Document 3JJY82OmZ0X2eROrEzr8MRBv0

! EXHIBIT Sft-53> I rfsi Medical Press and Greater Supplement, July 20, 1938 i1 j| INDUSTRIAL MEDICINE SYMPOSIUM No. 3, I$38 Contents: History of Industrial Medicine By T. M. U*c, iLA,, BJM.(Qxoa), M.R.CP, Lectorer m Industrial Medicine, University of Bristol. . Medicine's Contribution to Industry -- * -By Lidmaro ?. Loaourr, M.D,, Medical Officer, Masr*. Boots. Pare Dray Co. Ltd, Nottingham; Chairman, Association of industrial Medial Officers. Tbe Factory Clinic By Domaco SrtWAftT, 1LD., MJLCP., Medical Officer. LC7. Metals. X-ttt; Honorary Secretary. Association oi Industrial Medical Officers. -- Dusts and the Lungs By E R. A. Mjchcwcthc*. M.D., M.R.CP, 8arrt*c*4t*Law, One of !LM. Medical Inspectors oi Factories. Occupational Cancer and Dermatitis By W. O'Dowovax, OJJ.E. U.D,, MR.CP, Phyridaa. Dennatotesicai Department, London Hospital; Physician, Skin Department. Sl pint's Hospital for Urologiai and Skis Diseases, London. . Industrial Phimbism By Romauj E. Lame. M-B-lLond.), M.R.CP.fLond-L Hon. Assistant Physician, Salford Royal Hospital: Medical Officer, The Chloride Electrical Storage Co, Lxd, blanchester. Industrial Accidents and So-called Neuroses in Iudustry By Cvtfix, M.D, F.R.C.S, Professor of Medial Industrial Psychology, London School ot Hygiene and Tropical Medicine: Lecturer m Psychoneoroses, London Hospital. -h(46) J Uisiii 9/ Txx Matcu. Press and Circular Scrtuarar si of elaborate X-ray pUss. is needless and un economic and is one o ae ways is which industrial meriioJ serrias can be adversely criticised both by the eingioier aad die medical profession as a whole. _ Volusary i n'Jtj * f* **-- 'Hits particular aspectst die faqpry doctor's work has been iatenooosflr left to die last. It is not infrequently the case that his most effec tive work is earned oat in die privacy of his consulting room. The writer who is worried about his health, who xsstr be emotionally upset because his immediate superior is a bully, or who wants information m one of a dozen other problems, should be able to Sad in the medical' officer an adviser who da. guide aim through his difficulties, either by adjusting the position within (he factory '-3bf advising him to con sult his own private mudfral prarritinner and at the same dote offering his hdp in colla boration. There is ootring worse than a feel ing of disappointment ati frussaaon in one's work. Discontent is a mzior cause of indus trial unrest and strikes which have affected many thousands of oth-rwisc harpy and con tented workers have arisen as a result of the |xrfty. failure of .omaperson. In modem psychotherapy, the scientific way of dealing with a man 3 also die humane and understanding war and bsmasstr and under loading are wanted badly 00c csly in indus try but throughout the worid to-day. The scope for this type of metrical won; in industry is great and can play a part of fundamental importance in the futare development of the health services of this moony. And now* one word in conclusion. We have discussed very briefly some of the measures carried out hy the industrial medical officer and have shown how^ihey bear on the work of the factory ch.iic"' At the present day, however, there are probably not more than two or three hundred doctors engaged in this type of work in the country and it is estimated that of these only some titty or sixty are employed in a whole-time capacity. It is obvious there fore that only a small percentage of industrial workers--and very often those employed in large and enlightened tit mi have such facili ties offered to them. If it is conceded that the work which has just been described is of importance in the general health schemes of the nation then the problem within industry becomes one of considerable urgency. Whether the work should be undertaken by far-sighted employers now or whether it should be left to the State to develop and con trol must be a matter of opinion and of poll* tics. The important thing is that the work is there waiting to be done. There are those who firmly believe that the future-prosperity of the nation depends on the health and happiness of the individual work man. tf tin's is so how can we as doctors take our part? The problem, I believe, is primarily one for the medical profession, and in part therefore for the industrial medical officer. What can be learned in .the factory clinic to day will most surely become the accepted, practice throughout industry in the future and if properly developed cannot fail to contribute successfully to the. problem of national fitness which is bring so much discussed at the present* time. DUSTS AND THE LUNGS WITH PARTICULAR' REFERENCE TO SILICOSIS AND ASBESTOSIS i By sL R.A. MESEWETHER, M.D., M.R.C.P., Barxistek-at-Luv Om W IL1L. liuncww < Ksccmm 1 Since the birth of tie sanran race dust lias exerted its baneful effect* on civilisation. Some <>f our prehistoric ancestors died because of it, and cmmtie* are fee deaths which have 'ccurred since. To-dsy, the effects of dust on 1 he human mecluemxn aione one of the major problems of doe age. Two questions at mee obtrude themseries. Why. after so long, i< it still a major pratrisn, and what is the present position? 