/020300-15502.00/0 Copyright if) 1979 by Ac*Jcmic Prc*. Inc. All rigtm of reproduction in *ny form reserved. 300 uw HISTORICAL BACKGROUND 301 INTERMEDIATE YEARS The turmoil and superstition of the middle ages militated against development of the practical arts and manufacture in Europe, and apart from a passing reference to its use in ri body armor at the siege of Rouen (1490), the next we hear of asbestos is mention of a Chinese merchant's exhibit of "salamander's wool" in London in 1676 (21, 79, 85). Asbestos wicks and paper were apparently manufactured in Norway in the early years of % the 18th centuiy, and the discovery of substantial deposits in the Urals about 1720 led to C/I the establishment of an industry under Peter the Great, that persisted for about 50 years before lapsing for lack of demand (23b). According to Tara, the art of weaving was a little known and well-kept secret (85). To Lena-Parenti goes the credit of rediscovering the -Y making of threads early in the 19th century (50,85). She apparently went on to make paper, cloth, and even lace and received recognition from the National Institute of Italy in f>i: 1806-1807. Tara relates that asbestos threads were utilized in Africa and Asia for sewing the labia of female infants; that shepherds in the Pyrenees used the material in making leggings, ropes, belts, and bags; and that it was used as insulation in the construction of stoves in Corsica. In 1725, shortly after his arrival in London, Benjamin Franklin wrote to Sir Hans Sloane that he had brought with him from "the northern parts of America ... a purse made of the stone asbestos ... which is of the same nature and called by the inhabitants Salamander Cotton" (5). What is believed to be the same article now reposes in the British Museum, but since it is made of tremolite, the source of the fiber would seem not ro have been American, but possibly a mediterranean country like Italy. Aldini and Cavanessi experimented with asbestos clothing about 1827, but it was not until the period 1850-1870 that production of woven materials, including paper for banknotes, was started in Italy (23a, 50). In 1862 a specimen of Canadian asbestos was on display at a London exhibition., and in 1869 Wertheim came across some of the first asbestos yams manufactured in England and used them in Germany for ropes and packing (17). In 1866, two Glaswegians, Robson and McLcllan, formed a group with the prescient title of the Patent Asbestos Manufacturing Company, Ltd. (22). Industry was ready, all that was needed was a good supply of the magic material with which to work wonders. THE BREAKTHROUGH PERIOD t: z: I The rediscovery and development of very large deposits of asbestos in Canada and South Africa provided the opportunity. Development of deposits in other countries soon followed. Canadian Production Attempts to work chrysotile deposits discovered in 1860 in the Des Plantes River region were unsuccessful, but the Thetford-Colerain deposits, first noted by Logan in 1847 and rediscovered by Fecteau and Ward in 1876-1877, proved more extensive and amenable (21,23a, 49,50,51,74). [An overlapping account gives the credit to one Andrew Johnson, who transported handpicked material by oxcart 31 miles to the nearest railroad and established the pioneer producer of Canadian asbestos (12)]. The early optimism, subsequent disillusionment, and final realistic approach so often attending new commer cial ventures were well described for asbestos by Cirkcl (23a). The 1880s witnessed a rapid development, mines were worked on a large scale, and the surrounding population increased to several thousand. But the primitive methods of hand extraction permitted 8 . ,7 C-tiKa m c V r,..... 302 LEE AND SELIKOFF only Ihose mines with high grade material to prosper, and even so there was overproduc tion and the industry languished through the nineties. Mechanical methods of mining and milling were then introduced, demand increased, and by 1905 there were 16 mills with a capacity of 3500 tons of rock per day operating successfully. Thereafter the industry embarked upon the exponential growth that we know so well, with only minor and temporary aberations (19). The mode of mining was entirely by open pit at first, and this method is still common. But by 1959 it was reported that of 14 mines, 3 had changed entirely to underground mining, 2 more were intending to do so, and others used both methods (80). South African Production Meanwhile, events in South Africa were pursuing a parallel course. In 1891 Oats, a Director of the De Beers Consolidated diamond mines, formed a group to exploit the crocidolite which had first been noticed in the northwest of the Cape Province in 1803-1806, and named in 1831, but had remained unused. The syndicate had less success than the Canadian developers for a variety of reasons, including the Boer War. The first officially recorded production came in 1910, but the tonnage remained below 10,000 annually until 1940. In the 1940s, presumably with the stimulus of wartime demands, modern consolidated mining methods became the rule (81, 82). In the meantime, another type of asbestos, to be called "amosite" after the acronym of the company, had been discovered in northeast Transvaal. Once again, early experience was discouraging. Production started in desultory fashion in 1910, but it was not until 1926 that the Cape Asbestos Company, capitalizing on its experience with crocidolite, literally put the material on the market (6). By 1928, production has risen to 7000 tons. In South Africa, also, open-pit mining was the original method and some quarrying still persists; but underground mining became increasingly more common after 1930. Milling replaced hand cobbing after 1915 (81). Italian Production The historical experimentation with tremolite and chrysotile deposits, mainly in the northern Appenine valleys, culminated in the formation of the Italo-English Pure Asbestos Company in 1874, with a factory at Turin, but the discovery of the more workable Canadian chrysotile temporally ended significant use of Italian sources (II). Annual production remained below 1000 tons until 