Document emeD6Qg5EXL4m1rGKNEaVavdG

FILE NAME: ZMining (ASMI) DATE: 200 DOC#: ASMI03 DOCUMENT DESCRIPTION:Journal Article ZZZd,Z ZYD .. - AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 48:230-237 (2005) Historical Perspective A Report on The Health of Asbestos, Quebec Miners 1940 Morris Greenberg, Ma, FRcr, FFOM* Background Twenty years after the start-up ofthe Canadian asbestos industry, reports began to appear ofrespiratory disease and deaths in asbestos workers in England and in France. An inquiry from the UK in 1912 as to the health ofQuebec miners was met by a denial of ill-health, but the loading of the premiums of asbestos workers in the 1930s indicated that, despite junher reassuring health studies on Quebec miners, actuaries had data that gave cause for serious concern. Methods A repon made to the Canadian asbestos industry by a company doctor in 1940, reviewing the literature and presenting his health findings on some 500 employees, was studied in the context ofthe published information available at the time, andofunpublished contemporaneous material subsequently obtained by legal discovery. Results The physician denied that the health and longevity ofQuebec's miners andmillers were adversely affected, and was dismissive ofearlier reports ofthere being serious health risks associated with working with asbestos. Conclusions The methodology employed in his health study was defective and his denial of the literature uninformed. The study was widely circulated, and while it may have boosted Canadian industry morale, it met with a sceptical response from British industry. Jn derrying that conditions in Quebec's asbestos mines and mills disabled and killed workers, the author allied himself to fellow professionals loyal to Government and to industry. Am. J. Ind. Med. 48:230-237, 2005. 2005 Wiley-Liss, Inc. KEY WORDS: Canada; chrysotile; asbestosis; history INTRODUCTION Commercial mining for asbestos in Quebec began in the late 1870s, and alarming reports of ill health and excessive Alfiialilfl: Extramural Declaralion of interest The material on wllich ttis study is based was identified during a program of study supported by The Joseph Rt1Nntree Charilable Trust CorrespoOOence to: Dt Morris Greenberg. 74, North End Road, London, NWt1 7S Y. UK. E-mait mgreenberg@toucansurf.com AG<;epted 12 June 2005 OOl 10.1002/ajin.20206. Pubished onine in ~Y lnterScience (www.intersciell:e.wileycool) premature deaths in workers in asbestos manufacture began to appear abroad some 20 years later. In England in 1898, asbestos, for which Canada would have been the source, was designated as one of the four most serious occupational dusts of the year, with ascertained injury to bronchial tubes and lungs from sifting and carding [Deane, 1899]. The following year, a London asbestos textile worker who had earlier informed his physician that he was the last survivor of ten men who had been employed in the carding room 14 years previously, died in his early 30s. The diagnosis of nontubercular pul1'Wnary phthisis, was confirmed at autopsy [Murray, 1907]. Confirmation that severe respiratory disease and deaths resulted from exposure to dust containing Canadian 2005 Wiley-Liss, Inc. The Health of Asbestos, Quebec Miners 1940 23 l chrysotile, was provided independently from France with an account of some 50 deaths among women workers in an asbestos textile factory, 16 in the 5 years following its conversion from cotton in 1890 [Auribault, 1907]. In 1910, the Registrar General for England and Wales drew the Factory Inspectorate's attention to the deaths of five persons from "phthisis" in 5 years, among 40 workers employed at a factory where asbestos was woven. The processes at that factory and at two others were investigated and reported as being dangerous to health [Collis, 1911]. When the UK Factory Department asked the Canadian authorities about the health experience of workers in the Quebec mines, they were informed that on inspection of a large asbestos mine and mill, all the women looked strong and healthy [Department of Labour, 1912]. Further, death from lung diseases in Thetford was asserted not to be higher in the asbestos industry than elsewhere. The sketchy nature of the Canadian inquiry was hardly "State