13 me firs: we can only excuse ourselves hy peesring out that dusts arc legion in variesr. *oer act m manv ways 011 different organs and different individuals. Their actions are often subtle and insidious, and irretrievable damage is done before the person most concerned even appreciates the attack. Scientific appreciation of the poten tialities of the different dusts and mixtures of dusts, assessment of their effects, determina tion of appropriate preventive measures and the means of carrying them out, hare all had to wait upon advances in many collateral sciences before even the full scope of the pro blem could be appreciated. Chemistry, physics. -Mi The Medical P*ew axo Cikculae StTWLEuexT pathology, bacteriology, clinical medicine, anthrax, mooiUa, actinomyces and other radiology, petrology, microscopy, sociology fungi. , , T and general education have all bad toJxar a (6) Non-toxic inorganic dusts, the dusts part before the foundations could be tauL w commonly think of as M dust." What then has been achieved? Not much, we may say, if man has been busy at this pro* blea for Z000 years or more, but when one Although dusts belonging to aQ these groups, except the first, may affect the lungs in some cases seriously, it is the last group realises that the general state of human know which is the most important on this account, ledge has been such that it was not possible because in it are included all those dusts which until within the last 100 years to advance be exert deleterious effects on the essential pul. yond the appreciation that (lust was harmful, moaary tissues. then that the foundations have been truly laid Included in this group are a great varietr is not an inconsiderable achievement. It is not possible within the limits of this paper to survey all the pioneer work which of dusts differing in their physical and chemi cal : charaoerisrics, and these characteristics play an Important role in determining the has contributed to this in the past 50 years, nature of the local effects produced when in even if the writer was competent to Jo so. haled into the lungs. Although much work The complications and ramifications of the has been done cm this aspect, however, it is. subject and the labyrinths into which inquirers not yet possible to classify themembers of this are forced to penetrate, make a critical survey group so that the effects of any particular dust a matter for a team of experts. may be prognosticated from its physical ami It is possible, however, to consider the pro chemical characteristics. * blem from the point of view of any one of us Of chemical characteristics, solubility or in who wishes to know what principles emerging solubility and the presence or not of the silica from ail this work will help him to do the best radicle, and of physical characteristics, speri- for his patients, and to advise inquirers of the lie gravity, fragility and whether of a fibrous risks which may be associated with exposure character or not, are all believed to liave an to dust important influence on the action of the dust With some diSdencc,* therefore, an attempt when inhaled. will be made to set out some rough practical In spite of the" many difficulties resulting _generaiisadon^\tfiich may be of help in this from lack of knowledge, certain gencralisa- way. . dons can be made which are helpful in prac We are constantly exposed to dust, but tice, and that, after., all, is Jtvhat is required, generally it oniy causes temporary incon if knowledge is to be of practical value as vrril venience and is quitidy disposer! of. as of academic interest. . The effects on the human body depend on In the first place, that healthy lungs can the nature of the dust and, if inhaled, also on cope effectively with appreciable quantities of its concentration in the air breathed, the dost, but that all inorganic dusts, if inhaled in .median sue of the particles, and the existing concentration over a period of time, are harm condition of the chest and lungs. ful, is such an obvious proposition that its No simple and accurate classification of importance is liable to be overlooked. ^ dusts has yet been evolved, but