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FILE NAME State of the Art Literature SAL DATE 1933-34 DOC SAL019 DOCUMENT DESCRIPTION Journal Article - A Memorandum on Asbestosis /fi / 30 te TUBERCLE AN INTERNATIONAL MONTHLY JOURNAL DEVOTED TO ALL ASPECTS OF TUBERCULOSIS ea Published Monthly under the Direction of an Editorial Board Representative of All Aspects of Tuberculosis and Edited by S. R. GLOYNE M.D. D.P.H. +" he ies : F 4 ah tat. * Pspeaoe 7 RAMsBele . ad he fi Boney eep ww MP se Re a Loubou JOHN BALE SONS & DANIELSSON LTD 83.91 GREAT TITCHFIELD STREET WV 1934 <. p> oad Pay a ot Z4Y. af hdSAofaWe Se, aa a, iar Ry te 4, mre on - oo geo ee ayn2 ae af ame KO ne A ere,cig b feet t ras7, Set ey ce ee tes ee November 1933 A MEMORANDUM ON ASBESTOSIS 09 Se important to note that the inhalation of 10 gas tends to mise the basic e pressure and so to interfere with the circulation to the tissues This men interference was evidenced the estimation of the basic when the ration relapsed to 1sto 1 instead of the pressure normal to 1. Taber- Ce " culosis by reducing the area of lung tissues available for oxygenation oxygenation purposes diminishes the amount of oxygen carried by the blood and as a result interferes with the oxidation of the penultimate products of digestion giving rise to toxins which by themselves tend to raise the basic pressure For this reason whether the basic pressure be raised as a result of tuberculosis or by the inhalation of CO the fact that it was so raised gas or both together was an important factor in connection with the prognosis of such a case s 1 STEPHENS G. ARBOUR 1932 REFERENCE " Heart and Spicen in Health and Disease A MEMORANDUM ON . ASBESTOSIS By E. R. A. MEREWETHER M.D. One of HM Medirul Inspectors of Factories Great Britain INTRODUCTION This industrial disease of the lungs due to the inhalation of asbestos dust although only recognised and accepted recently as an entity of serious import has beeu during the past few years the object of much careful investigation in various countries In in legislative action to control the compensation of affected workers has Great Britain this culminated disease and to provide for the , It is timely therefore to pause to review the position in the light of all the knowledge obtained concerning the disease and to appraise the value of the preventive measures adopted considering critically not only whether they are adequate for the purpose but also whether they are No matter what the particular occupational disease necessary be such of the position is necessary from time to time in mtahye interests a bostuhrveoyf employees and employers for the reason that although ethically the provision of measures for the prevention and compensation of an tional disease is unassailable is none the less true that the imposioticocnupbaylegislative sanction of conditions of employment on an industry casts a definite financial burden not only on the industry as a whole but also on individual employers and employees Moreover since methods of manufacture are essentially fluid and changes in processes frequently result in a modification of the associated risk from occupational disease clearly the compensation law and the scope of the preventive regulations applied to the industry must be modified also from time to time.in time.in conformity with the altered risk In the case of asbestosis evidence already available is amply sufficient to demonstrate conclusively the necessity of particularising it as a com- 03453 70 ; TUBERCLE November 1983 pensatable industrial discase and of enacting regulations for the industry designed to control the incidence of the disease and ultimately to abolish it Asbestosis is new disease which illustrates only too clearly that the | march of civilisation does not solely confer benefits on the world but also harasses man with new problems and perplexities and with new diseases or by the dissemination of diseases long thought circumscribed The NaTURE OF ASHESTOS AND THE ASBESTOS INDUSTRY GROWTH OF THE Asbestos was known to the ancients as a substance believed to be of vegetable origin with unique properties it could be spun and woven to form a inflammable cloth For this reason and because of other attributes it was an early scientific curiosity and had an extremely limited vogne amongst the patrician element for some purposes as for instance funeral wrappings and lamp wicks yearsNo serious attempt to exploit commercially the resisting qualities of asbestos was made until the latter part of the nineteenth in 1876 in Italy and in 1878 in Canada quarrying of century when the mineral was commenced Some years elapsed however before difficulties in manu- facture were overcome and advantage taken of the obvious the mineral potentialities of Since then the increase in production has been remarkable In 1880 the world production of asbestos was little over 500 short reached to 35,000 short tons in 1900 to over 200,000 in 1920 and ttoonosveirt 430,000 in 1929. From 1910 to 1929 the world production of asbestos increased over fourfold The imports of asbestos all grades into the United Kingdom rose from 18.501 tons in 1922 to 33,520 tons in 1927 The figures for 1927 refer to Great Britain and Northern Ireland Of these quantities 8,844 tons and 3.794 tons only Thus the respectively were exported consumption of asbestos in this country trebled within five -- The fibrous minerals commercially known as asbestos are silice being combined with metallic bases maicly magnesium silicates the to a less extent calcium sodium or aluminium or iron and The term is a collective name applied to a variety of silicate tuinerals which differ from each other in chemical composition and physical properties but resemble in their finely fibrous nature and flexibility Their value one another facility with which they can be split up into long and depends dexible on the spinning and weaving on their resistance to heat and acids and fiobnresthefoirr insulating properties with respect to heat and electricity Varieties of asbestos possess these characteristics in differing degree Other of these minerals also find uses in industry properties Practically speaking all that goes under the name asbestos in is either fibrous serpentine or a fibrous mineral of the commerce hornblende which most important are crocidolite amosite and group of tremolite tine asbestos or chrysotile is essentially a hydrated silicate Serpen- little iron and almost of magnesium containing no calcium The hornblende varieties contain less magnesium and usually tuore calcium aluminium and crocidolite and amosite being mainly silicates of iron iron- The field of utility of asbestos products has rapidly expanded and day 03454 . : .- a : , 8 . {-" . . ~ i . November 1933 A MEMORANDUM ON ASBESTOSIS 71 is very large constantly new uses for asbestos are being found The mineral the yarn or the fabric composes or is incorporated in vast number of articles ranging from matches to filter pads from paints to rooting ales from high pressure jointing to electrodes and from linings to insulating materials in great variety The phenomenal expansion of the motor car industry in the past twenty years has caused a corresponding increase * in the demand for asbestos fabric brake linings asbestos composition cluten rings and latterly of moulded asbestos brake linings Many other examples will come to mind The number of workers employed in the quarrying of asbestos and in the manufacture of containing materials and articles is considerable but the industry is very small as compared with for example the coal mining industry and fortunately only a small proportion is exposed to risk from the inhalation of containing dust In 1929 in Canada which is responsible for 70 per cent of the world's production of asbestos 3.194 were employed in asbestos mines and mills and a further 351 | on the manufacturing side 1 In this countriyt is estimated that the number of workers so exposed in manufacturing processes lies between 2,000 and 3,000 It is therefore nearly comparable in point of zuuiber of workers exposed to appreciable risk from the inhalation of dust to a producing industry such as the refractories industry THE History of ASBESTOSIS AND ITS RECOGNITION AS A . Specific Industrial Disease Asbestosis may be defined as a specific occupational disease of the lungs caused by the inhalation of asbestos dust and characterised by progressive replacement of the essential active functioning tissue of the lung by inactive functioning fibrous or scar tissue It is essentially a pneumonokoniosis a ^...brosis of lungs caused by the inhalation of dust and therefore is in the same category as silicosis . which disease it resembles in some respects while differing considerably in others The first recorded case of asbestosis was that of a patient who died in 1900 in the Charing Cross Hospital London All that is known of this case is contained in the evidence given by Dr. Montague Murray before the Departmental Committee on Compensation for Industrial Diseases in 1906 2 The patient aged 34 at death had worked with asbestos for some fourteen years mortem examination revealed extensive diffuse pulmonary fibrosis with no evidence of pulmonary tuberculosis This man - stated that of the 10 men working in the cardroom when he went into it he was the only survivor all the others having died at ages round about 30 This Committee was unable to obtain any evidence of additional cases but in the same year 1906 Marchand and Riesal noted the presence of unusual bodies in the lungs of an asbestos worker 3 ; in the same year also in the French official Bulletin de l'Inspection du Travail 4 the high mortality in an asbestos textile factory is reported upon and considered as probably due to a pneumonokonicsis from the asbestos dust In 1910 following a death certified as acute pulmonary phthisis in an 1 anaes SRE Eyres grees 7 JT Ta ERE ce EL CUD Sih seh istry? oo weineses bok yar ' mi AE 72 TUBERCLE November 1033 asbestos worker and an unverified report that seven other deaths from phthisis had occurred in the same factory 5 a survey of the industry by the British Factory Department did not disclose any evidence of the existence of a serious health hazard in the industry nor were the replies to inquiries made to the Canadian Government suggestive of the existence of such a condition amongst the workers in the quarries and mills A the request of the British Home Office however Professor J. M. Beattie in 1912 conducted some experiments on animals and concluded that the inhalation of asbestos dust would cause a mild degree of fibrosis Although definite proof was not forthcoming at that time there were reasonable grounds for suspicion that the inhalation of much asbestos dust was to some extent harmful and so from then onwards the British Factory Department pressed for the installation of exhaust ventilation in the more dusty processes In 1914 Fahr demonstrated to the Medical Society of Hamburg 3 . the lungs of an asbestos worker with pneumonokoniosis and mentioned the occurrence of a large number of crystals in the lungs but did not describe them more closely In 1917 during the Great War the British Factory Department considered the matter again but no further evidence incriminating asbestos had come to light either at home or abroad and therefore no further action could be taken .It was not until 1924 that anything further of moment occurred in that year appeared a note by W. E. Cooke 6 concerning the death of an asbestos worker in which examination revealed not only extensive lesions of pulmonary tuberculosis but also evidence of pulmonary fibrosis of a diffuse nature which he attributed to the effects of asbestos dust This case was fully described by Cooke and Stuart McDonald in 1927 7 ] In the same year Cooke and Hill 23 and McDonald 8 gave the first detailed description of what are now known as the asbestosis bodies The latter confidently asserted that they originated from the asbestos dost inhaled in the lungs and gave definite reasous