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FILE NAME State of the Art Literature SAL DATE 1977 Feb DOC SAL081 DOCUMENT DESCRIPTION Barry Castleman Article - The Development of Knowledge about Asbestos Disease THE DEVELOPMENT OF KNOWLEDGE ABOUT ASBESTOS DISEASE Barry I. Castleman Copyright by the Author All Rights Reserved February 1977 Washington D.C. . The Development of Knowledge About Asbestos Disease Part I. Asbestosis The earliest recorded historical recognition of the hazards of asbestos goes back to the time of Christ Strabo the Greek geographer and historian 63 B.C. - 24 A.D. described the dangers of asbestos weaving and Pliny the Younger 61-113 A.D. in his description of the diseases of slaves called asbestosis an occupational disease Both writers stated that the use of asbestos in the manufacture of handkerchiefs headcloths and tablecloths was common and that the cost of these arti- cles was equal to the pearls of India 1 Pliny the Younger a Roman historian referred to the of use slaves I respirators to avoid inhalation of infer from Pliny's report that the the dust by the Romans realized that slaves weaving asbestos were first becoming disabled to the point that they could not exert themselves at all in their work and then they died as their breathing difficulties became severe The Romans instituted the use of respirators in order to extend the lives of these slaves much as one might oil a machine to keep it from wearing out too quickly The Romans did not have pathologists with microscopes or the science of radiology available to them but nonetheless they saw the gross effects of asbestos inhalation on their workers The modern asbestos industry began in the 1870's and commercial production 3 recorded as of 1874. of asbestos insulation products was Selikoff and workers wrote in 1965 -2- Asbestos as a mixture of fiber and sodium silicate was first used as an insulation material in 1866 and as asbestos cement about 1870. Magnesia with asbestos as a binder soon followed and cell covering made with corrugated asbestos paper was intro- duced in 1898. These materials are still in use with others The first modern reports of asbestosis were in asbestos 4,5 textile workers in England and France One of these Murray's - case was not published in the general medical literature but it was referred to in a 1918 bulletin published by the U.S. Department 6 of Labor's Bureau of Labor Statistics Hoffman his ee one aa ne? Murray had presented his case report to the Departmental Committee Committee on Industrial Diseases Diagnosis was verified by a post mortem examination Hoffman wrote In reply to a question by the Chairman of the Committee as to whether in view of the fact that there is something characteristic in the earlier stages of dust phthisis in the predominance of shortness of breath before physical signs become very obvious such a condition had been observed in the case of the asbestos worker under treatment by Dr. Murray under observation for 14 months the and doctor said that it had been noticed in the case in question and that in other words there was a definite relation between the course of phthisis and the physical incapacity resulting inhalation of asbestos dust added from the Emphasis Hoffman cited figures from the Prudential insurance Company that attributed 3 of 13 deaths of asbestos workers to tuberculosis Of the 3 who died from tuberculosis two died between the ages of 35 and 44 years and one was between 25 and 34 years of age at death two others died of pneumonia Nine of the 13 asbestos Phthisis is an old term for modifier whoever refers to cutter's phthisis tuberculosis Its use with a a pneumoconiosis e.g. stone ..3- workers died before age 45. Hoffman said that the mining and dressing of asbestos unquestionably involve a considerable dust- hazard but the hygienic aspects of the industry have not been reported upon It may be said in conclusion that in the practice of American and Canadian life insurance companies asbestos workers are generally declined on account of the assumed injurious conditions of the industry He continued It is regrettable that there should be no further information available regarding the asbestos industry in its various branches including the utilization of products of manufacture on accountof the self- evident injuriousness of asbestos dust as a predisposing cause of pulmonary tuberculo- sis Emphasis added His style is cumbersome but Hoffman appears to have been raising the question of health hazards in trades where asbestos products were used such as insulation work That 3 of these asbestos workers deaths were reportedly caused by tuberculosis and 2 were reportedly caused by pneumonia raised concern over the possible role of asbestos trapped in the lungs in causing these deaths The data pointed to one or more of the following as possible roles for asbestos 1 asbestos dust in the lungs might reduce a person's resistance to tuber-tuber- culosis and pneumonia infections 2 asbestos dust in the lungs might reduce a person's resistance to the progress of such infections once they are contracted 3 asbestos phthisis might be killing people itself and passing as tuberculosis and or pneumonia Although these are small numbers it is significant indeed that life insurance asbestos workers and that companies were already refusing Murray had identified a distinct red , 4- disease as the cause of death of an asbestos worker There had also been a British government report on an excessive incidence of tuberculosis in the production of asbestos mattresses and the . use of dust controls in 3 factories The relation of asbestos dust to pulmonary tuberculosis is reported upon at some length in the Annual Reporotf the Chief Inspector of Factories and Workshops for England and Wales for 1910. The investigation was made by Dr. Collis who states in part that-- Following up information received from the it registrar was found that five deaths of persons suffering from phthisis had occurred in five years among a staff of under 40 workers employed at a factory where asbestos is woven The process which appeared most dangerous is the production of asbestos mattresses These mattresses which are composed of bags of woven asbestos filled with short asbestos fiber are placed on a table and beaten out flat by a man with a wooden flail from which process much dust arises Women who sew the mattresses into sections with asbestos threads worked close to the man who beat the mattresses and of necessity inhaled the dust The reorganization of this process with the application of localized exhaust draft was called for and an annual medical examination of the workers by the certifying surgeon has been instituted in the hope of detecting and removing from exposure to dust those showing early signs of respiratory discase Weaving asbestos has only become an important Two other industry during the last large asbestos factories 15 years were visited each of which was found to have its own specialty in the production of which dust prevention is required The Department of Labor bulletin contained numerous pleas for research on health hazards in the growing asbestos industry The rapidly increasing development of industries using asbestos as ascertained from domestic or foreign sources suggests the urgency of more qualified medical consideration than has hereto- fore been given the subject _ Hoffman also noted that there was no medical literature available on asbestos diseases from the Surgeon General's Library the U.S. Geological Survey or the state of Georgia where asbestos was mined There is evidently an urgent need for a more qualified and extensive investigation of the health aspects of asbestos manufacture " he said in the paragraph describing Murray's case report The paragraph ends It is therefore to be anticipated that the conditions of asbestos workers will attract more qualified attention in this country in the future than it has in the past Also in 1918 Pancoast and workers reported finding fibrosis 7 in the chest rays of 15 asbestos workers was his The first report of asbestosis in the British medical literature 8 by Cooke in 1924. In 1927 Cooke published additional details of 9 case a year woman Another case of asbestosis in Britain was reported by Seiler in 1928 In 1929 whose average Iladdow age at reported 4 fatal cases 11 11 : death was 41. He also of asbestosis had four advanced cases under treatment women whose average age was 35 I know that many workers had drifted away from the asbestosfactory they be- lieved it was unhealthy whilst many women ceased work to attend to their homes . and any fibrosis present would readily be overlooked in later years when death over- took them Thus the asbestos_workers were apparently able see from the impaired condition and deaths of those longest employed at the impaired .. tee factorienso doubt that . Te grave dangers were ee me ALL CS, attendant upon _ es -6- dusty jobs in asbestos plants determined this without the aid of sputum cytology pathology epidemiology or radiology In 1928-1929 Merewether and Price of the Factory Department in Great Britain investigated the health of workers exposed to asbestos The asbestos textile industry was a logical place to conduct the study because these workers exposure was to pure or nearly pure asbestos No other potentially fibrogenic dusts were present In addition dust exposure did not fluctuate as much as in other asbestos trades and exposure in the asbestos textile industry was substantial Further such mills were centers of relatively large groups of workers They had employed many individuals for long periods of time thus giving the researchers an opportunity to observe the effects of prolonged exposure Merewether and Price examined 363 workers and found that 95 26 had asbestosis and 21 others had precursive signs 12 of it Based on these findings the authors wrote 11 . . it appears that the general incidence rate of fibrosis of the lungs amongst those employed in these sections of the industry is rather less than 1 in 8 or excluding those employed under 5 years rather less than 1 in 3. These investigators analyzed the workers exposures by lengths of time and dustiness of job and summarized their findings thusly While it seems necessary for the production of generalised fibrosis of the lungs that a definite minimal quantity of dust must inhaled the lower the concentration of dust in the air breathed the longer the lapse of before the fibrosis is fully developed and within a certain limit the higher the con- centration of dust the sooner the fibrosis becomes fully developed and the more intense the involvement of the lung tissue time % a ee ee If this hypothesis is correct and the evidence points to it the practical inferences are of very great importance since it follows that the reduction resulting application of measures in the of the concentration of dust in the air in the neighbourhood of dusty asbestos processes will cause first a great increase in the length of time before workers develop a disabling fibro- sis and secondlthye almost total disappearance of the discase as the measures for the suppression of dust are perfected J. C. McVittie of Great Britain's Ministry of Pension ansd National Insurance described the reaction to this report which contained lation and dust specific recommendfaortiimporonvs ed 13 Stew es tee suppression venti- Under section 79 of the Factory and Workshops Act of 1901 certificate the Secretary to the effect of State that the issued a manipulation of asbestos and the manufacture and repair of articles composed wholly or partly of asbestos and processes incidental thereto are dangerous The section the Workmen's Compensation Act of 1925 which provided for application of -that_Act- workmen suffering from silicosis was extended to certain processes involving exposure to asbestosdust asbestobecame compensable Compensation cover was fairly wide and the compensatable disease was defined as fibrosis of the lungs due to asbestos or thatdisease accompanied tuberculosis Regulations for exhaust ventilation dust control and housekeeping measures in asbestos plants were made effective on March 1 1932 In 1930 the same year the mentioned report was issued in Great American Britain Merewether publication Journal published a lengthy article in the ; 14 of Industrial Hygiene Io described his investigation of the British asbestos textile industry The article began with a description of Murray's 1906 asbestosis case report from which a grim picture of the early asbestos textile plants emerges The patient a male aged 33 came under the care of Dr. Hospital in worked with Montague Murray at the Charing Cross the beginning of 1899. He had asbestos for some 14 years 10 years as a cardroom hand and the remainder in some less other room dust He of the factory where there volunteered that of the 10 was people working in the cardroom when he went into it he was the the others had died only survior and that all somewhere about 30 years of age . . He Hospital for was two treated months in the Charing Cross and then returned to work After a few months however he became ill again and was admitted to the Hospital in April 1900 where he died The post mortem examination confirmed the clinical diagnosis of extensive pulmonary fibrosis There was no evidence of pulmonary tuberculosis " He describtehde terminal stages of asbestosis As the disease progresses if no acute illness has caused a fatal termination a stage is reached when the lungs can do little more than maintain life and the shortness of breath is extreme Even in its terminal stages the disease deceitful to the last may masquerade as chronic bronchitis pulmonary tuberculosis bronchopneumonia or the like Merewether noted the limitation of studies based on those still healthy enough to be found at work in the factories He pointed out that workers with asbestosis who develop a tuberculous infection would have cause to go to a doctor Such workers would likely be told to quit their dusty jobs Thus there tends to be a drift of such from the producing industry cases During the course of the inquiry information was obtained of a number of persons previously employed in asbestos who were either at home or in sanatoriums suffering from chest complaints Where an examination of workers is confined to those at work a certain number of advanced cases of fibrosis and a certain number of pul- monary tuberculosis with or without an asbestos fibrosis in work or who missed persons are off who have cither given up work temporarily will be -9- In presenting his statistics Merewether said that comparatively good exhaust ventilation which has been applied in some degree for more than seventeen years has been a positive factor in minimizing the production of probably in the direction lengthening the period before the fibrosis becomes fully developed The statistical highlights of Merewether's findings were also reported in the Journal of the American Medical Association on June 28 1930 at the time when Lord Russell had just introduced | a bill in Parliament to extend the silicosis provisions of 15 the Workmen's CompensatiAocnt to cover asbestosis as well oO Supporting the bill Lord Russell for the government said that many processes in silica working could not show a mortality approaching that for the asbestos industry in which 14 fatal cases had now been reported and in addi- tion 3 deaths from asbestosis associated with tuberculosis The same journal had run its first article on asbestosis in January 1928 to bring Cooke's 16 American physicians In 1930 the case to Journal the attention of of the American American Medical Association noted Mills report of an asbestosis case This report had been published in the journal Minnesota Medicine about a fatal case in a man who had worked in an asbestos mine 27 in South America prior to 1898 - --10- Concerning the relation of physicians of the United States to this industry Mills pointed out that asbestos is mined and manufactured in many parts of this country and that pulmonary asbestosis surely will be encountered Also in 18 asbestosis 1930 Pedley Pedley He remarked published the first Canadian that the asbestos mining and paper on milling industry was 40 years old in Canada but that o our knowledge however no case of pneumoconiosis has ever been reported from asbestos in Canada and the general impression among miners is that dust is not hazardous The writer acknowledged that asbestosis had been recognized by the British authorities as a compensable disease citing the notice on Lord Russell's bill before Parliament in the Journal of the American Medical Association He pointed out that Mining is carried out in open quarries and is not usually a very dusty job but in the milling a great deal of fine dust is created and men who work there are heavily exposed to whatever hazard may exist He provided no figures on the numbers of people employed in mining and in milling asbestos He acknowledgtheadt it is quite possible that the condition in mines may have gone unrecognized for mines are usually situated in the country whereas factories are apt to be in the city where facilities for autopsies