ofthe Art" even for 1912. Fifty years previously, when measures of the burdens ofdisease in UK mines and quarries were required, numerous clinical examinations had been conducted throughout the country, supplemented by analyses of national mortality data and even of local sickness-club records (Farr [1860]; Peacock [1860]; cited by Greenberg, M. [1992]. "Thomas Bevill Peacock, MD, FRCP: pioneer occupa- tional and environmental physician," Am J Ind Med, 21: 443-447.) An American report on "Mortality from Respiratory Diseases in Dusty Trades," included the information that American and Canadian insurance companies generally declined to accept asbestos workers on account of the assumed health-injurious conditions of the industry [Hoffman, 1918]. That same year, a study of a group of patients with dust diseases of the lungs, reported the adverse clinical effects and the peculiar radiological abnormalities in 15 asbestos workers [Pancoast et al., 1918]. The Department of Industrial Hygiene, founded at McGill University in 1926 by the Metropolitan Life Insurance Company, was asked in 1930 to conduct studies on asbestos workers and miners in Asbestos and in Thetford [Castleman, 1996]. Several small groups of miners in Asbestos and in Thetford were examined, and it was reported that although abnormalities were found they were of no significance, and further it was asserted that no case of pneurnoconiosis had been reported from asbestos in Canada [Pedley, 1930a,b]. In what would seem to have been an independent activity, the Metropolitan Life Industrial Health Service studied asbestos workers in mines and mills in Canada and in factories in the United States. They only reported on the US asbestos factory workers, from which they concluded that their pulmonary fibrosis was milder than silicosis, and that no marked disability had been observed [Lanza et al., 1935]. ASBESTOSIS IN ASBESTOS 1940 In 1938, Dr. Stevenson, the Company Doctor for the Johns-Manville plant at Asbestos, addressed the Quebec Asbestos Producers Association (QAPA). In a letter to Sir Samuel Turner about this talk, Stevenson informed him that it had included a reference to a report about the health of workers in a Rhodesian chrysotile mine, and stated: "Dr. Stevenson appears to consider that Rhodesian asbestos [is] more liable to promote Asbestosis than Canadian, by reason of the higher proportion of Si02, but as far as I can trace from the published analyses the Silica content ofCanadian and Rhodesian fiber is almost identical, that is, about 40%." A typescript ofthe text ofan informal talk that Stevenson gave subsequently in February 1940 to a QAPA meeting in Sherbrooke [Stevenson, 1940] was widely circulated: it exemplifies the work of a physician loyal to Government and to Industry. APPRAISING THE LITERATURE Stevenson introduced his study with a strong note of scepticism about the very great volume of reports on Asbestosis from South Africa, England, and the United States, that had attempted to show asbestos in a poor light, expressed in the following forms: "Asbestosis has been ... the victim [sic] of a great many reports;" " ... there has been a great diversity of opinion ... as to the seriousness of the affection;" "The one important point that seems to be emerging from the large amount of literature is that Asbestosis in this country is not the serious hazard to labor that it was a few years ago believed to be." The medical officer of the Shabanie [chrysotile] Mines of Southern Rhodesia was similarly persuaded of the benignity ofchrysotile, having reported that no genuine case of pulmonary asbestosis or any other form of offibrosis of an occupational origin could be ascribed in 1932 to the asbestos mining industry [Ireland, 1938]. Subsequent clinical and radiological investigations were asserted to have confirmed this. Despite the previous "negative" findings and the mine dust having been deemed negligible, a more extensive review was conducted in which several underground workers were reported to have "ante-primary silicosis" {sic] but in no case had this developed to a further stage. No mention was made 232 Greenberg that several of his mineworkers referred to South Africa had been reported to be suffering from asbestosis. real:Tithwe ocounldtrbaedipcltaiuosnibinletrtoodfuinceddrihgehrteviesnmtroicreulaaprpfaarileunrtethasana result of advanced asbestosis. 