Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from 599

PNEUMOCONIOSIS By A. MEIKLEJOHN, M.D. From the University of Glasgow7

Historical (I828) about the complete enclosure of carding and In medical writings from the ' Epidemics of spinning machines and how from the picking room Hippocrates' (460-370 B.C.) to the ' Treatise of alone 828 lb. of cotton dust was collected in the the Diseases of Tradesmen' by Ramazzini (I633- exhaust chamber during a single year. Calvert I714), the historian may discover references to the Holland (i843) discussed the advantages of down occurrence of lung diseases among workmen en- draught exhaust ventilation with flues under the gaged in dusty occupations, but the significance of floor-as against overhead hoods and ducts. these passages is largely speculative. By contrast On the clinical side, early detection of the the allusions contained in the texts (Meiklejohn, disease by regular medical supervision, chest 1947) of Benson's Patents, 1726 and 1732, for measurement, estimation of pulmonary vital grinding flints are precise and comprehensive: capacity and inhalation therapy, all are noted. ' Any person ever so healthfull or strong work- Lack ofco-operation bythe workmen then as now ing in that business cannot probably survive above was a problem:' We remark with regret the men's two years, occasioned by the dust sucked into his inattention to health, their indifference to the pre-Protected by copyright. body by the air he breaths, which being of a pon- vention of disease. They think nothing of in- derous nature, fixes there so closely that it is now jurious agents till their health is destroyed and the very difficult to find persons which will engage in time for prevention is past.' Employers have the business, to the great obstruction and detri- responsibilities and duties: ' It is especially in- ment of the said trade.' cumbent on masters to regard the health of the These statements appear authentic as it is re- persons they employ; to examine the effects of corded that calcined flint was introduced for use in injurious agents, to invent and provide remedies, earthenware manufacture in 1720 (Shaw, I829). and to enforce theit application.' But this cannot Thackrah of Leeds (I832) discussed at length be achieved voluntarily and so the need of Factory the health of ' operatives subjected to dust' and Acts is foreseen: ' Whatever improvement may be ever since physicians have recorded from their own effected without a legislative enactment . .. this local experience the melancholy tale of dust, con- improvement will be but temporary.' Finally, for sumption and premature death. Knight (I830) a the physician, there is wise counsel: ' He must not practitioner of Sheffield relates that, ' The fork be content with the loose statements of thoughtless http://pmj.bmj.com/ grinders who use a dry grindstone die at the ages and prejudiced workmen ' (Thackrah, I832), and of 28 and 32 ' and among the preventive measures nowadays I, personally, would venture to add which he recommends is that this occupation employers and trade union officials. should be confined to criminals. In support of their arguments these early The disease then, as now, was incurable, and authors provide extensive statistical tables re- so the demand was for prevention and control. vealing the dreadful toll of fibroid phthisis in the There is scarcely a single modern measure or de- i8th and igth centuries, but repetition here would vice which is not recorded and discussed by the serve little purpose; indeed by false comparisons on September 28, 2021 by guest. older writers. Thackrah (I832) mentions sub- might lead to a wholly unjustified complacency stitution of harmful by less noxious substances, ex- about the tragic present. I haust ventilation, wet processes in place of dry, The historical development of opinion on the face masks, alternation of employment and re- etiology and pathology of lung diseases in trades- duced hours of labour. In a very interesting men requires brief notice, but before this it is passage he describes the benefits of natural water necessary to examine the evolution of the nomen- infusion through fissures in the rock in lead clature of the disease. mines: ' The particles, on the contrary, are laid as they Nomenclature and its Significance are formed, by the continuous oozing, dropping During the i8th century the dust diseases of the and splashing of the insinuating water.' lungs were identified by terms descriptive of the At a Scottish cotton mill we learn from Ritchie clinical features, asthma, rot, phthisis or con- Si Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from 6oo POSTGRADUATE MEDICAL JOURNAL December 1949 sumption, to which was prefixed the name of the plied in ' active' and ' inert' dusts and ' benign associated trade, as in knife-grinders' asthma and pneumoconiosis ' (Prendergrass and Leopold, potters' rot. The next phase in nomenclature was I945). The problem is still further complicated related to the study of morbid anatomical changes by attempts to embrace certain legal and ad- in the lungs observed at necropsy. In I838 ministrative