1923. Thereafter it fluctuated until 1947. In the 1950s it began to share in the expanding world production, although in 1970 it still provided only 3.4% of the total (19, 24). Russian Production Until after the 1918 revolution, production methods remained fairly primitive (56). Production remained low until the period 1925-1928, when a new plant was constructed. By 1938 it had risen to 135,000 tons per year (10). By 1963 large fields were being developed in Siberia and other sites, and by 1970 it was estimated that annual production had reached 1,150,000 tons, third in world ranking (24). United Stares Production In 1899-1901 development started in Vermont of deposits at the southern end of the serpentine belt running through Quebec. These deposits remain the mainstay of United States production. Later developments took place in Arizona, California, North Carolina, .,nd Georgia (9,24). By ihe world figure (24). liltinlesion Productio, Mining of chrysotile ions occurred in 1968. C/) Other Production A --* . In 1970 3.855> of the Australia, and Finland ?> ~ Australia and anthoph; OV SO Machines for the pr i 1 INJ furnished an immediate SO insulation; but the pote start. On the Ament EncyJopedia America > products in 1868. The < its cover story. World I multiplied its uses in fresh ideas, and subsr indicates just a few o cited may be open to s 100 years' growth, ar development in spite fears of "dumping." In 1947 the trade j< neatly as providing pi electricity, noise, cm comprehensive list ol listed 40 uses for raw paper, 14 for asbestos composition material on the History of Asl such lists became vi dealing with only a fc data are for the Unitei years. Although many i employed was small 20th century. Pliny's dismissed as oflittle Inspectors of Facto paragraph: HISTORICAL BACKGROUND 303 ;,nJ Georgia (9,24). By 1970 the annual production amounted to 125,314 tons, or 3.3% of die world figure (24). Rhodesian Production Mining of chrysotile started in the Mashaba region in 1906. Peak production of 95,000 ions occurred in 1968. Later figures are somewhat lower (8). i r.Uer Production In 1970 3.8% of the world total was mined in various other countries, including China, Australia, and Finland (24). Included in those figures was some crocidolite produced in Australia and anthophyllite in Finland. MANUFACTURE AND USE Machines for the production and use of power introduced by the industrial revolution furnished an immediate stimulus to the asbestos industry through the need for packing and insulation; but the potentiality of the new material for other purposes was evident from the start. On the American scene, for example, a Mr. Johns read of asbestos in the Hncylopedia Americana as early as 1859, and began manufacturing some- asbestos products in 1868. The issue of Scientific American for February 26,1881 had asbestos for its cover story. World War II provided a tremendous boost in the demand for asbestos and multiplied its uses in spectacular fashion. The immediate postwar literature was full of fresh ideas, and subsequent decades have continued the challenge to ingenuity. Table 1 indicates just a few of the outstanding developments. While the precision of the dates cited may be open to some question, the sequence brings out the salient features of the last ii years' growth, and perhaps conveys something of the excitement that attended the development in spite of periodic hindrances from wars, shortages, labor problems and lean of "dumping." In 1947 the trade journal "Asbestos" was able to review the scope of asbestos uses neatly as providing protection against weather, corrosion, fire, heat, cold, acid, alkalies, electricity, noise, energy losses, vibration, accident, frost, dust and vermin (a fairly comprehensive list of environmental hazards) (7). But in 1953 the Asbestos Fact Book listed 40 uses for raw asbestos. 16 for asbestos yam, 29 for asbestos cloth, 17 for asbestos paper, 14 for asbestos mill board. II for asbestos-cement flat sheets, and 10 for asbestos composition material (13). In 1967 Johns-Manville took five pages in a brochure, "Notes on the History of Asbestos Fibers," merely to list the names of their products. By 1971 \uch lists became virtually impracticable, and statisticians were reduced once more to dealing with only a few major categories such as those used in Table 2(14). Although the dun are for the United States alone, they indicate how much the industry had grown in 100 years. RECOGNITION OF PATHOGENICITY Although many industrial sites were indescribably dusty, the number of persons employed was small and the duration of employment fairly short until the dawn of the 10th century. Pliny's report of sickness in slaves who worked with asbestos was probably dismissed as oflittle concern (1,34). The Annual Report of the Work ofthe HM Women l-ispectors of Factories for 1S98 in Great Britain included the following sentient paragraph: 304 Year 1857-1880 1866 1868 1868-1869 1866-1876 1871 1873 1874 1882 1888 1890 1893 1896 1899 Turn of the century 1903 1904 1906 First decade 1911 1918 1928 1931 1934 Fourth decade 1939-1946 1944 LEE AND SEI.IKOIF TABLE 1 Events in the Development ano Manufacture of Asbestos Event References* First lutings (flat sealings, packings) based on asbestos in England 16 First waterglass bonded molded asbestos material for heat insulation 13, 16 Research and development of asbestos published by Johns Mar. 1958, p. 2 (United States) First United States use of asbestos in roofing felt and cement 23a; Feb. 1971, p. 2 Start of systematic textile processing in Italy 16 Founding of Asbestwerke Louis Wertheim in Germany 16; Oct. 1958, p. 31 Robson and McLeilan founded in Glasgow, using Italian 23a; May 1966, p. 2 asbestos Mar. 1958, p. 2 Johns' first real factory (United States) Founding of Italo-English Pure Asbestos Co., in London for yarns and packing cords, in Rome for asbestos board 16 Mattison got idea of substituting asbestos for hemp in in Feb. 1971, p. 2 sulating "magnesia" (United States) Founding of Beii Asbestos Co. Ltd. In collaboration with textile mills of Turner Bros, in Lancashire produced yarns from Quebec chrysotile 