are better Note that mills are usually located adjacent to mines since it is most cconomical to separate the fiber from the host rock and sort it by grade length before transporting it Pedley suspected that if the miners were seriously affected by asbestos the effects should be reflected in a high tuberculosis death rate provided the mining population was fairly stationary and did not go to sanitoria or elsewhere to die These mills process ore where manufactured goods and are are not made the same as textile mills He went on to compare the 1926-1928 tuberculosis death rate from Thetford mines Quebec an asbestos mining center to the death rate for the Province of Quebec as a whole found they were very nearly the same The numbers of deaths on which the rates were based were not given Pedley then described the asbestos bodies that had been reported in published autopsy examinations of the lungs of asbestotics variously referred to in the early literature as asbestosis bodies and curious bodies Unquestionably these curious bodies have stimulated much interest in the disease asbestosis Pathologists whose interest in such a disease might languish come alive at the sight of the curious bodies From the public health standpoint however it seems hardly likely that asbestosis will become of importance either from the standpoint of morbidity or mortality Pedley in dismissing asbestosis as a pathologist's disease was compounding slipshod research with wishful thinking As he noted the population at greatest risk of asbestosis was the mill workers Yet he did not find out how many of these people there were If the mill workers made up only 1-2 percent of the town's entire population which is likely then there is little chance that their mortality from tuberculosis no matter how bad would show up as an excessive tuberculosis rate for the whole town Another serious error was the use of tubercu- losis rates as a sole index asbestotics usually died of heart failure pneumonia chronic bronchitis or tuberculosis The failure of physicians in this Canadian mining town to recognize asbestosis among miners and mill workers is typical of the situation the world over The Americans had just begun to learn about asbestosis in textile mill workers from the British in spite of the long history of the modern - asbestos manufacturing industry in England and in this country And , even the British doctors likewise took a very long time to recognize and investigate the threat of a fatal occupational disease faced by asbestos workers since the 1870's Finally one can hardly overlook the plight of the small physician who discovers that the industry the town depends on is killing people If he makes an announcement to that effect he might find himself branded an enemy of the people Pedley listed in his bibliography 17 articles on asbestosis including Simson's 1928 paper on two cases in Southern Rhodesia In the text Pedley mentioned the existence of reports of asbes- tosis in four Rhodesian minors Simson's two cases were men who had worked in a mill processing chrysotile asbestos fiber from a nearby mining operation Chrysotile asbestos by far the most abundant of the commercial asbestos minerals is the same type of asbestos that is mined in Canada Pedley did not attempt to explain how milling chrysotile in Canada presented no asbestosis hazard while milling this same mineral in Rhodesia and weaving Canadian asbestos in England could both cause asbestosis Whether Pedley actually read all of the papers in his bibliography is questionablte he last one Merewether's 1930 publication in the Journal of Industrial Hygiene Los In December 1930 Dr. J. ~~ Angeles to present a major V. Sparks of London paper on asbestosis journeyed to at the annual meeting of the Radiological Society of North America The -1- paper was published the following year in year the 19 Radiology Sparks remarked that practically American journal no literature on asbestosis has been published in America from 1925 to 1930. Sparks called attention to the striking . preponder- ance of workers who have been employed in the British asbestos factories for a period of four years or less referring to Merewether's finding that fibrosis begins to show signs in some cases after the first four years of exposure It seems reasonable to suppose that after some years of affected such employment the workers may become by the inhalation of asbestos dust and seek other industries The fact that they cease to be exposed to the dust does not how- ever prevent the disease when once established from progressing Thus the radiologists were the first to establish the startling fact that in some cases asbestosis became more serious as time passed even for workers who had been removed from workplaces where they were exposed to asbestos Not only did these workers fail to recuperate but their health continued to deteriorate as the asbestos fibers trapped in their lungs produced a steadily increasing fibrosis Sparks said It is too early in the study of this disease to say very once the much on this subject but asbestos bodies appear in the the course of the discase would appear ; sputum to be progressively downwards nor does cessation of exposure to the dust avail to check its spread Prophylaxis is important and the only hope for the asbestos worker lies in adoption of the proper means of protection against the risk attendant on the inhalation of the fibers At the end of 1930 Dr. W. B. Soper published a case report of asbestosis from Connecticut in the American Review of 20 Tuberculosis Noting the dearth of American medical literature -11- on asbestosis and acknowledging the flurry of British publica- tions on the subject he wrote Just as certain other dusts took their toll over a long period before the medical profession awoke to the true facts so asbestos dust to a lesser suffi- degree appears to be taking its toll without suffiIt cient recognition of the fact on the part of physicians In 1925 radiologists Pancoast and Pendergrass of Philadelphia 21 reported ray They published abnormalities among asbestos A Review of Pneumoconiosis they workers in 1931. In examined addition to some cases mentioned above they described asbestosis case reports from 1927 to 1929 by Oliver and by Wood and Page as well as the extensive study by Merewether and Price They noted the progressive nature of asbestosis The condition is apparently progressive even after cessation of occupation Merewether and Price state that with continued exposure to high concentration dust fibrosis may be fully developed in from seven to nine years and death may result in about thirteen years With less concentration fibrosis may not be fully developed for 15 20 or 25 years Inhalation of dust in high concentration results in a more marked degree of fibrosis in a shorter time than when the concentration is lower Another case report was published in 1931 by Lynch and 23 Smith in Charleston South Carolina The report began cee ee For a number of years one of us W.A.S. has observed in the chest clinic at the Reper Hos- pital Charleston and at clinics held at certain sections of Charleston County cases of respiratory disease which possessed charac- teristic nost ordinarily encountered The significance of the relationship of the occupation and the pulmonary disability was realized when in the fall of 1927 an adult male about 40 years of age who had worked for 17 years in an asbestos plant was seen in consulta- tion with a local physician The man exhibited the characteristic picture of the terminal stage of respiratory failure ee A literature review and the case report followed In their -15- survey of the available literature the authors counted a total of 172 cases of pulmonary asbestosis ene Stewart and workers in Philadelphia 21 cases of asbestosis in 1931 reported two more The two cases cited illustrate nicely the extremes and some of the features of the disease In the first case as far as the patient's health and life were concerned the presence of pulmonary asbestosis in the lung was relatively unimportant He had symptoms doubtfully attributable to it It was only through the history which was confirmed by postmortem examination that the possibility of such a condition was suggested It is however important to point out two considera- tions in this case First it is a question whether the asbestosis had anything to do with his emphysema and cough As an etiologic factor the asbestosis cannot be ignored The other point is one that has to do with preventive medicine The exposure was for nine years in a comparatively well ventilated factory in which precautionary appliances were used and yet the patient developed a minor grade of the disease It would seem that further precautionary means are neces- sary in this occupation to obviate a disease in itself so preventable In the second case the patient worked in an asbestos factory for a short time but without a mask This was long enough to per- mit his lungs to become densely filled with the dust Obviously the symptoms did not result from the asbestos per se but were due to the marked fibrosis resulting from the deposition of the pigment This demonstrates that the symptoms of a pneumokoniosis may come on years after a short exposure and emphasizes again wearing masks in the absolute necessity for even the less dusty atmospheres Once again the insidious progress of the discase after cessation of exposure is apparent especially for the second case a very severe one This report showed that high asbestos etiologic causative -16- exposure for 9 months could later prove fatal and that 9 years of textile spinner work under conditions of ventilation and respiratory protection regarded as good for those times did not prevent asbestosis The result of a year or less of high expo- sure was not observable to Merewether since the asbestos workers he examined with one year's exposure had first been exposed to asbestos only one year before he saw them Stewart and workers ended with the statement From the histories there appears to be a further need for study along the lines of prevention of this disease " Wood and asbestosis in Gloyne 25 1930. published a paper on As many others would the histology of note they found that the fibrosis was most marked at the bases of the lungs A later paper by Gloyne describes damage to the pleura 26 as well and even one case of pleural cancer with asbestosis 24 Stewart et al remarked in 1931 The marked fibrosis of cularly of that between lung and the diaphragm the pleura parti- the base of the is characteristic In Germany similar findings to those in England were reported on the clinical course of asbestosis in 1931-1932 A summary journal of early German literature appeared in 27 Lancet in 1932. Kruger and workers the British , reported among 48 workers examined 30 cases of definite lung changes and cough in 13 of the cases and dyspnea the commonest initial complaint The statistical tables appear to indicate that moderately severe asbestosis takes some five years to develop while none of the workers examined who had had ten years or more exposure was free from signs of the disease Dresden published 1931. -1 . \ Gerbis and Ucko examined 33 asbestos workers in another German factory in Berlin and found that early all the cases _ showed symptoms These symptoms were shortness of breath especially on exertion cough with sputum lack of appetite loss of weight pain in breathing palpitation of 27 ness and increasing pallor the heart faint- The authors noted that the severity of the disease did not appear to be dependent on the age of the worker but rather on the number of years he had been in the the amount of asbestos dust factory inhaled and on which varies considerably in different processes Whenever a patient had been working for more than ten years asbestosis could be demonstrated radiologically 1932 In a series of only 8 cases from Dresden it was noted that the radiograms in the obvious in the lower early lobes stageosf the illness were especially 27 of the lungs These authors found that the tend more serious to get worse cases after did not removal necessarily from their harmful surroundings which their experience appears to have differed from the early observations of W. Burton Wood in this country Wood later reported 1934 that he had seen asbestosis cases that did not worsen others did after cessation of exposure though many In the July 1933 issue of the American publication at Journal of Industrial Hygiene Dr. Philip described the first case of asbestosis in =. 29 29 29 to appear in the medical literature Ellman . __ an insulation worker A typical lesion of mild activity with an early stage of pulmonary asbestosis was present in one of my cases who had been exposed to asbestos dust for 10 years but the work which consisted in coating lead pipes did not entail exposure to high dust concentrations -18- Ellman's description of the asbestotic was vivid A case of simple silicosis often looks well declares that he is well and is even offended when any reflection is cast upon the soundness a case of of his lungs asbestosis is In contrast to this cyanotic emaciated anxious and often obviously going Such then is the clinical picture from asbestosis downhill of sufferers Only by an extension of meaning could the word sufferer be applied to anyone with simple silicosis Original emphasis ) Ellman described the progressiveness of the disease An interesting feature of this disease is the length of time which may elapse between exposure to the dust and a fatal termination and the fact that this period is only half of that in silicosis The dust particles once they have the lungs and one which if gained access continue to injure the disease is a progressive sufficient dust is present ends fatally the end being determined by some current complication such as acute bronchopneumonia or phthisis He also noted that diagnosticians would find the earliest development of asbestos fibrosis at the bases of the lungs The following year he again described the case of asbestosis in an insulation worker in a paper published in the 30 Journal of Radiology Ellman's first paper on case British reports of asbestosis had been issued several years before In October 1933 a report of an asbestosis case appeared 31 in the Medical Bulletin of the Veterans Administration The patient died at the age of 29 after 8 years of work in the dusty carding operation at an asbestos textile mill That same month Donnelly presented a paper at the annual meeting of the American Public Health Association in Indiana- polis which was later published in the American Journal of -1932 . Public Health Donnelly was a physician at the Mecklenburg Sanitorium in Iluntersville North Carolina and had the oppor- tunity to examine many workers from nearby asbestos textile plants Having had occasion some years ago to familiarize myself with the conditions in asbestos factories I have since been intensely interested in determining the extent of industrial hazard in this type of work For that reason I have attempted to obtain ray films of the lungs of all asbestos workers who have been referred to the clinic because of respiratory symptoms Of the films taken only 3 failed to exhibit some definite evidence of the condition called pulmonary asbestosis Donnelly collected 15 cases of asbestosis over a 3 to 4 year period He warned That exposure to the inhalation of this dust for even a comparatively short time is a definite and serious industrial hazard has been too frequently indicated to be open to doubt The fact that the condition when once acquired is permanent and more or less rapidly progressive is most important from a public health viewpoint He continued It also seems to be the consensus of opinion not only among writers on the subject but also among the asbestos workers that the protective devices now in use in many plants _ are most inadequate He went on to contrast the British Asbestos Industry Regulations with their requirements for dust suppression and annual medical examinations of workers with the lack of regulations in the United States and the lack of recognition of asbestosis in North Carolina's compensation laws After acknowledging the great usefulness of asbestos he said  -20- he workers should be provided with every facility for the protection of their health so that they may earn a livelihood for them- selves and families for at least an average period of time at the occupation in which they are most skilled Unfortunately every . worker handicapped by pulmonary asbestosis becomes almost invariably physically incapable of engaging in any occupation and many of them become an expense to the welfare agencies of the community Although the number of asbestos workers is much less than that in many other industries their occupation is extremely hazardous and they are amply justified in expecting whatever protection it is possible to give them He closed with a warning to factory owners Furthermore the fact that efficient protec- tive devices in this industry in spite of the added expense will effect a substantial financial saving is becoming more apparent The workers themselves are becoming informed of the