considerations in relation to work- Stratton proposed the term anthracosis to describe men's compensation (Fletcher, 1948). And again the appearances which he had observed in a coal- how are we to regard byssinosis, bagassosis, miner's lungs. Later, about i866, Zenker re- berylliosis, aluminosis, manganese pneumonitis, corded the presence of red iron oxide in the lungs bronchomycoses and a host of others ? The con- of women engaged in handling this powder. This fusion is world-wide and 4,as become so great that condition he named siderosis and for the various it almost appears as if the original terminology affections of the lungs produced by the inhalation should be abandoned and that some authoritative of dust-like particles he proposed the generic title body such as the International Labour Office pneumonokoniosis (nvev'p'ov, lung and KOVL5, should endeavour to formulate and establish a dust). Following this practice Visconti, in I870, classification and nomenclature for universal use. introduced the term silicosis for those cases in At present in this country the practical every- which the noxious dust was composed of silex or day consideration is the legal definition for pur- flint, and Merkel added chalicosis when fine gravel poses of workmen's compensation under the or stone was the offending agent. Byssinosis was National Insurance (Industrial Injuries) Act, I946. the form associated with the inhalation of cotton, '"Pneumoconiosis " means fibrosis of the flax and linen dusts. Thus a stage of finality was lungs due to silica dust, asbestos dust or other reached whereby pneumonokoniosis was recog- dust, and includes the condition of the lungs nized as the general title signifying a condition of known as dust reticulation.' dust disease of the lung. Under this heading cer- This is fully discussed in the contribution byProtected by copyright. tain varieties were identified and named according Dr. Sutherland. to the causative dust, anthracosis, siderosis, sili- cosis, chalicosis and byssinosis. Collectively these Pathology and Etiology constituted the pneumonokonioses or dust diseases The earliest references to the noxious effects of of the lungs. At present there is considerable con- substances inhaled into the lungs are to the fusion in the use of these terms as exemplified by clinical manifestations in certain occupations, this definition in the current Compensation notably metalliferous mining. Thus Hippocrates Act (I946) in South Africa: ' " Silicosis " means writes of 'the wan complexion and the difficulty any form of pneumoconiosis due to the inhalation of breathing of the metal diggers' and Georgius of mineral dust.' Agricola (I557) remarks that 'when the dust is So in effect silicosis may mean asbestosis. This corrosive it ulcerates the lungs and produces reflects the fact that the original generic term has consumption.' proved awkward and pedantic in regular use. In Apart from recording the same illness in an practice it has become shortened to pneumo- ever increasing number of trades and occupations, http://pmj.bmj.com/ koniosis; an attempt to abbreviate it still further to no advance occurred until the igth century when koniosis failed. Two forms of spelling, pneumo- study of the morbid anatomical changes at koniosis and pneumoconiosis, are in regular use, necropsy permitted correlation with the clinical but the latter receives most favour throughout the manifestations. Diemerbroek (I832) relates that world and is the only spelling recorded in the ' in dissecting the bodies of masons, dead from ' New Oxford Dictionary ' (I909 edition). Classical asthmatic affections, he found heaps of sand in scholars agree that both spellings are defensible, their lungs, and in dividing the pulmonary sub- but omission of the central ' no ' is wrong, render- stance, he seemed to be cutting a sandy body.' on September 28, 2021 by guest. ing the term etymologically meaningless. Usage Gregory (I83I) describes the lungs of a miner as and convenience, however, have established the being infiltrated with black matter resembling, if shorter form; the need is to adopt a uniform not identical with, coal. spelling. Calvert Holland (I843) is among the earliest With the advance in knowledge of pathology of observers to suggest that in cutlery grinders' dust affections of the lungs, a more serious asthma the ' structural modifications in the lungs difficulty has arisen, namely, interpretation of the are of two distinct types and so admit of an easy term pneumoconiosis. Does it signify simply the classification.' accumulation of dust in the lungs, a dust-ridden ' In the one case, they (the symptoms) were state, or does it involve the concept of disease, a often accompanied with considerable constitutional departure from health ? That 'there is no agree- vigour, and though harassing in the extreme, ment is reflected in such distinctions as are im- interfered comparatively little with the appetite Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from December 1949 MEIKLEJOHN: Pneumoconiosis 6oi Protected by copyright.

FIG. i.-Male aged 40 years. Radiographic appearances natural for age.