1 CONCERNING THE SIGNS AND SYMPTOMS OF ASBESTOSIS HEALTH MONITORING AT ASBESTOS Under the heading "Syomdpytoasmasnaenxdasmigpnlse,"ofhdeipvreersseitnyteodf Then followed a descriptiontolyf awshpaot shsaibdlebewehnattrieefdfeactt the riddle of the asbestos b opinion, citing "Lanza's book, 1938" as authority for the Asbestos to find out " ... as exac bestos dust had been having on employees." Originally, statement that the presence o f asbestos e bodies is a clear sign who was the author of aasnnual physical examinations and fluoroscopiccaesxeasmsihnoatwioinngs ofdisinctteiognratoionn "oPfaluthnogltoigssyu,e". Ghalodyqnuoted a suggestion of were conducted on all employees, and in dow or limitation of chest movement, a single tShteewsaert that the occurrence of asbestos bodiefrsoimn scpluustutemrs, eflxactepslsaivtee oshfathe chest had been taken. Later they instianlilnedg obtained by his method of concentrating them tissue disintegration in the lungs sufficient to might indicate l bronchioles in which they have been a stereoscopic X-ray apparatus with the aim of obta ition of employees' lungs. For the better records of the cond purposes of this report only men who had worked more than lfiobremraetde. frLoemrotyheGsamrdanl er was tthhaetnasqbueostteods b(sooduiercsecaunnnroeftebre- l 0 years were studied. , 1938] that it was not enced) as having maintained taken into the lung tissue, but remain in the smaller air cells. Quoting Dr. Pendergrass [Lanza le definitely to diagnose any degree of asbestosis less This, Stevenson said, indicated thattatthieorneowf athsessocmieencceonto- pthoasnsi"bEarly asbestosis," he commented: "Webasgrewehwoithhtahvise fpuesrimonit othf eidebaesttehrerceo, mbuptrehhiseninsitoenrpbrey his lay audience will it. s was interrupted because we see hilar many applicants for jo shadows, and more linear shadows than exaggerated l, which goes to show the truth of the are considered norma graphic have contributed to The presentation of the experts at odd unt of symptoms and signs of asbestosis that by an acco e fully agreed by all writers, and which efinitive above." While he stated that he considered estosis;" "Moderately the radio advanced asbes- signs of: "Early asb tosis;" and "Advanced asbestosis" as of significance, he considered to b importantly were to constitute his criteria for the d diagnosis of asbestosis. nreelvieedrtheexlcelsussihveelydioscnohuinstecdlinriacdailogfirnadpihnigcs afoprpethaeradnecfeisnitainvde 1. "Dyspnoea. The most common, but cannot be noticed diagnosis of asbestosis. except following violent exercise, such as stepping up THE EPIDEMIOLOGY OF ASBESTOSIS out of a chair 25 ariable times in 30 seconds. in amount and degree, generally dry AT ASBESTOS 2. Cough. though V in advanced cases after severe attack a little The text dealing with epidemiology is given verbatim to thick tough sputum may be brought up. allow the reader to evaluate the nature and quality ofthe data 3. Cyanosis. A late sympton [sic]. and of the investigation. 4. Clubbed pitting finger nails. Also of blood. But not late. in a big percentage of cases. 5. S ht and emaciation. A late sign. "Incidence of asbestosis in our works" 6. 7. Loss of weig Anorexia. When a man cannot eat it is time to stop 2We have 507 men on the payroll who have worked work. expansion. here more than 10 years. This is a larger number than I have seen referred to in any report on 8. 9. Poor chest Substemal pain. A frequent sympton [sic]." Asbestosis. Of cases of Early asbestosis we have [Stevenson, 1940]. Haebtrhieefnsreecvtieorntedhetaodheidg:h"liSgyhmtinpgtotmhes 17, with work peri2o-d1s8o, f1-11-91,1a,nd31-1o2f3, 72ye[asrese. foolnote]-13, 1-17, Of Moderate asbestosis we have 5, 1-16, 2-17, 1- differences of experts in and signs not fully agreed on," quoting two contrary 30, and 1-35 years. Advanced asbestosis-0. Thus opinions: "1. Heart failure. Lanzcao'ms mbooonka, c1c9o3m8p, asnaiyms ehnetaortf affections [are] a very asbestosis. Public Health Bulletin 241 of U.S. Tanredas[tuhrayt Dtheepret. iss]aynso: bTahsiiss fhoarsthbeeetnhoiungvhetstaigt aatlel.d", The photocopy studied was not entirely