16 Beginning of textile processing of Quebec asbestos in 16 United States First spinning of crocidolite by Cape Asbestos Co. 16; Dec. 1968, p. 38 Fabrication of first woven brake bands by Fedoro Ltd. in England 16 Wet machine process of making asbestos-cement deveioped by Hatschek in Austria 16 Asbestos-cement pipe industry had beginnings in Italy Sep. 1973, p. 8 Production of asbestos cement in United States Flat asbestos-cement board manufactured in United States Asbestos first used as brake lining Asbestos combined with formaldehyde resins 16 Nov. 1958. p. 10 13; Apr. 1946, p. 4 Apr. 1967, p. 2 Asbestos industry started in Japan Molded clutch facings developed First pipe making machines imported into United States Technique of spraying asbestos developed in Britain Amosite felt developed for turbine insulation Asbestos-cement pipes introduced into Britain 45 Apr. 1946, p. 4 16; Sep. 1973, p. 8 Sep. 1966, p. 6 33 May 1966, p. 2 Marked development of protective asbestos clothing during World War 11 Spraying of asbestos on deckheads and bulkheads begun in British naval ships Dec. 1946, p. 10 Feb. 1947, p. 10 40. 41 Year I "45 CO I"46 I "47 | "50 %o cr* U3 CO 1963 1967 I97t 1972 Multi n coat Asbest Asbesi stee Massi' for i Spray Asbes paii Bulk 70% i cer me * Dates followed b> the information was t: the article. The evil effects mineral dust whk jagged nature of i! room, in any quar In 1902 Anderson man (1). In 1908 S over the period 18 tuberculosis to be End uses Construction Floor tile Friction materials Paper Asphalt felts Packing and gasket Insulation Textiles Other * Chrysotile, she * Reproduced w ' Spinning. * Shingle and pr ' Shorts. c ST0096932 HISTORICAL BACKGROUND 305 TABLE I--Continued Year Evenl References* r-u< 1446 1947 1950 1967 1967 1971 1972 Multiflex material consisting of asbestos fabrics with July 1945, p. 12 coating of resin introduced for air-ducts Asbestos filters for wines, etc. Jan. 1946, p. 16 Asbestos-cement pipes adopted by Montreal because of Sep. 1947, p. 2 steel shortage Massive amosite sections replace 85% magnesia mattresses 40 for insulation Spraying of asbestos discontinued in British naval vessels 40,41 Asbestos now incorporated in a wide variety of plastics, Mar. 1967, p. 2 paints, and asphalt Apr. 1967, p. 2 Bulk handling system for fiber developed Mar. 1971, p. 8 70% of world's output (4 million tons) goes into asbestos- 24 cement. Britain weaves long asbestos fibers into 4 million meters of cloth and spins 16 km of yarn * Dates followed by page numbers indicate the location in the trade journal Asbestos from which the information was taken. Numbers by themselves refer to the list of references at the conclusion of the article. The evil effects of asbestos dust have also attracted my attention, a microscopic examination of this mineral dust which was made by H.M Medical Inspector clearly revealed the sharp, glass-like, jagged nature of the particles, and where they are allowed to rise and remain suspended in the air of a room, in any quantity, the effects have been found to be injurious, as might have been expected (94). In 1902 Anderson was moved to include asbestos in the dusts long known as injurious to man (J). In 1908 Scarpa reviewed the fate of 30 asbestos workers who attended his clinic over the period 1894-1906 with serious pulmonary disease and found rapidly progressive tuberculosis to be the rule (75). In 1906 H. Montague Murray reported to a Departmental TABLE 2 United States Asbestos Consumption--1972 (14)-' End uses BM V BM II* bm nr Construction Floor tile Friction materials Paper Asphalt felts Packing and gaskets Insulation Textiles Other -- 5.400 -- -- 2,000 2.600 7,600 1,000 18,600 214,800 4,700 24,000 2,100 17,000 18,000 2,300 -- 80,800 363,700 108,600 80,000 47,600 67,200 29,200 10,800 10.500 100 33,700 387,700 " Chrysolite, short tons. * Reproduced with kind permission of the publisher of Asbestos. r Spinning. 4 Shingle and paper. ' Shorts. Total 323,400 84,700 77,000 69,300 46,200 30,800 15,400 7,700 115,500 770,000 306 LF.E AND SEL1KOFF Committee on Industrial Hygiene in England on a case of pulmonary fibrosis in an asbestos worker on which he had performed a postmortem in 1899. The account seems not to have been published, but by great fortune histological material has been preserved, and a photomicrograph of tissue has kindly been given us by Dr. Morris Greenberg, Health and Safety Executive, London (Plate I). In 1899, also, Auribault reported numerous deaths in a French asbestos spinningimill and weaving factory over the period 1890-1895 (15). Vague warnings ofdisease asso ciated with asbestos were sounded in continental Europe as well as in Britain prior to World War I, but the etiological connection was not made. The British Factory Depart ment made a survey in 1910, following the report (probably Murray's) of a death certified as "acute pulmonary phthisis'* in an asbestos worker, but no health hazard was Plate 1. Photomicrograph of tissue from the original Montague Murray case of asbestosis (1899). Provenance is provided by the antique inscription on the slides, giving details, and by the chain of passage: Dr. Hislop (compensation doctor employed by mine owners ca. 1912); Dr. Middleton (H.M. Medical Inspector of Factories): Dr. Doig (H.M. Medical Inspector of Factories); Dr. Lloyd Davies (Chief Employment Medical Advisor and architect of Employment Medical Advisory Service) to Dr. Morris Greenberg. (Reproduced with the kind permission of Dr. M. Greenberg.) HISTORICAL BACKGROUND 307 seen. In 1917 The Department again found no evidence of disease, but nevertheless ordered improved ventilation (65,66). A Canadian health inspector in 1912 noted the remarks of one of the oldest practitioners in Bedford that the large amounts of dust floating i: the air of the cobbing room had a weakening effect on the lungs, but the generality failed to impress (3). In 1918 Hoffman called the attention of the Prudential Insurance Company in Boston to the probable harmful effect of asbestos dust, and apparently persuaded the company not to issue policies on asbestos workers (42). The turning point came in 1924, when