for this opinion While from the practical point of view the etiological relationship in this case between the inhalation of asbestos dust and fibrosis of the would have been strengthened by the absence of a tuberculous infelcutnigosn these two papers were however of the greatest importance and focussed the attention of investigators on the subject A few weeks later H. E. Seiler 9 10 discovered an asbestos worker with signs of a diffuse pulmonary fibrosis with no evidence of a tuberculous infection further investigation revealed no presumptive cause for the fibrosis other than the inhalation of asbestos dust This case at that time the third of which the Factory Department had - knowledge was however the first in which the four essential conditions necessary to establish a relationship between the inhalation of asbestos dust and the development of pulmonary fibrosis could be demonstrated These conditions are ; 1 Work involving exposure to asbestos dust 2 The existence demonstrable clinically and radiologically of a definite pulmonary fibrosis . a) Sakpe eoy, are a ees, tae - aa ana ealitiel ran Te ae A NE cain NRT Lagi aT gab Dre ah ty aoa ee e . es ae Oe ; i } i f H i i i . an 1 ; ~. ; | 1 : | | : 4 November 1933 A MEMORANDUM ON ASDESTOSIS 73 33 The absence of previous or present infections known toto cause pulmonary fibrosis e.g. tuberculosis intinenza or pneumonia 4 The absence of previous or present work involving exposure to other dusts which might cause pulmonary fibrosis . When therefore the investigation of Seiler's case showed that other industrial and infective causes of pulmonary fibrosis could be excluded definitely the necessity of deciding whether the supervention of this disease in an asbestos worker was an exceptional occurrence or evidence of health risk in the industry was apparent and a a grave Great Britain was commenced in comprehensive inquiry in involved the clinical examination of F:eibtiruwaorryker19s28o.r aTphpirsoxiimnvaetsetliyga1 ti6 on per cent of the estimated population at risk from pure or nearly asbestos dust 133 were examined pure radiologically and great care was taken to exclude all workers whose langs might have been affected by previous work in other dusty occupations The influence of work in different processes was assessed and the relative dustiness of them estimated The results of this inquiry were published in 1930 12 and except where indicated the conclusions and data given in this memorandumi are derived from it and from the results of the first cycle of the statutory periodic medical examinations in the asbestos industry Between the beginning of 1925 and 1930 and since a number of other papers dealing with the clinical pathological and radiological sides of the subject have been published both here and abroad Many of these are referred to and are noted in the bibliography appended Unfortunately no other general survey of the industry has yet appeared in print IV INFLUENCES WHICH DELAYED THE RECOGNITION AS A SPECIFIC INDUSTRIAL DISEASE OF ASBESTOSIS It is of some importance to consider why if asbestosis is a serious risk this industry has only recently excited attention by reason of its raw material becoming suspect as a cause of industrial disease ; of Several factors have contributed but the main one appears to be that in the past it was not practically possible to obtain proof the injuriousness of asbestos dust considering the limitations imposed by the state of the industry and the point reached by research work into the between dust inhalation and diseases of the lungs relationship In the closing years of the nineteenth century the position with regard to dust diseases of the lung was chaotic while it was realised as had been known for centuries that work in certain dusty occupations was dangerous since so many workers died of lung disease the nature of the disease the precise causes and their mode of action were the subject of acute It was not so long before in 1866 that Virchow the controversy last admitted the possibility both that dust might great pathologist at be inhaled cause discolouration of the lung 13 and might The literature was overloaded with many special names invented sotue on very slender evidence to describe the supposed effects of particular dusts Some of these terms for existent conditions still crop up day From 1900 onwards the attention of Governments and private investigators became more and more focussed on what is one of the gravest problenis of eo es 74 TUBERCLE November 1933 oe e the age that of the prevention and control of pulmonary disease amongst re workers in what are now known as the producing industries In Fd 1902 and 1903 the Milner Commission on Miners Phthisis in South Africa e pursued its investigations to be followed by another Commission on the same subject from 1907-10 and by third in 1911-12 The achievements _ of these Commnissions and the succeeding labours of the Miners Phthisis Prevention Committee and the Miners Phthisis Medical Bureau are ante classical In 1914 the British Royal Commission on Metalliferons Mines and Quarries in its report stated the position then with extreme clarity as " follows We do not know whether other dusts besides those containing free crystalline silica induce a pathological condition in the lungs though the experiments of Professor Beattie on animals suggest that this may , occur 14 - It appears therefore that this focussing of energy on the important problem of silicosis and the production of proof that the inhalation of free silica was responsible for the production of fibrosis of the lungs amongs workers in so many industries tended to obscure the possibility that dusts other than those containing free silica might be injurious In fact it seems that the Royal Commission's reservation quoted above slipped from memory and the opinion grew that from a practical point of view if dust contained free silica it was harroful if not it was negligible The second factor was the size of the industry As mentioned above only little more than 2,000 workers in Great Britain are exposed day to an appreciable risk from asbestos dust and these are distributed in various parts of the country Much less than this number have been employed in the tuore dusty and hence more risky processes for five years or more As noted above the industry has expanded at a remarkable rate but even so it seems probable that not more than between 35,000 and 10,000 workers in the world are exposed day to an appreciable risk from the _ inhalation of asbestos dust There are of course no precise data on which to assess this auniber accurately but this estimate which is based on Great Britain and Canada and the statistics of asbestos may not be far from the truth the the available figures for production of is useless to look in the mortality statistics of various countries for between any pointers that combined silica far less asbestos is dangerous It this very fact distinction as reflected in the vital statistics between industries where there is exposure to free silica and those in which was the exposure is to combined which at the same time incriminated free silica and apparently absolved combined silica That this was the is quite evident on reading the evidence submitted to the BritishposRiotyiaoln Commission on Metalliferous Mines and Quarries in the year just prior to the Great War Incidentally the fact that the vital statistics do not reveal an increased mortality from pultuonary disease amongst workers exposed to combined silica suggests strongly now that only some silicate minerals are dangerous when inhaled Another important factor which prevented earlier recognition of the disease was that twenty years ago radiography of the lungs was in its infancy and only just previously had that invaluable aid to diagnosis licen Lat at 03458 03458 - wee Seen November 1933 A MEMORANDUM ON ASBESTOSIS 73 applied seriously in the investigation of silicosis 15 Moreover the radiographic picture of developed asbestosis is distinct from that of typical silicosis and when compared with the latter is in the absence of definite knowledge likely to be dismissed as of little import e It is easy to understand therefore the influence factors in delaying the recognition of the disease as match may be surmised with accuracy but proof of these and other so often the case may have to await advances in collateral fines of research ne THE MAIN FEATURES OF THE DIAGNOSIS SIGNIFI- oe CANCE OF THE ASBESTosts BODIES Asbestosis pulmonary fibrosis of asbestos workers insidious in its onset irregular in its course and variable in its mode of termination It is helpful to visualise the disease as the slow growth of fibrous tissue scar tissue around the bronchioles or smaller air tubes of the lungs and between the air cells wherever the inhaled dust comes to rest 10 contrast to silicosis the former is the important site of deposition of asbestos in the lungs 30 While new fibrous tissue is being laid down like a spider's web that deposited earlier gradually contracts This fibrous tissue is not only useless as a substitute for the air cells but with continued inhalation of the causative dust by its invasion of new territory and consolidation of that already occupied it gradually and literally strangles the essential tissues of the lungs In common with other essential orgaus of the body the Inogs have a large reserve of tissue for use in emergencies and to permit of a diminution in functional capacity due to advancing age or disease For this reason and because fibrosis of the lungs is essentially local disease it is only when the fibrosis progresses to the extent of obliterating this reserve that undne shortness of breath on any extra e^-ort draws the worker's attention to the fact that his health is not what it should be The other symptoms of the disease such as cough are equally a. unassuwing and are readily ascribed to some common and trivial cause _ From this point the progress of the disease is more rapid since it is now encroaching on the remaining sound tissue of the lungs already only just suflicient to maintain the worker in his ordinary daily activities Ultimately if no acute respiratory infection has precipitated a fatal termination a stage is reached when the lungs can do little more than maintain life and the shortness of breath becomics extreme Usually the fatal issue is determined by the onset of soure acute infection with which the remaining undamaged lung tissue is quite unable to cope this is commonly a low grade bronchopneumonia but may be a lobar pneumonia bronchitis influenza or less often a subacute tubercular infection With the exception of a mild degree of bronchitis which is more often mechanical in origin and not infective being due to irritation of the retained dust there is no evidence that the existence of developed asbestosis predisposes to the onset of such acute infections but if however an acute infection does supervene the presence of the asbestosis seriously impairs the chance of recovery Details of cases in which the terminal 76 RCLE November 1983 infection was tubercular could be given which demonstrate this added risk unequivocably in these cases the onset of the tuberculosis was indubitably recent in origin and undoubtedly precipitated the fatal termination but on mortem examination the extent of the tubercular lesions was clearly insufficient to have caused death under ordinary circumstances In the absence of intercurrent infections the fibrosis may progress to an extreme degree bronchiectasis tubercular cavitation and spontaneous pneumothonix may occur but ultimately the strain of maintaining the circulation through the partially strangled lungs becomes insupportable general dropsy with an enlarged liver appears and death ensues from slow heart failure Intercurrent attacks of dry pleurisy which are partially responsible for the considerable thickening of the pleura which occurs are common but usnally only cause slight and temporary disablement Clinical Signs most important single clinical