danger to health and many civil suits for damages against factory owners are the result In December 1933 Merewether published a lengthy description 33 A Memorandum on Asbestosis He posed the question Does asbestosis shorten life and answered it emphatically Yes He presented figures showing that of 42 fatal cases of asbestosis the average age at death was 41. The youngest of the asbestosis cases died at age 26. One of the asbestosis cases died only 2 days after last exposure to asbestos The average duration of employment sufficient to cause a fatal degree of asbestosis was only 15.2 years as compared with 40.1 years for all cases of silicosis He not only presented statistics but also interpreted them based upon his experience While these figures show clearly the increasing risk with continued employment it would be wrong to assume that the opposite inference which the figures appear to support so long as the period of exposure does not exceed five years the risk of contracting asbestosis is almost negligible correct -21- Unfortunately that inference is wholly untenable The fact is that work in a dense concentration of asbestos dust over a compara- tively short period will lead inevitably to the development of a profound fibrosis provided that the worker lives long enough for it to develop It has been shown that experimentally in guinea fibrosis due to inhaled asbestos commences after about five hundred days expo- sure and the inhaled dust trapped in the respiratory bronchioles remained localised there for at least third years the length of the experiments up to the time of the report Of the fatal cases in Great Britain of which _ full particulars are available in two examina- tion over fourteen years after the last exposure to asbestos revealed numerous asbestosis bodies Since these bodies are merely altered asbestos fibres and still contain an internal core of asbestos and since unaltered asbestos fibres also can be found in the lungs years after the last exposure it is evident that asbestos dust trapped in the lungs remains and continues to exert its producing powers for at least many years - Merewether described the variable maturation period of asbestosis It follows therefore and this is important from the practical point of view of prevention that a certain minimum producing amount as it were of asbestos dust must be trapped in the lungs in order to produce a potentially disabling or serious amount of fibrosis and also that a certain maturation period must elapse before that amount of fibrosis is developed Particulars of cases seem to show that with high concentrations of dust the minimum period of time which must clapse between the commencement of exposure and the production of a serious degree of asbestosis is approximately seven years-which include not only the trapping period of the producing dose of dust but also the maturation period of the fibrosis which periods of course overlap The existence of this which may be referred to as the producing period i.c. the -22- period which must elapse from the date of commencing work before a serious degree of asbestosis can be produced accounts for the fact that it is not until the second five years .- of employment is numbers of cases reached that appreciable of asbestosis are discovered This period of seven years is of course the minimum and few cases mature in this minimum period in successive years however depending on the dustiness of the process in which employed more cases mature In the more dusty processes the producing period as defined above is commonly eleven . years At this point i.e. when fibrosis of serious import has matured worker is unduly short of breath on any extra exertion has a tinge of cyanosis of the lips and a little dry cough mostly in the mornings He is disinclined to climb stairs or walk up hills and he may even have changed from an upper flat or room to a lower one to avoid climbing the stairs He |. still however remains at work and usually is not anxious about the state of his health many refuse to admit any deterioration in " health at this stage Examination of the average length of employment of cases of asbestosis of the radiograms and of the particulars of the. recorded fatal cases also indicates that not only are spinners less likely to contract asbestosis but when they do it takes longer to develop in other words in spinners the maturation period of the fibrosis is longer In light of this recognition of the progressive nature of asbestosis he held out little hope for the victims of asbestosis The ultimate prognosis in those with developed asbestosis or in those who have incarcerated in their lungs a fibrosisproducing amount of asbestos dust even though no appreciable fibrosis or only a slight amount can be detected is bad Death from the disease is inevitable sooner or later if life is not cut short by accidont or by some unconnected disease 100 In 1934 Wood and Gloyne published a review of the first 28 cases of asbestosis they had seen Among the 67 women in their series The shortest exposure was six months 2 cases " . . . Most of the men and all of the women in this series worked at the same factory Among the men the shortest exposure was 11 months .. 10 Thus these authors reported seeing at least 3 cases of asbestosis resulting from less than one year of occupational exposure to asbestos Presumably these individuals worked at jobs with heavy exposure to airborne asbestos fibers The case with the longest exposure is also interesting_ That even serious damage to the lungs is not incompatible with many years of tolerably comfortable existence is proved by such an example as that of a patient who was still able to carry out administrative duties at a factory when nearly 40 years exposure to the dust had caused a fibrosis involving all except the apical regions of the lungs It is reasonable to consider the import of this case with regard to the asbestosis risk of insulation workers This case is described later in the paper as having had about 40 years clerical and administrative work at an asbestos factory as of 1934. Would he have had any higher exposure to asbestos than an insulation worker . The authors provided brief individual discussions for only a handful of cases They noted two that resulted from outdoor exposure to asbestos -24- It a van boy aged 18 whose spare time during two and a half years employment had been spent in mixing powdered asbestos in an 11 open yard . . . . a man who had been asbestos mattresses in the aerodrome employed open air handling at an Again one wonders how these exposures compared with the exposures of insulators Insulators worked in the open air at times but at other times worked in very confined enclosures where the airborne dust concentrations could accumulate in ) the course of doing a job The next example is the most relevant of all to insulation work " . . . a middle boiler riveter who had served his apprenticeship as a youth in a shop 1 where asbestos was used for lagging pipes .. It was not stated that this man ever applied insulation to pipes himself but if he did it could have been only inter- mittently during his several apprenticeship for the boiler riveting trade He did work in close proximity to insulation workers during his apprenticeship and thus was exposed to the dust this work created He may never have done insulation work himself but he probably did a little He may have been exposed to dust left in the air around boilers from which the old insulation had just been torn off or he may have worked mostly or exclusively in the manufacture of aerodrome for airdrome a landing field for airplanes which has permanent or extensive buildings equipment shelters ctc The American College Dictionary Random House New York 1956 1 new boilers thus having little or no opportunity to be exposed to asbestos after his apprenticeship But whatever the facts were one conclusion can be drawn This boiler riveter surely was exposed to less asbestos than an insulator who spent his entire working life on tearing off old dry insulation outfitting boilers with asbestos mattresses and mixing and applying asbestos powders for new insula- tion Much of the insulation of biolers and pipes was done in confined areas it was not outdoor work It is an inescapable truth that if this boiler riveter could develop asbestosis so could many insulation workers The authors noted that by 1934 they had seen some cases of the disease which did not worsen after exposure had ceased In a previous article we stated that the cessation of exposure to asbestos dust did not avail to check the spread of the disease This is certainly often true but we have now seen patients whose condition appears to have remained stationary since stopping work at ; the factory This report mentions that two of the asbestosis cases in the series also had carcinoma of the lung The following year Gloyne issued a separate report on these two cases of lung cancer The asbestos industry produced a study of its workers in 1935 conducted by Lanza and workers of the Metropolitan 34 . Life Insurance Company In 1929 the Metropolitan Life Insurance Company senting States was the who approachebdy officials repre- asbestos industry in the United were desirous of ascertaining whether asbestos dust was an occupational hazard in their establishments and if so what was the nature of this hazard and what should be done to prevent or control it . The investigation was conducted during the period ending in in January 1931 but was not published until four years later ray films were made of 126 persons 108 men 18 women working in asbestos plants in the United States All but five of these were were given physical examination The cases selected more or less at random from among those having more than 3 years of employIT ment in the industry No further clarification was given on the meaning of selected more or less at random Thus the asbestos industry's role in theselection process remains obscure and it is not possible to draw inferences on the health status of the workers industry from this report The ray films were read conservatively taking into and the age account the physical examination of the individual and were classed as positive only when there was no major dis- agreement among the examiners of the rays 20 The were films classified as negative for further subdivided into doubtful negative asbestosis and' : They went on to say without elaboration Only time classed as a definite can tell whether the individuals doubtful are progressing toward asbestosis This last remark disregards the extensive work of Merewether and others Though allusion is made to several articles in the English medical journals the only British paper actually cited was Cooke's 1927 paper on his historic case The authors went on to say that the definite cases of asbes- tosis were broken down into first stage and second stage the latter being the more extensive development of the discase -27- Of the total of 126 ray examinations 4 were diagnosed as second degree asbestosis 63 as first degree 39 as doubtful and 20 as negative In other words 53 percent of the workers had asbestosis by a conservative reading of the rays and another 31 percent had some ray signs of disease doubtful Only 16 percent had no signs of asbestosis on ray Most of the persons classified by ray as doubtful and negative complained of cough and dyspnea Of the 64 persons given physical examination and diagnosed as having positive asbestosis only 8 were entirely free from symptoms while 10 out of 37 with doubtful and 7 out of 20 with negative diagnoses were free from symptoms Referring to those that were classified as negative by ray who complained of symptoms the authors said too much emphasis should not be placed on statements of subjective symptoms The authors minimized their finding of widespread asbestosis in American asbestos workers by noting that in the cases selected for examination none had marked disability The threat of progressive maturation of fibrosis noted by many previous authors was not discussed one of these authorities Dr. Pancoast at the Universitoyf Pennsylvania had even been consulted by the Metropolitan Life investigators in the inter- pretation of ray films The Met Life study ignored the fine statistics Merewether and offered no data of its own to support the emphasized part of the following statement W are not justified in assuming that because available information suggests that asbestosis is a milder disease than silicosis the threshold of permissible dust counts is higher Emphasis added -28--28- The authors did not recommend that the asbestos industry should be regulated and did not mention that regulations were in effect in England The insurance company officials neglected to mention that asbestosis had been declared a compensable disease several years before in England They said this he experience attempt to define asbestos dust so far does not warrant a standard of dustiness an for A. J. Lanza who directed the Met Life study maintained cordial relations with the asbestos industry until he died in the early 1960's and his 1963 book The Pneumoconioses has a chapter on asbestosis that was Director of the Manville contributed by K. Smith Corporation In Lanza's Medical book terminal asbestosis was referretdo as respiratory embarrass- ment I point this out to make clear that this report was the result of collaboration between the insurance company and the asbestos companies in an attempt to downplay the published findings of hazards to workers in the asbestos industry Even so the report's findings were very worrisome The paper was presented by the authors as a preliminary report saying a more extensive study of the asbestos industry is now under way To the best of my knowledge the more extensive study if it was completed was never published Given the absence of regulations and workers compensation the authors recommendation that the industry seriously face the problem of dust control in asbestos plants seems too mild I think the authors were well aware of the seriousness of the hazards in the industry moreover civil suits and compensation cases were already beginning to bubble forth -20- In 1934 the Department of Labor and Industry of Pennsylvania began a study of the health of workers in four asbestos 37 plants of that state Airborne dust concentrations fabricating ne eee were sampled for the various industrial processes Of 57 asbestos workers examined 14 25 had asbestosis and 3 more had doubtful asbestosis The proportion of asbestosis cases was highest among the workers in the dustiest jobs The degree of' asbestosis likewise tendetdo be more extensive among the workers in the dustiest jobs The asbestosis cases were classed as slight and moderate no advanced cases were found The report published September 20 1935 contained a bibliography with 125 entries almost all of ' which dealt specifically with asbestosis On May 23 1934 the Supreme Court of North Carolina McNeely V.Carolina Asbestos Co. decided that asbestosis contracted unexpectedly and gradually during many months of exposure if due to the employer's failure to provide means of prevention is an injury by accident and as such was compensable under the Workmen's Compensation Act as it then which decision injected elements of undertainty into the law that rendered the hazards of occupational diseases particularly of silicosis and asbestosis often uninsurable at practicable rates 38 The McNeely case led to the addition of provisions to the North Carolina Workmen's Compensation Act effective March 26 1935 which specially regulate the liability to compensate for silicosis or asbestosis The NcNeely decision rendered the rates then in effect grossly inadequate for all classifications with asbestosis silicosis and other serious occupational disease hazards according to F. R. Jones .30- General Manager for the Association of Casualty and Surety 38 Executives in New York Manual rates for workmen's compensation nearly doubled going from 2.86 to 5.48 per 100 payroll for asbestos goods manufacturing Jones April 1936 article also discussed workmen's compensation rates in Massachusetts claim for workmen's compensation was where filed the first U.S. 35 in 1927 disability The stock company rates for the asbestos industry vary from 7 / to 10 where strict precautions are taken with a special rate of 12.5 for the making or repairing of asbestos mattresses In New York two categories of asbestos products manufacturing were established with separate rates for each effective September 1 1935. The Dust Occupational Disease Coverage for the New York rating plan was more expensive than the corresponding plan for North Carolina For moulded asbestos products asbestosis insurance cost 6.95 per 100 payroll compared to 3.47 for moulded asbestos goods production in New York and 2.98 for the asbestosis element of workmen's compensation insurance in North Carolina asbestos goods manufacturing But even these high rates were recognized as insufficient by the insurance companies High though these adequacy under the rates may seen their present New York law is generally doubted with the consequence that the private insurance