Cooke reported a second death in England from pulmonary fibrosis in an asbestos worker (25). Cooke, McDonald, and Oliver reported further on this case in papers published in 1927 (26). Zenker in 1867 had introduced the generic term "pneumonokoniosis" for lung disease caused by inhalation of dust and had opened the way to more specific names according to the dust involved. In the second of his 1927 papers, Cooke used the term "asbestosis" for the first time. In his 1924 paper Cooke had mentioned the presence in the lungs of mineral particles of various shapes, but not until 1929 did he describe the "curious bodies" later to be called "asbestos bodies" (27). Acceptance of the pathogenicity of asbestos came but slowly. Tuberculosis was still a prevalent disease, and the importance of silica tended to obscure the possible patho genicity of silicates (71,72). Further cases ofasbestosis reported by Haddow and others in 1927 (39), and what Seiler claimed in 1928 to be the first case free from any question of other causes (76), stimulated official recognition. In 1930 Merewether and Price presented j report to the British parliament establishing "the fact that the inhalation of asbestos dust over a period of years results in the development of a serious type of fibrosis of the lungs," and indicating that the remedy would be in dust suppression (67). Three almost 'imultaneous papers in 1930 made the first reports of cases of asbestosis in the United States (60, 68, 83). In 1929 the Metropolitan Life Insurance Company of New York initiated what may well be the first epidemiological investigation of asbestos workers (58). On the European continent recognition was developing slowly. After Fahr's 1914 brief demonstration of chronic indurative pneumonia in an asbestos worker (32), little seems to have been published until four papers on German cases appeared in 1931 (2). From Italy little was heard after Scarpa's early account until the Johannesburg conference on silicosis in 1930, when participants described well-developed situations (4). In other European countries, the first reports of local cases appeared later, possibly because intensive manufacturing got under way at a later time. CLINICAL COMPLICATIONS Although it presented some differences, the pulmonary fibrosis developing in response to the inhalation of asbestos seemed at first to be readily understandable in the light of other dust diseases: asbestosis was just another instance of Zenker's general pneu monokoniosis. In some respects it appeared simpler, because the progressive massive fibrosis (PMF) that commonly develops as a complication of silicosis and coal workers' pneumoconiosis seldom occurs in asbestosis. But other complications began to appear that were not so easily fitted into conventional patterns. These were finally to force re consideration of etiological ground rules. 308 LF.E AND SEI.IKOKF Plueral Asbestosis A certain degree of involvement of the visceral pleura is only to be expected in extensive pulmonary fibrosis. In the 1930s there were scattered references to calcareous markings in chest radiographs (77), and Gloyne described "hom-like" changes in the pleura (35). But it was not until 1935 that Lynch and Smith reported a case in which "the pleura of the right lung is thickened as a whole and is of cartilaginous and even partly calcareous quality over the base. That of the left lung is likewise thickened, but over the free portion it is rough, congested and "furred,' with small nodules in the surface" (61). -i| Lanza extended the description in his text of 1938 (57). The characteristic "ground glass" appearence seen in some chest radiographs was accepted as due to pleural involvement; but there was little mention of pleural calcification in the earlier accounts of asbestosis (77). In 1943 Siegal and his colleagues reported the finding of numerous instances in examinations of talc miners and millers (78). In 1955 Jacob and Bohlig found pleural calcification in some 5% of 343 asbestos workers examined in Dresden (47). Since that time the presence of pleural plaques has been reported with increasing frequency; to the point that their demonstration has often been accepted as fairly conclusive proof of exposure to asbestos. The explanation for the lack of early reports is that pleural plaque formation and subsequent calcification is a slew process that seldom has time to develop in those who are responding with marked parenchymal asbestosis and relatively early death (77). The pathognomonic nature of pleural calcification was brought into some question in I960, when Kiviluoto reported finding calcified pleural plaques in persons living in Finland many miles away from any asbestos workings; findings which were extended in later publications (53, 54). The explanation was offered that the soil was rich in asbestiform material and that the pleural developments resulted from long exposures to doses too small to induce parenchymal fibrosis; an explanation to receive support later by reports of calcified plaques developing without radiological evidence of parenchymal changes in workers exposed to low levels of asbestos, and in other rural situations with asbestiform material in the soil. Mesothelioma In 1931 Klemperer and Rabin published an account of five primary neoplasms on the pleura, although they did not clearly establish the relationship with asbestos exposure, but referred back to Wagner's account of such tumors in 1870, which was before asbestos was used in any but very small quantities (55). They did, however, suggest that the term mesothelioma "be accepted to designate all the diffuse neoplasms of the pleura that arise from the mesothelium, whether they appear to be composed of epithelium, connective tissue, or both." In 1947 Mallory et al. reported a case of mesothelioma of the pleura and pericardium in an asbestos worker (62). In 1953 Weiss reported that in the 31 cases of asbestosis autopsied in Germany and described by Wedler in 1947 there were two malignant tumors of the pleura, and he himself reported a third case (91). Leichner in 1954 described unexpected pleural growth of a type that would now be dassifield as mesothelioma in a patient with asbestosis and tuberculosis (59). In 1958 Van dcr Schoot reported on three insulation workers who had died of neoplasms, two of them apparently mesothelioma of :he pleura, and in the jviiumeal mesothcliom: H.