Document vBNNy9agkJNQk3gNnKzLmD2m6
TRANSACTIONS of the
McINTYRE-SARANAC CONFERENCE
OCCUPATIONAL CHEST DISEASE
Edited by G. W. K. Schepers, M.D., D.Sc.
Town Hall, Saranac Lake, N. Y. Feb. 7, 8, and 9, 1955
AMERICAN MEDICAL ASSOCIATION PRESS Chicago 10, Illinois 1955
Acknowledgments
Grateful acknowledgment is made to all the participants who contributed papers o this Conference. Appreciation is expressed also to:
American Medical Association for cooperation in printing the Conference transactions
Professor Philip Drinker for editorial advice Thomas M. Durkan for preparing index Edward L. (lockeler for photography
Secretarial Staff of the Saranac Lalxtratory for preparing manuscripts
Staff of the Saranac Laboratory for preparing Conference halls and exhibits
G. VV. H. Schepers. M.D.. D.Sc.. Editor
FOREWORD
For many years the Saranac Laboratory, of Saranac Lake, N. Y.. and the McIntyre Research Foundation, of Toronto, Canada, have been conducting research niong somewhat parallel lines. For the past five years the McIntyre Research Foundation has held its Annual Meeting on Silicosis and Aluminum Therapy in various cities in the United States and Canada, while The Saranac Laboratory, since 1934, has sponsored a series of Symposia on Industrial Pulmonary Diseases at Saranac Lake. These two organizations pooled their knowledge and resources for this conference, and the proceedings are documented in this volume.
Saranac Lake, for many years a center for the study and treatment of pulmonary tuberculosis and other chronic chest diseases and, moreover, a world-renowned recreational resort, provided a unique and attractive setting for the conference. The sessions, which were very well attended, attracted more than 250 persons, including visitors from the United States, Canada, South America, France. Eng land. Scotland, Wales, India, and the Union of South Africa.
The pronouncements in respect of occupational chest diseases, which have been emanating from The Saranac Laboratory and more recently from the McIntyre Research Foundation, have in the past influenced medical, engineering, and legal thinking in terms of these diseases. The views expressed at the preceding con ferences have guided management, labor, compensation courts, physicians, engi neers, lawyers, and educators not only in the United States and Canada but in many other countries. It is hoped that the record of this most recent conference will in equal measure also prove of benefit to those who seek firsthand information and guidance concerning the problem of occupational chest diseases. The prediction that this will be so is strong, because practically every paper presented at the con ference was Iwsed on original research.
Anthony J. Lanza, M.D., Conference Chairman Emeritus Professor of Industrial Medicine New York University-Bellevue Medical Center
Conference Program
Sfssiotu
1. General Chairman: Carey P. McCord, M.D., Consultant in Industrial Medicine. Institute of Industrial Health. University of Michigan. Ann Arbor, Mich.
2. Aluminum in Control of Silicosis Moderator: William A. Sawyer, MS)., Medical Consultant, International Association of Machinists, Rochester, N. Y. Discussant: Paul C. Bovard, M.D., Consulting Roentgenologist, Tarentum, Pa.
2. Epidemiology of Silicosis and Occupational Chest Disease Moderator: Thomas L. Shipman, M.D., Health Division Leader, Los Alamos Scientific Laboratory, Los Alamos, New Mexico Discussant: Philip Drinker, ScS., Professor of Industrial Hygiene, Harvard University School of Public Health, Boston. Mass.
4. The Evaluation of Experimental Research on Dust Diseases Moderator: Dudley A. InsAn, M.D., Medical Director, Aluminum Company of America, Pittsburgh, Pa. Discussant: Norton Nelson, Ph.D., Chairman, Institute of Industrial Medicine. New York University-Bellevue Medical Center, New York. N. Y.
5. Medico-Legal and Clinical Aspects of Pulmonary Disability Moderator: Ivan Sobouriu, Q.C., Counsel to Quebec Asbestos Producers Association, Montreal, Quebec Discussant: Warren A. Cook, B-A., Associate Professor, Industrial Health and Hygiene, University of Michigan School of Public Health, Ann Arbor, Mich.
6. Experimental and Engineering Aspects of Occupational Chest Diseases Moderator: Angus D. Campbell, Manager, McIntyre Research Foundation, Schumacher, Ontario Epilogue: Corey P. McCord, M.D.
7. Conference Banquet Master of Ceremonies: Manfred Bcwditch, Director of Health and Safety. Lead Industries Association, New York, N. Y. Leroy U. Gardner Memorial Address: Paul S. Richards, M.D., Senior Consultant. Memorial Medical Center, Salt Lake City, Utah Personal Impressions of Edward Livingston Trudeau and Edward R. Baldwin: Hugh M. Kbighorn, M.D., Saranac Lake, N. Y.
Contents
Foreword.........................................................................
?AC hi
Program Committee ........................................................................................................................ iv Conference Program ........................................... .*.......................................................................... v
Prologue Carey P. McCord, M.D., Ann Arbor, Mich........................................................................ 1
The Objectives and Achievements of the McIntyre Research Foundation Francis B. Trudeau, MS)., Saroncc Lake, N. Y.......................................................... .... 2
The Contribution of the Saranac Laboratory to Research on Chest Diseases . D. Fox, M.E., Toronto. Canada..................................................................................... 4
- Comparative Vascular Pathology of Occupational Chest Diseases C. W. H. Schepers, MS)., DSc., Saranac Lake, N. Y....................................................... 7
The Value of Lung Biopsy in the Diagnosis of Occupational Pulmonary Diseases
H. S. Van Ordstrand, M.D.; Donald B. Effter, MS).; Lawrence J. McCormack, MS)., and John B. Hazard, MS)., Cleveland................................................................................... 26
Occupational Chest Diseases in Gold Miners G. W. H. Schepers, MS)., DSc., Saranac Lake, N. Y....................... ................................ 23
Accomplishments in the Epidemiologic Study of Silicosis in the United Slates H. A\ Doyle, BS.; Victoria M. Trasko, A.B.; W. M. Gajajer# DSc., and S. E. Miller, MS)., Washington, D. C........................................................................................................... 43
Silicosis in Canada V. F. Parkinson, MS., Toronto, Canada................................................................ ............56
Commentary cm References by N. F. Parkinson Concerning the Silicosis Problem in Ontario Andrew R. Riddell, MS., DSJd., Toronto, Canada............................................................. 63
Talc Pneumoconiosis
Morris Kleinjcld, M.D.; Jacqueline Messite, MS., and Irving R. Tabershcw, MS.,
New York ..........................................................................................................................