or the digestive functions; and in connection with lesions and associated changes in the lungs. these symptoms, the chest was observed to be Considerable controversy, however, has ranged prominent and well-developed. In the other case, over the separate and combined effects of the dust the thorax was remarked to be flat and contracted, and tuberculous infection, and this problem re- the powers of life feeble, and the animal frame ex- mains unresolved. hibiting indications of gradual emaciation.' From the outset dust was generally recognized The same author gives an equally compre- as the noxious agent though Laennec (i8I8) re- hensive account of the marked structural changes jected the idea that dust could be retained in the in the lungs, among which he particularly notes lungs and so induce disease. Calvert Holland http://pmj.bmj.com/ the hard, black, gritty enlargement of the bronchial (I843) dismisses this opinion as lack of experience glands immediately at the bifurcation of the of manufacturing processes. Summing up the trachea and: chapter of his book on dust diseases, Thackrah 'In some instances the lungs have presented an (I832) records: appearance as if black currants had been dis- ' Dust is the great bane of manufacture, and tributed throughout the whole substance of them.' whether it be farina, animal or vegetable fibre, or This is still an accurate description of ' classical evolved from minerals, stone, lime, coal or metal, silicosis.' These quotations reveal that the it injures the respiratory organs, in proportion to on September 28, 2021 by guest. physicians were already beginning to distinguish the mechanical irritation it induces on the between simple dust fibrosis and this condition bronchial membrane.' complicated by tuberculosis. Hall (I857) asserts During the ensuing years the occurrence of the this quite clearly: disease was reported from practically every ' There is no necessary connexion between the country in which metalliferous mining was carried Sheffield grinders' disease and thoracic consump- on. Presenting evidence before a Royal Com- tion, although both affections may be present in mission, Haldane (1914) made this significant the same individual.' declaration: The absolute distinction was not possible until ' I believe the disease is the same all over the Koch's discovery of the tubercle bacillus in i882. world, and the end comes through tubercular Since then pathologists have added greatly to infection; ' and our knowledge of the minute histology of the 'We ought to know what the qualities are in B2 602 POSTGRADUATE MEDICAL JOURNAL December q49 Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from Protected by copyright.

FIG. 2.-Male aged 58 years; china biscuit placer (pottery, pure flirt risk), 45 years. Generalized fine silicosis ;died 4 months later ;mvocardial degeneration; silicosis without tuberculosis; confirmed post-mortem. the dust which makes it dangerous, so that we 'Finely divided silica in the lungs slowly forms may be able to say with regard to any dust off- a silica sol, which acts as a direct cell poison.' hand whether that dust is dangerous or not.' While this has proved generally acceptable some In the following year Collis (I915) provided part authors (Heffernan and Green, I928, and Heffer- of the answer when, as a result of comprehensive nan, 1946) dissent. Reviewing this aspect of the analytical studies in various industries, he con- subject in I945 King concludes: cluded: ' Successful as the solubility theory may be in

'While most dusts have an injurious influence, explaining the observed facts of silicosis and in http://pmj.bmj.com/ silica in the form of free silicon dioxide alone indicating new lines of approach, it must be stimulates the formation of fibrous tissue.' recognized that it does not always appear to work So just as Haldane had proclaimed the essential in practice.' unity of the pathological process, Collis had de- For a time (Middleton, 1936) it was thought, but fined the essential unity of the causative agent. now rejected (I.L.O., I938), that alkalis could The disease was silicosis and the problem was to accelerate the action of silica, while Haldane discover the mode of action of the silica particles. (1917) had suggested that coal dust had an in- Thackrah and Calvert Holland had attributed it hibitory action, a quality which Heffernan and on September 28, 2021 by guest. to mechanical irritation. McCrae (19I3) had Green (1928) had likewise attributed to ' clay demonstrated that ' the largest particles which substance, carbon and shale dust,' and Kettle gained access and became embedded in the lungs (I935) to oxide of iron. This idea has been did not exceed io microns in diameter and 70 per advanced still further in relation to powdered cent. of all particles were less than i micron.' metallic aluminium (Denny, Robson and Irwin, This enabled Gye and Purdy (I922(a) and I922(b) ) I937, I939(a) and i939(b)). to determine: (i) ' that particles lose their sharp- Gardner (I920) in America represented another ness when embedded in the phagocytic dust viewpoint, namely, that ' the lung lesion is due to cells,' and (2) ' that the reaction (fibrosis) is a combined irritant action of the tubercle bacillus noted at points remote from the presence of and the silica, which action neither of them alone silica.' can produce.' This reflects the other character- They advanced a chemical hypothesis of action: istic of the disease which remained unexplained, December 194(9 \IEIKLEJOHN: PuiOtlnl,oeoiosis 6o0 Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from namely, the excessively high incidence of tubercu- revealed in the classical statistical surveys of Farr losis as a complication of silicosis. Following ex- (I875) and Ogle (i885). Today, as never before, tensive laboratory observations Gye and Kettle they constitute a major political problem. (I922) concluded that ' silica caused a coagulation Commencing in IgI9 the various forms of necrosis in which all of the tubercle bacilli were pneumoconiosis have been brought within the protected from phagocytosis and enabled to scope of workmen's compensation under which multiply rapidly with impunity,' a process further certification of the disease is solely the re- facilitated by disorganization of the lymphatic sponsibility of the Pneumoconiosis