-tf.isi (64). but gave n !!.Nj'ital since 1948, wa w :th asbestosis, one hac carcinomatosis of the </> In I960 Wagner am itvlioma and finally pi v hKsified as primary m secondary" (73). The p>67 (92). Wagner et biologically proven c .Ksociation with the < industry. By contrast, i examined at the Pnei Research. In the folio' eases (81). Wagner lat mesotheliomatous tutr l7). At the Intematio on more that 120 case the asbestos industry importance of neigh made in the course i the severity of asbe: servation opened th dosage has been lo\ to appear. Associated Bronchog. In May 1935 Lync! silicosis" (61). This weaver. An extensiv extensive fibrosis am coexistence ofthe tv, that had occurred in author refrained fror these two diseases.' In July 1936 Egbe as a weaver in an as! with extensive meta. third case in Britain In 1938 Nordmar previously reported of the tumor (69). association. These reports fr asbestos industry w HISTORICAL BACKGROUND 309 the pleura, and in the discussion Schornagci mentioned a case that he had seen of peritoneal mesothelioma (86). McCaughey in the same year described a series of cases in Belfast (64), but gave no account of exposure. Keal, searching the records of the London Hospital since 1948, was able to report in I960 that of 23 women who had been inpatients with asbestosis, one had an ovarian carcinoma, four had peritoneal growths, and four had carcinomatosis of the peritoneum without a primary lesion being found (52). In 1960 Wagner and his colleagues (89) firmly established the existence of meso thelioma and finally put to rest the objections of Robertson that "only sarcomas can be classified as primary malignant tumors of the pleural tissues, and that all other growths are secondary" (73). The distinguished Willis, however, continued his opposition even to 1967 (92). Wagner et at. announced that in the previous 4 years they had seen 33 histologically proven cases of mesothelioma of the pleura, and that 28 of these had some association with the Cape asbestos field, and four had been exposed to asbestos in industry. By contrast, no neoplasm of this nature had been diagnosed among 10,000 lungs examined at the Pneumoconiosis Bureau or the South African Institute for Medical Research. In the following year they were able to supplement the record with eight more cases (81). Wagner later went on to demonstrate the experimental development of pleural mesotheliomatous tumors by the intrapleural injection both of chiysotile and of crocidolite (87). At the International Congress on Occupational Health in 1963 he was able to report on more that 120 cases seen since 1956 (88). More than half of the cases never worked in the asbestos industry but lived in the vicinity of the mines and mills, so that the importance of neighborhood exposure was established. Another important point made in the course of this presentation was that there was no correlation between the severity of asbestosis in these persons and the presence of the tumor. This ob servation opened the way to a later speculation that, perhaps, it isjust those whose dosage has been low that escape asbestosis sufficiently long for the mesothelioma to appear. Associated Bronchogenic Carcinoma In May 1935 Lynch and Smith published the first report of lung carcinoma in "asbestosilicosis" (61). This was in a man who had worked for 21 years as an asbestos mill weaver. An extensive epidermoid carcinoma was found in the right lung, together with extensive fibrosis and asbestosis, but the authors did no more than draw attention to the coexistence of the two diseases. In October of the same year Gloyne published two cases that had occurred in Britain (36). Both had asbestosis, both had small carcinomas. The author refrained from "any attempt to make out a case for an actiological association of these two diseases." In July 1936 Egbert and Geiger reported the case of a man who had worked for 18 years as a weaver in an asbestos factory, in whom there was a large tumor in the left lower lobe with extensive metastases (31). In December of that year Gloyne published the report of a third case in Britain (37). In 1938 Nordmann published an account of two cases in Germany which, like those previously reported, exhibited a long period between initial exposure and the appearance of the tumor (69). Nordmann, too, declined to draw firm conclusions about etiological association. These reports from three countries intimately concerned with development of the asbestos industry were to be supplemented and other cases added from France (29). By I 310 LEE AND SF.UKOFF iN><c that happened ti 1943 Homburger was able to list 19 cases by the addition of three of his own (43). He was still cautious, however, in saying merely that the association of the two conditions was u (rich the cases came I'.vurrence of mesothi remarkably high, but that there was no reliable answer to the question of whether asbestos vvrisiderable doubt. T was involved in the etiology. bronchogenic carcino Wedler, in 1943, found a prevalence of 16% ofpulmonary carcinoma in 92 postmortem very likely to occur it reports on asbestos workers described from various parts of the world (90). Merewetber ihe industry was cie reviewed the accumulated data in his 1949 Report of the Chief Inspector of Factories introduced in the 19 (Britain) and found a prevalence of 13.2% in 235 necropsies on patients with asbestosis, possibility that quite compared with 1.32% in 6884 cases of silicosis (63). In 1949 Wyers reported a prevalence of 14.8% in 115 necropsies (95) and Gloyne in 1951, after reviewing 1247 lung specimens first exposure was st Many things were sent to him for examination for pneumoconiosis over the period 1929-1949, commented studies up to that tir as follows: "whether [workers with a dust hazard] have a risk over and above [that of the needed of large ecl general population] as a