66
Pneumoconiosis on the Kolar Gold Field, South India Geoffrey E. Fjrench, M.A., MS., FS.C.P. (C), Oakville, Ont., Canada........................ 73
'`The Dust Diseases in Great Britain A. I. G. McLaughlin, MS., FS.CS., London.................................................................... 3
Clearance of Radioactive Dust from the Human Lung Roy E. Albert, MS., Washington, D. Cu and Lawrence C. Arnett, MS., Brooklyn.... 99
The Antagonistic Biological Action of Quartz and Potassium Carbonate G. W. H. Schepers, MS., DSc., and A. B. Delahant, Saranac Lake, N. Y..................... 107
An Experimental Study of the Effects of Rare Metals on Animal Lungs Anthony B. Delahant, Saranac Lake, N. Y............................................................................ 114
CONTENTS
The Biological Action of Tantalum Oxide
PACl-
C. W. H. Scheprrs, HD., DSc., Saranac Lake, N. Y..................................................... 119
The Biological Action of Cobaltic Oxide C. IP. H. Scheprrs, HD., DSc., Saranac Lake, N. Y......................................................... 522
The Biological Action of Particulate Cobalt Metal C. IP. H. Scheprrs. HD., DSc., Saranac Lake, N. Y......................................................... ^
The Biological Action of Particulate Tungsten Metal C. IP. H. Scheprrs, HD., DSc., Saranac Lake, N. Y................................................... 132
The Biological Action of Tungsten Carbide and Carbon C. IP. H. Schcpcrs, H.D., DSc., Saranac Lake, N. Y......................................................... 135
The Biological Action_pf Tungsten Carbide and Cobalt C. IP. H. Schcpcrs, M.D., DSc., Saranac Lake, N. Y......................................................... 13S
The Pulmonary Disability Legislation of South Africa C. IP. H. Schcpcrs. HD., DSc., Saranac Lake, N. Y......................................................... 145
Evaluating Disability in Compensation for Pneumoconiosis Theodore C. Waters, Baltimore.............................................................................................. 157
The Radon Problem in Deep-Level Mining Duncan A. Holaday, BS., H-A., Salt Lake Gty................................................................. 161
Current Problems in Dust Control in Metal Mines C. S. Cibson, MS., Timmins, OnL, Canada........................................................................ 165
The Disability Pound in Persons Exposed to Certain Beryllium Compounds Harriet !.. Hardy, H.D., Boston.............................................................................................. 172
The EfTecls of Inlulcd Talc-Mining Dust on the Human Lung C7, IP. H. Schcpcrs, M.D.. DSc., and T. M. Durkan, US., Saranac Lake, N. Y.......... 180
Pulmonary Disability in Asbestos Workers Kenneth IP. Sntith, HD.. New York................................................................................... 196
Pulmonary Disability Associated with Coal Mining J. IP. C. Hannon, HD., Washington, Pa............................................................................... 202
Pathological Study of the Effects of Inhaled Gypsum Dust oo Human Lungs C. IP. H. Scheprrs, MD., DSc., and T. M. Durkan, US., Saranac Lake, N. Y..........207
The Demonstration of Aluminum in Animal Tissues Dudley A. Irtirin, H.D., Pittsburgh.................. .................................................................... 216
Experiences with the Control of Silicosis in a Foundry Leslie H. Osmond, HD., Homestead, Pa............................................................................ 219
Prophylaxis and Treatment of Experimental Silicosis by Means of Aluminum H. Dworski, H.P.H., Saranac Lake, N. Y.......................................................................... 224
Experiences with the Control of Silicosis in the Ceramic Industry D. L. Perry, M.D., New Castle, Pa...................................................................................... 242
vtt
CONTENTS
Some Experiences with Silicosis Control in Gold Mining
pace
J. K. Codin, M.E., Belleterre, Que., Canada...................................................................... 245
Reaction of Chromium Compounds with Body Tissues and Their Constituents
A. M. Baetjcr, Sc.D.; C. M. Damron, PhD).; J. H. Clark, PhD., and V. Budacz, Ph.D., Baltimore.................................................................................................. 253-
Study of Surface Properties of Quartz Dust Lester D. Schecl, PhD., Saranac Lake, N. Y...................................................................... 257
' Cytobiological Manifestations of the Surface Properties of Quartz C. W. H. Schepers, M.D., DSc., Saranac Lake, N. Y....................................................... 261
An Experimental Study of the Effects of Glass Wool on Animal Lungs C. W. H. Schepers, MD., DSc., and Anthony B. Delahant, Saranac Lake, N, Y......... 271
, The Biological Action of Glass Wool C. W. H. Schepers, M.D., DSc., Saranac Lake, N. Y....................................................... 275
Differential Susceptibility of Animals to Dust W. R. Franks, M.D., Toronto, Canada................................................................................ 2S3
An Experimental Study of the Effects of Rare Earths on Animal Lungs
C. W. H. Schepers, M.D., DSc.; Anthony B. Delahant, and Andrew J. Redlin, Saranac Lake, N. Y................................................................................ 292
The Biological Action of Rare Earths C. IV. H. Schepers, M.D., DSc., Saranac Lake, N. Y. I. The Experimental Pulmonary Histopathology Produced by a Blend Having a Relatively High Oxide Content.................................................................................... 256 II. The Experimental Pulmonary Histopathology Produced by a Blend Having a Relatively High Fluoride Content................................................................................ 301
An Experimental Study of the Effects of Talc Dust on Animal Tissue C. W. H. Schepers, MD., DSc., and T. M. Durian, MD., Saranac Lake, N. Y........... 312
The Biological Effects of Calcined Gypsum Dust C. W. H. Schepers, MD., DSc.; T. M. Durban, M.E., and A. B. Delahant, -Saranac Lake, N. Y............................................................................................................. 324
Effect of Inhaled Commercial Hydrous Calcium Silicate Dust on Animal Tissues C. W. H. Schepers, M.D., DSc.; T. M. Durian, M.E., and A. B. Delahant, Saranac Lake, N. Y............................................................................................................. 343