Medical Board drainage of the lung. of the Ministry of National Insurance. As a Just when it appeared that free silica had been result comprehensive authoritative statistics are established as the single causative noxious agent, a available and the present position may be con- niew dust disease was reported and confirmed. cisely represented in the following table derived 'T'his was asbestosis, fibrosis of the lungs due to from this source. the inhalation of asbestos dust. Asbestos is a complex mineral silicate, so the whole question of CEIRTIFICATES OF TOTAL OR PARTIAlAI)1DSABL,EMEN'INT BY the etiology was re-opened in relation to this and REASON OFTI;HE DISEASE* (1939-1947) other silicates (combined silica as opposed to free ' ' Yearly average silica) and for a time the term silicatosis was Industrv or Process No. of (nearest whole current. Then Jones (I933 and 1934), following certificates number) analyses of the ash of silicotic lungs, disputed the free silica hypothesis by submitting that while free Refractories Industries. 153 17 silica might be the causal agent in isolated cases, Sandstone Industry .. 306 34 Pottery Industrv .. 474 53 its action was insignificant compared with that of Asbestos Industrv IO3 II a fibrous mineral silicate, known to geologists as Metal Grinding In- Protected by copyright. sericite. 'This hypothesis, in turn, has not with- dustries .. .. 35 4 stood the critical judgment of experts and has not Coal Mining Industry 1 , 66 2,130 Masons and Stone been confirmed by animal tests. Dressers .. .. 220 24 Finally the alarming incidence of chronic pul- Sandblasting anid Steel monary disease among coal-miners, particularly in Dressing .. 2I8 24 South Wales, focused attention. 'The occurrence Metalliferous Mining so8 12 of silicosis among the stone workers in the mines Haematite Mining In- dustry .. 8I 9 was well known, but these cases accounted for a Slate Mining Industry 157 I very small number of the total. A special inquiry Other Industries 210 23 was instituted by which Hart and Aslett (1942) All .. .. 20,885 2,32I established that among underground workers and * The disease means silicosis, asbestosis or pneumo- certain others engaged in handlinig coal, there coniosis or any of these diseases accompanied by exists another form of pneumoconiosis, to which tuberculosis. ' they applied the name dust reticulation,' a term http://pmj.bmj.com/ descriptive of the radiographic and pathological The absolute numbers are impressive, but their changes. Belt and Ferris (1942) originally relative significance involves consideration of many described the pathological changes and Gough factors. Thus in the pottery industry 53 cases in (1940, I947(a) and I947(b)) has since added con- a year may not seem a large number unless it is siderably to this knowledge. As yet the causative appreciated that they accrue from a population of dust constituent has not been defined and is 6,ooo workmen (Meiklejohn, 1949). This is even proving a very difficult problem as ' coal' or more cogent in relation to sand-blasters and steel ' mine ' dust is a very complex mixture ot mineral dressers (Merewether, I936). By contrast the on September 28, 2021 by guest. dusts, including not only carbon but free and population at risk underground in coal mines combined silica, silicon dioxide and silicates. In (55o,ooo) helps account for the large total of cases addition the workmen are exposed to various gases but does not reveal that the certified cases are derived from explosives and to volatile emanations almost entirely derived from South Wales (65,000 resulting from the natural decomposition of coal. underground workmen) (Fletcher, I948). Be- Moreover, the possible role of associated tubercu- tween IgIg and I927 the average annual incidence lous infection in the production and course of the of cases in the metal grinding industries in disease remains undiscovered. Sheffield alone was 30 as against 4 at present for the whole of Great Britain. This reflects the re- Social Aspects placement of sandstone grindstones by non- Throughout our industrial history the pneumo- siliceous wheels, which has taken place since I928. conioses have created serious social problems as The related social problems are alarming and 604 POSTGRADUATE MEDICAL JOURNAL December I949 Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from admit of no complacency; workmen's com- through tubercular infection' is fundamentally pensation is no solution. Morris (1947) and true. The incidence and severity of the disease Meiklejohn (I947, I949) have dealt with these in and the accompanying clinical manifestations in coal-miners and pottery workers respectively. particular communities, however, by reason of Coal-miners may be taken as an example. It is different industrial practices, associated dusts, estimated that every single certified case involves racial constitution and habits and climatic con- compensation payments to the workman and his ditions, vary considerably from one country to dependants of at least £i,ooo. This means that another. This is equally true within a single the coal mining industry since I939 has acquired geographical area as exemplified by the disease in an average annual liability of £Z2,ooo,ooo. Even Staffordshire potters, Cornish tin miners and more important is the fact that the men involved Aberdeen granite masons. Likewise there are are the most highly skilled face workers at the differences within an industry as observed in height of their production. Every certified case foundry workers and even among workers in the represents the loss of I0 to 20 years' man-output. same occupation. These significant matters are Many are only partially disabled and require re- all too often overlooked both by writers and settlement in alternative employment, a peculiarly readers. Nevertheless certain facts are of general difficult problem in areas so long restricted to application and provide the background against heavy industry.. Most serious of all is the drift which the problem in particular industries or of population from the mines and the mining processes may be studied. areas; wastage of man-power exceeds recruitment. Silica is widely distributed in nature, forming In varying degree this picture is true of all dan- 70 per cent. of the earth's crust. It is the chief gerous