carriers are rejecting many risks whereas the State Fund which is not bound by manual rates is exacting yet higher charges especially for risks rejected by the companies The asbestos companies were clearly aware of the threat of occupational disease insurance to their profitability , As a and the consequence of these very high rates inability of some industries to get any kind of continuance insurance at a of operations price that permits many establishments -31- are laying off workmon and either closing down or sending their hazardous work out of the state and an insistent demand has arisen for drastic amendment of the law in so far as it relates to silicosis and other dust diseases In 1935 D. reported a fatal S. Egbert of the Yale University Medical School 39 case of asbestosis in year man The author noted That the asbestos industry is growing rapidly and that as a result pulmonary asbestosis will continue to become more important is seen from the has fact that increased total world from 96,490 production of asbestos tons from 1910 to 434,938 tons in 1929. He included a table Summary of reported fatal cases of pulmonary asbestosis in which the reference age of the victim time exposed before onset of symptoms total time exposed and principal findings were recorded Total time of exposure was only 9 12 15 24 and 28 months for some of the cases which Dr. Egbert listed In 1935 Donnelly of the Mecklenburg Sanatorium in Hunters- ville North Carolina presented another paper at an annual meeting of the Industrial Hygiene Section of the American Public Health Association in Milwaukee 40 . It was published the following ycar Donnelly's opening remarks called attention to the public health implications of the rapidly rising demand for asbestos products That the serious industrial hazard of this type of work has not previously received sufficient attention is becoming more apparent The manufacture of asbestos products has increased more than four in the last 20 years and hence because of the greater number of workers exposed and the more frequent recognition as a pathological entity of the resulting pulmonary condition the subject of asbestosis has rapidly assumed greater importance He doubted that the controls then in use would completely protect against asbestosis noting that he was still finding fatal cases of asbestosis from one plant in spite of the installation of protective devices in 1916 in that plant It is indicated that the owners of asbestos plants and the workers themselves are beginning to realize that exposure to asbestos dust is a serious occupational hazard and it also is apparent that these workers must be protected against the hazard as effectively as is possible That this protection can be made complete seems very doubtful It seems to be the opinion of engineers that the most effective types of suction apparatus now in use will remove a maximum of not over 90 per cent of the dust but the remaining 10 per cent may be definitely injurious In 1916 protective devices of the suction type were placed in a certain asbestos mill and yet 15 years later cases of asbes- tosis with fatal termination were reported , among workers from this plant Since the most efficient type of protective machinery known apparently does not completely protect although the number of workers somewhat reduced and affected the time is probably required for the production of an advanced type of disease is probably lengthened the problem becomes a matter for serious consideration Introducing his own data he said I have seen no statistics in the literature in regard to the incidence of asbestosis among the workers in the industry It would seem to be a matter of some importance to determine the average number of employees who may be now or who are likely to become disabled by the condition Donnelly examined the ray films of 151 workers and found definite evidence of asbestosis in 52 34.4 Of those with asbestosis 48 had worked in the asbestos industry for five years or more 3 had worked for four to five years and 1 had worked for less than four years in the industry Donnelly reported several cases in which the asbestoshiasd progressed after the -33- cessation of occupational exposure to asbestos confirming this important fact which was first noted by Sparks One of the most important problems in the consideration of pulmonary asbestosis is whether or not the disease is progressive even after an individual handicapped by it ceases to work in the industry Information on this question is of considerable moment in rating the eventual degree of disability of a worker either in the assessment of damages in civil suits or in claims under State Compensation Laws He noted that shortness of breath in the more advanced cases precludes any form of muscular exertion he victim of asbestosis as a rule eventually becomes totally disabled from engaging in any form of labor His closing paragraph was a plea that the best available dust controls be installed by the owners of the asbestos textile mills and he warned that in the final check up the installation of such controls would be cheaper than the numerous damage suits and claims for compensation An industrial worker is entitled to every protection that may safeguard his health so that he may earn a livelihood for himself and family for at least a reasonable period of years in the work in which he is most skilled If he is prevented from continuing in such work because of impairment of health through no fault of his own he is entitled to some remuncration for his loss of earning power That protection of asbestos workers has been woefully lacking in the past has been definitely shown It is imperative that such protection as nearly complete as possible be provided by mill owners Efficient protective devices will be far less expensive in the final check up than the aggregate of numerous claims for compensation and frequent damage suits That complete protection can be afforded by the devices in use at the present time seems to be somewhat doubtful but workers are entitled to the highest type of protection which the engineers familiar with the hazard can provide 134- In the same issue of the Journal of Industrial Hygiene and Toxicology S.B. McPheeters of Charlotte North Carolina reported on clinical the examination of 210 asbestos textile workers seen at work None of the workers had been exposed for more than 20 years O 9 persons exposed for more than 15 years to dust concentrations effective in producing disease four 44 percent escaped asbestosis of 32 persons exposed for more than 10 years to similar concentrations fourteen 43 percent escaped of 70 persons so exposed for more than 5 years forty 64 percent escaped and of 28 persons exposed for more than 2 years and less than 5 twenty four 85 percent escaped McPheeters noted that individual differences in susceptibility to asbestosis appeared considerable judging from the different responses to exposure to various amounts of dust seen in this work force He recognized the limitations of his study just as Merewether had To make a scientific appraisal of the effect on the employees in this plant of exposure to asbestos dust it is necessary to know how many employees during the 15 to 20 years covered in the study have died or quit and how many of these had asbestosis available Certainly This knowledge is not it might add greatly to the gravity of the picture The most that could be done was to note the effect on those now present in of exposure the plant after varying periods In his opening paragraph the author said While it employs a relatively small number of persons the asbestos industry has had a . remarkably rapid expansion and by reason of the widespread and varied uses of its products which include matches filter pads paints roofing pressure jointing electrodes brake linings clutch rings and insulating material in a great variety the industry occupies an important increasing and per- manent place in our economic establishment Soon after McPheeters paper was released the radiologist 42 J. R. Shull published another report from the same city During the latter part of 1934 it was my privilege to examine the chests of 71 of 100 workers who had been dismissed from local as- bestos plants All had undergone physical examination before they were referred for roentgenologic study and were found to be physically disabled The average age was 34.4 years and the of exposure varied from 16 months to 21 time years These 71 cases of asbestosis were classed as slightly advanced 16 moderately advanced 35 and markedly advanced 20 Shull examined 21 of his patients a little more than a year after the first examination by which time one had died of asbestosis of 5 markedly advanced cases 3 showed increased fibrosis on ray 1 showed no change and 1 had improved of 7 moderately advanced cases 2 showed spread of the disease and 3 showed improvement Of 9 slightly advanced cases 1 showed increased fibrosis and 5 had improved His results showed that over a short exposure period of observation progression of the disease occurred in all three groups more commonly in the more severe cases and conversely the condition remained unchanged or improved more frequently in the milder cases once these people were removed from asbestos exposure Longer term follow would have been necessary to verify any lasting improvement among those whose conditions were seen to have improved during the year between examinations in light of the previous literature Shull's conclusion that asbestosis is not primarily a progressive disease emphasized the least worri- some of his findings Shull mentioned the McNeely case and the fact that the North Carolina legislature had recognized asbestosiass a compensable -36- The U.S Public Health Service was requested by the health and compensation authorities in North Carolina to make an engineering and medical study of the conditions in the state's asbestos textile industry The results were published in detail as a Public Health Bulletin in August 1938 and in 43,4 more concise form in the American Journal of Public Health in 1939 In all 242 dust counts were made to measure workers exposure The counts employed standard methods for that time and all particles in the air were counted not just asbestos fibers The unit of measurement of airborne dust concentration was 1 million particles per cubic foot mppcf and the maximum value observed was 74.3 mppcf Medical examinations were made of 541 men and women representing practically all ees at the time of the studTy he studied had been in operation from of the employ- three factories 6 to 16 years About 15 months before the study approximately 150 workers were replaced by new ones with little or no asbestos experience As a consequence there was an abnormally large percentage of workers with less than 5 years employmenitn the asbestos textile industry and an abnormally ' small percentage who had worked 10 years or more in the industry The Public Health Service reported The percentage of persons with asbestosis increases greatly with increasing length of employment . lmost three fourths of the workers employed for more than 15 years have the early stages at least of a disabling disease asbestosis Since there is no satis- factory way of locating and examining persons who drop out of an industry because of disa- bility of the incurred therein the percentage foregoing tables are necessarily values minimal evidence of the prevalence of asbestosis en otal ri 7@ -37- " >. 16.3 percent of the 69 former asbestos workers who had been traced and 378 men and women employed at the time of the study in three asbestos textile factories had asbestosis Persons who were not exposed to quantities of asbestos dust have appreciable not been included" The exposed persons may have been office workers and other production personnel Eight percent of the 378 workers employed at the time of the study had asbestosis This does not completely represent the incidence of asbes- tosis because about 150 employees were discharged from these factories 15 months before the present study was made had asbestosis Many of the discharged workers as the reports of Shull Donnelly and McPheeters show Although an attempt was made to examine as many as possible of these dis- charged cases only 69 could be examined 43 persons of whom had asbestosis according to the diagnostic standards employed in this study The investigators went on to estimate that another 50 cases of asbestosis among the recently discharged workers had escaped observation In other words there were 30 cases of asbestosis in the factories by the time they were inspected by the Public Health Service and an estimated 93 more asbestotics had been fired by the mill owners shortly before the Public Health Service conducted its survey By firing employees with term exposure especially in the least dusty processes the companies wiped out most of the data base the Public Health Service needed in order to develop any good response data on asbestosis Only 5 workers in the study who were considered at risk of discase had been exposed to levels under 5 mppcf for over 10 years None of the 39 persons exposed to dust concentrations below 2.5 million particles per cubic foot had a case of asbestosis although as a matter of fact only 6 persons had been employed more than 5 years -38- There were 3 doubtful or borderline cases of asbestosis found among the workers exposed to 2.5 to 4.9 mppcf Despite the paucity of data on the risk among workers exposed to less than 5 mppcf a tentative threshold value for asbestos dust exposure of 5 mppcf was designated This value stood as the recognized standard in the U.S. for the next 30 years The Public Health Service investigators were assigned the difficult task of prescribing a limit that would be safe and demonstrably attainable with available process controls They cited the 1935 Pennsylvania study that showed that incidence of asbestosis increases with the concentration of airborne dust and that found no safe threshold In their report of a similar study carried on in Pennsylvania asbestos textile factories Fulton Dooley Matthews and Houtz found that 8 percent of the workers exposed to an average . dust concentration of 5 million particles per cubic foot had asbestosis 22 percent of the million particle group and 57 percent of the 44 million particle group had asbestosis The conflict between the Pennsylvania findings and the 5 mppcf threshold set by the Public Health Service study was not resolved in the Service's report One attractive feature of the 5 mppcf limit was that it could be achieved and in fact was being achieved in every process except picking at one of the North Carolina asbestos textile mills in the study The use of pitchforks to feed the picker machine was also described However the exhaust equipment used in that plant could not get dust concentrations below 2 mppcf for most of the processes in the plant The exhaust fan flow rates were by no means large handling air flows of only 625-2570 cubic -390 -390 feet per minute CFM A 1948 manufacturer's table on design of local exhaust system 45 15,120 CFM A 2520 CFM fans starts at fan would have 2520 CFM and goes a power rating of up to about 2 horsepower The use of more powered fans and better process enclosures than had been voluntarily applied by this textile mill were clearly technologically feasible but the Public Health Service was unwilling to draw conclusions about the need for dust controls it did not justify in its own study The British and American literature on the progressive nature of asbestosis was disregarded though both Merewether and Donnelly were referenced The Public Health Service investigators did cite the British statistics showing that asbestotics generally died nearly 15 years earlier than silicotics after an average duration of employment only about one third as long as that . of silicotics They remarked that more than 90 percent of the raw material used in the manufacture of asbestos textiles in this country and Great Britain is Canadian chrysotile indicating that very little difference is to be expected from the standpoint of biological reaction in the two countries As near as dust concentrations in the various operations of asbestos manufacture of British practice can be compared with results obtained in this country no greater differences are found than exist in the inherent limitations of the sampling devices It would seem therefore that quite negligible differences exist in the manifestations of the disease ~* here and abroad with the possible exception of associated or complicating tuberculosis Nonetheless the Public Health Service proposed a standard based solely on its own health and engineering study Because of the importancoef the problem it seems to be desirable to use such data as are at hand to define tentative safe working conditions that may serve as standards for the guidance of factory managers and engineers until more complete data are -10- Because clean cases of asbestosis were found only in dust concentrations exceeding 5 million particles not found per cubic foot and because they were at lower dust concentrations 5 million particles