certain broad The longs, in common with other essential distinctions can be made which are useful. organs of the body, have a large reserve, to Thus we have.:-- permit of effective reaction to the demands of (1) Dusts which are systemic poisons, as disease or ox advancing age or of any emer lead, arsenic, manganese, trinitrotoluene gency, and it is oniy when this reserve is and many others. . seriously enouached upon that clinical sign* (2) Irritant or corrosive dusts, as lime, of embarrassment appear. Moreover, the arsenic, chromic acid, the bichromates and filtering action of the nasal vibrissas and pas many others in varying degrees. sages* aided by the moist and ciliated mucous (3) Allergic dusts, exposure to which may result in the development of a hyper sensitive state, and cause on* further membrane of the upper respiratory iract, to gether with the indefatigable efforts of thr end/vheliai ceils (** dust edls ") in seizing upon minimal exposure asthma, rhinitis, urticaria, ht intrusive dust and transporting it into thr etc Usually these are due to foreign lymphatic drainage system, are more than ade ' proteins in the dust, but not always, as, quate to cope with the normal average of aiv for example, workers with chromic acid and borne dust and with intermittent abnormal the bichromates who may become hyper concentrations. . sensitive to these chemicals. It stands to reason, however, that the nrns** (4) Carcinogenic or cancer-producing effect of daily exposure to a heavy concentra dusts, as the dust of pitch, of radioactive tion of even a totally inert dust will wear materials and of certain ores. even the most well disposiooned and resp0" (5) Dusts which carry infections such as sive mechanism; dust will collect in the na.' u IF Ttrt Medical Passs asp ii. Jiges and sinuses, ciliated epithelium :. v--7-*v sS'frJZT?:: 3ped and replaced progressively with less ^y differentiated and less efficient cells, !p of alveoli will become choked and vn oot o action, intermittent and uncon.- d inflammatory conditions may interfere the lymplntic drainage and cause further don of dust, and over-action of less areas may result m localised emphy- Ultimately, therefore, such heavy and uuoas exposure to a dust which with less iure is inert, will, however, result in per - -.^aSSsS ot changes and loss of efficiency, which ue manifest lit course of time as a chronic hitic tendency'. It is not easy to deter- to what extent lieavy and continuous ex e to such inert dusts m w sliorten life, rsome intermittent disaudity docs result *- A >e be gainsaid. Thus, the generality of doers lias an excess liability to chronic lutis and other affections of the upper *?tory tract, cement and basic slag m*s have an excess incidence of upper ratory tract affections, and the latter also cesr liability to pneumonia, is mechanical choking up effeci of ex- c over a period to heavy concentrations of :.v. ' ' ^organic dust can be demonstrated dirric- in young persons with ease after ex e for a month or two, ue^ before it is _ ___ _ At for permanent changes to have -4^5i^gSii)i'iVJj3red. A very slight, but appreciable, dlf- -- 0 thc pcfcu^sion note--less chat associated with diffuse fibrosis--wilt - .vtse*jsa -dSs. '* ted, and ou auscultation sticky rales will ard, particularly when, die amplitude of rum is increased. cse effects are not specific to particular but are common to all inorganic dusts 0/ roup, Neither are they due to any sped- Ion of the dust on the lung parenchyma; simply mechanical mass effects of the given the chance, the lungs will dis- of harmlessly in most cases the greater -7-~ rdon of the dust, leaving no permanent ` effect. . come, therefore, to the useful gencrali- that inorganic dusts which exert no parenchyma are because of the mass heavy con* because there insuperable difficulties in preventing . . conditions, and the Factories Act, 1937, cognisance of it in enacting (Section 47) *" of dust practicable those ent- ScmjatexT im removing the minute burrs from china by means of a toy size abrasive wheel and a paste of tlint and water, may die in middle life of an intense diffuse fibrosis of the lungs due to the rime dust.' ' * What is the distinguishing characteristic of a dust so potent? The researches of many able men all point to the same factor---the presence of the silica radide in the dust. Silica may be present, of course, either "free" as silicon dioxide. SiO, or " combined " with many bases as silicates. Proof has been piled upon proof incriminat ing the free sfltca in so many dusts' encoun tered industrially, such as quartz, Sint, sand stone, gapister, etc.; and this, together with evidence of the relatively innocuous character