iling clear. There were problems of the total of 17 cases of "Early legibility, as Asbestosis" well as those of reconc given in the text, with the shortfall of 6 when the sub-totals in the table are added "Cases" must refer to up. the number of employees in those years of ditor. service categories, rather than 10 nnmbers affected Letter to the E The Health of Asbestos, Quebec Miners 1940 233 we have a total of 22 cases of 507 men, a percentage of 4.33; and of Moderately Advanced cases a percentage of 0.98. These figures are arrived at by taking results of Stereoscopic examinations only. When these cases are studied from a case history and physical examination standpoint, our percentage of these suffering from asbestosis is exactly zero. If we used all of our employees in making these figures, the percentages would be about three times smaller. [Elsewhere there is reference to a total of over 1,200 wage earners in the works, but even assuming the denominator were of the order of 1,500, their inclusion would have made no impact on the percentage of radiographic "Advanced asbestosis" or of "Oinical" asbestosis.'] This may be a little difficult to believe in view of all the literature that has been issued showing the lart [hard] lot of the asbestos worker, but the facts as we find them are as follows: We have two cases in men who have worked over 40 years 6 II II II II II II II between 35 & 40 yrs 12 11 11 II II 11 II II 30 & 35 II 2811111111111125&3011 41 II II II II II II II 20 & 25 II 148 II II 11 II II II II 15 & 20 II 269 II II II II II II II 10 & 15 II 503[sic] We have a Quarter Century Oub which consists of all those who have worked 25 years for the Company; whether they are still with the Company or not, they still are members. The 48 mentioned and a few others bring the living members above 50, and in addition there have been about a dozen who have died since the Oub was organized in 1929, a total of well over sixty. "Death due to Pneumonia Bronchitis, Influenza, and less frequently by TBC"-Sirois. [Dr. Sirois was a physician at neighboring Thetford, Quebec.] "I have investigated the cause of death in all these cases, and not one of them has died of a lung affection. It is a remarkable fact that no one died of pneumonia, asthma, or anything even suggesting a lung condition. Of those living, there is not one that displays the classical signs of asbestosis ... A good percentage of these oldsters are still doing as hard manual work as they ever did. and with no more sign of fatigue than any other men of similar age in other occupations." [Stevenson, 1940]. FURTHER EXAMPLES OF EXPERTS DISAGREEING The document then returned to the presentation of disputed opinions, taking issue, for example, with the pathological significance attributed to signs in the chest radiograph. In this he cited: "Page 175. Merewether and Lanza, in Lanza 1938. States that X-ray estimate of fibrosis will be an under-estimate of what would be found at autopsy." This is a free paraphrase of Dr. Pendergrass's text which read: " ... as Merewether states, that an opinion as to the degree and intensity of an asbestosis fibrosis, based upon a comparison of roentgenographic changes with those shown in standard silicosis films, will be an underestimate.'' In the absence of correlation studies between the chest radiograph and lung pathology, it is probable that Merewether was reporting the severity ofdisability in asbestosis as being greater in relation to radiographic changes than is the case in silicosis, as had been pointed out by Dr. Sutherland in his internal report on the early working of the Asbestosis Compensation Scheme. In contradiction to Merewether's experience, and to Pancoast's earlier observations in 1918, Stevenson gave his opinion: "From my own experience I would say that the Xray picture would lead a person to believe that that there should be a greater impairment of health than there actually is.'' Having earlier in this study set Lanza and the US Public Health Bulletin 241 at loggerheads over the association between asbestosis and heart disease, he repeated the charge with: "Page 185. Pendergrass, in Lanza 1938. Merewether in same, says heart not affected." Page 185 included no reference to Merewether, and Pendergrass refers not only to radiological blurring of the cardiac outline, but to: " ... right-sided hypertrophy and ultimate decompensation of the heart. Realizing, therefore, that ventilation of the lungs is seriously interfered with, one can readily understand why these patients are embarrassed with dyspnea, weakness, and cyanosis." 