tively as per the cubic foot may be regarded tenta- threshold value for asbestos dust exposure until better data In order to find out the are available levels to which asbes- tos dust concentrations have been reduced in practice an engineering study was made in an asbestos textile factory in which dust control equipment has been recently installed shows that means are already available This for re- ducing the dust exposure of a majority of asbes- tos textile workers less than 5 million particles per cubic foot The investigators were optimistic that no new cases of asbestosis would appear if asbestos dust concentrations in workplace air were kept below 5 mppcf-- followed by describing 5 mppcf as a tentative threshold that could be achieved with available methods of dust control The Public Health Service study had failed to develop the technical basis for establishing a threshold exposure level to protect workers from asbestosis Idcally a threshold concentration of dust should be the highest dust concentration that would not produce pneumoconiosis in originally healthy workmen during their entire working life Unfortunately nothing was published after 1938 that led to the determination of a threshold for worker exposure that would protect against asbestosisf-o-r the next 30 years Worldwide sales of asbestos fiber from 1938-1968 rose from 492,000 in in 1968 tons per year to 3,315,301 consuming consuming about 25 percent tons per of world year with the 46,46,47 47 output U.S. In 1949 reported on 115 Wyers medical fatal cases of director of the Cape Asbestos Company- 48 asbestosis The average age at death -41- was 40.8 years and the average duration of exposure was 10.4 years The author said that a few of these persons had begun work with asbestos after the implementation of dust controls in . factories imposed by the Asbestos Industry Regulations took effect in 1931 The reduction in the intensity of the dust cloud seems to be producing a more chronic type of disease Merewether's investigation of 1929 indicated a period of seven years exposure for the disease to develop whereas this series which commenced in 1931 indi- cates that an exposure of ten years is necessary The progressive development of asbestosis is evident from the long employment survival of the women in this series 9.8 years on the average No doubt many women ceased work to marry and symptoms of asbestosis did not appear until some time later The author pointed out that asbestosis was crucial in causing women's deaths in childbirth Pregnancy was associated with the deaths of two women suffering from asbestosis The disease does not seem to be adversely affected by pregnancy but the strain of labour may tip the balance in favor of right heart failure In 1968 the British Occupational Hygiene Society evaluated data on 290 men at work in an asbestos factory data provided by the factory owners As a result a new standard was set based as it had been in the U.S. on a study with a note- - worthy . . preponderance of individuals employed less than 20 years The standard required no application of controls exposures for below 2 fibers per cubic centimeter air For asbestos textile plants this reduction cc of from 5 mppcf was about fold The British Occupational Hygiene Society predicted that the risk of having earliest signs of. asbestosis would be less than % for a cumulative lifetime exposure of 100 years 2 fibers per cc for 50 years of work 4 cc for 25 years etc However the workers in the same factory where the Society did their research on which the new standard was based showed a greater prevalence of ray 50 50 abnormalities four years later The debate over the safe threshold of airborne asbestos dust concentration that will protect a worker from asbestosis is still going on In December 1976 the Public Health Service National Institute for Occupational Safety and Health recommended a standard of 0.1 cc which it said would protect against the carcinogenic effects of asbestos materially and reduce the risk of asbestos cancer For asbestos textile plants the reduction from 5 mppcf to 0.1 cc is about fold Whether workers can tolerate even 0.1 cc of asbestos and not develop asbestosis is not yet known However the evidence is continuing to unfold In a study of 232 former insulation plant employees Selikoff 1976 reported positive ray findings among individuals having exposures to asbestos known to be as short as one day 50 - -33- -33- There were a few papers of interest published after World War II about the asbestosis risk of insulation work These studies showed that 1 insulation workers are still dying from asbestosis although death rarely occurs within 20 years of the onset of , the workers exposure 2 exposure of insulation workers whose work has not changed very much for decades appears to be some- what less than 5 mppcf of dust particles in their workplaceosn a daily average basis and 3 the major cause of death resulting from insulators occupational hazards is cancer Indeed this latter fact is true for all asbestos workers today In 1945 U.S. Navy doctors took rays of 1,074 men who were working as pipe coverers in Navy yards They also found that exposure to asbestos dust was below 5 mppcf in most of these workers tasks but that level was exceeded in some measure- ments This study had several deficiencies in its methods First they did not monitor the dustiest job of all in ship insulation work removal of old insulation Second only 51 of the men had been doing insulation work for more than 10 years and only 3 cases of asbestosis were identified of these three two had worked for 22 and 30 years at pipe covering and the other had worked in an asbestos factory before coming to work in the Navy yard Third the authors ignored the experience of many previous investigators that a complete clinical examination is necessary to diagnose asbestosis accurately Symptoms of cough and shortness of breath may be pronounced in cases where the ray shows little sign of pneumoconiosis -14- The main shortcoming of the study was that very few workers had been exposed long enough for cases of asbestosis to mature Only 125 workers had worked for 5 to 10 years in the pipe cover- ing industry only 176 had been exposed for 5 or more years Yet in spite of these limitations the authors cited a ridicu- lous statistic and concluded that the trade was safe The incidence of asbestosis among pipe coverers in the shipyards studied was low 0.29 percent or 3 cases out of 1074 Since each of the 3 cases of asbestosis had worked at asbestos pipe covering shipyards for more than 20 years it be concluded that such pipe covering not a dangerous occupation in may is These authors ignorance of the literature on asbestosis is suggested by their lack of discussion of asbestosis per se and by their brief bibliography which contained only three references book by Lanza the Public Health Service study and a Navy manual on ships and planes In Denmark the insulation workers union of Copenhagen approached a university clinic for occupational diseases for a 53 clinical study of the health of union members Workers with less than 20 years experience were not even included for study After consultation with the union officials we began examinations in 1953 by selecting workers who had been in the trade for twenty years or more ... The average age of the subjects was 52 years ranging from 41 to 70 the period of exposure averaged 27 years ranging from 20 to 45 years Six of them complained of short- ness of breath which they considered ab- normal for their age All of them were working full time The researchers who were radiologists found definite signs of pulmonary asbestosis in 9 of the 31 workers usually associated with pleural abnormalities In no less than 19 cases abnormalities of the ploura were found These changes ranged from obliterated sinuses and pleural adhesions to extensive thickening of the pleura with calcification ... Some workers chest rays were so whited by pleural calcification that there was no way to get a look at the condition of the men's lungs In a few cases the abnormalities of the pleura were so widespread that no diagnosis could be made regarding ditions of the lungs definite the con- The authors considered the pleural damage to be a reliable sign for judging asbestosis among these insulators In their introduction they referred to a 1950 Danish case report of asbestosis in an insulation worker In 1964 Marr reported a fatal case of asbestosis in an insulator at Long Beach Naval Shipyard who had had 10 years employment as a pipecoverer and insulator Marr noted that ship insulation material and work methods had remained essentially the same since 1945 Selikoff and workers reported in 1964 a follow study 55 of the specific mortality of asbestos insulation workers The work force studied was the membership of New York and New -16- -16- \ Jersey insulation workers unions among the oldest such unions in the United States The investigators traced a group of insulators employed as of December 31 1942 and others who joined the union between 1942 and the end of 1962. They observed that very among large 392 workers with more than 20 years exposure the asbestosis majority had ray evidence of pulmonary In general severe clinical symptoms of asbestosis did not appear until after 20 years or more after the start of their asbestos work By 1962 255 workers in the group who had had 20 or more years of insulation work had died Of these 12 died of asbestosis Another 95 died of cancer and some of these would have later died of asbestosis had they not developed cancer McVittie reported that 41 percent of the cases of asbes- tosis recognized between 1955 and 1963 by the Pneumoconiosis were workers Two Medical Panels in Great Britain insulation of the insulating workers who entered in 1956 had only four years exposure In 1968 Harries reported on new asbestosis cases certified Dockyard These by the Pneumoconiosis Panel from Devonport cases included men from the following occupations who are NOT recognized asbestos workers Boilermaker Plumber Electrical Fitter Engine Fittor Engineer Iron Caulker Joiner Rivetter Shipwright Shotblaster Stoker Welder -17- According to industry output soared to 5,708,000 estimates worldwide asbestos fiber 57 tons in 1976. A scarcity of the magic mineral has been forecast by the year 2000 by the U.S. 58 Bureau of Mines Part 2. Cancer Two of the earliest reports of cancer with asbestosis were made by the British pathologist Gloyne He wrote at length of the damage to the pleura and lungs in asbestosis and reported the first published case of pleural cancer with asbes- 26 tosis in 1933. In 1935 he reported 2 cases of lung cancer in 59 female workers with asbestosis He considered the pleural cancer a complication unrelated to asbestosis He suggested the possi- bility of industrial origin of the lung cancer though he realized that there was insufficient evidence to make out a case for an actiological association of these two diseases One of Gloyne's cases was a year woman who had worked as a spinner for 8 years and had not worked with asbestos for 9 years since making 17 years from onset of exposure until death The other woman died at 71 15 years after periods of 6 and 13 months exposure in the mattress and opening departments of the factory These Lung cancers were not recognized during the lives of the patients but were discovered at atopsy For both cases -18- 1 . The growth was in a portion of lung in which the asbestosis was fairly advanced This was particularly clearly marked in Case 2 Gloyne suspected that even small lung tumors in vital places could precipitate death in asbestosis At this point an interesting question arises The asbestosis though fairly advanced was not sufficiently advanced to cause death The neoplasms were small and had involved no vital parts Indeed compared with the squamous carci- noma of the lung in general as it reaches the post mortem room the growths were unusually small A tentative sugges- tion may be made that in asbestosis a small tumour turns the scale just as bronchitis with early brochopneumonia will do probably as a result of toxaemia* Also in 1935 Lynch and Smith of South Carolina published the first case of asbestosis lung cancer in the American litera- 60 ture Lung cancer was an uncommon disease in 1935 and the occurrence of even one case of asbestosis with lung cancer was noteworthy As worthy of record in the interest of both disease as well as their possible relationship the following case of pulmonary asbestosis with associated carcinoma of the lung is reported The man had worked in an asbestos textile mill for 21 years toward the end of which time he developed cancer The authors noted that the cancer had developed after there was fibrosis of the lung They concluded A conception of the tumor's by reason of chronic bronchial is compatible with the current the etiology of such tumors origin irritation view of toxemia - entry into and persistence in the bloodstream of bacterial toxins absorbed from a local lesion from which these poisons are borne by the circulation to -Al- -Al- The state of medical knowledge as of 1935 was recently described by Dr. Irving Selikoff who has achieved 61 prominence from his research on asbestos diseases Thus by 1935 the main directions of the problem were known Chrysotile asbestos virtually the only fiber then used could produce spread disease this disease could be fatal and malignancy might be a result of exposure bestosis In lung 1936 Dr. Gloyne reported another case of as- 62 cancer His first two cases had had squamous cell tumors this one had an oat cell tumor The tumor was in the lower lobe of the lung It was well known by 1936 that the more extensive fibrosis of the lungs in asbestosis cases is likewise found in the lower lobes The occupational history was presented The in an patient asbestos began works work as in 1912 a packer and eighteen months to be a foreman later was promoted in the stores depart- ment The man died 21 years after starting work in the asbestos plant lle was at work there when he developed chest pains died 6 months before he died Lebert and Geiger at the Yale University School of Medicine published another case report G3 lung cancer in July 1936. The patient of asbestosis with was a man who worked as a weaver in an asbestos factory for 18 years He had to leave his job when he developed a disabling pain in his back he died shortly afterward with lung cancer -10--10- The authors concluded That the irritating effects of the inhaled asbestos particles may in this case have been a significant factor concerned in the development of the primary lung cancer seems sufficiently plausible to be worthy of consideration The authors also referred to Gloyne's 1933 report of asbestosis with pleural carcinoma they had not seen the 1935 reports of lung cancer with asbestosis at the time their paper was submitted for publication entitled In 1938 Nordmann in Germany published a paper 64 The Occupational Cancer of Asbestos Workers He reported 2 new cases of lung cancer with asbestosis in a 35 year old woman and a 55 year old man These two were asbestos textile workers Nordmann reviewed the cumulative literature and was the first to propose that lung cancer be recognized as an occupational disease among asbestos workers De tabulated statistics from all of the carlier reports except Gloyne's 1936 case which he apparently missed For the sixes sixes he looked at a number of factors for signs that they werk difat difat from from i pay oe. or then seen in th general population He also looked for the specific signs of occupational cancer Nordmann noted that 3 of the 6 asbestosis lung cancer cases were young compared to the usual age of people dying with lung cancer two were 35 and one was 11 In the ' older cases entry into the asbestos industry had occurred at an older age A consistent finding for all cases was the time clapsed from the start of asbestos work until the time of death no less than 15 years and no more than 21 In 5 of the 6 cases the tumors developed in the lower lobes of the lungs whereas in the general population lung cancer was usually in the upper lobes The relatively frequent finding of multifocal cancers -- the development of more than one primary malignancy in the lungs of one person -~ also suggested that occupational exposure to a carcinogen was the cause The microscopic appearance of the tumors in the group of asbestosis patients also was different from the pathology of lung cancer usually seen in the population There were frequent findings of squamous cell carcinomas and adenocarcinomas with asbestosis while the most frequent type seen in general was round cell carcinoma Finally Nordmann assembled the scant autopsy data on asbestosis cases to reveal that an unusually high fraction of these cases had cancer Referring to Wood and Gloyne's report of 100 cases of asbestosis he noted that of 12 autopsied cases 2 17 had lung cancer In Germany he knew of 12 autopsied cases of asbestotics and of these also had lung cancer Though there were few reported cases in which an autopsy of an asbestosis patient had been done and determina- s: tion of the