of some common silicate dusts, such as clay, have combined to establish the unhappy pre eminence of silica in the free state in this con nection, and to overshadow the possibility that some silicate dusts may be harmful. Until a few years ago, therefore, the im pression was widespread that dusts containing free silica were dangerous, and dusts contain ing silica only m the combined state were harmless. Since, however, there is now con clusive proof that one group of silicates, to wit asbestos, are equally as dangerous as free silica, the above view is not strictly accurate, and we are led to the following generalisa tions : all. dusts containing free silica are dangerous; dusts containing silica only m the combined form are relatively harmless, with the exception of the asbestos group and possibly also other light silicate dusts in which the parride form ts fibrous or plate-like and' comparatively large. The asbestos group of minerals are mainly silicates of magnesium and iron, and to a less extent calcium*; the particles are elongated and fibrous, and can split up longitudinally and tray out to an indefinite extent, thus aiding their retention m the bronchioles. It seems likely that this physical characteristic of asbestos, which tends to immobilise the par ticles in the longs, may point to one dis tinguishing attribute of the dangerous sili cates : there seems to be no other feature which will explain-, ior-exampierwhy asbestos-- has disabling and lethal potentialities, whereas talc has not, yet chrysotile asbestos and talc are both magnesium silicates. For practical purposes, therefore, so far as present knowledge goes, the dusts which cause serious local effects on the lungs and which may and often do eause disablement and death, are those containing free silica and asbestos: other dusts are harmless in this respect unless, as has been said so happily, " inhaled in insulting concentrations."* * Air Fwwjiuw *f Amriau Imu; Silicm* AM Di*rUr*. Hittorr k iwiaMriai Ijrpmtomc. Mctti- e< Sm. Hvilctm S*. .1, p 4. 1937. 4.. . .... - .. ' ! *v i siv The Medical Pxess and Ciicula* Sctplescext The siliceous dusts and asbestos also differ course of tncf* nodules of fibrous tissue from other dusts in that they cause a .diffuse appear. This explains many things; for ex fibrosis of the lungs, silicosis and asbestosis respectively: that is to say that they irritate and destroy the essential lung tissues and ex cite the formation and*the proliferation of ample, that healthy lungs can dispose of quite a lot of dust, even silica, for so long as thetraffic can be kept moving no serious effects will result; again, it explains the ill-effects of ordinary scar or fibrous tissue, due, it. is gener any antecedent illness which has damaged the ally believed, to the very slow solution of the lungs permanently, even if locally; the 01- silica* This scar tissue is nbt only useless effects of a coincident infection, for that con lumber but also, if there is much of it, exerts gests the traffic in the lymphatics still more; secondary harmful effects by blockage of the and the danger of a hie infection when silico lymphatic drainage system, interference with sis has developed generally and the lymphatic die proper aeration of the blood, production system is already grossly damaged. Also dear of strain on the right side of the heart, block are the causal factors underlying the produc ing and distortion* of bronchioles by contract tion of massive sSlcosis, in which a mass of tion of die fibrous tissue, production of | fibrous tissue, the size of a hen's egg, or larger, localised emphysema, and definitely acts as a ! and consisting of. Innumerable small nodules bait for the- tubercle barillas. : tightly packed together, appears. * Moreover, The dust particles must be small, very small, the obstruction of the lymphatic drainage by to be dangerous, since they must be. small the silicotic nodules accounts also for the great enough to noat in the air and small enough to retention of ordinary carbon and other dust get past the outer defences of the lungs, at in the sHicotie lung. . least as far as the smaller bronchioles; There? fore, an industrial process which does not pro-'' ject dust particles into the air in sufficient number and^sf^uch size and weight that they will remain fioating for a considerable time cannot be dangerous in this way. With the siiiea dusts the dangerous partide size range is up to 10 microns, with the lighter asbestos dust it is much greater, extending even up to 200 microns. The majority of the partides, however, which get into and stay in the lungs are much smaller in each case--up to 5 microns m the case of silica dust and up