result of their occupation cannot yet be clearly shown, but the adequate control po; mortality ofthe asbestos workers is striking. In the present series 14% of the patients with for the results to b asbestosis also had primary cancer of the lung. This is all the more striking because so stemmed from coir many of them were females" (38). cinogenesis had ha Hueper, also writing in 1951, came to the following conclusion after reviewing the Kduction of heavy c literature: "Although Warren rather recently maintained that the connection between diseases as mesotl asbestosis and lung cancer is of a coincidental nature, the actual existence of a causal foreknowledge was relationship appears very likely" (46). the auguries were i In 1955 Doll, reporting on all of the coroner's necropsies since 1935 on persons known disease processes to have been employed at a large asbestos works, concluded from the data that lung cancer changes, were bad was a specific industrial hazard of certain asbestos workers and that the average risk planning stages, wt among men employed 20 or more years had been 10 times that experienced by the general an exciting time v population (30). entirely dissipated. But opposition was not dead! Bohlig and Jacob in 1958, basing their position on cases The material prc from industries of Saxony and Thuringia, came to the conclusion that there did not seem inonograph, Asbes r to be an increased prevalence of pulmonary carcinoma in asbestos workers, although it did and published by seem to be higher in women and did seem to affect the lower parts of the lung more than usual (18). Braun and Truan, writing in the same year, opposed any significant association as a result of surveying death certificates of a cohort of some 6000 Canadian miners who had a total exposure of 5 or more years (20). The conflicts of evidence were to be resolved in the immediately succeeding years through better appreciation of epidemiological techniques and realization of the long time interval required from initial exposure before definite conclusions could be entertained about the prevalence of cancer. Intimations of cancer in other organs, notably the gastrointestinal tract, which had been sporadically included in the above reports, had to 1. Anderson, A. M. industries in En 2. Annotation (1932 3. Anonymous (191 (Coji.) 12, 761 4. Anonymous (!9.' August, 1930 wait for still further clarification. SITUATION IN THE 1960s "What's past is prologue!" The decade of the 1960s provides a convenient time at which to terminate a historical review of asbestos disease. With admirable hindsight from the late 1970s we can see that the essential evidence had already been reported, but not yet assembled or vested with sufficient credibility to be entirely convincing. With few exceptions (30,58,81), the evidence at that time rested on scattered reports of small numbers of cases, and the cases themselves suffered from being either selected or simply 3. Anonymous (19 6. Anonymous (19 7. Anonymous (19 8. Anonymous (13 9. Anonymous (It tO. Anonymous (If 1). Anonymous (15 12. Anonymous (I! 13. Anonymous (1! 14. Anony mous (1` 15. Auribault, M. ( Bull. lsp. 1 3 HISTORICAL BACKGROUND 311 i Invc that happened to come to the attention of the reporter. The population base from *.i I'.icli the cases came was seldom mentioned. The significance of pleural changes and the (Vnurrence of mesothelioma in persons without a distinct history of exposure remained in c itsiderable doubt. The idea that asbestos could be at least a cofactor in the production of bronchogenic carcinoma was far from fully accepted. That parenchymal asbestosis was v cry likely to occur in those who had been exposed to heavy dosage in the early years of the industry was clear enough, but what effect environmental controls that had been* introduced in the 1930s might have upon its future prevalence was not known. The' possibility that quite low dosages might have grave consequences 30 or more yars after first exposure was still unproven. Many things were needed to confirm the suggestions that were emerging from the studies up to that time. Most importantly, systematic epidemiological investigation was needed of large cohorts drawn from various types of industry, with the inclusion of adequate control populations. Some of these were already organized, but it was too early for the results to be meaningful. We now know that much of the negative evidence stemmed from coming to conclusions prematurely, before the slow processes of car cinogenesis had had a chance to make themselves evident. We now know also that reduction of heavy exposures that lead to early death would reveal such slowly developing diseases as mesothelioma and bronchogenic carcinoma with increasing clarity. But foreknowledge was not available at the time, although some investigators suspected that the auguries were not good. More sophisticated and sensitive ways of recognizing the disease processes at an early stage, before the appearance of marked radiographic changes, were badly needed. A series of international conferences, some already in the planning stages, were to accelerate these developments greatly. Those who felt that it was an exciting time were not to be disappointed. The excitement has not even yet been entirely dissipated. The material presented here has been condensed from the opening chapter of a recent monograph. Asbestos and Disease, prepared by Irving J, Selikoff and Douglas H. K. Lee, and published by Academic Press. REFERENCES 1. Anderson, A. M. (1902). Historical sketch of the development of legislation for injurious and dangerous industries in England. In "Dangerous Trades" (T. Oliver, Ed.). Dutton, New York. 2. Annotation (1932). German work on pulmonary asbestosis. Lancet II, 92. 3. Anonymous (1912). Effect of asbestos dust on workers' health in asbestos mines and factories. Lab. Gaz. (Can.) 12, 761. 4. Anonymous (1930). "Silicosis. Records of the International Conference held at Johannesburg. 12-13 August, 1930." Stud Rpt. Ser. F. (Ind. Hyg.), No. 13. lnt. Lab. Office, Geneva. 5. Anonymous (1939). Benjamin Franklin and his asbestos purse. Asbestos 21 (Mar.), 2. 