sign is that of diffuse bilateral impairment of the percussion note this is slight in degree and best elicited by very light rapid percussion of the back of the chest from apex to base on each side and is associated with a slight sense of resistance The other physical signs do not differ materially from those presented by silicosis and need not be detailed here The symptoms exhibited also as might be expected closely resemble silicosis For a considerable period the disease causes almost no incoavezience to the worker and for long time the symptoms may pass almost nuncticed Between and 60 per cent of cases of asbestosis complain of cough and of undue shortness of breath on exertion and show a duski- ness or slight bineness of the lips which contrasts with the general pallor of the face not uncommonly seen Diagnosis common with other forms of pneumonokoniosis the diagnosis of the disease is fraught with difficulty particularly is this the case in the early stages in the late stages when associated with pulmonary tuberculosis and in any stage if the disease is implanted on lungs already the subject of emphysema or if some intercurrent infection has supervened The fibrosis although diffuse and bilateral may be most marked basally and on one side less commonly the bases may be more or less emphysematous and the maximum fibrosis in the central zones of the lungs rarely the fibrosis is most marked in the apper portions of the lungs These factors modify the physical signs present as also does the existent state of the chest and of the lungs upon which the fibrosis is implanted The signs however are not so tenuous as has been suggested that it is impossible to make a diagnosis with fair certainty on physical examination alone Radiographic examination of the chest is however invaluable and should never be neglected A high level of technique is required and this should be standardisedadequately a technique which will produce an excellent film and demonstrate adequately silicotic lesions may fail to reveal the asbestos fibrosis entirely or more often partially ; in the latter case the radiographic picture is not only inconclusive but most misleading The cause of this is not far to seek and lies in the essential difference between the two types of fibrosis While typical silicosis consists of dense 03460 November 193 A MEMORANDUM ON ASBESTOSIS 77 discrete and fairly large nodules of fibrous tissue embedded asit were in more or less normal and even ~ slightly 14 ballooned lung tissue typical asbestosis consists of a network of fibrous tissue permeating the lung the air cells in the immediate vicinity tending less " to balloon than to collapse . Minor variations in technique therefore will have in the case of the silicotic fibrosis comparatively little effect in reducing the contrast between the nodules and the sound lung on the resulting filu and the permissible margin is fairly large ; not so however in the case of asbestosis since the fibrous tissue lesion is far more diffuse and the areas of relatively sound lung tissue with which contrast must be obtained if the fibrosis is to show on the film are small and interspersed in the fibrous tissue network hencethe case of asbestosis much care is necessary to take advantage of the small contrast available and to produce a film of real value in diagnosis and prognosis The ascertainment and standardising of the optimum technique for this purpose is complex problem which is occupy ing the attention of the Industrial Pulmonary Diseases Committee of the British Medical Research Council This fundamental difference between the two types of fibrosis referred refer ed referred referred to aboveis of great importance explaining as it does a number of the features of thegreat disease The diffuse dispersion as it were of the fibrotic lesionsin the lungs in asbestosis as compared with the discrete localisation of the lesions in silicosis is reflected in both the physical signs and the radiographic picture of the disease diffuse slight general impairment of the percussion fine pinhead veiling striking note and the diffuse ground glass appearance i or as it were together with the mottling of the radiographirc adiographic film being The tendency to uniformity and the unobtrusive nature of the symptoms physical signs and radiographic appearances are at the same titue the most outstandingoutstanding and the most deceptive features of the disease The radiographic appearances of the developed or advanced stages of of the disease are distinctive although they are not specific While as is the case with silicosis certain radiographic appearances may be looked upon as typical of the disease frequently modifications of and departure from the typical picture occur No one who has the opportunity of examining a large number of radiograms of the lungs of workersin different dustyoccupations can fail to appreciate the infinite gradations which appear and how it is a possible to duplicate film from worker in one industry with a film from a worker in another totally distinct industry describe Badham was the first to the fine type of fibrosis which 17 can be caused by an inorganic dust containing no free silica and to draw attention to its serious nature An inquiry in the United States[[ 18 showed thatin cases of silicosis in granite cutters the radiographic features were atypical Pancoast Pancoast and Pendergrass 19 in their comprehensive review of the whole subject have given it as their view that the appearances of asbestosis in the radiographic film are not specific for that dust and there can be no te ~~, 03461 03461 03461 79 TURERCLE November 19 doult but that their opinion founded on a very wide experience of radiography of workers in dasty trades is the correct onc In developed cases of pneumonokoniosis however the fairly large " discrete mottling of the stornr of silicosis and the fine hol mottied ground glass appearance of asbestosis do it seems represent the two typical extremes and reflect the two types of lesion found in the lungs _ the discrete nodular silicotic type and the fine network of the asbestosis type The infinite gradations that one sees in films of workers exposed to different inorganic dusts often in mixture therefore it appears reason- able to suggest represent the effects of the components of the dust encountered according to their relative preponderance on the lungs and the radiograms accordingly approximate more to one or other end of the scale In general therefore both the pathological and the radiographical appearances do appear to reflect more or less proportionately the actions of the producing silica and silicate Radiograms of certain granite workers of certain pottery workeransd of some mixers of boiler coverings present examples of some of these gradatious and illustrate this point In workers exposed to the insulating material known as magnesia 85 per cent magnesium carbonate and 15 per cent asbestos approxi mately with signs of pulmonary fibrosis one finds a type of radiogram which is totally distinct from either typical silicosis or typical asbestosis and from appearances intermediate between the two It is impossible to say what the underlying lung lesion may or may not be as no autopsy findings are available Haynes 20 21 bowever states that magnesia is a dangerous dust so the radiographic picture may truthfully reflect a modification of the asbestos fibrosis effected by the introduction of a preponderance of a more quickly soluble dust ee Radiograms of asbestos workers are very puzzling more so than in the case of silicosis when it comes to assessing the degree of asbestosis present ee particularly in the earlier stages and also in women owing to the shadows en cast by the breast tissue Keating 22 of the Silicosis and Asbestosis Medical Board bas pointed out that pregnancy may produce a mottling ne suggestive of asbestosis Presumably this is due to pressure on the ee diaphragm as well as to engorgement of the breast tissue The 5lm was one of an asbestos worker with less than two years exposure too short time to produce radiographical appearances of developed asbestosis in the absence of an additional period elapsing since the last exposure to permit of the development of the fibrosis On first examination the film was very suggestive of developed asbestosis but on close examination in the spaces between the fine mottling the lung field lit up well which would not have been the case if the picture represented developed asbestosis In the light of present knowledge therefore one can say that asbestosis cannot be diagnosed with absolute certainty on either physical examination or radiological examination alone with the aid of both the pneumo^-okoniosis can be diagnosed with certainty if present in some degree although not necessarily to an extent sufficient to cause either symptoms or any disablement But is not possible to say from physical and radiographical examination that an asbestos worker has not trapped in the lungs lungs an rh ae ee we eee eee ey g n e] a . oe November 1933 * A MEMORANDUM ON ASBESTOSIN 79 of amount of dust sufficient to canse the development of serious fibrosis after a lapse of time ; The greatest possible aid to the diagnosis of ashestosis is to have have available for comparison a series of films of asbestos workers together with with their whole history and the mortem findings if death has occurred The questions of degree of disablement and prognosis are discussed later The Asbestosis Bodies and their Significance In addition to spicules of asbestos which may be very numerous and other particles identified by Cooke 7 as derived from the raw material certain foreign bodies are found in the lungs of asbestos workers These ladies were first seen apparently by Marchand and Riesal in 1906 and later by Fahr in 1914 8 but Cooke and Hill 2 and McDonald s gave the first detailed description of them They are microscopical in size of a yellowish brown colour and of various shapes but commonly with an elongated beaded appearance and with one or both ends bulbous Gloyne 24 who gives the most comprehensive description of them and their attributes illustrates 44 various forms They give both the Prussian blue and ammonium sulphide reactions for iron but do not stain with ordinary aniline dyes but may be made to take on colour by methods described by Gloyne which enable their structure to be studied more precisely and aid in photomicrography The same observer has opened up a new field in this connection by the use of infmred methods of photomicroscopy 25 They are found in sections of the lungs sometimes in enormous numbers in direct films from the lung juice at the time of the mortem examination 26 in the juice obtained in by lung puncture during life Stewart and Haddow 27 first suggested by S. A. Henry occasionally direct filtus of the sputum but frequently although usually in small numbers after digestion with antiformin and centrifuging Stewart and Haddow 28 f^cesGloyne 29 They have been detected in the Dewirtz 48 and Gloyne 24 have both independently failed to find them in sections of the asbestos corns which are common amongst asbestos workers and are caused by the irritation of the retained portions of spicules of asbestos which have penetrated the skin and broken off experimentally 30 In dusted animals they occur in the lungs of guinea after an exposure of approximately seventy days in the rabbit they have not been discovered after exposures as long as hundretd hirty duys and in the white rat they are very rare Gardner and Cummings Gloyne 24 found one in wild rat caught on an asbestos factory premises Schuster 31 in dog long residen in an asbestos factory could find co trace of the asbestosis bodies although the lungs showed typical asbestosis Asbestosis bodies are not found in asbestos dust but McDonald came to the definite conclusion that they were derived from asbestos fibres modified by residence in the lungs The asbestos fibre forming the central core in the asbestosis body was identified by Gloyne 32 The typical bodies have not been found in any other disease but forms superficially resembling them have been found in a coal miner Tylecote and Shaw Dunn 3 and Cooke 45 How far therefore is the presence presence of the aid diagnosis diagnosis bodies in the sputum an aid to diagnosis of the ? disease . 