presence or absence of cancer made Nordmann still considered asbestos a proven carcinogen He favored the view that fibrotic changes of asbestosis preceded development of cancer Hornig also wrote about one of the cases reported 65 by Nordmann the year woman He considered the evi- dence sufficientto establish beyond doubt the causal connec- tion between asbestosis and lung cancer He urged the recog- nition of the secondary disease as an occupational disease E. W. Baader in Berlin wrote in March 1939 that the government regulations on compensation the combination of asbestosis and lung did not provide for 66 cancer However Baader said the state insurance carriers in Germany had readily recognized and compensated light asbestosis asbestosis with fatal lung cancer as an occupational discase Thus in 1939 the German governmengtovernment recognized that life could be cut short by the development of lung cancer in a worker whose asbestosis had not become severe It is possible that such a worker would have later died of asbestosis and that it had takenno less asbestos exposure to cause lung cancer than to produce an ultimately fatal asbestosis But the more likely inference is that the German government recognized that workers who had not been exposed to enough asbestos to die from asbestosis had nonetheless been exposed to enough asbestos to develop lung cancer and die from it -53- It is also noteworthy that the existence of asbestosis diminishes the likelihood that lung cancer once found can be successfully operated upon The asbestosis destroys the reserve breathing capacity that is necessary if one is to survive the removal of a cancerous lung Thus asbestos wrokers life expectancy was known in 1939 to be lessenebdy two fatal competing risks the diseases as- bestosis and lung cancer Moreover asbestotics in general had less chance of surviving lung cancer surgery than others in the general population who developed lung cancer In England the Senior Medical Inspector of Factories reported that a total of 12 cases of cancer of the lung had occurred in 103 autopsied cases with asbestosis on 67 record as of 1938 11.66 The same year Lynch and Smith of South Carolina reported another in a year fatal case of 62 men The man asbestosis with lung cancer had begun work with asbestos 15 years beforhee died and had worked with asbestos for 13 years The malignancy of the Jugs was so extensive that no definite foons et origin could be positively determined The authors reviewed other literature on lung cancer with asbestosis noting that Nordmann considered lung cancer with asbestosis an occupational disease The authors reported that 2 of the 7 cases of lung cancer they had seen at autopsy over a 12 year period were in people with asbestosis Such people were a very small minority of the total number of autopsy cases During the past twelve years in 2343 consecutive necropsies we have oncountered 7 cases of primary lung carcinoma including the two asbestosis cases Among these necrop- sics are 35 showing some degree of asbestosis In the majority this is a minor finding and not the cause of illness or death in a few the con- dition is advanced Including all necropsies and all lung cancer cases the evidence of primary pulmonary carcinoma in our necropsy service over this period is 0.3 percent . Among the asbestosis cases 35 the incidence of lung carcinoma 2 cases is approximately 6 percent The authors did not conclude that the figures con- stituted significant evidence that the lung cancer rate was higher among asbestotics due to the small number of cases involved Their finding of an unusually high rate of lung cancer with asbestosis was strengthened by the fact that similar observations had been ce red in Gray and England In 1940 Koelsch in Gwany reported two cases of asbestosic with lung cancer giving no details of occu- pational histories and Wedler in 1941 Two also more were cases reported by Linzbach 70 in Germany One was in a man of age 61 exposed for at least 3 years to asbestos No details of the other case were known Also in 1941 two more cases of asbestosis with lung cancer were reported in Quebec in men who were 50 and 57 71 20 years In both and had each worked with asbestos for over cases from Canada the authors described the tumors as epithelioma pulminaire though they were believed to have originated in the lungs not the pleura In both cases there was extensive malignancy of | the pleura . In 1942 the lengthy book Occupational Tumors and Allied Discases was published in the United States by Dr. 72 W. C. Hueper Hueper had begun his research on cancer in 1925 in Chicago By 1942 he had established himself as one of the leading American authorities on experimental toxi- cology and carcinogenesis with dozens of studies and books on a wide range of substances used in industry Hueper appraised the evidence on asbestosis and lung cancer thusly An evaluation of the evidence presented reveals certain features connected with these cases which are suggestive of an occupational causation dence of lung cancer in There is an inciasbestosis of the lung which is definitely excessive The relatively smail number of necropsics on which this conclusion is based represents an urgent indication for more extensive post morton examinations in cases of as- bestosis especially considering that pul- monary malignancies seen in previously reported cases were in several instances very small and were coincidental observa- tions A second point favoring en Industrial origin in the young age of velable portion of the cases thus an far recorded and the relationship existing . between the time of exposure exposure to asbestos dust and the manifestation of the neoplasms throughout the entire series The third factor consists in the shift of the histological types observed ... and in the multicentric development of two Nordmann and Gloyne and possibly even three Lynch and Smith of these pulmonary neoplasms The relatively small number of asbes- tosis carcinomas of the lung reported does not disprove an occupational origin . of this condition Previous experience with other industrial ncoplasms lung cancer of the Joachimsthal miners and lung cancer of the chromate workers shown that such isolated cases may has represent the first warning of a subsequent appearance of large numbers of similar tumors of undeniable occupational derivation . He went on to discuss medico and social as- pects and to urge wide ranging studies of the cancer risks of asbestos work Asbestosis carcinoma of the lung is not included in any group of occupational tumors recognized by any country The evidence presented is sufficiently serious and the number of persons exposed to the suspected causative agent large enough to indicate a thorough and extensive clini- cal statistical and experimental investi- gation of the incidence and causative interrelation of asbestosis and pulmonary . carcinoma In view of the fact that several of the states with many large asbestos plants do not include asbestosis asbestosis among compansatory occupational discases this study is even more urgent Such a condition militate against an offective hygienic control of an important industrial hazard and impedes the collection of per- timent and essential information in regard to the incidence nature and potentialitics of an occupational disease growing steadily in general significance Workers dying from asbestosis should be subjected to a postn^rtem examination including a histological study of the pulmonary lesions as multiple neoplastic manifestations in asbestosis may be mistaken for Luberculosis Lynch Holleb and Angrist in New York reported two more cases of asbestosis with lung cancer in 1942. The deceased were men worked applyingapplying insulation experienced before his death for over 20 years years The older one begining progressively progressively worse disability beginning beginning 15 although although for the last last 10 10 years of he was employed as a salesman and was not exposed to asbestos dust DyspneaDyspnea progressed slowly but steadily so that during during the last few years of life he was almost almost completely exhausted after climbing only only had frequent frequent frequent one flight of coughing of of stairs Ha especially severe occurred throughout The patient patient of facturer of of age of 23 years until a " his death products few by a manu- since since the the months before authors wrote authors wrote that that that in in a city city hospital hospital o ov ve err a a year period they had seen 50 brochigenic carcinomas comprising 2.4 percent percent percent of of all all r ro ou ut ti in ne e autopsies autopsies autopsies autopsies autopsies They They They They had had had soon only two cases pulmonary pulmonary pulmonary pulmonary of pulmonary asbestosis asbestosis asbestosis asbestosis asbestosis and and and ir ir both both there was lung cancer cancer present present present as as well well well appears appears to to the the earliest earliest earliest report report report report of of and cancer among among among insulation insulation insulation workers workers workers workers 29 On January 29 1943 1943 the the German government government government government declared declared declared declared asbestosis asbestosis asbestosis asbestosis asbestosis asbestosis asbestosis in in ccombinatoion mbination combination with lung cancer a compensable compensable occupational discase , acknowledging acknowledging acknowledging acknowledgin acknowledging acknowledgiacn knowlegdging that lung cancer occurs in clinically clincaly clinically clinically clinically slight slight slight slight slight 74 cases of of asbestosis asbestosis asbestosis asbestosis asbestosis as well as in well developed asbestosis . Thus Thus the citationcs itations of this healin -180-180 hazard in the medical literature since 1938 by Nordmann Hornig Baader Linzbach and Wedler -- resulted in the German government formally recognizing this occupational disease within a period of 5 years Germany's tradition of industrial disease compensation stretches back to 1884 German Industrial Insurance Act The U.S. with private insurers and 50 different state worker's compensation laws has still not fully caught up with the standard of compen- sation that Baader described in practice in Nazi Germany in 1939. Hueper wrote in 1942 that 24 states in the U.S. still did not hold employers liable for diseases workers 72 contracted as the result of conditions of their employment In 1943 Hueper was no longer uncertain about the occupational origin of lung cancers with asbestosis He had no way of knowing that the German government had for- mally recognized lung cancer with asbestosis as a compensible discaso This is from an article on occupational and environmental cancer in the 75 for the Control of Cancer Bulletin of the American Society Asbestosis cancer of the lung is the most recent newcomer among occupational cancers 01 this outan First described in 1935 there are now 18 cases of this industrial - cancer on record observed among asbestos workers States in England Germany and The latter contributed the United 5 cases Inasmuch as the asbestos industry is most extensively developed in this country asbestosis cancer of the lung has for us a special hygienic and sociologic significance 2: Hueper urged that industry take action to control occupational cancer saying among other things Industry should devote considerably more effort than heretofore in determining the cancerous or noncancerous nature of their numerous products which may be suspected on general grounds in cancerigenic respects ... Industry should make serious attempts to eliminate all potentially cancerigenic agents from further use by the development of suitable substitutes To the asbestos insulation manufacturers in parti- cular and the asbestos industry in general he might as well have said Go into some other business for the sake of your workers and customers H. W. Wedler in Heidelberg filed a report in 1943 which mentioned pleural breath with lung tumors tumors with asbestosis in the same 76 as an occupational disease He reported that in Germany a total of 29 necropsies had been performed on workers with asbestosis and there were 4 with lung cancers and 2 with pleural cancers Wedler recalled that Gloyne had also reported finding a case of pleural cancer with asbestosis in 1933 In a survey of the world literature Wedler found a total of 92 reported necropsies necropsies of patients with asbestos disease in which 14 malignant lung and pleural tumors werc found 168 This far exceeded the prevalence of lung cancer normally found in the general autopsy statistics 2-63 accord- ing to Wedler There were probably no figures available for -60- 1 the incidence of primary pleural tumors at autopsy since these were extremely rare No pleural tumors would have been expected in a random series of 92 autopsies Wedler noted that the histology of lung cancers among asbestotics was different in general from the histology of lung tumors usually seen the tumors appeared most often in the lower portions of the lungs where asbestotic changes are also most pronounced the period from onset of exposure to asbestos dust until evidence of cancer appeared was 12-42 years the youthful ages of some of those afflicted was striking And an unusually high proportion of females in the series also pointed toward an occupational disease since women comprised a majority of the workforce in asbestos plants ordinarily lung cancer was 3 to 4 times as prevalent among men as among women Wedler concluded that cancer of the lung in asbestosis was a legally justified disease for insurance claims It is significant that Wedler and Ilucper submitted papers that were published at nearly the same time in Germany and the United States August 6 and June 1943 respectively They were obviously not corresponding with each other during the Second World War Yet both authors surveyed the world literature and came to the same conclusion Jung cancer with asbestosis was an occupational disease -61- A summary of Wedler's article by Gloyne was published the following year in the British journal Bulletin 77 of Hygiene Homburger at Yale published a report of three more 78 cases in the American Journal of Pathology in 1943 The deceased were men aged 43 and 45 and a woman of age 49 One had been exposed to asbestos for 5 years one for 20 years and the last for an unknown period Homburger's paper con- tained excellent tabular presentation of the literature on asbestosis with lung cancer Homburger reported that from 1918 to 1938 his laboratory had conducted thousands of autop- sies and found asbestosis in 8 lung cancer was found in 4 of them a remarkably high ... association of the two condi- tions The Journal of the American Medical Association carried an 77 1944 The editorial Environmental editorial warned that Cancer On November 25 The largest and most important group of environmental cancers is represented by occupational cancer elicited by exposure to chemical and physical agents in the course of regular occupations ... The agents known or suspected to cause occupational cancer die asbestos " The article said that 5000-9000 cases of occupa- tional cancer had been recorded and that there was clearly reporting of cancers attributable to occupation investigation of occupational cancer was urged Organized - 2 - 1 The benefits from such efforts will be not only the early detection and improved prognosis of cases of occupational cancer but also the prevention of industrial cancer by the elimination of exposures to cancerigenic agents In 1947 Kennaway and Kennaway published a report on lung cancer in Great Britain From a search of death certificates of lung cancer in males between 1921 and 1938 they found 8 with asbestosis listed as well They were unable to obtain satisfactory figures on the number of persons occupationally exposed to asbestos but believed the number of lung cancers was probably greater than would be expected for the number of workers exposed One of the cases they found was a boiler and pipe asbestos coverer The following year the British pathologist Cureton reported a case of lung cancer with asbestosis in a woman who died at the age of 37. This woman had worked for 7 years in a factory making asbestos pipe covers starting at the age of 15. That asbestos insulation manufacturing was hazardous was supported by the additional note that the patient's aunt had worked in the same factory and died at 40 of asbestosis The author considered the woman to be unusually young compared to others that die of squamous cell carcinoma of the lung Merewether Chief Inspector of Factories produced cumulative statistics for autopsied cases of asbestosis in England from 1924 to 1946 in his annual report for the year 1947 In a total of 235 cases cancer of the lungs or pleura was present in 31 an incidence of 13.23 This was contrasted with the incidence of such cancers in silicotics 1.32 and the general adult population 1.08 In other words the expected number of lung cancers in a series of 235 would be 2 or 3 0.01 x 235 and instead 31 occurred The chance that as many as 31 . lung cancer cases in 235 would