dusty trades. Over one hundred years ago constituent of many rocks and also# occurs as Calvert Holland (I843) wrote this of Sheffield flint and natural quartzose sands. In addition to grinders' asthma: being abundant, readily available and compara-Protected by copyright. ' It will also be obvious, from the various facts tively cheap, it has certain qualities peculiarly brought under consideration, that the evils must valuable in industry. Thus it is insoluble in all in various ways be felt by every portion of the acids except hydrofluoric (pottery manufacture community, vice, ignorance and destitution, exert and glass making), highly abrasive (metal grinding a widely pervading influence. The inability of the and sand blasting) and refractory to very high artisan to continue his occupation from disease, temperature (brickmaking for furnace linings and throws him and, perhaps, a numerous family, upon moulding in foundries). the parish for support, not in a few solitary cases, All processes which involve the manipulation of but in hundreds of instances; and it is scarcely silica, especially in the dry state, in such a way necessary to observe that on his death the same that it is broken up into minute particles and dependence, if not indeed in an aggravated form, inhaled, are liable to produce silicosis. Thus in becomes indispensable for years. When the parish Great Britain the disease is associated with coal is not burthened in this stage of suffering, the and metalliferous mining in siliceous strata, injury to society, from the inadequace struggles of and dressing cutting of sandstone, grinding of http://pmj.bmj.com/ the afflicted artisan to live, is scarcely in any metals on sandstone, pottery manufacture, making degree mitigated. The children, without having of silica bricks (the refractories industries) and in received any education at all, are put to work at foundries, the cleaning and freeing of castings seven, eight and nine years old, from which cir- from adherent sand. In these industries large cumstances, and the fruitful consequences which numbers of men and women are at risk, but there flow from them, in a later stage, additional claims are many other operations such as flint crushing, upon the parish funds are created, or ignorance packing of scouring powders, tunnelling and the and immorality extend, maintaining low and de- cleaning of the stonework of sandstone buildings on September 28, 2021 by guest. praved habits of feeling among the labouring in which the exposure may be very intense though classes.' involving only a small number of workmen. As Social legislation may have advanced but will appear later the purpose of the occupational effective practice still lags far behind knowledge. history of a patient suspected to be suffering from pneumoconiosis is to define the period, intensity Silicosis and character of the dust hazard. In the pro- Silicosis is the specific variety of pneumo- duction of the disease it is generally accepted that: coniosis due to the inhalation of silica dust. Its i. The silica must exist in the crystalline form occurrence is world-wide, affecting all races, males as free silicon dioxide. and females alike. In relation to the pathological 2. To gain entrance to the lungs and establish lesion, Haldane's (I914) assertion that' the disease effective occupation, the particle size must be is the same all over the world, and the end comes under io microns. lDenember I949 MEIKLEJOHN: Pneumoconiosis -605 Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from

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3. The dust particles are most active when progression of the disease. This factor has not under 2 microns in diameter and freshly fractured been defined, though infection, especially tubercu- mechanically or by heat at very high temperatures; losis, is suspect. this ensures the maximum superficial area relative to size. Pathology and Course of Silicosis 4. The intensity and period of exposure are in- With every breath the workman inhales the versely proportional so that if the dust cloud is dust, sometimes the concentration is high, some- very intense the period necessary for development times low. The coarse particles are arrested and of the disease is correspondingly short and vice rejected bv the natural defences of the respiratory

versa. tract, whiie the finest particles gain access to the http://pmj.bmj.com/ 5. The action and reaction are intensified by alveoli from wbich they are transferred by infection, notably tuberculosis, and the growth of scavenger cells and aggregated in the lymph nodes the tubercle b?.ciJ1us is favoured. within the lung parenchyma under the pleura and Under present conditions in Great Britain, at the hilum. Over a period of years the attack silicosis in a diagnosable stage seldom occurs under goes on and the occupation of the lungs by the I5 to 20 years' exposure to the risk, and so is dust advances. All the while a reaction is oc- rarely seen under the age of 40 years. If adequate curring in the lymph nodes, which is finally re- precautions to control the dust cloud are not taken vealed by the appearance of tiny spherical nodules on September 28, 2021 by guest. or effectively maintained then the disease may of fibrosis. Slowly these nodules increase in occur in flint crushers, rock tunnellers, sand diameter and others appear elsewhere. Individual blasters and scouring powder packers after two to nodules achieve a size up to 5 mm.; contiguous five years' exposure. The writer once observed a nodules become confluent and in the most ad- group of cases in flint crushers after less than vanced stages large ' cricket ball' masses result. twelve months in the process. While in very These fibrous areas diminish the amount of func- intensive risks it is almost certain that every work- tional lung so the healthy areas try to compensate. man will be affected, in the ordinary run of in- The lung between the fibrous areas becomes dustry it is not inevitable that every workman emphysematous and bullae appear along the free should contract the disease in the course of a margins. The bed of the pulmonary circulation working lifetime. There is a personal con- becomes greatly extended and narrowed and this stitutional factor involved in the development and is reflected by hypertrophy of the right ventricle. 6o6 POSTGRADUATE MEDICAL JOURNAL December I94) Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from