234 Greenberg To which Stevenson commented: "Our experience conforms to that of Merewether, as our workers show less heart trouble, age for age, than that of the general population." Next he proceeded to discuss the likelihood ofasbestosis regressing after withdrawal from further exposure: "Page 187. Pendergrass. In Lanza 1938. Says in [the] early stages if they leave work their condition improves, but in advanced cases this is not so" A reading of page 187 referred to provides no support for this sanguine asseveration from Pendergrass, and littlein the way of data-based support from the three opinions on the natural history of asbestosis cited by Pendergrass on that page. "Shull states that it would seem that improvement could be expected in early cases, but that, as the disease progresses, improvement is less likely. Sparks feels that it is too early in the study of this disease to say very much on the subject. Lanza believes that it is by no means certain that asbestosis progresses as does siliosis after withdrawal from dust exposure ..." Pendergrass had indeed stated on page 186: "The condition is apparently progressive, even after cessation of occupation." And on page 187 had written: "My experience in this condition is also limited. but I feel quite certain that, when asbestosis can be diagnosed by roentgenologic examination, the condition is likely to become progressive ..." valuable material, while there is such disagreement among the experts." STEVENSON's DIFFERENTIAL DIAGNOSIS OF ASBESTOSIS Stevenson listed a few conditions that might be misdiagnosed as asbestosis. "Page 188. Pendergrass, Lanza 1938. Differential diagnosis: States that in X-ray, asbestosis might be diagnosed when the condition is: 1. Passive congestion due to a failing heart. 2. Advanced bilateral Bronchictosis [sic]. 3. Erythremia. 4. Disseminated cancer. "Dr. Sirois, of Thetford, Que., has shown that many conditions could easily be confused with Asbestosis." He went on to claim: "Page 199. Dr. Gloyne mentions other dusts that would cause lung shadows, and like asbestos, are not likely to cause harm. For example, pure iron and pure coal; and in my opinion our men resemble more the picture of pure anthracosis than that of Silicosis." The page reference to Gloyne is an error: nowhere on that page is there reference to the topic, and Gloyne was unequivocal about the fibrogenic property of asbestos. THE CONSEQUENCES OF ASBESTOSIS Stevenson on the contrary was less diffident: "Our experience certainly goes to show that on leaving the dust laden air the X-ray appearance does progressively improve. As we have no advanced cases we cannot comment on the effect cessation of work would have on them." The citation of differences of scientific opinion, real or apparent, has constituted an effective public relations technique employed in the defence of the continued use of hazardous or suspect agents, in the form: "It would be irresponsible to put the livelihood of workers at risk or to deny society the benefit of a As there was no disease in Asbestos, Stevenson had to rely on the experience of others. "Page 244. Sequelae. Lanza 1938. Gloyne says: 1. Purulent Bronchitis and Broncho Pneumonia and Tuberculosis. The first two we very definitely do not have as sequelae, [but presumably, no asbestosis no sequelae] and as for the standing is as follows. Munther 417 says that in [the] general populati[on] the incidence of TB isl to 11/2%, and in industrial workers it is 21/2%. He rules out asbestosis as a cause of Empyerna [sic], Bronchictosis [sic], Pulmonary cancer, which seem to have been mentioned as sequelae." "In our works, with over 1,200 wage earners, we have not managed to find three active cases ofT.B. per year during the last 4 years. This may go to confirm the statement we sometimes see that asbestos dust has a restraining effect on asbestosis [presumably a typographical error for Tuberculosis] for we have