6. Anonymous (1945). Note. Asbestos 27 (Aug.), 10. 7. Anonymous (1947). Asbestos protection. Asbestos 29 (July), 12. 8. Anonymous (1948). Asbestos production. Rhodesia. Asbestos 30 (Aug.), 4. 9. Anonymous (1948). Asbestos production. United Slates of America. Asbestos 30 (Oct.), 22. 10. Anonymous (1948). Asbestos production. V. Russia. Asbestos 30 (Nov.), 20. 11. Anonymous (1949). Asbestos production. VI. Italy Asbestos 31 (Jan.), 26. 12. Anonymous (1954). Johnson's Company. Asbestos 36 (July). 2. 13. Anonymous (1953.1970). "The Asbestos Fact Book." Asbestos, Willow Grove, Pa. 14. Anonymous (1973). Product information. Asbestos SS (Dec.), 32. 15. Auribault, M. (1906). Note sur t'hygiene et la securitc des ouvriers dans les filateurs et tissages d'amiante. Butt. Ittsp. Trnv. Priris 14, 120. 312 LEE AND SEL1KOEK 16. Berger, H. (1963). "Asbestos Fundamentals--Origin, Properties, Mining, Processing, Utilisations'' [R. E, Oesper, transl.). Chem. Publ. Co., New York 17. Bloomfield, G. M. (1958). Historical facts on the asbestos industry in Germany. Asbestos 40 (Oct.), 31. 18. Bohlig. H., and Jacob. G- (1958). Die Haiifigkeit des Ltingcnkrebs bei deutschen Asbestarbeitern, Dtsch. Gesundheilsnes. 13, 1101. 19. Bowles, O. (1955). "The Asbestos Industry." U.S. Dep. Interior. BOM Bull. No. 552. U.S. Govt. Printing Office, Washington, D.C. 20. Braun, D. C-, and Truan.T. D. (1958). An epidemiological study oflung cancer in asbesios miners. ArcA. Ind. Health 17, 634. 21. Cape Asbestos Fibers. Ltd. (undated). "Asbestos the Raw Material." Brochure. 22. Carroll-Porczynski, C. Z. (1966). British asbestos industry, I. Asbestos 48 (May), 2. 23a. Ciriel, F. (1905). "Asbestos--Its Occurrence, Exploitation and Uses." Govt. Printing Bur., Ottawa. 23b. Cirkel, F. (1910). "Chrysotile Asbestos--Its Occurrence. Exploitation. Milling and Uses." 2nd. ed.. Govt. Printing Bur., Ottawa. 24. Clifton, R. A. (1972). Asbestos. In "Minerals Yearbook, 1970," Vol. I, p. 195. 25. Cooke. W. E. (1924). Fibrosis of the lungs due to the inhalation of asbestos dust. Ur. Med. J. II, 147. 26. Cooke, W. E.. (1927). Pulmonary xsbestosis. Br. Med. J. II, 1024. 27. Cooke, W. E. (1929). Asbestos dust and the curious bodies found in pulmonary asbestosis. Br. Med. J. II, 578. 28. Cooke, W. E. and Hill, C. F. (1927). Pneumokoniosis due to asbestos dust. J. R. Microsc. Soc. 47,232. I . .... R. H. HS97). Aluroillv'Lowcr Ca , t p. (I960). Ash . ;.;;it...to.R.lI960). ! c/> -tu'phvll',e asbestos luow. R.d*a-R; " V ,,,vror. P.. and Rab .. L,,:iTin.N-l-*ndM4 .. i A. J- (1938). "" .. I jam. A. I.. McConnc lungs of asbestos wi ... , .-whiter. F. (1954). Pr Di n-erbehyg. 13. 38 i uvh. K. M.. and Sm 659. *. 1 uwh. 1C- M.. ar>d Srri! " ,-twr. J. Cancer 24. Mallory. T. B., Castle Oiij- J- Med. 236, ..: \i.i>*:rs. M- R* (*952) McCaughey, W. T. E. 29. Desmeules, R.. Rousseau. L-, Giroux, M. and Sirois, A. (1941). Amtentose et Cancers Pulmonaires. Laval Med. 6, 97. 30. Doll, R. (1955). Mortality fmm lung cancer in asbesios workers. Br. J. Ind. Med. 12, 81. 31. Egbert, D. S., and Geiger, A. J. (1936). Pulmonary asbestosis and carcinoma--Report of a case with necropsy findings. Am. Rev. Titberc. 34, 143. 32. Fahr, T. (1914). Demonstrationen: Prdparale und Mikrophotogrammes von einem Fade von Pneu- monokoniose. Muench. Med. Wochenschr. 11,624. 33. Fleischer, W. E., Viles, F. Gade. R. L., and Drinker, P. (1946). A health survey of pipe covering operations in constructing naval vessels. J. Ind. Hyg. Toxicol. 28, 9. 34. Frenkel. M., and de Jager, H. (1961). Mesothelioma peritonei in asbestosis pulmonum. Jahrb. Kunkerzonderzoek Kankerbestiijding Ned. 11, 99. 35. Gloyne, S. R. (1933). The morbid anatomy and histology of asbestosis. Tubercle 14, 445. 36. Gloyne, S. R. (1935). Two cases of squamous carcinoma of the lung occurring in asbestosis. Tubercle 17, 5. 37. Gloyne, S. R. (1936). A case of oat-cell carcinoma of the lung occurring in asbestosis. Tubercle 18, 100. 38. Gloyne. S. R. (1951). Pneumoconiosis. A histological survey of necropsy material in 1205 cases. Lancer I, 810. 39. Haddow, A. C. (1929). Clinical aspects of pulmonary asbestosis. Br. Med. J. II. 580. 40. Harries, P. G. (1968). Asbestos hazards in naval dockyards. Ann. Occup. Hyg. 11, 135. 41. Harries, P. G. (1971). Asbestos dust concentrations in ship repairing: A practical approach to improving asbestos hygiene in naval dockyards. Ann. Occup. Hyg. 14, 241. 42. Hoffman, F. L. (1918). "Mortality from Respiratory Disease in Dusty Trades." Bull, U.S. Bur. Labor Stat. No. 231 (Ind. Accident Hyg. Ser. No. 17). U.S. Bur. Labor, Washington, D.C. 43. Homburger, F. (1943). The co-incidence of primary carcinoma of the lung and pulmonary asbestosis. Analysis of literature and report of three cases. Ant. J. Pathol. 19, 797. 44. Hoover, H. C. and Hoover. L. H. (1950). "Georgius Agricola: De Re Metallica." Translation from the first Latin edition of 1556. Dover. New York. 45. Horai, Z.. and Ucshima, M. (1961). Studies on asbestosis. J. Nura Med. Assoc. 12, 1148. 46. Hueper, W. C. (1951). Environmental lung cancer. Ind. Med. Surg. 20, 49. 47. Jacob, G., Bohlig, H. (1955). Die rOntgenoIogischen Komplikationen des Lungenasbestose. Fortschr. Ceb. Rontgenstr. Ver. Rontgenprax. 83. 515. 48. Johnson, H. E. (1945). "Lives of Sixty-Three Illustrious Persons" [transl. from Sanskrit], (Quoted in Asbestos 27, (Nov.), 12.) 49. Jones. R. H. (1890). "Asbestos: Its Properties. Occurrence and Uses." Crosbey. Lockwood, London. (Quoted inAfbestos 38 (Mar). 2. 1950). 31 ,.s Morcwether. E. R- A. mv Merewelher. E. R A Merewelher, E. R A. Suppression in the vs Mills. R. G. (1930). -, i Nordmann, M. (1933 .i Norn. L. (1968). Occ 195. . Pancoast. H. K-. Mil upon the lungs. A "3. Pancoast. H. K-, arr based upon roeni; Radium Ther. (N. -\. Robertson. H. E. (I "4. Royall, H. J. (1968) s Scarpa. L. (190S). I' 76. Seiler. H. E. (1928) 982. 77. Selikoti. I. J. (1965 Acad. Sti. 132. 7g. Siegnl, W.. Smith, roentgenological TS. Sinclair, W. E. (19 80. Sinclair, W. E. (19 81. Sleggs. C. A., Mar S. A/r. Med. A si S2. Sluis-Cremer, G. ) 83. Soper, W. B. (19.3 84. Strack. L. H. (19-1 85. Tara. A. (1848). " Italy. 