to about 50 microns in die case of asbestos. That is to say, that the dust parades which are in* visible to the naked eye are the. important ones: this leads us to the practical point that if a silica or an asbestos process produces visible dust m the air,, then the invisible dust is cer tainly in dangerous concentration* The silicotic .fibrosis is laid down in nodules, whereas that of asbestos is laid down as a cob web. This distinction is important since it is reflected in the typical radiographic appear ances. The explanation lies in the different physical and chemical characteristics of die dusts. The smaller and more stimuiadag silica parades are taken up by "dust ceils'*' and. hurried away from the alveoli into the lymphatics and towards the many minute lymph nodes at the junctions of these*passages, mid from thence to the large ones at root of the lung. Unfortunately, many phagocytes succumb and drop their hostile passengers on the way for others to collect the debris, until ultimately, with continued exposure to the dust, the traffic along the lymphatics becomes In asbestosis, the course of affairs Is dif ferent. With the longer, awkward and often frayed-out asbestos fibres, transportation Into the* lymphatics is impossible, and Gardner and Cummings have shown that the fibrosis com mences around the-smaller bronchioles where the asbestos panicles felt up and become im mobilised. In some way or another, the silica is dissociated, and dissolved out and diffuses into the neighbouring tissues, and the fibrous tissue is formed in radiating strands. The lymphatic system does not, therefore, bear the first brunt of the attack, and it may be that the longer patency of the system aids the cobweb like formation of the fibrous tissue. Within a few weeks of the lodgment of the fibres,, the curious beaded and dubbed asbestosis bodies, which* are altered asbestos fibres, begin to appear. Sines the fibrous tissue formed is the result of the solution of the silica, the extent of the fibrosis, which will develop in any given case, is limited by the amount of silica immnboltscd and retained in the lungs : therefore, on post mortem examination one sees all grades of simple silicosis from a few scattered nodules up to massive silicosis occupying over half of the lungs* ' Knowledge of the pathology of these two diseases, together with inquiry into the length of exposure to the dust and the dustiness of the process concerned in any given case, gives one such an appreciation of the symptoms, signs and clinical course of these diseases that the alleged difficulties in diagnosis mostly vanish. * * very congested and at the cross-roads com Needless to say, fibrous tissue takes time tc plete stoppages occur; here we get accumu develop, and also the less the concentration o< lations of parades of silica and dead phago the dust in the air breathed, the longer ex cytes, and slowly the silica dissolves and, in posure to the dust will be required befon Tin Mjesxcu. Pxgss a.vp Cixcuxa* SOTnanurr XV develop? to such an extent as to cause As a rule, however, cases are carried off by I'^sEecta appreciable by the patient. some infection* which the remaining sound .* is true that cases of so-called "'acute" lung tissue is quite insufficient to cope with; '?yC\ >*xs and similar cases of asbestosis, due to not iweommoniy this is a low grade broncho #ure to intense concentrations of dust, pneumonia, but inflat .za*ora lobar pneumonia <i occurred with a fatal outcome in less -may precipitate death, and the commonest of five years, but usually IS or more years all intereurrent and terminal infections is % ri <iuired tor the disease to develop, de tuberculosis. Some 60 per cent, of silicotics ling on the concentration of dust in the air. die from silicosis, with tuberculosis and about * -.* ^ cpuat-y the average duration of em 30 per cent, of fatal cases of asbestosis are inent of a series of 311 cases who died Of also associated with tuberculosis. It is not . *os without tuberculosis was 35.1 years, known exactly why this should be, but a super- i the average in the different industries added tubercular infection is the supreme risk I ged from 302 years in the pottery Indus- for silicotics and is an added risk for cases of to 92 years in the manufacture of scour- asbestosis. powders. As the effects of additional pre- Tuberculosis may appear at any stage, and idve measures become apparent, which also then the symptoms and signs of that disease matter of years, the average duration of tend to mask those of the pneumoconiosis. rployment in fatal cases increases pari passu. Wasting, fever and hemoptysis are not signs ^mce these diseases are not infections, they