03463 03463 03463 , 50 TUBERCLE November 1931 Since they are found in the lungs following very short exposure to asbestos Sitison 34 has recorded the presence of the bodies in human lung from a case with a history of only two months exposure fact of their presence in the sputumi can only be said to be indicative of exposure to asbestos dust Where however the bodies are found in clumps instead of individually in the sputum identical with the clurims seen in sections of the fibrosed lungs their presence points to disintegration of lung tissue and it is suggested Stewart Tattersall and Haddow 35 that in such cases they have a far greater significance and that it is reasonable to conclude that there is a definite underlying asbestosis Since they may be found in the lungs at any rate up to fourteen years after the last exposure to asbestos dust their presence does not clue as to whether the exposure has been recent or long past give any REFERENCES No attempt has been made to compile a complete bibliography but the following are particularly valuable in connection with the points discussed in the foregoing memorandum 1 2 Ross G. Chrysotile Asbestos in Canada Canadian Department of _ Mines Publication Ottawa F. A. Acluad 1931. hensive and valuable monograph on the subject The most compre Departmental Committee on Compensation for Industrial Diseases Minutes of Evidence Appendices and Index 1907. 1907 Cd 3105. p 14 C. 3496 p 127 Report, 3 KRUGER ELIZABETH ROSTOSKI and SAUPE Gewerbeing 1931 2 555 Arch j Gewerbepath u 4 ACHIBAULT Bulletin de l'Inspection du Travail 1906 p 125. Imprimerie Nationale Paris 5 Annual Report of the Chief Inspector of Factories and Workshops for 1910 p 188. London H.M. Stationery Ollice 1911 -- 6 Cooke W. E. Brit Med Journ 1924 ii 147 T Idem Ibid 1927 ii 1021 ; S McDONALD S. Ibid ii 1025 19 Siez H. Ibid 1928 ii 982 10 SEILER H. E. and Giour M. Ibid 1931 1 1112 11 12 13 14 35 16 MEREWETHER R. A. Journ Ind Hyg 1930 12 19 and 239 MSHEWETHER E. A. and Price C. W. Report on the Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos Industry London H.M. Stationery Office 1930 Wittis II S. " Pneumonoconiosis and Tuberculosis Medicine 1930 9 413. A valuable monograph with many references Royal Commission on Metalliferous Mines and Quarries 1914. C. 7176 p 116 Second Report Inviss L. G. A Review of the History of Silicosis on the Witwatersrand Goldfields Silicosis Records of the International Conference held at Johannesburg 1930. p ISS Geneva International Labour Office 1930 Woon W. B. Tuberete 1920 10 353 17 BADHAM C. Notes on Fine Type of Fibrous Pneumonokoniosis producedby Silicates and other Minerals Studies in Indust Hyg No. 13 Rep Gent Pub Health New South Wales for 1927 Section L.D L.D Ludust Hyg p 103. Sydney 1929 03464 A naa geass, 4 ss . * | November November 1033 1033 A MEMORANDUM ON ASBESTOSIS S1 10 20 21 [ 2323 [ 21 ] 21 25 ] [ ] 26 ] [ 27] 29 30 31 32 33 34 35 36 [3736 ] 4 [ 1] 43 14 45 16 47 48 Russant A. E. BRITTEN R. II Thomson L. R. and BLOOMFIELD J. J. Exposure Siliceous The Health of Workers in Dusty Trades 11. Exposure to Dust Granite U.S. Pub Health BullNo. 187 1929 p 87 Industry Pascoast H. K. and PesDPRGRASS E. Amer Journ Roentgenol and Rud Therapy 1931 25 591 . HAYNES F. Annual Report Safety in Mines Research Board for 1928 71. London H.M. Stationery Office 1929 Idem Annual Repor Safety in Mines Research Board for 1920 p 52 London II.M. Stationery Office 1930 KEATING N. Personal Communication Cocke E. and HILL C. F. Series III 232 Journ Roy Micros Soc 1927 47 Glorx S. Lancet 1932 i 1351 Idem Tubercle 1933 14 20S STEWART M. Brit Med Journ 1928 ii 509 HADDow A. Ibil 1929 2 551 Stzwart M. and Haddow C. Journ Path and Bact 1920 22 172 GARDNER Tubercle GLOYNES. R. 1931 12 15S L.U. and CuarINGS D. E. 65 and 97 Journ Indust Eyg 1931 13 Schuster N. Journ Path and Bact 1931 24 751 GLOYNE S. R. Tubercle 1929 10 404 TYLECOTE F.and Duxx J. Lancet 1931 ii 632 Sorsox F. W. Ann Rep S. African Institute for MedResearch 1929 p 64 STEWART M. J. TATTERSALL N. and Habbow A. Journ Path and Buct 1932 35 737 Wood W. B. and GLOYNE S. R. Lancet 1931 II 954 Report on Conference between Employers Methods for Suppressing Dust in Asbestos , H.M. Stationery Oflice 1931 Statutory Rules and Orders 1931 No. 344. Ollice and Inspectors concerning Textile Factories Londou _ London H.M. Stationery Statutory Rules and Orders 1931 No. 311. Office London H.M. Stationery LOVISETTO D. Pulmonary Silicosis Johannesburg Office 1931 Asbestosis Records International Coni os 1931 p 506. Geneva International Labour Mussa G. Clinical and Radiological Notes on Pneumoconiosis due to Asbestos Ibid p 493 LONGA G. " Pneumoconiosis in Italy Ibidp 493 Sixson F. W. Brit Med Journ 19291 833 Statutory Rules and Orders 1931 No. 1140. Ollicc Cooke W. Brit Med Journ 1932 , 656 London H.M. Stationery Stationery Sources Asbestos its Extraction Prevaration Manufacture and Uses in Industryand Engineering Berlin Becker and HaagHaag 1928 Asbestos a monthly trade journal publishedin Philadelphia Pa Pa DEWIRTZ A. P. Arch j Dermat u Syph 1930 elxi 1 To be continued 0 08465 08465 ~ OF, he ae Bee ONE December 1933 PLOMBAGE IN PULMONARY TUBERCULOSIS 100 than for the thoracoplasty If we take presence of bacilli and allow a minded view of the is always as a result of an open tuberculous case to restart work it circumstances into mature reflection We take the patient's personal consideration and see that all are observed necessary precautions The long cure that we deem and which is mostly dependent absolutely necessary after the operation is a sufficient proof that on pathological considerations collapse which in we consider plombage as simply a process of a relatively limited number of patients can be with advantage applied 4 O.K. O.K. A MEMORANDUM ON ASBESTOSIS / By E. R. A. MEREWETHER M.D. One of H.M. Medical Inspectors of Factories Great Britain . Continued from p 81. ONSET AND MATURATION OF THE DISEASE Within certain high and low limits the air of workrooms is the concentration of dost in the also within limits determining factor in the onset of the disease and concentration of dust and length of exposure determine the incidence rates in different processes in the will be discussed later as industry These limits preventive measures they have an important bearing on the scope of longitudinally fibreAssbmeastyosbehsapslita low specific gravity is comparatively brittle and the ww there is no ultimate fibre apparently to an indefinite degree since Asbestos fibres have been comparable to a vegetable fibre such as cotton measured down to a diameter of 0.00075 mm but it can be demonstrated that even the finest filament composed of fine threads ROBB 1 measured is itself Any manipulation of asbestos therefore produces dust which is projected into the air Different varieties and easily differ materially in dustiness grades of asbestos also Exposure to asbestos for less than five ment of a degree of asbestosis years can result in the develop- sufficient to cause death Commonly however cases of definite asbestosis are not discovered within five years of on examination commencing work although a few are found Thus amongst 89 asbestos workers with under five years employment examined in 1928 and 1929 no case of diffuse fibrosis discovered and amongst 749 such clearly due to ashestos was workers Silicosis and Asbestosis Medical examined recently by the Board only four cases of asbestosis were found Amongst those working who have been and ten years the incidence rate is employed between five ment a steep rise in the incidenceaprpart^e'occiacbulresanadndafotferttheonseyears employ- twenty years or longer more than fourth employed for to be affected The incidence were found by the Board rates for the periods of employment 0-4 years 5-9 years 10-19 years and 20 years and over found from the A Reet 2 KS fi ie. peat q it i x Lig afty is : : : me ue. AER 3 fad y : ae tee TS ir a a, <a f a HENS Ee ERSRe oe) ead , Sate Rdy Re MUe ale! Sn Ns ae rte oe a Hy Sook og ots . fi Byes^' 743 Aye a eS : the eRae ied $ ee < Ne nma ie we ay a 2 eeewhe4 Ms bey fte aed A ark ee i eel Uaehes Vien TRO. od Dp ol 62, 5 x+ONS = Oe oaneg ohWE Py aw .- ate eeThe Ovni, eee. -am hates MOem oe eR whem Oe 6 110 TUBERCLE ( December 1933 ane owe e5 xa6 mina3t0i1o4n 5 of31,512 workers by the Board are proportionate to the figures aeg , 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 Unfortunately that inference is wholly untenable The fact is that work in a dense concentration of asbestos dust over period will lend inevitably to the development comparatively short of a that the worker lives long enough for it to profound fibrosis provided develop It has been shown that experimentally in guinea fibrosis due to inhaled asbestos commences after aixout five hundred days exposure 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 30 Of the fatal cases in Great Britain of which full particulars are available in two examination over fourteen years after the last asbestos revealed numerous asbestosis bodies exposure to 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 . Examination of the particulars concerning cases of asbestosis in con- junction with the relative dustiness of the processes at which they worked leads to the conclusion that while increasing concentrations of dust in the air reduce the period before developed asbestosis occurs after a certain high concentration of dust in the air is reached a further increase in con- centration does not further reduce the period of maturation as it be called of the fibrosis may Similar considerations also show that below a certain concentration which will be referred to later development of a disabling degree of asbestosis will not occur within the space of an working lifetime average It follows therefoarned 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 also that " certain ^finturation period must elapse before that amount of fibrosis is developed Confirmation that this hypothesis is from the practical point of view an accurate statement of the position can be adduced from particulars of cuses alive day and from particulars of deaths which are now available . Certainly this minimum dose of dust can be trapped in the lungs und ordinary industrial conditions in under five years Two eS uuples will illustrate this -- Matterns maker emi loved four this work the age of 12 from itionfera examination Maser enidoyed two years and years and five months night years after leavin8 advanced asbestosis asbestosis with leavin8 no taberexqu se eventiel Ly seven months months dil twelve yours hter the agh of December 1933 A MEMORANDUM ON ASBESTOSIS 111 48 from a moderato twelve degree degree of asbestosis together with twelve to eighteen months duration verified by a superimposed mortem tuberculosis of examination producing Particulars of cases seem to show that the minimum with high high concentrations of dust ment of period of time which must elapse between the commence exposure and the production of a serious degree of asbestosis is approximately the seven which include not only the trapping period of fibrosis which dose of dust but also the maturation period of the periods of course overlap The existence of this which may be referred producing period i.e. the period which to as the fibrosis- commencing work before a serious must elapse from the date of accounts for the fact that it is degree of asbestosis can he produced ment is reached that not until the second five years of employ- discovered appreciable numbers of cases of asbestosis are This period of seven years is of course the mature in this minimum period in minimum minimum and few cases on the dustiness of the in successive yearsyears however depending process which employed