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FIG. 4.-Male aged 72 years; coal-miner (Scotland), FIG. 5.-Male aged 50 years.; colliery fireman 21 years, 56 years. Bilateral massive silicosis with bullous then steel-dresser i2 years. Massive silicosis and emphysema at apices. dust reticulation. (Reprodutced by couirtesy of Drs. Sutherland and Tyrrell, Pncumno- (Reprodiuced by courtesy of Drs. Suitherland and lyrrell) coniosis Medical Board) An indolent pleurisy anchors the lungs to the of a certain minimum size and radio-opacity chest wall,9 diaphragm, pericardium and media- (maturity of fibrous tissue) before they can be stinum. At first the changes are localized in the distinguished from the normal structures of the root zone or the upper lobe of one lung, usually lungs. These are personal opinions but are the right, but slowly and inevitably the disease supported by the fact that occasionally at necropsy appears in the contralateral lung and so it advances the extent of the disease is considerably greater in both. But it is not necessarily an orderly than is revealed by a recent radiograph, and advance, indeed it rarely is; from the stage of indeed histological examination may establish the localized nodulation massing may result even presence of the disease when the radiograph is con- http://pmj.bmj.com/ before the nodulation has extended elsewhere. sidered normal. This is particularly true in acute This is usually suggestive of an infective process. risks such as sand-blasters. The fact that patho- At any stage overt tuberculosis may appear and logical examination is more precise than radio- lead to a fatal outcome. In the absence of tubercu- graphic examination does not invalidate the fact losis the advance is slow but death may be pre- that during life the diagnosis of the disease must cipitated by acute intercurrent disease such as in- include demonstrable X-ray changes in the lungs. fluenza or pneumonia, while in older patients on September 28, 2021 by guest. death may occur from cardiac failure. Diagnosis The foregoing description indicates a slowly In life the diagnosis depends on the following developing continuous process and some may triad, and while any of these may lead one to wonder why so long a period elapses before the suspect the presence of the disease, it must disease can be diagnosed. The explanation would ultimately be firmly based on all three. Any appear to be that a substantial period is necessary anomaly should raise doubt in the mind of the to complete the silica reaction. Moreover, in the physician, indicating the need for further investiga- beginning the individual nodules are very minute tion and even for a visit to the place of work to and the fibrous tissue immature. The actual investigate the actual environmental circumstances identification of the disease during life depends on of the particular case. the appearance of abnormal radiographic opacities i. Clinical history and examination with special in the lung fields and presumably these must be reference to symptomatology. Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from Derember 1949 MEIKLEJOHN: Pneumoconiosis 607

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FIe. 6. Male aged 39 years; flint crusherman for I4 months; no other dust risk. Massive silicosis; died 4 years later of congestive heart failure; diagnosis of silicosis without tuberculosis confirmed post-mortem.

2. The history of the occupational risk to define good; he is not sick, only distressed. At this precisely the period and intensity of the silica juncture he becomes the victim of a host of ex- risk. traneous aggravating circumstances. Con- 3. Radiographic examination of the chest. valescence is prolonged and sick benefits in- adequate; the family begins to run into debt. Clinical and Related Aspects The doctor advises an X-ray examination of the For a period of years, save in very serious dust chest and the diagnosis of early silicosis is con- hazards, the workman, though inhaling silica firmed. Anxious as the workman may be to re-

particles regularly at his job, is unaware of any turn to work, this must be postponed for the http://pmj.bmj.com/ injury to health; the pathological process is doctors and his trade union have advised a claim latent, the onset of the disease insidious. During for compensation. This involves more delay dur- this phase radiographic examination of the chest ing which his domestic problems increase and his may disclose definite silicotic changes but the mind is focused on his chest. All the while the patient denies any inconvenience. This, however, work habit is slowly being lost. He is sick with is not strictly true for close questioning will usually fear and worry; he knows the doctors are not reveal that he is troubled by a cough and slight mistaken because 'it is on the X-ray.' Some- breathlessness on exertion. He is fully aware of where and to someone this tragedy happens every on September 28, 2021 by guest. these symptoms but has dismissed them as due to day, a tragedy in which the practice of the art of smoking or his ' age.' The cough is dry and medicine and the well-being of an individual and harsh, occurring in bouts first thing in the morning his family are sacrified on the altars of scientific or last thing at night. The shortness of breath is medicine and the welfare state. Facts triumph over reflected by the fact that he now prefers to ride judgment, life becomes more important than living. where he had previously walked, or if he does walk The change to an easy cough with muco- his pace is slower and he is aware of the hills. purulent sputum, occasionally blood-stained, loss Then suddenly and indirectly the disease in the of appetite, weakness and wasting indicate lungs is discovered. The workman suffers from a associated tuberculosis. The patient is now ' cold' or an attack of influenza; recovery is de- obviously a sick man and thenceforth deterioration layed while the cough and breathlessness are is rapid. aggravated. Even so his general condition is In simple silicosis even when the changes in Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from 6o8 POSTGRADUATE MEDICAL JOURNAL December 1949 Protected by copyright.