Relationship of Particle Count. Weight, Shape, and Size of Air-Borne Dusts M. L. Roberts, MS., EJi., Saranac lake. N. Y................................................................. 356
Personal Impressions of Edward Livingston Trudeau and Edward R. Baldwin Hugh Sf. Kinglwrn, M.D.. Saranac I-ake, N. Y................................................................... 36.1
Memories of Leroy Upson Gardner Paul S. Richards, M.D., l-'.J.CS., Salt Lake City...................................................................... 3o/
Annual Report of the McIntyre Research Foundation for Year Ended Dec. 31. 1954......... 375
DL 2w 2)/ (jreat dSritain L6eci5e5 in
A. I. G. McLAUGHUN, M.D., F.R.C.P., London
The story of dust diseases in Great Britain .vs back a long way. E. L. Collis, in his
issical Milroy Lectures of 1915, quoted ier!>ert Spencer as saying that the starting -hit of human progress was the "localization ' industries." There was such a localization ! prehistoric factories for the making of flint .'leinents at Grime's Graves, near Brandon
Suffolk, where the flint knappers still use 1> like the deer-hom picks of their prehis"io ancestors. In 1914, Collis showed that sc workers have a high mortality from iicosis. He said that it is probable that "the .irting point of human progress" was asso- ated with at least one form of pneumoconiis. It has been long known that the dust of lint, which is nearly pure Si02, is dangerous ,< health. Over 200 years ago, Thomas Ben son, of Newcastle under Lyme, was granted r. patent for grinding flints by a wet method. At that time it was said that a man who ground the flints dry'could not live longer than two years.
Our greatest localization of industries took place during the Industrial Revolution, and this was really the starting point of our in tensive knowledge about the effects of dust on the lung.
The first notable contribution was that of Pearson (1813), who, after many autopsies, decided that the black pigment in the bron chial nodes and the lungs was due to the in halation of small particles resulting from the burning of coal, wood, and other inflammable materials. The German pathologists, on the other hand, thought that the pigment came from inside the body. Meiklejohn (1951) has dcscrilied the hitherto little-known and re-
Rccordcd for publication April 7, 1935.
H. M. Medical Inspector of Factories.
markable contributions of the Scottish physi cians of the 1800's on the connection between disease of the lungs and coal dust; he also tells how the incidence of anthracosis diminished with improved ventilation of the mines. The Scottish physicians decided that simple coal dust was comparatively harmless and that stone dust was the really noxious factor.
Charles Turner Thackrah, a physician in Leeds, played a major part in the study of oc cupational diseases (including the dust dis eases) in Great Britain. In his hook "The Effects of Arts, Trades, and Professions," the second edition of which was published in 1832, he crystallized the idea that the inhala tion of large quantities of dusts of any kind can damage the lungs but that some dusts are more harmful than others. His conclusions were based on first-hand observations of workers in hospitals, in their homes, and in the factories.
Two other great Englishmen in the history of pneumoconiosis about the middle of the 19th century were T. B. Peacock and E. H. Greenhow. Peacock first established miners' disease as an entity and distinguished it clin ically from pulmonary tuberculosis before little was known about bacteriology and noth ing about x-rays. Greenhow carried out the first large field investigations into the dusty industries of England and Wales, including the heavy-metal industries, the potteries, coal, copper, and lead mining, and even agriculture. In the Transactions oj the Pathological So ciety of London (1S60-1S66) there are to be found excellent descriptions by both of these physicians of the disease, which was later to be called silicosis by Visconti, in 1870. They even found the dust of free silica in the lungs and examined it under polarized light.
For a long time after this excellent work nothing much was done about the dust dis eases, but about the beginning ot the 2Cth
McLaughlin
century a new interest began to be taken in the problem not only in England but also in other parts of the world. About the same time the tempo of life in genera! began to in crease, and there was an urge for increased speed of production--an urge which has grad ually gathered momentum. With the replace ment of hand labor by the machine, dusty processes have become more dusty and meth ods of dust control have lagged behind output. The result has been a remarkable increase of the incidence of the dust diseases.
A noteworthy contribution in 1892 was Arlidge's book on the occupational diseases, which was only the second to be published in England.
In 1504, J. S. Haldane and his colleagues ascribed the high mortality among tin miners to the inhalation of rock dust. A little earlier, dust phthisis among slate workers was shown to be related to the dust of slate, particularly when it had a high quartz content.
E. L. Collis (1915) pinpointed the dust of free silica as the main cause of. most of the dust diseases. He also drew attention to the role that dust inhalation plays in determining the mortality from lung diseases experienced by the general population. Long ago he showed the influence of air pollution on the mortality from lung diseases in general. Though Collis did this work 40 years ago, he is always up-to-date. He had, and still has, an uncanny knack of seeing to the heart of any problem. Just now in England there is controversy about chronic bronchitis and emphysema and whether they can be held to be caused by the inhalation of dust. It is true that the incidence of chronic bronchitis and emphysema is high among the general popula tion, and the possible causes are legion. It is difficult to decide (in Arlidge's words) how much of the malady is "town-made" or "trademade." But as Collis showed years ago, an agent which irritates the lung parenchyma can also irritate the bronchial mucous membrane. At present there is one industrial pulmonary disease of which the diagnosis is made largely on the presence of chronic bronchitis and emphysema, and that is byssinosis.