more cases mature In the more dusty processes the producing is commonly eleven years period as defined above At this point i.e. when fibrosis of serious serious worker is unduly short of breath import has matured a cyanosis of the lips and is disinclined to climb on any extra exertion has a tinge of little dry congh mostly in the mornings He stairs or walk hills he from an upper flat or room to a lower may even have changed He still however remains at one to avoid climbing the stairs state of his health work and usually usually is not anxious about the many refuse to admit any deterioration in health this stage at COURSE OF THE DISEASE DISABLEMENT PRODUCED AND PROGNOSIS ? deveWlhopaetd tahsebnestisostihse outlook for those those who have reached This question of crucial significance to the and the legislature may be considered individual heading-s conveniently this stage of the industry under three 1 Does Asbestosis Shorten Life The answer to this question is following tables will show that emphatically this is Yes so Reference to the Table I gives particulars of forty fatal of , asbestosis with tuberculosis of which cases asbestosis or except two were verified precise information is available all by mortem examination In Table II comparison is made between these 42 consecutive fatal cases of silicosis or silicosis with cases and 281 full particulars are available tuberculosis of which In Table III the cases of silicosis and and are distributed in the industries concerned It will be observed that : silicosis y ad with tuberculosis 1 The average duration of degree of asbestosis was only 12 12 employment employment sufficient to cause a fatal years as compared with 401 years for . : : 5 , 'y fan] i . iy ct 4 ' uly :| is ae tg! 4 ; ; 48] Br Ywes pe, 112 TUHERCLE TABLE 1 December 1983 MMaakeke Asbestosis Abbertonis with tuberculosis ; ; Xumber Age at deatl~- | Duration of | emplovinent In asbestos industry of nanan. \ Rene! wah penton | tw Shortest | drathe ! NUWAY Longest Shortes Avanage Shortest NUWAY Shortes Avanage Duration of exposure to late lust in gener } Period slapsing betwang betwang leat exposure to animatsi not and death in yo H eee 5 7 III Short i III t ~ III III III III III III Shortest Sait NUWAY Longest Ss; III III III III | Sane eene ' neti| pn ermn eatd ed bated :iienamnd beienened ieoneetel: III ' | 27 63 | 26 40-8 27 4.4 15.2 52 | 2 fae 13-3 | 14 days 2.96 || 15 j 67 22 41-6 21 | 2.6 | . | | | ' 11-7 26 11.3 12-2 0.9 4.6 | | | " , | ! l'articulars only known for 12 casos Dlacane i} | Number af deaths ~_ Silicosia ~~ teas 114 Silicosis with tuberculoxis ! 147 Asbextoxix ., os 27 Asbestosis with tuberculosis | 15 : TABLE II _ Average $ traili | 34-1 0.6 | 10 | 11 Iluration of employment employment in years Lobvest Lobvest 57.0 67 27.0 210 Mhortest | 2.8 2.0 4 2.6 Average 40.1 320 15 117 TABLE H. Julustry Sumber ..f deatho i Avernonage Avernonage 21 drath Pottery- Silicosis Silicosis tuberculosis with tuberculosis i 55.6 | 22 { 55-2 SandstoneSillcoxin with Silicon with tuborculosis tuborculosis tuborculosis i | : 32 ; 37-3 39 52.9 Grinding of metals Silicosia oe we tuberculomin Silicone with tuberculomin Sandblasting - | ' 4 : 26 231 i Siliconix with a tuberculosle Siliconix with tuberculosle 7 40.7 16 | 412 Manufacture of powdery-- Silicisi with Siliques with scouring tuberculosis tuberculosis tuberculosis tuberculosis 8 337 j | 2 ats : * Miscellaneotta- | Silkosin Silicosis with with tuber ubaix tuber ubaix 7 SA 3 ; a) 5000 Juration of employnient in yeate ercem TTT gene in 7 - Longest ! Shortest i Average 1 57.0 | 67 i 37 : 59.0 150 : 48.0 ' 16 weg | : , 11 1075 10.0 130 20.0 16 19.0 2.9 4.5 25 j 39.8 , 37-2 30.1 | 34.A | 3018 302 : 10.8 ; K 4 ari ) rar ny 4.5.0 340 oo i) yy om , December 1933 A MEMORANDUM ON ASBESTOSIS 113 all cases of silicosis The actual average length of exposure to asbestos dust was however still less and not more than 13 years 2 The shortest length of exposure to asbestos dust which ultimately caused death from advanced fibrosis of the lungs was 4'4 years 3 Asbestosis is comparable with the more serious silicosis risks with . respect to length of exposure which will cause a fatal degree of fibrosis 4 Although the figures in the asbestosis group are very small it will be observed that in 35-7 per cent the disease was accompanied by tuber- culosis while in the silicosis group 59'4 per cent were accompanied by tuberculosis suggesting so far as the figures go a lesser incidence of tuberculosis in asbestos workers compared with workers in the silicosisproducing industries Further confirmation is shown by the history of the 95 cases of asbestosis and five cases of asbestosis with tuberculosis found in the original inquiry in 1928. Of these 100 cases although a number have migrated from the industry and have been lost sight of 17 are known to have died 10 from asbestosis six from asbestosis with tuberculosis and one from mortem carcinoma of the pancreas in whom also was found on examination a considerable degree of asbestosis Of the remainder 13 are partially or wholly disabled on account of the disease and have been given certificates to that effect by the Silicosis and Asbestosis Medical Board The toll of the disease is evident even in these incomplete figures av 2 The Ertent of the Disablement produced by Asbestosis The amount of disablement produced by the development of asbestosis is surprisingly slight for a number of years This is partly due to the character of the disease and partly due to the nature of the work which in the majority of processes in the industry in which there is a risk of asbestosis does not involve much physical exertion Those affected may and often do continue at work with occasional intermissions latterly due to exacerbations of bronchitis until the condition is advanced although increasing inconvenience from shortness of breath on exertion 18 experienced work Usually these cases cease work a year or more before death but some- times a terminal bronchopneumonia or other acute infection commences oe while they are still at work and there is no long period of invalidism Uepte 3 The Outlook for the Individual Affected Worker lenge The ultimate prognosis in those with developed asbestosis or in those SUES who have incarcerated in their lungs a producing 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 accident or by some unconnected disease The immediate prognosis in any individual case is uncertain With eee the presence of a moderate degree of asbestosis many other factors such as the worker's level of resistance to infection his general health the ease wave? or arduousness of the daily round and the state of his circulation become important These are only approximately calculable in each individual and 8 NM ges Tate | r - weeee es am e " 7 e382eaCet __ tre se Tren ee En PR > : ed, AE 111 TUBERCLA December 1933 the course of the disease and the immediate outlook for the patient are dependent far more on these extraucous considerations than on the precise degree of fibrosis present in the lungs It is remarkable to what extent the lungs can be affected and yet life in a fair degree of comfort remain The reserve is however so slender that the addition of any burden to the system in the form of a disturbance of health which would only slightly inconvenience a normal person may overcome the remaining resistance and precipitate the fatal outcome It is apparent therefore that while the onset of an acute respiratory infection is most ominous the development of any disease which directly or indirectly throws an added strain on the heart or lungs is of serious import For these reasons and from consideration of the features present in recorded fatal cases the view is forced upon one that the existence of even a moderate degree of asbestosis is a sericus and present potential risk to life . VIII PRoducing Amount of ^ sbESTOS DUST the influeNCE OF Work in DifferENT PROCESSES and As shown previously if a certain and as yet unknown amount of asbestos dust is trapped in the lungs death due to the development of asbestosis is an inevitable sequel provided the worker is not carried off from some unassociated disease or from accident during the maturation period of the fibrosis It is important therefore to consider what is the amount of dust which will produce this result or conversely what is the amount of dust. which from the practical standpoint can be inhaled with impunity TABLE COMPARISON Between tite ^ ncIDENCHRATES of Definite Fibrosir ^ rBESTOSIB AMONGST WORKERS EMPLOYED IN GROUP iii Lear Dusty Proceraes and the Curreb- PONDING INCIDENCE RATES Amongst WorkeRS EMPLOYED Ix Gaours ) ii iv and TAKEN TOGETHer More DUSTY PROCESSER 1.4 years empius ed |- - Group iii Nuin- ber 013mined 300 Groups ) ii iv and v taken to- y gether Number | examined 945 | ' cf) 0.7 Incidence rates of asbestosia per cent | 5-9 y6116 empinget 18-19 years ehrjoyed ehrjoyed and ove yearn empla m~- | +} te Ce . 34 8.3 | 5.0 : Da | 190 { 40 \ : : If only the slightest exposure to the dust results ultimately in death then the scope of the necessary preventive measmes de summed up in ong . word prohibition practically speaking it is impossible to prevent such Fortunately however there is evidence that an appreciable exposure amount of dust must be incarcerated in the lung to produce a serious =p. F} a thse Sai: oh . x4 any a 2 rs, \ hy =i er: December 1933 A MEMORANDUM ON ASBESTOSIS 115 re degree of fibrosis Inquiry into the relative dustiness of various processes ey and the relative incidence rates of asbestosis amongst workers in those processes provides data which go far to confirm this point of view The processes concerned may be divided into six groups in which similar processes are grouped together as follows ) Crushing opening disintegrating and mixing ii carding iii spinning twisting doubling plaiting & iv insulating mattress making v weaving and associated processes vi miscellaneous The groups of processes differ in their average levels of dust production that of group iii being easily the lowest in the absence of any dust suppression devices Certain operations cause intense clouds of dust although sometimes only momentarily With high concentrations of dust estimations of particle count are liable to gross errors of underestimation but nevertheless such counts show that some operations may be at least twelve times as dusty as braiding and probably much more so Furthermore comparison between the incidence rates of asbestosis amongst workers in group iii those working in the less dusty processes and termed spinners for short and the incidence rates amongst workers in the more dusty processes groups i ii iv and v taken together shows Table IV how much more serious is the risk in the more dusty processes Moreover the distinction is still more marked than is indicated in the table The majority of spinters have either worked for a period in more dusty processes or have been or are exposed to dust generated in neighbouring more dusty processes Also those employed at ring spinning which is definitely a dusty process and more so than flyer spinning braiding and plaiting are included in group iii The evil effects of exposure to high concentrations of asbestos dust for even a year or two has been already commented on These factors have operated to increase the incidence of asbestosis amongst spinners and in consequence the true incidence rates for this group are even less than those given in Table IV and particularly so in the earlier years of employment It seems clear therefore that amongst workers in the less dusty group of processes the incidence of asbestosis is very much less than amongst workers in the inore dusty processes 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 ninturation period of the fibrosis is longer than in workers in the more dusty processes For these reasons and from examination of the varying conditions of exposure to dust amongst spinners in individual factories it appeared reasonable to infer that the exposure of workers in