FIG. 7.- Female aged 32 years; china polisher (pottery FIG. 8.-Same case 8 years later; had not worked in pure flint risk), I9 years. No specific appearances interval; at home nursing husband suffering from of silicosis. tuberculosis of lungs. Post-mortem reI-ealed massive silicosis both lungs with active tuberculosis left; note cervical rib (R) and influence of tuber- culous infection. the lungs and pleura are gross, clinical examination comitant disease of the cardiovascular system' or of the chest yields remarkably little information; kidneys. it is a silent disease. Inspection properly carried In the case of silicosis complicated by tubercu- out as a definite technique is probably superior to losis the signs and accompanying changes are all other methods of examination, but un- those usually associated with tuberculosis of the fortunately so few doctors nowadays take time to lungs. As a useful generalization it may be said http://pmj.bmj.com/ look at the patient. The excerpt quoted from that in simple silicosis the patient is fit but dis- Calvert Holland (see page 6oo) is a salutaryreminder tressed, in silicosis accompanied by tuberculosis of how much we have sacrificed to instrumental he is sick and in declining health. aids. Important points to note are the general condition and facies, response to the effort Occupational History of undressing, configuration and movement of The purpose of the occupational history is to the chest, line of the trachea and, if visible, the define the period and intensity of the silica dust position and extent of the cardiac impulse. hazard. This is only to be achieved by recording on September 28, 2021 by guest. Cyanosis occurs only in advanced disease and then the periods of employment in chronological order, only if associated with cardiac embarrassment; noting the nature of the work, the materials in- clubbing of the fingers is very exceptional. Areas volved, the tools, the environmental conditions of fibrosis cannot be mapped out by percussion and any protective measures taken to eliminate or but when massing has occurred near the apex of diminish the risk. It is supremely important to the upper lobe dulness may be noted posteriorly note that the disease may not necessarily have been with resonance, due to emphysema, anteriorly. On acquired in the latest employment but in some auscultation one is impressed by the patchy antecedent one. Thus a bricklayer's labourer diminution or absence of breath sounds and may have worked previously as a sandstone mason adventitia due to bronchitis and pleurisy are rarely or a cutlery grinder may now be using emery audible. The heart is seldom displaced or en- wheels but during his early years in the trade larged; obvious enlargement usually signifies con- worked on sandstone grindstones. Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from December 1949 MEIKLEJOHN: Pneumoconiosis 609 Radiographic Examination of the Chest judgment and obsessed trade union officials often It is generally accepted that the radiographic to the detriment of the individual patient. findings in'silicosis afford the most reliable single Prognosis, Management and Treatment piece of evidence in establishing the existence and actual stage of the disease in any particular case. .Simple silicosis, even of advanced degree, is This, however, is only true if the radiograph is compatible with many years of life and con- technically satisfactory, properly exposed and care- siderable capacity for work in the patient's own fully processed. The, radiographic appearances skilled job. There is no reliable evidence that are represented by changes which reflect the silicotic patients are more liable to acute respiratory characteristic pathological lesion. In the early infections than their fellows and even if they are, stages they comprise small opacities, variously the danger of contracting these is no greater at described as nodulation or mottling, at first work than in their own homes or at the street localized and later in classical silicosis involving corner. Ifthey do suffer such an illness recovery is the whole lung fields, thus presenting a ' snow- often delayed and bronchopneumonia may be storm) appearance. When the disease is con- fatal. The important issue which arises is what fluent, massive. shadows appear usually in the advice should be given to a patient about his job. root or' sub-apical zone; it is very rare for an On first principles he should not again expose isolated opacity to occur in the basal area. When himself to any dusty work. This is the advice active tuberculosis supervenes the whole picture which is regularly given, but it altogether ignores is modified and continues to alter with the advance a whole host of equally important social factors. of the tuberculous process. He must work, not for economic reasons alone, but Frequently when the patient is first paradoxically because work is the only treatment'of seen the any real value for him and, strangely enough, for whole clinical and radiographic picture is that of Protected by copyright. extensive tuberculosis of the lungs, but chiefly for his wife and family. If under the age of 40 years, reasons related to workmen's compensation the an age at which he is still adaptable and has young clinician must decide whether or not silicosis is dependants, he should seek