SA
In the last 50 years in Great Britain (as elsewhere), there has been intensive research' into all aspects of the dust diseases, such as causation, pathology, incidence in various in dustries, and prevention. For the first 25 years or so, much of the impetus came from H. M. Medical Inspectors of Factories, and prominent in the study of the chest diseases were Collis, Middleton, and Merewether. It might be said that they played almost a lone hand, with meager facilities for investigation. However, they were helped greatly by hospi tal physicians, general practitioners, radiolo gists, and pathologists, notably Hall, Robertshaw. Kettle, Gloyne, and Cooke. During this period much attention was paid to silicosis, and it, with tuberculosis, was established as being the cause of disability and death in most of the industries where there is exposure to the dust of free silica. Pari passu, regulations laying down dust-control measures were is sued by the Factory Department for most of the major industries. Notable contributions were Collis's work, already mentioned, on the role of free silica and Middleton's field in vestigation (with E. L. Macklin) into the,., grinding industry in 1923. In the late '20TjT a series of brilliant observations by Cooke.) Gloyne, Burton Wood, Stuart McDonald, and.'! M. J. Stewart on the clinical, radiological,^ and pathological features of a new disease, which Cooke named asbestosis, led to field in vestigations by Merewether and Price (1930), , These firmly established that the dust of as- l bestos was dangerous to health, and it wa;\t/
the first time that the dust of combined silica.) as opposed to free silica, was found to damageV the lungs. The condition, as Legge points out, was first seen in 1906 by Murray at Charing Cross Hospital, but little or no notice of it was taken at that time.
An important landmark was the passing of the Workmen's Compensation (Silicosis) Act of 1918, which came into force in 1919. For the first time compensation for disable ment or death was given in respect of an in dustrial pulmonary disease. The Act pro vided initial and periodical medical examina tion of all workers in the refractories indusirv
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.'1ST DISEASES IN GREAT BRITAIN
..nd suspension from the industry on a diag nosis of simple silicosis as well as silicosis '.vith tuberculosis. The medical officers re.-ponsihle for the examinations were the Tuhi-rculosis Officers of the Local Authority ad ministering sanatorium benefit under the .National Health Insurance Act. The scheme -.as revised in 1925, and again in 1931, to -rrivide for examinations by a medical board. ' his was the beginning of the whole-time h'licosis and Asbestosis Medical Board under - first (and only) Chief Medical Officer, I.. Sutherland.
A close association began between the
(Medical Inspectorate of Factories and the .Mitosis and Asbestosis Medical Board, both .-roups working under the Home Office. In f- neral, the Medical Inspectorate made the
tlcl investigations which established the risk \ : silicosis (or asbestosis) in an industry or -5 process and which led to the establishment of T .he various compensation schemes. But the < members of the Board (stationed at Sheffield, t - Manchester, Stoke on Trent, and Cardiff) f also carried out field investigations into vari-
"iis industries, such as sandstone (Sutherland and Bryson, 1929), granite (Sutherland and Bryson, 1929), and potteries (Meiklejohn, 1949). But perhaps the most significant re sult of the formation of the Board was that there was begun a systematic and valuable collection of case histories with x-ray films, together with occupational details and post mortem findings.
At first the Board was limited to a few in dustries, but gradually its scope has increased and more and more dusty industries have come under examination. Workers in the re fractories industry first came under a com pensation scheme in 1925. metal grinders in 1927, and sandstone workers in 1929. In 192S, the Various Industries Scheme included the processes of mining, quarrying, drilling, and blasting in silica rock, the crushing and grind ing of siliceous materials, and also isolated j processes in steel foundries (not iron foun dries) and metal works, in potteries, and in tin mines. In 1934 the Various Industries Sch erne was amended to include coal miners
with silicosis; in 1935 hematite ore miners were included, and in 1939 slate miners. Workers with asbestosis were first compen sated in 1931 ; compensation for byssinosis was introduced in 1941 and w-as dealt with by a specially constituted board. Pneu moconiosis, as opposed to classical silicosis, in coal miners was brought under the compensa tion schemes in 1943 and in coal trimmers in 1946. The Various Industries Scheme was again amended in 1946 to include molders of iron castings who used siliceous parting pow ders and also blasters of any type of metal castings to free them from adherent sand, even if the blasting abrasive was nonsiliceous. The National Insurance (Industrial Injuries) Act was passed in 1946 and altered the whole basis of compensation in that it became the re sponsibility of the Government but with con tributions from employers and workers. Ber yllium "poisoning" became compensable in 1949. In 1954 all foundry workers (iron, steel, and nonferrous) became entitled to com pensation under the Industrial Injuries Act. A fuller account of the development of com pensation in Great Britain has recently been written by Meiklejohn (1954). The Silicosis and Asbestosis Medical Board was trans ferred from the Home Office in 1946 to the Ministry of National Insurance (later com bined with the Ministry of Pensions). The Board was divided into a series of Pneu moconiosis Panels, but they work in much the same way as the Board did, except that there is now no Chief Medical Officer.
The various compensation schemes men tioned above reflect the evolution of the study of the industrial lung diseases in Great Brit ain. There are comparable legal enactments and regulations designed to control the risks in each industry, but they are too numerous to mention in detail.
To "flashback" a little, in 1936 Middleton, in his Milroy Lectures, reviewed the position of the dust diseases in Great Britain. He covered all the dusty trades, including cord mining, but at that time only cases of silicosis in coal miners were recognized as being eligi ble for compensation. Most of the miners.