a much greater percent or incidence in office workers." healtShtye:venson conjectured why Quebec miners were so "After reading a very great volume of reports from South Africa, England, and the United States ... one is tempted to wonder if our immunity from asbestosis may not be due to some variation in the arrangement of the elements in the Mollicule (sic] of the Quebec asbestos. I believe there may be chemical support for this theory, when one considers the enormous variety of things that can be made by the carbohydrates with only slight rearrangements in the elements. Also the various different effects produced by the hundreds of different Salvarsan groups and the newly discovered Sulphanilamides." He noted: "There are a good many reports of autopsies which seem to show that asbestos dust does cause a bad condition of the lungs, but we have never had a reason to have autopsies on our men, owing to absence of symptons [sic] suggesting Asbestosis." causes other than Asbestosis. -- ----....-. "v U\.I uuc:; LU "Dr. Stevenson has obviously had but little experience of post-mortem examinations and we shall therefore have to be guided more by men who have the opportunity of many such examinations. I cannot but feel that with their experience of known cases if our Medical Board were to examine the 501 men mentioned there would be more cases to report." [Bussy, 1940] It was also seen by other company members, and a manager at the Turners Asbestos Cement Co plant in Erith, LreQpDlideodnfroafnfikcleyoafnTduartngerreaantedr Nleenwgtahllt;o an old colleague at the " ... I am afraid that as a whole our Home Office Doctors and our Works Medical Officers would not agree with Dr. Stevenson but, of course, it must be remembered that the Home Office Doctors have specialized in lung troubles for Silicosis for many years and have now had an appreciable amount of experience in Asbestosis. I think we are all agreed that X-ray may not always give the true story in connection with Asbestosis, but it is definitely a guide and gives a certain amount of contributory evidence as to the condition of the lung ... It may interest you, but this is unofficial, that the Home Office medical experts have even gone to the extent of examining the cats that we have that live in our Fiber Treating Plant and, in fact, from time to time we lose one and unofficially we are asked to try and get some more kittens brought up in that area. Possibly this sounds a little cruel, but the men's health is more important than a cat ..." [Cann, 1940] THE UK INDUSTRY RESPONSE TO STEVENSON 1940 A copy was sent from Bell Mines, Thetford to their parent UK company (Turner and Newall Ltd.) where it was circulated to members of the Board. One commented briefly to a fellow director W.W.F. Shepherd: " ... It is very evident that there is quite a difference of opinion on this subject; personally, I agree with some of Dr. Stevenson's findings and disagree with others." Our experience shews that as stated on page three, it is difficult to definitely diagnose any degree of THE INFLUENCE OF STEVENSON 1940 ON QUEBEC OCCUPATIONAL DISEASE LEGISLATION An account was produced by the head of JohnsManville's legal department in New York of a brief meeting in April 1940 [Brown, 1940]. At it, the management of four asbestos mines, in which Dr. Stevenson was included, and representatives of asbestos miners, were infonned by the Minister of Labor and Mines of proposed changes in the law on lung fibrosis. The present law, which treated asbestosis as a form of silicosis, was to be amended to apply solely to silicosis. If the miners wished, asbestosis would be included, but the Commissioner was reported as having been told that they 'flt 236 Greenberg A l t h o u g h a s b e s t o s d i s e a s e in Quebe<; m Cartier was in nt ers imd millers PAifl~ to a!'