alternative employ- present. It is useless to believe that in such ment, but this is supremely important, he should cases one can distinguish radiographically between not give up his work until he is assured that the silicotic and tuberculous opacities. In such cir- alternative job is available, secure and suited to his cumstances a presumptive diagnosis only is capacity. Over 40, unless he is fortunate in possible based almost entirely upon a critical finding a suitable alternative job, then he should assessment of the occupational risk. continue in his own skilled work. It is the job he knows and can accomplish with the minimum Differential Diagnosis effort. If the hours of work can be adjusted for him so much the better. Craftsmanship, self- If the case is investigated as outlined above, then respect and happy living are inseparable and all almost absolute accuracy can be achieved in the too often to sacrifice one's craft is to lose all. It recognition of silicosis and its complications. is not disputed that there is danger in continuing to http://pmj.bmj.com/ Difficulty only arises in the earliest stage in an' work in the dust, but the danger is relative and attempt to anticipate the disease radiographically must be assessed accordingly. The craftsman is and in the determination of associated tubercu- intelligent and if left to make the choice prefers to losis. It is usual, however, to record that the wear rather than rust out. disease must be differentiated from miliary Active tuberculosis may become manifest at tuberculosis of the lungs (acute and chronic), car- any stage so it is important that the silicotic work- cinoma of the lung especially carcino- miliary man should be under regular periodical medical on September 28, 2021 by guest. matosis, haemosiderosis in mitral disease, sar- supervision. As a means of detecting the transition coidosis, bronchomycoses, virus infection of the from simple to complicated silicosis E.S.R. lungs, tropical eosinophiiia, bilharziasis, ascariasis (erythrocyte sedimentation rate) tests have been and retained radio-opaque dust. While it is true advocated but, in this matter, there is nothing that these conditions may on occasion closely superior to the shrewd clinical observation and simulate the radiographic appearances, X-ray judgment of the experienced physician. examination of the chest, absolutely indispensable In silicosis accompanied by tuberculosis the as it is, is only a single factor in clinical diagnosis workman must give up his employment not only and must be recognized as such. While it is true to safeguard himself but his fellows. As a general to say that radiology has contributed more than rule this is no undue hardship as he is or soon will any other method to the accurate recognition of be totally unfit for work and present rates of com- the disease, it is no less true that the dramatic pensation and additional benefits approximate to radiographic appearances have warped clinical his previous earnings. Postgrad Med J: first published as 10.1136/pgmj.25.290.599 on 1 December 1949. Downloaded from 61o POSTGRADUATE MEDICAL JOURNAL December i949 Treatment is almost entirely restricted to relief exhaust ventilation and the use of wet methods in of symptoms. In the case of the partially dis- place of dry. Respirators are of limited value abled workman emphasis has already been made on either because they fail to arrest the most dan- the importance of work. Therapy by means of gerous minute particles or because they are un- inhalations of powdered metallic aluminium is at comfortable for continuous wear during heavy present under trial in Canada and in this country, work. Other aids are comprised in good house- but the method is still in the experimental stage. keeping in the factory. Inhalation of powdered aluminium metal for therapeutic purposes has Prevention and Control already been mentioned. The same method is This is the only satisfactory approach to being applied as a prophylactic measure, but due the problem and the principles are reasonably to the nature and course of the disease many years well-defined. Wherever possible non-injurious must elapse before any opinion as to its value can materials should be substituted for silica; thus in be pronounced. cutlery grinding, carborundum and alundum have replaced sandstone grindstones, in china manu- Conclusion facture alumina has replaced flint and in sand The foregoing account has necessarily been blasting non-siliceous abrasives have been sub- restricted to general consideration of the subject.. stituted for quartzose sand. It should be noted Particular occupations and centres of industry that due to the chronic nature of the disease the have individual characteristics and social prob- beneficial results of these measures are not im- lems. Some of these will appear in the con- mediately reflected in morbidity and mortality tributions which follow. statistics; one must wait the passing of the old generation. Mechanization of processes is another Acknowledgment valuable method whereby the number of men at I am greatly indebted to the Ministry ofProtected by copyright. risk is substantially reduced. The intensity of the National Insurance for permission to publish the noxious dust cloud can be reduced by effective table on page 603.

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