this group to dust as a whole was not greatly in excess of the maximum safe limit One of the conclusions therefore of the original investigation was that in order to prevent the full development of the disease amongst asbestos workers within the space of an average working time it is necessary to reduce the concentration of dust in the air of the workrooms to figure below that pertaining to spinning at the time over which these cases were exposed This deduction was later accepted in the light of the evidence 1 ety ae em = cc- es,tee we aant i o LO Shily ert, ~ ee et+we 6 ape Se ... eeO@ CE \ t Oo T WA.tae = 7 7 te 116 TUBERCLA December 1933 available and with the reservation that it was subject to alteration in conformity with further medical experience as a safe basis on which it would be possible to work out appropriate dust suppression methods For this purpose therefore the conditions arising from flyer spinning carried on without exhaust under good general conditions was considered as tho safe criterion and was termed the dust datum The application of this dust datum is considered below The Risk FROM TUBERCULOSIS As mentioned previously the risk to life associated with asbestos is a complex one The fibrosis of the lungs itself when it reaches an extreme degree kills by mechanical embarrassment of the pulmonary circulation causing back pressure and consequent heart failure The presence of fibrosis in much less amount while apparently not predisposing to the onset of acute respiratory infections such as bronchopneumonia and pneumonia does most adversely affect the chances of recovery from these diseases Thirdly there is the unknown influence of asbestosis on the course and outcome of totally unrelated diseases which cause added strain on the circulatory and respiratory systems In category by itself comes pulmonary tuberculosis The importance of determining whether or not the presence in the lungs of asbestos dust or of asbestos dust and of fibrosis due to predisposes to the development of pulmonary tuberculosis cannot be overstressed It does not follow of course that because pulmonary tuberculosis is so definitely added risk in silicosis that similar considerations apply to asbestosis The evidence unfortunately is at the moment insuflicient to settle the question Gardner and Cummings 30 have shown that experimentally in guinea primary tuberculosis infection is influenced only to a limited degree by inhaled asbestos and that the tendency to healing by fibrosis is marked In this respect they emphasise the contrast between the effect of asbestos and of free silica in the form of quartz dust with which the tendency was overwhelmingly towards the production of generalised chronic tuberculosis of the lungs and viscera These satue workers found that another group of experiments where the tuberculous infection was implanted on to an existing asbestos fibrosis the stimulating effect on the tuberculous infection was more marked than when the infection and inhalation of asbestos were instituted simultan- eously but the ultimate outcome had not yet been observed They also stated that the combined action of asbestos dust and tubercle bacilli in the lang produced more fibrosis than did either agent acting independently Available data on this point relating to asbestos workers are very mengre as might be expected having regard to the comparatively amall population at risk Burton Wood and Gloyne 36 state that in their series of 57 cases of pulmonary asbestosis there were 10 cases of active tuberculosis Nearly all these 57 cases were cumployed at the same factory where there were some workers is probable as they state that the cases with tuberculosis are more prone to seek advice and that their vv 4 RSwe SESS: y a: aN LAN ww < Ae At A we om em m nau . i a vate ais moO = Lon Ot g OD ae ~ ne. < ee * fa 58 $ et & pace _~\ ctcn i Fea Fy rr ' Or +, . me . smATSee a SE N Le SNE,re oeos rr . re es oo 9 Res as SOE y Ege - December 1933 M EMORANDUM ON ASBESTOSIES 117 proportion with tuberculosis represents a maximum Even so the figures they produce emphasise the urgent need of full inquiry into this problemi These observers also make the important statement that obsolescent tuberculosis may retuain quiescent in spite of exposure to asbestos dust Equally too examination of workers whilst at work cannot indicate the true incidence of pulmonary tuberculosis but such data are also suggestive Of 374 workers examined while at work only four showed signs of active tuberculosis The Silicosis and Asbestosis Medical Board in the first cycle of periodic examinations of workers in the industry found only one case of the mixed condition asbestosis with tuberculosis in 1,512 examinations Generally on mortem examination of the lungs of asbestos workers one finds that the cases showing active tuberculosis fall into three : 1 Those with evidence of rapid tuberculosis and groups of asbestosis 2 those with much fibrosis due to bovtehrydissliegnhsteosr 3 no tshiogsnes ; with advanced asbestosis and a slight amount of active tuberculosis Of those in group ) a number are definitely of the adolescent type and the incidence rate of pulmonary tuberculosis in young women in whom the majority of these cases have occurred has increased in recent years Unless therefore it can be shown that the presence of asbestos dust in the lungs favours the growth of the tubercle bacillus this of cases has no bearing on the question of an added risk of pulnionargyrotuubper- culosis in asbestos workers since they would have occurred in the absence of exposure to asbestos From the experimental work of Gardner and Cummings quoted above it appears not unreasonable to deduce that since the coincident inhalation of asbestos dust did not affect the ultimate healing of the lesions produced by s tuberculous infection of low virulence whereas the inhalation of quartz not only prevented healing but induced a generalised spread of the tuberculous infection therefore the coincident inhalation of asbestos dust and tubercle bacilli of greater virulence would result in an infection the outcome of which would be precisely the same so far as risk to life is suggest concerned as if there had been no coincident exposure to asbestos dust If this hypothesis is correct and the experimental work referred to Joes more than it the important practical point emerges that we can dismiss as being unconnected with asbestos dust the whole of the deaths in group ) and a few of the deaths in group ii This is of major importance in connection with the employment of young persons in the industry The remaining cases in group ii include those cases of fibroid tuberculosis who become exposed to asbestos dust In these the effect of the asbestos dust is to cause more fibrosis than would occur with either agent acting independently but whether in the long run its influence is favourable or unfavourable would appear to depend on factors peculiar to each affected person The number of these cases however obviously must be negligible In this group however must be placed the apparently small number of cases in which in spite of the presence of extensive asbestosis virulent rapidly caseating tuberculosis does occur These occur in middle life and would appear to depend more on the virulence of the particular strain of tubercle bacilli than on the presence of asbestos dust me ee Le Nek Ne Oe a pe ee ge Nee A aE s3 eS =mte nalw=Se _ ao . oe - font Fy a Awe, e Pw. ~.oa we o8 te ae ea e 8 ek ee ow ode - ~ 8 ad me eBrae ome tw em it sufficient to maintain life In these dust in the lungs but the results of cases is not the presence of asbestos have contributed to the fatal it in the form of gross fibrosis which lungs or any other illness outcome Certainly any other infection of the whatsover which demanded a reserve of lung tissue in excess of that sound effect Death in these actually available would have had the like adjuvant cases therefore effect of asbestos dust is not the result of any particular on a tubercular infection The inhalation of asbestos dust does not pulmonary tuberculosis nor does it appear to affect old inactive coincident tubercular infection appear to modify the result of While the presence of asbestos dust at exacerbation of a tubercular any rate temporarily induces an of more fibrosis than wouldinfection it also conduces to the development have occurred in its absence which is localising and reparative process permanent loss of On the other hand this effect results ian ultimately function in a greater unfavourable results in area of lung tissue with probably A tubercular individual cases infection may precisely as with other infections precipitate death in cases of advanced acute pulmonary the lungs been normal recovery would have asbestosis where had The factors of taken place prime importance which are of general in their application are massiveness of course not dose local but tubercular infection and virulence of the The evidence therefore points to the hypothesis that added risk to asbestos workers from at present the definitely less than in workers pulmonary tuberculosis is limited and infections will as in the exposed to free silica virulent virulent massive result in general population cause death lesser more widespread fibrosis than would ones will general population and slight appear in eases eases infections in amongst the affections are likely to precipitate death in common with many other where they would not do so the cases of advanced advanced asbestosis This general population appears be the position at the alter as effects of measures for dust moment whether this risk will apparent as is apparently happening insutphperessilsicioosins silicoisisn the industry industry become cannot be foretold as yet producing producing industries industries To be continued . 7 eGate EnPena ha ab . a Oe Terweft m:. wna 6 es _ Ot e me Be rea ae aeaedaca aetar 2 .t. Go RIK ry _ war e 0 ee bk ee es = ADP 2 DON e ww e leh.-_ 152 TURKRCLE January 1934 3 It is essentially essentially serial skiagramis necessary to control pneumothorax cases with 4 The hypothesis is advanced advanced that the R.E.S. produces an immunologic sanecrysin through stimulation of body immunologic or immunobiologie response in the . of 5 Sanocrysin in conjunction with with pneumothorax representa worthy advance in the treatment pulmonary pulmonary tuberculosia In conclusion I wish to acknowledge acknowledge my indebtedness to Dr. H. C. Calvey for his very valuable help in taking the skiagrams to Mr. Hall for aid in the preparation of this article article and to Dr. H. G. Superintendent permission to publish Trayer Medical publish hospital material REFERENCES 1 2 3 4 5 6 7 8 9 10 11 12 13 PETERS A. Amer Rev. Tub 1928 17 348 Gillies S. Med Jawn Austral 1930 il 119 " FINDLAY G. M. Recent Advances in Chemotherapy 1930 p 473 KRITSCHEWSKI I. L. Zentralbi f Bakt 1927 5 101 JUNGEBLUTT W. Zeitschr f Hyg u Infect 1927 107 357 FELDT A. and SCHOTT A. Ibid 1927 107 453 JIMINEZ DE ASIA F. and Kunts M. J. Compt Rend de la Soc Biol 1928 99 1414 KOLMER J. H. and SCHAMBERG F. Amer Journ Syph SCHR^ DERG. Zeitschr f Laryngol 1932 23 273-379 HUGHES T. A. and SHRIVASTAVA D. Brit Med Journ HOUGHTON E. Tubercle 1932 13 393 SABIN F. R. Ibid 1932 13 206 CLARKE B. R. Brit Med Journ 1929 II 576 1933 1930 17 197 H. 248 | O.K O.K ee A MEMORANDUM ON ASBESTOSIS By E. R. A. MEREWETHER M.D. Continued from p 119. - PREVENTIVE MEASURES As noted above pp 69 the risk from asbestosis in the industry is no less grave than the most serious serious risks from silicosisasibnestthoes producing industries While mortality rates for this disease not obtainable all the evidence and it amongst asbestos workers are that in the absence of all is not inconsiderable goes to to show preventive measures the risk to workers in the most dusty prncesses which appraisement of the recorded case and was made by the first quoted previously pp 72 is substantially correct of those employed in such processes continualy continually from leaving school survive ten