3
McL.WCHUN
such as hardbeaders, drifters, or rippers, had been exposed to stone dust, but Middleton also showed that there was a high incidence of a lung disease among coal miners, particularly in South Wales, which was not classical sili cosis. Much of his evidence was drawn from the findings of the Silicosis and Asbestosis Medical Board. Following his paper, there began a series of intensive investigations by the Medical Research Council into the health risks of coal mining, which covered nil as pects, such as clinical, radiographic, and en vironmental (Medical Research Council Spe cial Reports I [1943], II [1943], and III [1945]). The important fact emerging from this work was that coal dust by itself could cause pneumoconiosis, and this was followed, as previously mentioned, by the extension of compensation to coal miners and coal trim mers. In 1945, the Pneumoconiosis Research Unit of the Medical Research Council was set up in Cardiff, and an impressive body of work has emerged on various aspects of coal miners' pneumoconiosis. This work is well known, and I propose, therefore, to limit my remain ing observations mainly to the dust diseases resulting front work in places which come
under the Factories Acts, with only inciden tal references to coal mining.
3. Stone quarrying, crushing, and dressing. This group includes workers with sandstone, millstone, gritstone, slate, granite, and other igneous rocks. The risk varies with th amount of free silica in the rock and, of course, with the protective measures adopted. Recently some limestone quarrymen have contracted silicosis, but the limestone con tained a fairly high proportion of free silica.* In this group could !>e included rock tunnelers, in whom the onset of silicosis may be very rapid. As regards- slate workers, a bil liard-table maker has recently received com pensation for silicosis.
silicosis .
Silicosis has been found to be a cause of disability in the following broad groups of in dustries as well as in coal mining and other forms of mining, such as tin, hematite, copper, barites, and fire clay.
1. Refractories industry. This group in cludes-the making of silica bricks, furnace dismantling and rebuilding, and retort setting and. repairing.
2. Pottery industry. Workers in this group have been engaged in the manufacture of both earthenware and china with their various subdivisions and as flint millers and polishers. The substitution of ground flint by alumina for the placing of biscuit ware has resulted in a diminution of deaths from silicosis among workers in that process.
Fig. 1.--Chart showing diminishing numbers of deaths among metal grinders during the period 1930-1951, inclusive.
4. Metal grinding. The silicosis risk in the grinding of metals has gTeatly diminished, owing to the replacement of the sandstone grinding wheels with artificial ones comjiosed of Carborundum, alumina, or emery. Apart from the lower "toxicity-' of the dusts from these substances, the wheels are much harder than sandstone, and less dust is created. But the grinders of castings (iron, steel, and nonferrous) are still exposed to a silicosis risk on account of the presence of burned-on sand on the castings. The diminishing number of deaths among grinders is shown in the chart (Fig. 1).
- Doig, A. T.: Unpublished data.
DUST DISEASES IN GREAT BRITAIN
5. Sandblasting. This job, as Merewether H936) showed, had a high silicosis risk. The position has altered materially after sand be gan to be replaced by other nonsiliceous abra sives, such as steel shot, and since the use of sand as an abrasive was prohibited in 1949 by the Blasting of Castings (and other Articles) Regulations. The process of wet sandblasting of ships' hulls does not come under the Regu lations (because legally a ship is not an arti cle), but it is thought that there is also a risk of silicosis in the job. Sandblasting is still used in the open air on works of engineering construction, e. g., in order to prepare large metal surfaces for the application of paint.
6. Manufacture of abrasive soap. Middleton showed in 1936 that the manufacture of abrasive soaps carried with it a risk of acute jr subacute silicosis, accompanied by tubercu losis. There was a disastrous experience at one factory in London between 1921 and 1928, when there were 13 deaths among 81 workers. This experience led to rigorous dust control in the processes, but between 1941 and 1952 there were nine deaths from silicosis among this type of worker. It is not possible to state the incidence of disease and disability, because there is a rapid turnover of labor (mostly young women) in the job. Silica flour is still being used as an abrasive, though efforts are being made to find a less harmful substitute which will be acceptable to the manufacturers and the users. There were no new cases of silicosis in this trade in 1953.
7. Foundry industry. The iron and steel foundry industry has been investigated in great detail during the past 10 years or so, and the results were published in 1950 in book form by McLaughlin and others ("Industrial Lung Diseases of Iron and Steel Foundry Workers"). Pathological studies of 64 cases, as well as clinical and x-ray examinations of some 3000 workers, showed that there was a varying risk of silicosis and mixed dust pneu moconiosis (to which reference is made be low) in the various categories of foundry workers.
Steel fettlers (dressers or castings clean ers) had a severe risk, largely owing to the
fact that the dust from the pneumatic hammer is not controlled. The main pathological lesion was classical silicosis, with or without tuber culosis. Among iron fettlers, the risk was not so great as among steel fettlers, and the main pathological lesion found was mixed dust pneumoconiosis, though classical silicosis did occur. Steel molders were less affected by dis ease and disability than iron molders, though statistically the incidence of x-ray abnormal ities was greater among steel workers. More deaths occurred among iron molders, and this fact appeared to be related to the use of siliceous parting powders. The use of siliceous parting powders has now been prohibited by the Foundries (Parting Materials) Regula tions, 1950. Silicosis still occurs among shot blasters of both iron and steel castings, but the risk is controlled by ventilation and per sona! protective devices, and the numbers of cases and deaths, in contrast with the experi ence among steel fettlers, are not increasing. Other categories of iron and steel foundry workers are subject to much less risk than the above groups of workers. New and strin gent regulations (Iron and Steel Foundry Regulations) were issued in 1953. They re quire strict dust control in the dusty proc esses.
The question of pneumoconiosis among nonferrous foundry workers is now being ex amined in detail. Isolated cases of silicosis and mixed dust pneumoconiosis have occurred among both casters and.dressers of nonferrous metals, but an extensive survey has not yet been carried out. Harding and McLaughlin f have described the pathological, clinical, ra diological, and environmental details of six fatal cases.
Table 1 shows the number of new cases oi pneumoconiosis (i. e., silicosis and mixed dust pneumoconiosis) in foundry workers diag nosed by the Pneumoconiosis Panels in 1953.