of uncomplicated silicosis and "dry" diseases during most of their although loss of weight does occur very late in rse, and since the eari gst symptom is both diseases. >rtnuss of breath on slight extra exertion, The signs of uncompftoted. silicosis and ' i to the mechanical interference of the asbestosis are by no means obtrusive, and most rosis with the proper aeration of the blood, clinicians form their own conceptions of them. |.se diseases are slow, silent and insidious. As would be expected from the pathology, >ugh, such as there is during the develop- there is a very slight diffuse impairment of the | nt of the disease, is a slight, dry, morning percussion note, which some clinicians recog ugh, which may well be ascribed by the nise more as a ' sfighf diffuse resistance on dent to too much smoking. The shortness percussion rather than impairment of note. breath, occurring in the eariy-40ts, may also The uniform bilateral character of this put down to getting old too soon and little change is misleading since it is easy to miss it rcntion paid to it, except perhaps to move entirely, there being no normal area for com om an upper to a ground Hoot fiat because parison. It must be admitted that it is some hunting the stairs becomes inconvenient. what of* a strain attempting to detect this We have, therefore, as symptoms a little dry alteration cccepc a advanced cases: it must | orning cough, a little shortness of breath on be detected quickly or appreciation soon dulls :tra exertion, a little M tightness of the chest" and doubt occurs; rapid fight percussion, how. A, with asbestosis cases more than silicosis ever, usually revmls it, and comparison with ses* slight pallor with a tinge of cyanosis of a normal chest of similar build will restore e lips. The finer, more diffuse, fibrosis of one's appreciation when dolled, as is likely to ''lestosis is much more effective in causing happen if two or three eases appear consecu elective aeration of the blood and ultimately tively amongst a group of workers for icreased strain on the right side of the heart, examination. Naturally, also, the chest move on silicosis. As .the disease progresses, the ment is restricted, and the breath sounds more itortness of breath increases until it is present distant--usually but not always--and the ,,ven u rest and in the late stages is very: inspiratory murmur thin and higher pitched. - `*^^*ing: " colds go to the chest " and there As already mentioned, these are silent ' v ^ re intermittent attacks of bronchitis; there is diseases, and therefore the presence of adven |:*m from adhesions and attacks of dr}* titious sounds are indications of temporary 'tansy; emphysematons bulls may burst, superadded intereurrent infections, except in luring partial pneumothorax, which is not cases with coneorent tuberculosis and those racnomxm in both diseases. In advanced with the bilateral and mainly basal bronchiec I obestosis, bronchiectasis due to dragging and tasis seen in very advanced asbestosis. -lUtortion by the fibrous tissue is quite a com- The presence of tuberculosis gives the usual fnon concomitant, and also the pericaniium indications, but may make recognition of the way be so anchored and dragged upon as to dust fibrosis more difficult. Usually, however, acreage materially the dyspneea. | one can determine what may be described as Occasionally (more commonly with asbes- 1 the of tuberculosis in the desert of the \=tsA uiis) dentil na.y occur from heart failure with diffuse fibrosis. Silicosis and asbestosis may, uiasarea and a nutmeg liver, owing to back of course, develop in lungs already diseased, pressure on the heart from the extreme and their occurrence in emphysematous chests * i *?'-?. ' -, Wifosis. is perhaps the most confusing. The writer i "*'**.i- .'.'3=%5?. ,-v- .* ^*- ? MS*S~, ' - r. *. * XTl...................................... TKE MeDICAI. PE3S ASP CutCLUia SCTrT-EttffXT ` has seen one <** in which asbestosis edited The radiograghual appearances of silicosis conjointly with silicosis. ^ are classified in`different ways, but the essen Radiographic examination sliould never be tial point m the radiographic diagnosis of omitted and. as that great pioneeriwatkins- silicosis is the presence of typical nodular Pitehtord laid down a number of years ago. mottling. radiograms must be44 technically satisfactory," To form a sound opinion mi the radio* or doubt and confusion is certain. "The value graphical appearances of the lungs of an in of the radiogram is in confirming the results dustrial worker, it will be agreed, is often a of occupational and clinical investigation and matter of extreme difficulty or impossible. in