occur if their real likelihood were only the same as that of the general population 18 is remote -- less than 1 in a million This Merewether report was often cited in later papers The large number of asbestosis cases with lung cancer pointed unmistakably to an occupational origin of these cancers Lynch in South Carolina updated his figures on 83 asbestosis in 1948 with a report on 40 autopsied cases In the 5 new asbestosis cases one had lung cancer The total incidence of lung cancer was thus 3 out of 40 or 7.5 This was contrasted with the % general incidence of lung cancer seen in the authors previous ten years experience The authors also reported that they had identified another case of lung cancer in a patient still living in a man who had been exposed to dust irregularly for twenty years asbestos " All three deceased cases of asbestosis with lung cancer had moderate and advanced fibrosis of the lungs Most of the 40 asbestosis cases had pleural fibrosis for all grades of asbestosis . A 1949 Editorial in the Journal of the American Medical Association cussed Merewether's Asbestosis 84 findings and The Cancer of Editorial the Lung discited epidemiologica and experimental evidence suggesting that asbestos workers were at increased risk of lung cancer It characterized this risk as probable and stated that workers in consuming industries should be considered at risk along with manufac- turing plant workers Since some 20,000 workers are employed in the producing industries of this country and Canada and many additional thousands in various consuming industries increased attention to this probable occupational hazard of cancer of the lung by the medical profession is desirable . Wyer's report on 115 deaths from asbestosis in England also offered statistics on the 48 lung and pleural cancer There were incidence of accompanying 17 such cancers in all at least one of which was a pleural cancer Lung and pleural cancer were referred to as one entity The proportion of pul- monary cancers in the series was therefore 14.8 percent Seven others died with canceorf other organs No doubt about it the author considered pleural cancer in the same class with lung cancer an occupational disease His discussion concerned how ashestos caused cancer not whether it did 38 was striking that the pulmonary cancer cases had the longest exposure to asbestos and died the oldest of any subgroup in the series As previouslypreviously noted the average age at death for the hire 115 cases wh 40.8 years and the average duration of asbestos exposure was 10.4 For those with pul- monary cancer the average age at death was 52 years and the average duration of exposure was 17.3 years One possible explanation is that these individuals had the least dusty jobs and that they therefore lived long enough to develop cancer because they were not killed off sconer by asbestosis This thought might have occurred to a thoughtful student of the - 65 - Hucper Chief of the Environmental Cancer Section of the National Cancer Institute wrote in 1951 that most researchers had concluded that there was a 85 asbestosis and lung cancer causal relationship between Although Warren rather recently maintained that the connection between asbestosis and lung cancer is of coincidental nature the actual existence of a causal relation appears to be very likely Lecoeur Koelsch Saita Hueper Teleky Editorial Gross That year of Tabershaw of New York published a list of 86 occupational diseases covered by social insurance in West Germany One was Asbestosis with diminished capacity to breathe and impaired circulation or associated with cancer of the lungs Coverage was not limited to any group of asbestos workers Another fatal case of asbestosis with lung cancer was reported in New York in 1951 in a year man He had worked as a pipe coverer starting in 1940 Por the next four and a half years he continued to work as a pipe coverer in shipyard where he again used asbestos only During this time he was told to wear work while working but neglected to do so and complained that the smell always made him sick Aside from illustrating the problems of implementing respiratory protection in the carly 1940's this story shows that at least in one shipyard in the United at that time the authorities knew that asbestos insulation work was hazardous The cause of death was lung cancer with the possi- bility of multicentric origin with metastases to the kidney brain and liver The authors one of whom had reported 2 a earlier cases of these complications in inutators introduced their report with a good revieowf earlier literature They concluded that it was time to compensate asbestos workers for occupational cancers The importance of carcinoma in cases this association of asbestosis is of indi- cated from the review of the literature presented This association emphasizes the hazards of industrial exposure the compensability of the cancerous process as well as asbestosis and the need of careful preventive measures tosis Owen in England with lung cancer in reported another case of asbes- " " "fl 1951 The victim died at age 39 and his only exposure to asbestos had been a month job in a London asbestos factory twenty years before A tabular presentation of the literature on cases of lung Behrens cancer with asbestosis was published in 89 in Germany He reviewed the cumulative 1952 by world literature for the frequency of lung cancer with asbestosis and compared that with the reported rate of lung cancer with silicosis For asbestosis he found 509 autopsy case reports in which 44 14.25 had cancer For silicosis there were only 35 cases with lung cancer out of 2,475 autopsy reports 1.4 known to the author That year Cartier reported 2 casun of pleural 30 mesothelioma among Canadian asbestos miners and mill workers Hardy of the Massachusetts Institute of Technology referred to prior case reports of asbestosis with lung cancer in an insulation vorker and in a man who worked for seven years sorting and cording asbestos fibers foes . intended for insula- These cases have particular signifi- significance since there are nearly 10,000 workers exposal to varying amounts of asbestos in American industry many of them in some operations not properly safeguarded against a potential carcinogen Hardy used the term potential carcinogen though she seemed convinced by Merewether's 1947 statistics The use of such an expression docs raise the point that whether one was inclined to accept the carcinoginicity of asbestos as proven or await further data before drawing a conclusion one had to already acknowledtghee immediate and pressing need for providing warnings and improved safeguards to protect asbestos- exposed workers such as insulators Isselbacher and workers reported another case of asbestosis with lung cancer in a year 92 worker in 1953. The man was a chain smoker asbestos mill They exten- sively reviewed the literature They pointed out that in Merewether's 1947 report of 31 cases 9 29 were women This was contrasted with general population rates of 4 to 10.3 The higher figure in asbestosis supports the theory that asbestos particles act as carcinogens A second case of lung cancer with asbestosis was noted as an addendum to the article The patient was a year contractor's helper whose work since age 17 consisted of cutting and sawing asbestos board to insulate pipes boilers and refrigerators The man was a 1 pack cigarette smoker Weiss in Germany reported a case of pleural cancer with asbestosis in 93 worker The man's a man who had been an asbestos exposure spanned 22 years the insulation latter part of it in a supervisory role Thirty years elapsed The author referred to2 earlier cases of pleural cancer with asbestosis seen by Wedler and noted that tumor tissue from his new case contained asbestos bodies Weiss con- sidered pleural cancer confirmed as an occupational cancer of asbestos workers In 1954 Leicher in Germany reported a case of mesothelioma peritoncal 94 with asbestosis in an asbestos . factory worker The man began asbestos work in 1919 and died 33 years later Asbestos dust was positively identified in the tumor Leicher considered the cancer to be of occupational origin noting that such tumors were very rare in the general population Earlier reports had listed metastatic tumors in the pleura and peritoneum in cases of asbestosis with lung cancer Reports of primary tumors of these sites suggested that some of these carlier cases may have been misdiagnosed primary tumors not metastases Bonser and workers reporting in 1955 on mortem examination of 72 factory worker with asbestosis asbestosis in the ; 0C found 2 pleural and 4 peritoneal dancers Lung cancer U.S. was also common Cancer arising primarily in the pleura lungs or bronchi was present in 26.1 per- cent of males and 8.7 percent of females This significantly higher incidence in malcs may be accounted for by the fact that 7 women died before the cancer ago ... It was noted that the degree of fibro- - (1 Nee sis was rather cancer than in less in the lungs those without with : Also in 1955 Doll in England reported that of 105 : workers asbestos textile examined at 18 had lung cancer Follow study necropsy from 1935-1953 of 113 men with at least 20 years exposure showed that 39 deaths had occurred whereas only 15.4 would have been expected based on general mortality rates The excess was entirely due to lung cancer 11 against 0.8 expected and other respiratory and cardiovascular disease 22 against 7.6 expected Doll noted that all of the workers with 20 years or more exposure had been first exposed before the implementation of the asbestos industry regulations Though he had no data on the fate of workers with 20 years exposure under the improved conditions Doll believed the cancer risk of these asbestos workers had become greatly reduced after 1933. As noted by Dressen and workers in 1938 the British asbestos textile mills used the same asbestos that was predominantly used in the American asbestos industry the chrysotile asbestos from Canada details Lynch and for cases of Thomas in asbestosis with South Carolina lung cancer in reported 97 1955 In a discussion of the paper Thomas was asked What is the present industrial compensation status of the coexistence of these two diseases The reply was that the courts were beginning to recognize that lung cancer was an occupational hazard of workers who developed asbestosis We have seen cases in which at least partial compensation has been allowed It was thought they might have not died quite as fast if they had not gotten carcinoma and that the evidence . for asbestosis producing cancer though not proven was sufficinetly questionable so the cases were judged in favor of the plaintiff or at least partially so Hueper authored a Public Health Service monograph 98 on environmental causes of lung cancer in 1955 By this time he noted that there were 99 cases of asbestosis cancer of the lung on record though there may have been some duplication of cases reported by the various authors Hueper was also struck by the large proportion of women with asbestosis and lung cancer Equalization of carcinogenic exposure as represented by asbestosis for the two sexes thus resulted in a trend toward equalization of liability to lung cancer He went on to declare that many asbestotics had died before they had time to develop cancer citing Merewether's 1947 figures It is of 128 of importance to note that the mean age noncomplicated cases of asbestosis was only from 44.2 this years Morewether observation that some One may conclude of these indi- viduals apparently died their lung cancer had a Linzbach and Wedler from asbestosis before chance to develop Thus Hueper who was quite familiar with the lung latency period before tumor development from occupational exposure to carcino gens recognized the significance of the older average age at death of asbestotics with lung cancer compared with other asbestotics It is noteworthy that Hueper credited Linzbach and Wedler with having made similar observation in their 1941 * The average age of the 31 cases of asbestosis with lung cancer reported by Merewether was 52.1 article Bonser and workers had also alluded to one fourth of the women in their series dying before the cancer age of other causes One could infer from Hueper's statement that as conditions in asbestos factories were improved so that workers would not die of asbestosis before they reached age 50 their lung cancer rate might go up instead of down This questions could have been resolved by a mortality study of exposed asbestos workers A relatively large group of such workers had long existed and their exposure to asbestos had changed little since the turn of the century asbestos insulation workers Two doctors in Pennsylvania reported that over 16 years they had seen 27 cases with asbestosis at autopsy or in surgery surgseurrgeyry surgery surgery surgery surgery surgery These appear to have all been asbestos textile workers and 13 of them about half also had lung cancer In all of these the primary site of tumor growth was in the lower lobes of the lungs reported Another case of in an insulation asbestosis and lung cancer was 100 worker in 1960 also in the U.S. This man had been a heavy smoker and the authors suggested that more attention be paid to smoking histories and the possible role of smoking in the lung cancer mortality of asbeste hers In 1960 Wagner of South Africa reported 23 cases 101 of pleural mesothelioma A history of occupational or environmental exposure to crocidolite asbestos in the North West Cape Province where it was mined was established for 32 of the 33 cases Most of these people had not been occu- pationally exposed to asbestos but had lived near the mines and roads where asbestos was hauled and mine tailings were used in road construction Late that year Keal reported on 23 women and 19 men treated as patients with asbestosis in one hospital in London Of the 15 men known dead 10 had died with lung cancer and 1 was thought to have had pleural mesothelioma The men with lung cancer included 1 asbestos lagger and 2 boiler coverers The 4 women in the series that developed lung cancer were all smokers The most surprising finding was that 8 of the women had cancer of the peritoneum exposure Keal noted that the lapsed period from onset Shorter was lenger on the average for the lung cancer of cases under 25 years than the cases with peritoneal cancer 30 years He also called attention to two cases in which cancer developed long after cessation of occupational expo- radiological sure and in which there were no symptoms or changes to indicate asbestosis Both had asbestos bodies in their sputum but showed no other sign of asbestosis Keal pointed out that these cases had definite medico interest rs asbestosis in these two cases was very slight yet tha por ous appeared to have died Frus occupational cancers Real also noted that 10 of the 42 cases his series had first been exposed to asbestos after 1930 when asbestosis was recognized as an industrial disease and measures were taken to prevent it - 73- In 1962 the British began to develop - 103 mesotheliomas of the pleura and peritoneum a register In calling of for information Smither and workers acknowledged that There appears to be no correlation between the severity of any pulmonary asbestosis and the occurance of these tumors In a number of cases the exposure asbestos dust appears to have been minimal and the only histological evidence of asbestos exposure is the presence of a few asbestos bodies and fibres in the lung tissue However a detailed occupational history has in nearly all cases revealed some contact with asbestos fibre McCaughey in Belfast had first reported 15 cases of pleural further in mesothelioma in 1958 which he investigated 104 1962. Lung sections revealed numerous asbestos bodies in only one of these cases Detailed occupational histories were obtained for 9 of the 12 cases in which asbestos bodies were present in the lungs In 4 of the 9 there was a clear cut history of intermittent exposure to aslante In the other 5 there was no krosni asbestos occupation but all had jobs tably broncht with with with alentos alentos alentos in the shipyard which inevi- them into intermillent contact work work -- for example shipyard plumbing anu furnace repairing The authors went on to deserike a more recent case of mesotha- lioma in a year man For all his working life he had been an engine room fitter and had worked for periods each year cleaning down and dismantling machinery which had been embedded in asbestos insulation The asbestos exposure in shipyards arose from use of insulation and this report suggested that not only ' insulation workers but workers in other trades were at risk of developing mesothelioma of the pleura In a study of workers employed in an Ohio asbestos plant as of 1938-1939 followed through 1960 Mancuso and Coulter found an excess of deaths from asbestosis . lung 105 cancer and cancer of the digestive organs and peritoneum There were 19 lung cancer deaths compared with 5.6 expected based on general population mortality data There were 18 deaths from cancers of the digestive organs and peritoneum compared with 