These figures can be regarded as an under statement of the real position. More than halt
t Harding, H. E., and McLaughlin. A. 1. G.: To be published.
s:
McLaughlin
Table 1.--New Casts of Pneumoconiosis--1953 Foundries
Occupatloo
Total
Iron molding1..,......................................... ................. 57
Iron dressing......................... -....................................... Iron foundry knockout........................................... Sted moldinf..........................................................
H 1
<
Sted dreaaing..........................
AS
Nonferrou* drewing................................................... Welder* and burners (Is easting* cleaning
shops) .....................................................
General foundry work...................................
1
Total.....................................
192
* Twenty-seven of these worken bad also been exposed to coal dust for varying periods.
of the cases in iron molders came from one area where there had been an x-ray survey of three foundries. If more iron foundries had been similarly surveyed, more cases would have been found. In certain steel foundries the dressers (chippers or castings cleaners) are x-rayed each year, but a complete picture of the true position will not be obtained until all workers undergo periodical medical examina tion. This statement also applies to other dusty industries.
In Table 2 details are given of fatal cases of silicosis and asbestosis investigated fully by the Medical Inspectorate of Factories between 1930 and 1953. The average ages at death and the length of employment in the dusty indus tries are also given.
It is seen that as regards silicosis the manu facture of scouring powders and sandblasting were10the most dangerous industries, with the
5!*
lowest average' age at death and the shortest average period of employment. Another in teresting point is that' tuberculosis occurred in about half of the cases of silicosis, whereas it was found in only about two-fifths of the cases of asbestosis. The average age at death and the length of exposure in the cases of as bestosis were much lower than in the silicotic group as a whole but more on the level of sandblasters and makers of scouring powders.^
The connection between asbestosis and cancer of the lung is becoming dearer, and in one series of 100 autopsies on asbestosis cases there were 25 cases of cancer of the lung.Wyers (1949) has pointed out that the x-ray
Taslz 2.--Fatal Cam of Silicosis and Asbestosis Investigated by Factory Department, 1930-1933
EUlcosii Pottery SnieoiU ................................................ Silicosis with fcuberailoiis...................
6*odtocie snicoii............................... ................. Silicosis with tobercukui*..,..................
Grind lag of Metals Silicosis ................................................ Silicosis with tuberculosis......................
Sandblasting Silicosis........... .................................... Silicosis with tuberculosis......................
Manufacture of aeouriog powders Slllcosli................................................ Silicosis with tuberculosis......................
Miscellaneous Silicosis ................................................ Silicosis with tuberculosis......................
Total Silicosis.................... ........................... Silicosis with tuberculosis......................
Asbestosis AJbestosis .................................................. Asbestosis with tuberculosis.......................
Dea tbs, Ho.
Average Age at Death,
Tr.
- D. --er.a... tio--n-o--f E* m- p.l.o..y = C2t s loo test. Shorten, Average,
Tr. Tr: Tr.
61.7 66-J
609 57 A
GOA 54.0 '
50.4 it*
to.s 40B
53.4 S1A
59.4 54.4
aJ
so.;
61-0 CiXt
tts> biX)
t\J> 56.0
42.0 46.0
37.0 11-1
37.0 50.0
e;.o 67.0
48.0 33.0
tJ> bJj
9 JO i.o
34.0 ;a
3.7 :.o
:.o
1A 0.7
1.5 0.7
0A 0-3
38.4 34.7
29.0 37.4
33.9 33.0
13.4 13.1
SJ 7.0
71.3 HA
34.1 31.2
J6.fi/ 11.4
DUST DISEASES IN GREAT BRITAIN
appearances of asbestosis are undergoing some change in that nodular as opposed to ground-glass shadows are beginning to ap pear. He thinks it probable that this is because of the lessened exposure to dust over a longer period, owing to the rigorous application of exhaust ventilation to the dusty processes and the use of personal protective devices. Cases of asbestosis, however, are now appearing in workers who do asbestos lagging of pipes and i oilers. In this process, particularly if asI iestos is being sprayed, it is difficult to apply adequate protective measures, more especially ' iecause the workers are usually peripatetic.
PRESENT POSITION
How many cases of pneumoconiosis (sili cosis, asbestosis, coal miners' pneumoconiosis,
In all industries there were 8789 deaths from occupational fibrosis of the lung in the 12-year period, and it will be seen that the total yearly figures are going up. Over the same period there were 6907 deaths from nonoccupational fibrosis of the lungs. About twothirds of the total number of deaths in the occupational group occurred in coal miners, who form the largest group (about 700,000) exposed to dust inhalation. The figures rose steeply from 232 in 1940 to 937 in 1951 (in 1952 the figure dropped slightly, to 912). It may well be that part of the increase is due to more accurate diagnosis, or at least to greater interest in the pneumoconiosis problem, among coal miners. In Figure 2 is shown a comparison, based on the crude figures of Table 3, between the coal miners and factory
Table 3.--Deaths from AH Types oj Pneumoconiosis m England and Wales, 1940-1951
tedustr?
/'orreries ........................................................ StOdltOEK ..................................................... ^rlodlcr of tuetiU, etc.......................... ................. Wcfractorie*.................................................. MiwelUsxou*. .............................................. Col rnioietc.................................................. Oliver mlolnt................................................ .llbestOS ........................................................ ................. Cotton (byuico*!*)..................................
1940 41
11
1941
45 St 26 12
5 196
40 17
1941
47 4 2d
7 7 230 44 11 6
1943
41 77 ;i
7 5 276 43 6 7
1944
32 57 24 6 13 311 39 10
1
1945 41 65 r
9 19 3S7 40 11 10
1946
49 61 S3
8 14 421 51 16 3
1947
54 55 27 10 26 577 50 15
4
1948
48 68 26 33 27 639 49 15
8
1949
63 51 57 33 25 756 64 i:
7
1950
73 29 22
8 70 846 42 12 11
1951
62 71 21 8 129 237 51 18
8
Toul toe 779 125 337 347
5,SOS 579 161 65
Toul......................................................... ................. i33 423 434 4&5 4S3 604 655 818 893 1.033 1.113 1,305 8.733
N*OOOCCUpt<(O0l .................................... .