estimating the stage of the disease and Apart from shadows caused by diseases affect presence of complications. . ing equally the non-industrial population, Both diseases result in the production of which may cause confusion, such as diffuse abnormal radiographic shadows, and these carcinomatosis, tuberculosis--chronic miliary shadows reflect the underlying pathological process to a sufficient Client as to make it worth while considering them from this angle. or ocher manifestations--etc, the inhalation ot mixed dusts produces variations in the picture; thus, silicosis in the potter tends to vary radio Thus, following ttposur* to silica but before graphically from silicosis in the sanoblastcr. the formation of nodules of fibrous tissue, all which again differs from silicosis in the granite that is sees radiographically is accentuation of worker; the mixer of boiler insulating the linear markings and incensed root materials exposed to asbestos fibre, ground up shadows; these are not characteristic of pitchers (fired earthenware body), kieseiguhr, silicosis since they occur with, ccposure to ground up brides and other organic and In many harmless dusts, and also irrespective of organic dusts,' shows a radiographical picture any special exposure to dust at ail; they are which can often be recognised as intermediate within normal limits in the absence of ether between those of silicosis and asbestosis. signs of intrathoradc disease, and no diagnosis Again, expositfo to fine particulate metal of silicosis or of adverse effecs of exposure spray (eg* in ane metallisation), iron oxide, to dust can be made on these appearances. fine partides projected during electric welding, This stage is followed by4 the appearance of fine metal partides from shot blasting, and nodular shadows, discrete and fairly uniform gross exposure to talc, or cement dust--in the in appearance, diffusely scattered, over both absence of added fiint*-<aiises diffuse mottling lung fields; this reflects the underlying patho m the tadiogxaphic pictures in some variety, logical condition in silicosis and therefore is which is very confusing as in none of these strong contributory evidence in the diagnosis examples does the picture indicate the etist- of that condition. In between the discrete ence of a true diffuse fibrosis in the lung mottling the lung lights up well, the white and parenchyma. A point of some help is to dark areas being aiceiy contrasted. This is regard with grave suspicion a picture in which important as this contrast is not evident in a a diffuse.fish net appearance instead of a typical radiograph of asbestosis. diffuse discrete nodulation can be identified, As the silicosis progresses many changes in since considerable exposure to some harmless the picture may be sees, the nodules become dusts produces this appearance. larger, may aggregate into large masses, and In asbestosis, also, the underlying patho areas of increased transiucescy indicating logical process suggests the typical radio- associated load emphysema may appear. graphical appearances. Increased density of 'the discrete nodular The diffuse fine cobweb fibrosis in its de shadows mar even be so pronounced as to veloped stage results in the production of a suggest calcification and also, of course, quite diffuse fine cobweb- mottling, which at the commonly indications of an active tuberculosis ordinary distance from the viewing box looks process may show. like a fine pinhead molding; the result of this The co-existence of a tubercular infection at is that the whole film limits up very badly, any stage modifies the picture in many ways and compared with a typical film of silicosis, and may obscure the diagnosis especially if, the absence of the dark areas between the when first seen, the tubercular infection is well shadows is striking. This lias been aptly developed and the associated silieosis not so described by Burton Wood as the " ground well developed. The general effect is to soften, glass appearance." Typically it is very agglomerate and biur over the silicotic uniformly distributed and denser towards the mottling, even remote from the original focus. bases. As the fibrosis increases, becomes The more evident this softened, blotted and denser and contracts, the typical pinhead blurred appearance is, the more certain one mottling tends to disappear at the bases, but can be--provided the original mottling is there is no difficulty then in interpreting the associated with silicosis--of a co-existent ' shadows as the result of gross and- massive tubercular infection, even if die sputum is fibrosis. The obscuration of the pericardial repeatedly negative. i and diaphragmatic ouiiines witi the " shaggy " ..4 Thz Medical Pvess a.'co Circular SosvtfxssT* xvn Itcan ore outstanding at this stage. No dis- produced obviously depends on the extent of linctive gradations m the radiographic appear* the fibrosis, and die nature of the man's work. nnces of the asbestos fibrosis have been, Usually the disaoility is remarkably slight generally accepted as yet* and there is extreme' until the disease is advanced, and there is no difficulty in evaluating such stages. * long period of imraiidism; the advent of tuber i-.