years exposure and none none will reach the few will age of 30 . ; ty oh. os . a eae ae ae e ns o's te a an Pee,Ve aa .; 4 4 - at vt as wae.yeyaA r ok, ATS Ps cr ^' aa ate ar d eaeati a: mg omenare <eO& aoe : y a January 1934 A MEMORANDUM ON ASBESTOSIs 153 Fortunately in Great Britain for more than twenty years some measure of dust suppression though an inadequate one has been applied in the industry This has come about by virtue of Section 74 of the Factory and Workshops Act 1901 persuasion by H.M. Inspectors and cooperation of important firms in the industry in consequence of the vague belief which could not be supported by evidence that the dust was harmful In some processes such as carding the amount of dust suppression has been considerable for quite this period On the production of proof of the existence of the specific disease and of its incidence and serious nature the gravity of the position and the necessity of enforcing a high standard of ventilation and of dust suppression was realised The usual steps under Section 79 of the Factory and Workshops Act of 1901 were then taken the Secretary of State certifying that the manipula- tion of asbestos and the manufacture or repair of articles composed wholly or partly of asbestos and processes incidental thereto are dangerous and a code of Regulations designed to abolish the risk was drawn up These Regulations were termed the Asbestos Industry Regulations 1931 44 and by the direction of the Secretary of State came into force with the exception of a few March 1,1932 The excepted Regulations came into force six months and twelve months later it being impossible to carry out the extensive alterations and additions to premises and ventilating machinery required under them by the date specified for the main body of the code The complete code of regulations for the producing processes of the industry has been in force therefore since March 1 1933 The carrying out of these regulations casta no light burden on the industry nor could they have been applied in their entirety and with full effect within three years from the date of the certificate of the Secretary of State without the hearted operation of the trade Problems of ventilating engineering of the utmost difficulty had to be faced particularly on the textile side of the industry where the application of local exhaust ventilation and other methods of dust suppression of a high standard to operations in which the necessity for it had never been envisaged before was required That this was the case was realised from the outset and immediate steps were taken to arrange a conference of asbestos textile manufacturers and representatives of the Home Office to consider these practical difficulties and the best methods which could be adopted generally for suppressing dust in manufacturing and other processes The Conference agreed unanimously that everything practically possible should be done to suppress dust and the manufacturers promised their full assistance to secure this result It was then decided to set up a joint committee consider the problem in detail and to collect all inform- ation available concerning dust suppressing methods manufacturers The high public spirit shown by the leading British manufacturers in the industry particularly in their readiness to pool their experience in regard to the difficult problems to be solved enabled this Committee to do invaluable work = Further experimental work was done and new methods tried out in various factories and by the expenditure of much time and labour the 2 ~a BE Fede ak se Spor 2eon! wr tay AG PE OER CEM, suo eee er ee ST pe e=o 4: ~_ ts ES We } eOsd a cme een a ak awe ee te . ow BSee are- ee ee epaeNDa:e Cd 1) AS PSR ar per wen 15-4 TUBERCLE January 1934 Committee were enabled to report in January 1931 within six months of its constitution Its report is set out in series of twenty agreements covering the main processes concerned and embodying concrete and detailed recomiuen- dations of a practical nature for dust suppression 37 The Committee agreed on a practical standard of dust suppression based on the considerations previously discussed Section VIII and concluded on the evidence in this memorandum " available that For practical purposes the conditions arising frotu flyer spinning carried on without exhaust under good general conditions may it seems to the Com- inittee be taken as the dust datum . . . If therefore a particular process appears to give rise to dust in excess of that associated with such iyer spinning the Committee regard the need for preventive measures as established The Agreements and Recommendations put forward in its report are aimed at the reduction of dust in other processes to this dust datum level The Report of this Committee together with certain suggestions of the General Council of the Trades Union Congress to whom the Report was communicated were taken into account in drafting the Code of Regulations previously referred to which gave statutory effect to the Agreements arrived at by the Conferences These Regulations apply the following principles as and where requisite to achieve the agreed standard 1 Application of efficient localised exhaust ventilation at dust- producing points 2 Substitution of enclosed mechanical methods for hand conveyance and for dusty hand work generally 3 Effective enclosure of producing machines and plant ; 4 Substitution of wet methods for dry 5 Elimination of certain producing appliances 6 Effectual separation of processes to prevent unnecessary exposure to dust 7 Use of sacks of close texture material for internal work in the factory and cleaning of them by machinery 8 Efficient cleaning system 9 Precautions to prevent dust from asbestos in storage chambers or bins entering the workrooms 10 Regular examination and testing of ventilating plant dust settling and filtering apparatus not to be allowed in workrooms 11 Breathing apparatus approved type to be provided for persons employed in certain operations The Regulations also prohibit the employment of young persons i.e. under the age of 18 in the most dusty processes Other preventive measures in forco include the control of the disease by periodical medical examination of the workers by which those unfitted by health reasons are prevented from entering the industry Section 12 of the Silicosis and Asbestosis Medical Arrangements Scheine 1931 and cases of fibrosis and of pulmonary tuberculosis are detected at the earliest possible moment These section in connection with are Biore conveniently discussed compensation for asbestosis in the next ~~ me Ty 2:i r pret > ae rah by Se atesae w%AB we . Ae Bs aR - me peery Bre. PP TSS OWT on Gm ot pee ver nnee e Lr EON 7a dine, ce f wi wjax 4 f ; ao ie January 1934 A MEMORANDUM ON ASBESTOS19 155 COMPENSATION FOR ASBESTOSIS In Great Britain by the Workmen's Compensation Act 1925 na extended by the Workmen's Compensation Silicosis and Asbestosis Act 1930 the Secretary of State was empowered to minke a scheme of compen- sation for industries and processes involving exposure to asbestos dust and also a general Scheme for ordinating the medical arrangements in connection with this Scheme and with all the schemes of compensation for silicosis in the producing industries and processes Following this the Asbestos Industry Asbestosis Scheme 1931 38 providing for compensation for asbestosis and asbestosis accompanied by tuberculosis was made and came into force on June 1 1931. It applies to all workmen employed at any time on or after May 1 1931 in any of a comprehensive schedule of specified procESBAR On the same date the Silicosis and Asbestosis Medical Arrangements Scheme 1931 39 came into force This Scheme effectively simplified and different medical arrangements already in force in ordinated the connection with compensation for silicosis or silicosis accompanied by tuberculosis and also applied the same general procedure in connection with compensation for asbestosis or asbestosis accompanied by tuberculosis Under this Scheme a whole Medical Board of specially qualified practitioners supervised by a Chief Medical Officer with the view of securing a uniform standard of efficiency is charged with the duties of Periodical Medical Examination of workers employed in the specified industries or processes of examination of workmen in connection with claims for disablement from these diseases and of granting of the appro- priate certificates in connection with disablement or death claimed to be due to these diseases The Medical Board acts in different areas of the country by panels of not less than two members of the Board and all certificates are granted with the authority of not less than two members and are conclusive evidence of the matters therein certified in pursuance of the provisions of the Scheme Furthermore under Section 12 of the Scheme every new entrant must be examined within two months of com- mencing employment by a member of the Board or by other duty qualified medical practitioner specially appointed by the Secretary of State for the purpose If he fails to satisfy the following requirements with respect to physique 1 The chest must be at least of average development and the respiratory passages must be free from obstruction 2 there must be no signs of disease of the lungs or heart and 3 there must be no tuber- culosis of any region the case must be referred to the Board who if Batisfied must suspend the workmen from further employment in the industry or process and shall certify accordingly The prescribed interval between the periodical examinations of asbestos workers one year and if a worker is found to be suffering from asbestosis or from tuberculosis to such a degree as to make it dangerous for him to continue work in the industry or process the Board must suspend the worktuan and certify accordingly In the case of a death claim the certificate of the Board can only be given after a mortem examination except only in such cases where the workman at the time of his decease was in receipt of weekly payments oT Sid Te s bes seca. se B | hetro ft a = t q ee es ee Oe "yy i ee ee rot ee Lae its 7 +7 e ied: Vag ; ane i rir 1 ; Ce oe Ce = ee ee i] vl Ve am Ae Pg rao CEMTTT Tm Rat Al: ids y aba Sn Ur 3 8 e,3 HEE weed 2 sf , 5 bode p J Ue ARR ae Lae sired pitty OT, avr calle MNS ea teed Bis G ee Ee oe ih se * 8 he rt eA ER ae ie pee ee FTA xd we. om ey ee em ee we e o ee peg me Pers 3 a snes ars. 79" a eee Ati BB. ~ e el ee ee ey. me o_O me ees ae a wer Await ae meaoom cS we > < odoto en ne 4 - chan - a + $ on a Oe) TUBKACLE January 1934 under the Compensation Scheme and the Board is satisfied that mortem examination is a post- unnecessary The Schemes therefore in their application to asbestos workers vide for the periodical medical examination of all workers pro- exposed to any appreciable risk of developing asbestosis for compensation for death and for partial or total disablement due to asbestosis or asbestosis accompanied by tuberculosis for the suspension of workers auffering from asbestosis asbestosis accompanied by tuberculosis or tuberculosis to such a degree as to make it dangerous for them to continue work in the and for the exclusion of new entrants who are unsuitable on medpircoaclesgsreosunds for employment in the industry It will be observed that broadly speaking these Schemes are effective in three directions - 1 They protect the worker and his dependants by providing expeditiously and economically for compensation if death or disablement is produced by asbestosis by minimising any added risk from tuberculosis and by preventing those who on medical grounds are especially liable to be adversely affected by work in the industry from entering it 2 They protect the employer by raising the physical standard of entrants into the industry and by provision for expert scrutiny on uniform standard throughout the country of claims for compensation a 3 The data obtained from the records of the Board's examinations form the ultimate and only reliable criterion of the effectiveness