461 443 493 531 529 568 616 651 554 679 732 6,907
etc.) occur in Great Britain? It should be mentioned that at the present time it is im possible to give accurate figures of the popu lations at risk in the various trades and proc esses. Both the Registrar-General and the Ministry of Labour classify occupations in groups too broad to give specific figures of the populations in the dusty industries, and those in the possession of employers' asso ciations and trades unions are not complete. It may be possible in several years' time to give more accurate information. All that can be done now is to state the numbers of deaths reported to the Registrar-General and to give the figures for one year of the new cases diag nosed by the Pneumoconiosis Panels.
The deaths from all forms of pneumoconi osis between 1940 and 1951, inclusive, in England and Wales are given in Table 3.
workers. In the factory processes, the yearly number of deaths was going down until 1943, but there has been a slight rise in the later years.
In both groups, it should be emphasized that the deaths in each year are related to conditions which obtained in mines and fac tories some years previously, possibly 10 to 20 years or even longer.
New Cases in Factory Occupations.--The following Table 4 gives the numbers of new cases of' pneumoconiosis diagnosed by the Pneumoconiosis Panels in 1953. These fig ures have been kindly supplied by the Minis try of Pensions and National Insurance, but it should be noted that they differ slightly as regards the numbers in each occupation from the figures originally supplied. The Ministry usually classifies the cases as falling into the
S9
UcL.-ICCHUX
CCatms raoH m types of pntvMoco"to$is. * --1/3 >+** "P.
m ^ rw
nx mat m*i ml *** m(
fiXTorr wet titi
*4 mu mu mi m+* m*t m** mi Fig. 2.--Chart showing trends of deaths from fibrosis of the lungs among coal miners and factory workers during the period 1940-1951, inclusive. category of the last jolts done by the workers, whereas Dr. G. O. Williams, of the Factory Department, has reclassified some of the cases on the basis of all occupations done by each worker in order to determine the most likely cause of the pneumoconiosis. There were 896 cases of pneumoconiosis diagnosed, and this figure includes 54 cases of byssinosis. The cases with an uncomplicated occupational history numbered 665, and in the
remainder there was exposure for varying pe riods to other dusts, mainly coal dust. Addi tional exposure to coal dust occurred mainlyin those industries situated in coal-mining areas, such as refractories, stone (sandstone and granite), pottery, slate, and foundry in dustries. The pottery industry contributed the greatest number of cases (353. mainly sili cosis), and the foundry industry came next with 190 cases. There are roughly 25.000 pot tery and about 220.000 foundry workers (iron, steel, and nonferrous) ; so it is probable that the pottery industry has a higher pneu moconiosis risk than foundries. Such general statements are not of much value, because the risk varies from process to process within the same industry. The substitution of ground flint by calcined alumina has reduced the sili cosis risk among placers of biscuit ware in potteries, whereas the fettling of steel castings is still a dangerous job.
Ntr.v Cases in Mining.--Table 5 gives the numbers of new cases of pneumoconiosis oc curring in all mining operations in 1953.
These figures show dearly the tremendous problem which faces the coal-mining industry. There is no space to give in detail the varying degrees of severity of pneumoconiosis found in the 404$ cases, but the figures are given in the "Digest of Pneumoconiosis Statistics
Table 4.--Xnp Coses of Pneumoconiosis--1953 Factory Occupations
Indus try
O) (2) (*> (4)
(3> ffi) (71 (8) (9) (10)
(ID
Oil () 04) (!i> (IG)
Refractories ............................................................... Stooe workers (sandstone. erriite>................. Pottery ........................................................................ Siate *orkrm Ojnarrylnf anil Foundries ..................................................................... iletal jrrlndinf (other than foundries)............ SfiOdbUitioj,* ............................................................ Shot blasting,..................... ...................................... J'lsrtjaee dismantling, etc....................................... Boiler scaling.............................................................. Abrasive wheel manufacture................................ Asbestos .................................................................... Abrasive aoap poM^lers......................................... tiraphite nod earl*on electrode*............. ..
Tlo smeltioc...................................................... ..... Colton (hyst(uu-.U)...............................................
(H) Coni trimming....................... .................................. OB) Miscellaneous ...........................................................
Total......................................................................
No Other
Exposure U S5
61 liri
5 5 2 17 .4 3 U
1 40 10 24
fVv'l
Other Dust Exposure
' Coal 20 20 86 30
* 4
Other
..
13 9
7 1
53
11
Tot 2i fSi
V>7 mi 190
7 9 2 2t 5 3 22
1 .Vi :o ?<
SCd
90
DUST DISEASES IN GREAT BRITAIN
Table 5.--Nczv Cases of Pneumoconiosis--1953
Mining
lndustrj
(?) Coal miofot.......................................................... li) Tin TTiioioc............................................................ O) Barite* mioinc.................................................... til Tin cUf rainier f............................................. (5) Other elmy mining............................................ (0) Hematite mlnlor................................................ (7) Lead mtalof........................................................
Tunneling .............................................................
No.
4.043 3 1
36 ! 4 2 3
Total................................................................. 4.079
' No raea la chert, oil shale, or stratified Ironstone imnmc.
Fourteen fire clay mioers were also exposed to coal !n.-i.
for 1953,M issued by the Ministry of Fuel and Power (1954). It can be said, however, that more than 50% of the cases had only slight disability, and only about 3% were totally disabled.
The number of cases in hematite mining is diminishing, but the small numbers found in tunneling are usually instances of rapid and severe silicosis.