8.1 expected There were 3 deaths certified as peritoneal cancer 0.08 expected and two others were iden- tified by examination of available histological slides out of a total of only 195 deaths in work force by 1960. The authors considered their findings conservative estimates of excess risks in part because the government data base on the workers did not distinguish production workers from office staff and so the total plant population had to be taken as the exposed group The government dota base was also insufficient to dhuructerize the workforce by duration of exposure The authors noted that over 2/3 of the workers were aged 15-34 in 1938 and the War and related events affected the pattern of continuity and duration of employment of the workers By the end of 1963 the Ministry of Labour had knowledge of 584 persons in Great Britain whose death certifi- cates mentioned 106 asbestosis The proportion with lung cancer also listed had risen from 13.2 in Merewether's 1947 report to 25 in 1963 In 1964 Sclikoff and workers reported on 55 the mortality of building trades insulation workers There were substantially more deaths observed in these workers than would be expected from general population mortality figures Of 632 insulation workers who entered the trade before 1943 and were traced through 1962 forty died of cancer of the lung or pleura whereas only 6.6 such deaths were expected Three of the pleural tumors were mesotheliomas there was also one peritoneal mesothelioma Four mesotheliomas in a total of 255 deaths is an exceedingly high incidence for such a rare tumor in addition an unexpectedly large number of men died of cancer of the stomach colon or rectumi 29 compared with 9.4 expected The authors noted that smoking habits alone could not account for the high rate 17.6 of lung and pleural cancer deatus in th two 0175 Subsequent study be Selikoff and Hammond showed that asbestos workers who smoke cigarettes are about 8 times as likely to develop lung cancer 107 as they would be if they did not work with asbestos It was calculated that asbestos workers who smoke cigarettes are 92 times as likely to get lung cancer as they would otherwise be This makes lung cancer far more common among insulators who smoke than those who do not The risk of mesothelioma and cancer of the lower gastrointestinal tract is high in asbestos workers 61 of smoking habits regardless - 16 - Newbouse and Thompson reviewed the records of London Hospital Hospital through 1964 108 on mesothelioma Eighty cases were confirmed by necropsy or biopsy and 76 full . residential occupational histories were obtained by interviews with surviving relatives Forty 52.6 had a history of occupational or domestic living in the house with an asbestos worker exposure In comparison only 9 out of 76 11.8 control patients from the same hospital suffering from other diseases had such exposure Among those with no evidence of occupational or domestic exposures 11 of the mesothelioma cases had lived within half a mile of an asbestos factory compared with 5 of the control series Vv 4 The associations of occupational domestic and neighborhood exposures to asbestos and the fatal disease were all statis- tically significant The mean interval between first asbestos exposure and death varied from 29.4 years among the factory workers to 48.6 years among the neighborhood cases Out of the 31 patients with occupational exposure only 10 were in jobs covered by the Asbestos Industry Regulations of 1931 There were 8 mesothelioma cases classed as laggers and insulators k rid ar of roachold roachold end environmental environmenetnviraonmelntal environmental cancer from asbestos illustrate the seriousness of the hazards of asbestos making it all the more perplexing that the occupational hazards were not more carefully studied long ago Environmental hazards such as exist in modern buildings with sprayed asbestos ceilings would never have come into e tence had the occupational asbestos problem been properly 7 studiod in the 1930's 1940's or 1950's Likewise the families of asbestos workers would have been less exposed in the past had the hazards in the workplace been better recognized Anderson and workers recently counted 37 reported cases of household contact mesothelioma in the literature 122 4 more and added The occupational hazards of handling asbestos are so great that even one month or less plant has been shown to cause cancer of work in an asbestos deaths among workers Seidman and workers have recently reported on the lung cancer mortality of workers briefly employed in a plant making asbestos insulation The plant opened in New Jersey in 1941 and those employed between 1941-1945 were followed up through the end of 1974. The ratio of observed to expected deaths from lung cancer was 2.24 for workers with less than one month exposure 3.47 for those with one month exposure 6.15 3.57 and 5.52 for those with 2 3-5 and 6-11 months exposure respectively and reached 7.84 for workers with duration of employment of one year The excess of lung cancer deaths was first observed 10-14 years after onset of work and increased significantly with Ionuar observation Overall there were 157 cancer deaths in this work force through 1974 compared to 50 expected cancer deaths It is now becoming apparant that the proliferation of asbestos in society has resulted in widespread hazards to workers only incidentally exposed to asbestos Menck and Henderson have recently identified excessive rates of lung cancer among clothing ironers plasterers dry wall workers electricians and plumbers they suspect 110 that asbestos of recognized asbestos workers alone is enormous The Ill present situation was assessed recently by Dr. Selikoff Cancers now being seen are a legacy of past inadequacies The USPHS has estimated that there are some 1,000,000 Americans who : are either currently working with asbestos or previously regularly worked with the material asbestos workers In addition millions of other workers have or have many had less intimate but still substantial as in the construction industry ship- exposure yards brake repair work etc. Unless we learn to intervene in what seems to be the inevitable development of asbestos cancers among those exposed in the past and assuming that asbestos cancer rates remain about the same approximately 400,000 40 will die of cancer in the course of the next 45 years or so 200,000 of lung including an estimated cancer and perhaps 50,000 of pleural or peritoneal mesothelioma Development of Literature on Excess Cancer Risks - by Site of the Primary Cancer As asbestosis caused the deaths of a decreasing fraction of asbestos workers at early ages before age 50 or so the competing cancer risks became increasingly evident As noted lung cancer was first reported in 1934 asbestotics and it was recognized as an occupational among disease of asbestos workers as carly as 1938 in Germany and 1943 in the U.S. Pleural mesothelioma was first reported with asbestosis in 1933 and was recognized as an occupational disease by the early 1950's in Germany Peritoneal mesothelioma was first reported with asbestosis in 1954 An excess of gastrointestinal cancer among a defined population of asbestos workers was reported in 1963 and was firmly established by - 19- about 1973. In 1973 reports appeared that linked occupa- tional of the to asbestos with excessive incidence exposure 112,113 larynx There appear to be other sites where of cancer ; asbestos workers also have an excess risk of developing cancer though the sites of major excess risk have by now been identified It is remarkable that a group of workers could have so many sta- tistically significant excess rates of so many fatal diseases -- competing risks as the epidemiologists say It is obvious that a worker who is at risk of 6 fatal discases recognized at different times in history should have been warned as soon as there was cause to suspect that he or she was at risk of the first fatal disease Whether an asbestos insulation worker dies of asbestosis mesothelioma or cancer of the larynx should not alter the manufacturers liability for the occupational disease - 80 - What Could American Asbestos Companies Reasonably Be Expected to Have Known and When Pliny's writings tell us that the Romans discovered the disease asbestosis in slaves who weaved asbestos The managers of asbestos factories at the turn of this century should likewise have been able to see that their workers were becoming stricken with a progressive fatal respiratory disease The literature shows that the American asbestos industry realized health problems existed in U.S. factories before a case of asbestosis was published in the American litera- ture 1930 In the introduction to their paper published in 1935 Lanza and workers said that their investigation had been requested in 1929 by officials representing the asbestos industry in the United States From Wood and Gloyne's 1934 description of asbestosis one can visualize the senior workers in the 28 asbestos industry at that time The distress occasioned by constant breath- lessness is so great that the disease might be described as monosymptomatic It is the patient's first and last complaint In the earlier stages dyspnoca is only apparent during exertion - I found I could not hurry to work in the morning -- in the later stages the act of undressing or even the effort - required pant for for speech breath ... may cause the patient to Malnutrition is very evi- dont in the terminal months when the patient may pass into a condition of extreme cachexia * dyspnea dyspnoea -- difficult or labored breathing The American College Dictionary Random House New York 1956 ** cachexia -- general ill health with cmaciation due to a chronic disease as cancer Ibid In 1973 U.S. government scientists reported a much increased death rate from respiratory disease among both lung cancer and malignant 114 asbestos manufacturing workers The majority of these deaths occurred within 5 years of termi- nation of employment in the asbestos industry Twenty out of 45 lung cancer deaths and 41 out of 52 pneumoconiosis deaths occurred within this five year interval The report which was introduced into the Congressional Record by Senator Taft of Ohio continued A breakdown of pneumoconiosis deaths which occurred within five years since termination of employment may be seen in Table 6. The majority of these respiratory deaths occurred within one year since termination of employment including 17 deaths which at an average age of 53.8 years occurred within six months of termination ... Lung cancer and pneumoconiosis deaths which occurred within six months of ter- mination of employment are evaluated further according to month intervals since termination of employment Table 7 The majority of both lung cancer and pneumoconiosis deaths which occurred within six months took place within three months of termination Note that five lung cancer deaths and eight pneumoconiosis deaths occurred within one month The workers in this study manufacturel asbestos textile friction and packing products in Pennsylvania during the period 1940-1962 and their mortality was followed up through the end of 1967. Of the 13 lung cancer and pneumoconiosis deaths that occurred in this work force in the 1940's 9 occurred within six months of termination of employ- ment In the days before workers compensation unemployment compensation and welfare and before formal recognition of the hazards of asbestos there was great economic pressure for asbestos workers to stay at their jobs as long as it was physically possible for them to work Taking the statistics for the 1940's from the above study as a guide one can only conclude that many of the senior workers in the asbestos factories of the r 1920's and the years of the Great Depression were severely afflicted with asbestosis and some worked virtually until the day they died Many of them died in their forties many others in their thirties It is hard to imagine that the condition of these people and their deaths went unnoticed by their employers regardless of the extent of the medical literature in the early part of this century The world medical literature has long been acces- sible in this country of course Foreign journals were carried in the better medical libraries around the country Though some of the better literature on estos cancer was German that should have presented little obstacle to American scientists who were encouraged in college to learn German so that they would be able to read German scientific papers and patents etc. From 1927 until the early 1950's the index of the world literature was called Quarterly Cumulative Index Medicus This was published by the American Medical Association in Chicago Much of the material published in the medical journals worldwide though not all of it was listed by subject in the Index For example Wedler's important paper on asbestosis with cancer of the lung and pleura in August 1943 was listed in the Index about one year later The Index also recorded that the paper had also been summarized in another journal Thus at the height of World War II an American reader could look up asbestosis in the Index be referred to pneumoconiosis and find the reference for Wedler's paper of the year before in the German Medical Weekly Aside from the Index the best sources of references to medical papers were other more recent publications Many of the authors even some presenting a single case report would present a fairly good review of earlier work in the field Finally the 1936 report by Jones shows that asbestos manufacturing firms were jumping state lines to avoid workman's compensations laws Thus in a number of states the cost of running an unsafe workplace was becominga major operat- ing expense for the asbestos industry The asbestos industry has not only failed to make reasonable cfforts to discover and control the hazards of its products It has forcefully opposed such efforts North Carolina asbestos textile firms sabotaged the Public Health Service study in the late 1930's by firing 150 out of than 600 workers workers suspected of having asbestosis less The cozy relationships that the American asbestos industry has set up with universities and government officials descrile were descrile by Now Now Hauser Hauser writer Paul Frodeur as the medical.116 industrial complex in his book Expendable Americans More - 84 - than half of Rachel Scott's chapter Science The Drab and Slut of Industrialism was spent discussing the publication , of red for the herrings in the scientific literature to 123 asbestos industry Two other scathing buy time accounts on the asbestos industry in the U.S. and Canada have been published by the Health Policy Advisory Center of New York 118 in its Bulletin The granddaddy of occupational health coverups however is the coverup by the asbestos industry of asbestos hazards ... A historical review of the research papers on the subject since 1900 reveals industry's strategy Ignore the problem then minimize or deny it and when all else fails try to shift the blame An example of an industry study is a paper by Enterline and Henderson at the University of Pittsburgh of retired asbestos in Manville New factory 11w9 orkers including those Jersey This paper is described from in a a plant new document on asbestos from the National Institute for Occupa- 50 tional Safety and Health part of the U.S. Public Health Service Of 802 deaths only one mesothelioma had been recorded in the several plants investi- gated tion by In contrast a subsequent investigaBorow et al 1973 found 70 cases of mesothelioma from only one of these plants The discrepancy was due to methodological variations for example Enterline and Hen- derson 1973 had limited their investiga- tion to men of 65 or over while many of the mesothelioma cases reported by Borow et al 1973 had died before that age In the medical literature the asbestos industry has been accused of adversely influencing two separate attempts to investigate the health hazards in the mines and mills of 1,45 Canada In my own experience of urging government agencies to increased provide public and worker protection from asbestos the has bitterly opposed any regulation of its activities industry A recent example is a petition to the Consumer Product Safety Commission which I helped draft for the Natural 120 Defense Council The petition asked the agency Resources to ban the use of asbestos in widely sold wall taping and spackling com- pounds In spite of the fact that the use of such products entails long term indoor contamination and short term exposures to asbestos levels in excess of those now allowed in asbestos plants and despite the fact that these products can be made . without asbestos and the use of asbestos in these products con- stitutes only 1 percent of the sales of asbestos in the U.S. - the asbestos industry trade association Asbestos Information Association of North America asked the govern- ment to deny the petition This is only one recent example of the asbestos industry's refusal to accept a decline in sales in protect the health of its customers REFERENCES Demy N.G. 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