of the preventive measures adopted in the industry ASBESTOSIS IN OTHER COUNTRIES It appears that other European countries as well as Great Britain have experienced prior to the Great War isolated or the inhalation of asbestos dust might be dangerous but vague warnings that generally that to a variety of causes which have been discussed owing already it was not recognised that these warnings were portents of a serious risk in the industry . Thus in the French official Bulletin de l'Inspection du Travail for 1906 4 the year in which Dr. Montague Murray gave his evidence before the Departmental Committee on Compensation for Industrial Diseases there appeared " Note sur l'Hygi^ne et la S^'curit^'des Ouvriers dans les Filatures et Tissages d'Amiante by M. Auribault He states that the atmosphere of the workrooms " surcharg^'ed'une multitude de particules siliceuses is an eminently suitable milien for the production of an occupational phthisis identical with those of potters millstone makers & and he gives un exemple frappant to corroborate this inference He continues En 1890 une usina de filature et de tissage d'amante s'~tab-s'~ tab- lissait dans le voisinage de Cond^'Noureau Calvados An cours de eing premi^resann^'esde marche ancune ventilation artificielle P^'vacuation dire te des n'assurait n'assurait poussi^res siliceuses produites par les divers nombreux m^'tiers cette inobservation totale des r^gles de Thygiene nombreux inobservation d^'c^s dans le Thygiene occasiona de : personnel personnel une cinquantaine d'ouvriers et January 1934 A MEMORANDUM ON ABBESTO8I9 157 d'ouvri^resmoururent dans l'intervalle pr^'cit^'lee Directeur pr^'c^'demment propri^'taire d'une filature de coton ^ Gonneville Manche avait recrut^' 17 ouvriers parmi son ancien personnel 16 d'entre eux furent enlev^'spar la chalicose de 1890 & How comparable is this to the statement of Montague Murray's case in 1900 that he was the last survivor out of ten employed in the cardroom Auribault continues that the workmen 2h justement effray^'s believed erroneously that lead poisoning derived from the asbestos occasionnait la disparition rapide de leurs camarades usmee Following this local exhaust ventilation at first primitive in type but OST later improved was applied to the cards and the teasers eflocheuses were isolated with the result that the inortality diminished considerably This is a valuable picture of the conditions which must have been common to asbestos textile factories in any country in the early days of the industry moreover he goes on to recommend ventilation of cards and enclosure of opening machines and prohibition of employment of young persons under 18 unless there is " une captation rigoureuse des poussi^res The first record in Germany was a demonstration by Fahr to the Medical Society of Hamburg in 1914 of specimens and photomicrographs of a case of pneumonokoniosis in an asbestos worker Fahr mentioned the occurrence of large numbers of crystals in the lungs but did not describe them more closely He stated however that they had been seen by Marchand and Riesal in 1906 who had speculated on their origin In the last year or two a number of fatal cases have been reported from other countries including South Africa Germany the United States of America and Italy German observers evidently regard the risk as serious Kruger Rostoski AF and Saupe 3 stating that of 52 workers whom they examined 30 showed oe definito lung changes Their general conclusion was that moderately ae severe asbestosis takes some five years to develop Of the workers they eS examined who had bad ten years or tuore exposure none was free from signs of the disease From Italy 40 too comes confirmation of the | existence of severe pneumonokoniosis amongst workers which can reach complete development after a period of seven to nine years and can cause death after thirteen years continuous exposure to much dust Cases with a fatal issue are however that all workers who had Lovisetto continues rare worked for some time in Mussa 41 states the asbestos works showed lesions of pneumonokoniosis which could be recognised clinically and radiologically he met with no case of association of pneumonokoniosis with tubercular lesions Scarpa however prior to 1906 found 29 out of 30 asbestos workers to be suffering from tuberculosis 42 Simson 43 in South Africa examined the lungs of two native asbestos mill workers one of whom had been employed for twelve months and had died from a miliary tuberculosis and the other employed for two years had apparently never recovered from an attack of lobar pneumonia a year before death He comments the amount of the fibrosis in two of the se human cases . . . was quite definite and if due to the presence of arid asbestos dust the initial rate of production was rapil when compared with ; present day infective silicosis on the Rand The same observer examining the lungs of a guinea experimentally dusted by Mavrogordato for one hundred hours during a period of fifty days meee y i - a @: > . ...ee . H ... i if + \ y 4 t a Se Te .s -w } 2 | ' =i 3 tiarhe n hae bee t: I} e, bi vt mee ne e e vat fae ih . Se ~~ || nT oer : 3 eS tte 1 ian . ! \" \sf | i | \ al Ay | | i ie i dew | ... ... ...at t w mw a mw -- = n 158 158 TUBEROLE January 1934 showed that this exposure ultimately resulted in the development of a slight generalised fibrosis Gardner and Cummings the United States of America whose detailed already researches have been quoted showed that in experimentally dusted in guinea the fibrosis begins those portions of the lungs where the dust is localised and that this reaction can be detected in ray pictures after about two years exposure to the concentration of dust used Evidence from all quarters therefore confirms the risk of pulmonary fibrosis attendant on the inhalation of asbestos dust While no doubt the risk varies in different places and different works depending on the local conditions and the amount of dust produced the risk is general wherever more than minimal amounts of asbestos dust are produced in a manu- facturing process Of the risk associated with quarrying of the mineral this country has no experience since there are no deposits of the mineral in Great Britain which are worked commercially It is not unlikely that the risk of true asbestosis in quarrying the mineral may bo less than in the comparable dusty manufacturing process owing to the low percentage of asbestos in the dust produced in the quarries and the open nature of the work but the risk in the dusty milling and manufacturing processes is patent and serious XIII OUTLOOK ES anes, eo hte Bet yar a 54+: teary < repay. is Svat " She APT >: e ee me e ne we No discussion however slight of the characteristics of a specific of occupational disease its effects on the workers and its reactions on employers and the State can be considered adequate in the absence of some examination of the position at present and of some appraisal of the prospect before the industry In asbestosis we have an industrial disease comparable in its general effects to silicosis and equally menacing to the industrial host which is harbours it In Great Britain fortunately as compared with silicosis the risk in point of number of workers exposed to the disease a limited one but it takes a grievous toll of those workers When the inevitableness of the outcome of exposure for even a year two or to the high concentrations of asbestos dust commonly encountered in certain operations and the shortening of life which results is realised the imperative and immediate need of adequate preventive measures is apparent The aim of these preventive measures is of course to make it impossible for new entrants into the industry to develop the disease and the main agencies by which that goal can be attained are the trind which have Berved industrial hygiene so faithfully exhaust ventilation enclosure of dusty operations and wet methods of manufacture A high standard is essential as is evidenced by the failure of past efforts although those early ones were however partially effective The practical engineering difficulties are great but can be surmounted In spite of these difficulties the industry is in a very favourable position because experience in this country is showing that in contradistinction to soma of the producing risks the problems in the asbestos industry are finite ones and when tackled successfully do not leave anyany further subsidiary but at present insoluble probletus ee "th A ek oy rCayMsCae , & te. ta i he pit Par doh, a ie z i fad Sa Bi WES ayer oy Re January 1934 A MEMORANDUM ON ASMESTO919 159 Apart from the necessity of the application of effective methods of dust suppression to obvious dusty processes such as opening and carding and to others less obviously dusty such as dry weaving and ring spinning many incidental operations involving the handling of fiberised asbestos have to be eliminated and replaced by dusty enclosed mechanical methods In this connection a practical maxim of the greatest value is that every translation of fiberised asbestos in the factory produces dust which if not controlled is dangerous It is this principle which underlies the dust suppression methods in use now in Great Britain Then what of the outlook If we accept that the dust datum level p 154 is for practical purposes a safe criterion of dust concentrationcon-centration- and although one cannot be dogmatic on this point as yet nothing has arisen which casts doubt on its validity as a safe limit the dust produced in more dusty processes is suppressed generally to this level and this standard is conscientiously maintained then the outlook is bright Some years must elapse before the cases representing the accumulated risk disappear from the industry but then it is believed that the minimal amounts of asbestos dust inhaled by workers under the new conditions will neither shorten life nor cause disablement The position is strengthened by the evidence that any added risk from tuberculosis is less than in the producing industries Moreover the added safeguard in this country of periodical medical examination at yearly intervals of almost all asbestos workers exposed to appreciable risk with suspension from employment in such processes of all cases of open tuberculosis diminishes this residual risk The influence of these three factors the diminished power of asbestos as compared with free silica of aiding a tuberculous infection suppression of dust in manufacturing processes to a level below that which will produce a disabling fibrosis within the space of an average lifetime and periodicul medical examination of all workers exposed to potential risk with exclusion of those workers with open tuberculosis cannot fail to be effective in achieving the common goal This goal is not the prevention of minimal and microscopical effects of asbestos dust which must occur however slight the exposure but the abolition of the risk from the development of diffuse fibrosis and of any residual added risk from tuberculous infection The way is undoubtedly hard and to attain the object the urge for incessant vigilance must arise in both the management and the workers within each factory . In grappling with this problem the asbestos industry as compared with the producing industries in tackling the problem of silicosis starts with considerable tactical advantages because of the method of action of the dust of the nature of the processes in which protection is required and for other reasons The problem of the control of asbestosis is definitely finite as compared with the control of silicosainsd it is this fact coupled with the evident desire of the leading manufacturers as shown by the remarkable progress in dust suppression made in the past two years and their courage in dealing with the practical difficulties which relieves the apprehension inevitably associated with a serious occupational disease and cheers with the conviction of success tusaaret a OUT even F : Baae h ngSTRtauLaaaetec CR aS e eeiy | Apia ict og ct oye bate