{!ft fiftrcffed It not m lxl, lne~ded; if i!1'1~d, it be listed t (!OUld no Jsowngeerrebneotgaasinbsaadyeads.some made out: ~f ~jlfitfefy: ~ group r' <b;isron " reached at a prior meeting that thing could be] a serious disease in some was The mining stated to be hued oo the following considerations: " ... [asbestosis instances ... more frequently it remains a disease any years, een no cases of disability or which can be toleratceidabqlueitseywmepltlofmors,mas long as "(aa)thTrheesrueltihnagvifnrgomb asbestosis, there is no hnaevciensg- even without appre other serious disease does not supervene to cause more dsiety from the employees' spaobilnet; of view of adneath ... in practice, this dtismeaesdeicmolaeygalloporkoblems the disease made racket" compen having developed in connection serious andecnatuifsice immepdoicrtaalnconcept or a too liberal (b) No " with Common Law actions, there is no need from ing the disease isfoaciatol oinscteirpretation is accepted by modedieisc.o"legal the employers' point of view in bav professions, labor and compensation b compensable; and ) The listing of the disease by name would point ining (c in the direction of the asbestos m able many groundless The Quebec Asbestos Mining Association, of doubted the lung cancer application to its employees of the excess 1955]. This despite a so definitely industry as to render it prob ld be filed." claimed for textile workers [Doll, ompleted or published study at Saranac claims wou recent, never to be c oratory, in which mice were exposed to Thetford A that at 14 HEALTH OF QUEBEC MINERS ER 1940 Lab chrysotile asbestos, which reported to the QAM pulmonary tumors [Vorwald, mon2th].s Wthherielewtahsisanhaedxcneosts roefached statistical sitgunmifoircsanhcaed, AFT ears after Stevenson's clean bill of health for his orkers 195 the researchers warned that the incidence of ost recently killed group of Eight y Johns-Manville Asbestos workers, Thetford millw ere still reported not to increased ominously in the m ls. The QAMA had in the early 1940s received at wsuiftfherhefarovmy eaxspboessutorseisto[Jaoshbnessttoonsew, 1948]. The explanation : exposed anima and suppressed a report o f a similar study at that institute th rogenic [Schepers, strated asbestos to be mortality tumo study of its miners, which had demon a given was " ... very fineolyn ghraosusnudppaosrbteisntocslinisicnaol todbasenrgveartoiouilnsl.s, I995]. They sponsored luded that Quebec asbestos miners did not have a ancer" than conc higher death rate from "lung c neral population, and even significantly e Tfohrisitcohnasclluosni g been known that ateTvhenetftohrodugMh in comparable segments of the g orld-wide the experience of the asbestos there rwyaseanrso tchleinaitcmalosapshbeersetowsiass very dusty and contended that w exposed was not worse than that of the non-exposed [Braun clusions were treated with forme the dust was extremely fine." rnerBrothers asncdeptTicriusamn,ev1e9n58w]i.thTithleisned"cs~tocny~{~Ko!ox.\H~l~ST]u.~l~ "f~th~ A few years later, the meedbiecca'lsaadsvbiessotrotsomTiunes and mills., At ft ~ ~Mt V{.!jlt W,~ infn""'Vi \\l hv f\'l.n-r~tihg~r t\h,\'l~t\ h""~ hi.-,~ti n'(hV.i~"-~~>r:.'.t..u.~ 1'1~1~. Arespboerstteodsbaifsteimr aprveisssitioton Qthuat at Thetford: ~~ m'l\'JI~~ ~ ~so fi->J".", rao l !>~, 7!%ofwhi'eb hadnomhereVidence g cancer found in stosis, and knew of 29 cases of lun s, and 4 cases of mesothelioma in e " ... there is a considerable amount or of asbestosis AI) ... I am here of sub-cl.imniacnaly twypoerke(rPs2 over 70 vyiegaorrsouosf. of asbe t8h4e3cdoeuartsheso[fK1n4o7x,au1t9o6p4s]i. aasgseuarered s1ti?lal te.m. ployed aenednaarendactthiveye awnedre alleged, CHRYSOTILE AFTER 2000 Several of these were s after 30-40 years in the mm, to have negative even ms." [Knox, 1952) Under the aegis of WHO, ILO and their agencies has been reached independent international expert consensus blic health risk. X-ray fil ical, radiological, and pathological tha_t chrysotile presents an unacceptable pu ssive banning of asbestos use Reporting on clin that had accumulated between 1945 and 1953 from persistent data o~e 4,000 !hetford asbestos iwneosr'kemrse,didceaslpoitfeficer found :nus bas led to 'eloped the progre World, and a shift of chrysotile exports to essors m the J?m the :rrurd World. There, Stevensons'os tislpei,raitnudalarseuacdcvising searlier negativeharveepoar~tbse,stthoseismofvarious degrees ofseveritoy,f continue to deny the hazards workers of of chry its health and economic 112218 woofrwkehrosmto were diagnosed radiograpphsicya[lClya,rtaienrd, 139355]. goenveefrintsm. eAntss laanted as 200 I, the Journal of the Canadian whom were additionally confinned at auto b