> The effect of a superadded tubercular in culosis or of some other acute infection quickly fection is. as with silicosis, to obscure the doses the scene, since the margin of unaffected .typical mottling, and to render the identifica and fully functioning lung tissue is too small tion of the asbestosts element more difficult, to cope with added strains of this nature. more so than in thecase of silicosis. Treatment is obviously symptomatic and The main features of the radiographic preventive of further infections; if superadded apporances of asbestosis.are, therefore: (1) infections are avoided, life in fair comfort may general lack of translucent?; (2) diffuse bi continue for many years, even in developed lateral pinhead mottling, denser at the bases cases. The fibrosis does not develop further --the ground-glass appearance; and (3) pro after the., retained silica has. exerted .all ius gressive obscuration of the diaphragmatic and potential action, bat in asbestosts the secondary pericardial outlines with the " shaggy heart." mechanical and other sequels which occur in The latter is rare in radiograms of simple cases with dense basal fibrosis are an added sUcosis. , danger. It win be agreed that distinctive radio In this slight survey only some of the more graphic appearances are very strong contribu practical, points which appeal to the writer tory evidence in diagnosis, but that many have been stressed. The literature on the borderline and difficult cases will be sent for subject of the pneumoconioses is now very -opinion. This- being so, a personal collection extensive and no reference has been made to of radiographs of eases, m which the occupa much invaluable work. A few recent publica tional and case histories together with- the tions only are arbitrarily selected and recom post-mortem findings are known,, is of the mended below as being encyclopaedic in range utmost value for comparison. and eminently readable, and by acknowledged In diagnosis, weight should always be given to all throe aspects: (1) occupational history --nature -4f, coneentratJWJop and length of exposure to the dust, remembering that the authorities. nmcs ft) Air Rtimm Tiiiiti ;auky Im. SUSmI* tmd AftM Otaardcn. Hiiwr amd Ifttfannai bfoniw. 2i*oi Saha. BaiM . U Phamt%*. UAA* dusty job may have been many years pre viously: (2) clinical signs and symptoms; (i) radiographic appearances. With regard to disability in uncomplicated silicosis or asbestosis :.the amount of disability (2) Ocakfab** ah ttaaftfc. SmltatM. Bwakwrw (4> ISiiuiMiiiiiii a*d <S) SiBaaaab IiHawii--J T itnar OSea. liawn. tSL _ _ (3> laimoml Owl Hjmm .lipnltiiu il m4 CaacraC P* k'ifip DraJmt aiaattf TklmMJitaoin JlatcU. Ua*>HUI ftaafc G* 1* Nir Vark md Lwdm, I93C (41 Due ftlafciM. SX. Oi)wa 4 *, US. Lawrt--, 1*24. OCCUPATIONAL CANCER AND . DERMATITIS- ' By W. J. O'DONOVAN, O.B.E.,' MJX MJtCP. Wiyaihaa, DnaMteCM' J' OtiMMit Lawdaa HawataJ; fkrhciaa. SW* Ocjataatc. St. P**Ti 3o*aat imr Uraiacmi *md Sio OiMun, Lank-- Tke consideration of cancer of the skin that has an occupational origin cannot be a dis cussion of the causing cause of cancer, for cancer of the skin occurs both in employed and amongst, the unemployed. It occurs m those engaged in modern industry and in'those en gaged m domestic occupations, but m some industries its occurrence is so regular and so frequent that one can properly say that, but for the patient's occupation in this industry, die cancer would not have occurred, so that it may be said to be produced by the siaa hazard ot the trade and the more abstract question of the causing cause is left for further research. The registration of deaths was put on an organised basis in this country in 1237, but, as regards industrial medicine, death certificates provide no statistics of the necessary facts for coming to any conclusion on this mailer. They do not give us the requisite Information as to the victim's former employment. Death certi ficates supply no due as to the technical pro cess on which a man may have been antece dently engaged. There is no cross-reference either to cases in his family, grandparents, parents, brothers or sisters.