86. VanderSchool.) 87. Wagner. J. C. (19 dusts in laborai 50. Jones, R. H. (1897). "Asbestos and Asbestic: Their Properties. Occurrence and Use." Crosbey. Lockwood. London. HISTORICAL BACKGROUND 313 t; Jones. R. H. (1897). Asbestos and asbestic: with some account of the recent discovery of the latter at Danville in Lower Canada. /. Sac. Arts, Apr. 30,1. Kcal. E. E. (I960). Asbestosis and abdominal neoplasms. Lancet II, 1211. 4. Kiviluoto. R. (I960). Pleural calcification as a roentgenologic sign of nonoccupational endemic .mthophyllite asbestosis. Acta Radio. Suppl. 194. 4 -. Kiviluoto, R. (1966). Radiological aspects of pleural hyaloserositis. Ur. J. Radiol. 39, 233. Klemperer, P., and Rabin. C. B. (1931). Primary neoplasms of the pleura. Arch. Pathol. II, 385. 4:- Knrepin, N. I., and Mel'nikov, G. P. (1967). Umls asbestos. Strait. Mater. 6, 2. _ Lanza, A. 3. (1938). "Silicosis and Asbestosis." Oxford Univ. press, London, New York 4- Lanza, A. J., McConnell, W. }., and Fehnel. 3. W. (1936). Effects of the inhalation of asbestos dust on the kings of asbestos workers. Public Health Rep. 50, L *'i Leichner, F. (1954). Primary mesothelial-cell tumor of the peritoneum in asbestosis. Arch. Gtwerhepatk. Geuerbehyg. 13, 382. mi Lynch, K. M., and Smith, W. A. (1930). Asbestosis bodies in sputum and lung./. Am. Med. Assoc. 95, 659. '!. Lynch, K. M., and Smith, W. A. (1935). Pulmonary asbestosis. 111. Carcinoma of lung in asbesto-silicosis. Am. J. Cancer 24, 56. r_\ Mallory, T. B., Cajtleman, B.. and Parris. E. E. (1947). Mesothelioma of pleura and pericardium. New Eng. J. Med. 236, 407. ii.1, Mayers, M. R. (1952). Industrial cancers of the lung. Compens. Med. 4,11. t.i. McCaughey, W. T. E. (1958). Primary tumours of the pleura./. Pathol. Bacterial. 76, 517. (5. Vterewether, E. R. A. (1933/1934) A memorandum on asbestos. Tubercle IS , 69. o/'. Merewether, E. R. A. (1933/1934). A memorandum on asbestos. (3rd instal.). Tubercle 15, 152. P. Merewether, E. R. A., and Price. C. V. (1930). "Report of Effects of Ashestos Dust on the Lungs and Dust Suppression in the Asbestos Industry." H. M. Stationery Office, London. t'N. Mills, R. G. (1930). Pulmonary asbestosis. Report of a case. Minn. Med. 13, 495. i t. Nordmann, M. (1938). Der Berufskrcbs der Asbestarbeiter. Z. Krebsfarsch. AT, 288. 'i> Noro, L. (1968). Occupational and "non-occupational" asbestosis in Finland.dm. Ind. Hyg. Assoc. /. 29, 195. fl. Pancoast, H. K., Miller, T. G., and Landis. H. R. M. (1918). A roentgenologic study of the effects of dust upon the lungs. Ant. J. Roentgenol. Radium Ther. (N.S.) 5, 129. '2. Pancoast, H. K.. and Pendergn>s. E. P. (1925). A review of our present knowledge of pneumoconiosis, based upon roentgenologic studies, with notes on the pathology of the condition. Am. J. Roentgenol. Radium Ther. (N.S.) 14. 381. 73. Robertson, H. E. (1924). Endothelioma of the pleura./. Cancer Res. 8, 317. 74. Royall, H. J. (1968). The health of the public and asbestos usage. R. Inst. Public Health Hyg. J. 31. 126. 75. Scarpa, L. (1908). Industria dell'amianlo e tuberculosi. Proc. 18th. Internal Med. Congress, Rome, 358. 76. Seiler, H. E. (1928). A case of pneumoconiosis. Result of the inhalation of ashestos dust. Sr. Med. J. ff, 982. 77. SclikofT. I. J. 11965 J. The occurrence or pleural calcification among asbestos insulation workers. Ar'.n. N. Y. Acad. Sci. 132, 351. 78. Siegal, W., Smith. A. R., and Greenburg. L. (1943). The dust hazard in tremolite talc mining, including roentgenological findings in laic workers. Ant. J. Roentgenol. Radium Ther. (/V.J.) 49, II. 79. Sinclair, W. E. (.1959) "Asbestos -- Its Origin, Production and Utilization." Mining, Publ., London. 80. Sinclair, W. E. (1959). Open pit asbestos mining in Canada. Ashetios 41 (Jan.), 12. 81. Sleggs, C. A., Marchand, P.. and Wagner, J. C. (1961). Diffuse pleural mesotheliomas in South Africa./. S. Af*. Med. Assoc. 35. 28. 32. Sluis-C.emer, G. K. (1970). Asbestosis in South African asbestos miners. Environ. Res. 3, 310. 83. Soper, W. B. (1930). Pulmonary asbestosis. A report of a case and a review. Am. Rev. Tuberc. 22, 571. 84. Strack, L. H. (1941). "Asbestos. A Magic Mineral." Harper, New York. 85. Tara, A. (1848). "Dell'Amianto." Inaugural Dissertation. University of Pavia. Tipo Fusi e Comp., Pavia. Italy. 86. Van der School, H. C. M. 119581. Asbestosis en pleuragewebezellen. Ned. Tijdst hr. Geueeskd. 102,1125. 87. Wagner. 1. C. (1962). Experimental production of mesothelial tumours of the pleura by implantation of dusts in laboratory animals. Nature 196, 180. ST0096940 ! !k. wn*a! 314 LEE AND SELIKOFK 88. Wagner, J. C. (1963). Asbestos dust exposure and malignancy. Prttc. Nth. Ini. Congr. Occup. Health, Madrid. 89. Wagner, J. C., Sleggs, C. A., and Marchand, P. (1960). Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province. Br. J. Ind. Med. 17, 260. 90. Wedler, H. W. (1943). Uber den Lungenkrebs bei Asbestose. Dtst h. Arch. Klin. Med 191, 189. 91. Weiss, A. (1933). Pleurakrebs bei Lungenasbestose, in vivo morphologisch gesichert. Mediznische 3,93. 92. Willis, R. A. (1967). "Pathology of Turnon," 4th ed. Butterworth, London. * 93. Wilson, 3. C. (1973). The addition of taic and asbestos to pot clay by past and present inhabitants of Karamoja district in Uganda and adjoining districts of Kenya. Man 8, 300. 94. Women Inspectors of Factories (1899). "Annual Rpt. for 1898." H. M. Stationery Office, London, 170. 95. Wyets, H. (1949). Asbestosis. Postgrad. Med. J. 25, 631. % ' !j i -,4 ,v 't 5 T , MIKOVURM-M KISR.t Hem t Uranium U9 W. I. s- a%\> AustraHan A to The conversion analysis, ir spectra was measured for; Ns + Ha. Thermal Hi + N, gave m activity of a mater Oxides of uraniir uranate (AU) to at hydrogen whereas i final produce (calc Air contaminatk following inhalatio (i) Materials sue 1972), undergoing hazard because of (ii) Radiation-inc from inhalation of radioactivity of na amounts of insolub animals indicate th Less attention contributing to lun might partly accou natural UOc. Slant significant in deter An assessment c take into account t of these propertie decomposition of / intricate sequence surface area, chem 1971; Price and St