DUSTS OTHER THAN SILICA, ASBESTOS,
AND COAL
About the middle 1930's the Factory De partment began to turn its attention to other dusts. Middleton, in his 1936 review, referred to dusts, such as tripoli, sillimanite, kieselguhr, talc, china clay, and fullers' earth. In the same year Doig and McLaughlin pub lished a paper on the x-ray appearances of the lungs of electric-arc welders. From this has arisen a world-wide study of the inert and radiopaque dusts, and notable American contributors have been Sander, Enzer, Pen dergrass, Vorwald, and Hamlin. Perhaps the most interesting outcome of this study has been the alteration of the approach to the interpretation of x-ray films of the chest, because the x-ray features of siderosis, baritosis, and stannosis, in the absence of occu pational histories and clinical examinations, can be mistaken for fibrotic changes in the lungs. In fact, an alarming x-ray picture is often found in a worker who has little or no disability. The study of siderosis was helped by the excellent work of Stewart and Faulds (1934) and later Craw (1937) on the hema
tite miners, in which group the lesion was found to be siderosilicosis, often accompanied by tuberculosis. Craw's later work (1947) in eliminating tuberculosis from the hematite mines and in improved dust control methods is of major importance.
Other occupations and dusts which have been studied include those of boiler scalers, graphite workers, grain dockers, and workers exposed to beryllium and its oxides, to the dust of leather mixed with other dusts, and to bagasse. Attention has also been given to exposures to the dusts of aluminum, man ganese, and vanadium and to asthma occur ring in workers exposed to the double salts of platinum and also to various wood dusts, such as western red cedar.
Pathology.--A great deal of work has been done on the pathology (gross, histological, and experimental) of coal miners' lungs by Gough, Harding, King, Heppleston, Wright, Gloyne, Nagelschmidt, and others. I might, however, state some conclusions about pa thology which Harding and I (with our late colleague, S. Roodhouse Gloyne) have ar rived at after studying the lungs of workers in many diverse industries.
Until about 10 years ago, the pathology or the dust diseases was dominated by the class ical silicotic nodule (Fig. 3). In the same way, before a diagnosis could be made, the patient had to have x-ray nodulation, or the classical "snowstorm" effect. Classical sili cosis usually occurs after the worker has been exposed to dust containing a high proportion of free silica. It is becoming increasingly clear, in our opinion, that even small propor tions of free silica in a dust can cause a fibro sis which is composed of nodules not of the classical type (Fig. 4). The arrangement of the fibers is linear and radial, and the outline of the whole nodule is stellate. It looks like a black star. ..Harding, Gloyne, and I have applied the term mixed dust pneumoconiosis, or mixed dust fibrosis, to this nodule. It has been found in foundry workers, especially in cleaners of iron castings, in persons exposed to the dust of graphite containing about 10% free silica, and in boiler scalers who are cx-
McL. H'l.HLIX
Fig. 3.--Classical silicotic nodule from lung of a gold miner (30 years old) ; hematoxylin and eosin; X 24.
mixed dust pneumoconiosis nodule. Indeed, there are also nodules which show a transi tion stage between the mixed dust nodule and the classical one (Fig. 5). It should be men tioned that the x-ray appearances of the lungs of a worker with mixed dust pneumoconiosis differ little, if at all, from those of one with silicosis, and the disease is just as disabling and as fatal.
Boiler Scalers' Piinuuacoiuosis.--Experi ence of pulmonarv diseases in ships' Ixhler sealers illustrates well the etiology of mixed dust pneumoconiosis. These men are exposed to a mixed dust which varies according to the type of fuel used to heat the boilers and also according to the source of the water used
posed to a mixed dust with a low proportion of SiO-j. Tlie coal nodule of coal miners' pneumoconiosis has much the same appear ance as nur mixed dust pneumoconiosis nodule. Coal contains varying proportions of free .-ilira. In any case, the common de nominator in those cases and occupations in which this type of nodule is found appears to be the presence of a small proportion of free silica in the dust. Where there is a high pro portion, as stated above, the classical silicotic nodule is found. But in the same case, there may he both the classical nodule and the
Fig. 4.--Mixed dust pneumoconiosis nodule from a steel fettlcr's lung; hematoxylin and eosin; X 24.
Fig. S.--Transition nodule, from mixed dust pneu moconiosis nodule to silicotic nodule in an iron dresser's lung; hematoxylin six! eosin; X 24.
in them. It contains carbonates, silicates, iron, and carbon. There is usually under of free silica, hut there is often a high pro portion of iron and its oxides. Flue dust contains more iron than does the scale on the water tubes, sometimes as much ns 4^gr.
In the first case oi lioiler scalers' pneumo coniosis the worker had lx-cn scaling boilers for over 40 years (Harding. Tod. and McLaughlin. 1944). In 193S an x-rnv film Of his chest showed nodulation in the upper and miter lung fields, ami in the lower zones reticulation (nr micronodulation). At that time we made a tentative thagnocis <u' sili cosis in the upper zones, with sidormis m the lower zune. Seven wars later the patient
, NST DISEASES IN GREAT BRITAIN
v'! of cancer of the lung, and histological able to study the histological appearances of
lamination of the lungs showed (apart from a proved case of talc pneumoconiosis (.Mc
:a- cancer) the presence of classical silicotic Laughlin, Rogers, and Dunham, 1949).
-iiiles in the upper and outer zones, and in A man, 51 years of age, had worked for
lower zones (where there was x-ray 37 years in a rubber-tire factory, where he
li. nlation) there were mainly deposits of had been exposed to a fairly high concentra
r!mi and iron dust in the lungs, with no tion of talc dust. Moderately advanced pneu
: ri.isis. In all other parts of the lung there moconiosis of both lungs was found at au
re nodules of mixed dust pneumoconiosis. topsy (in addition to incompetence of the
:o the present time we have had autopsies aortic valve). Throughout the lung substance
nine boiler scalers, and all showed this were scattered small gray nodules, more
of fibrosis. Only one scaler had classical numerous in the lower lobes. In some areas
-.otic nodules in addition. But five of them the nodules had coalesced to form small
Jied of cancer of the lung, and this may masses. The fibers appeared to be arranged
II have been partly caused by carcinogenic concentrically around small vessels, giving
-tances present in the soot.
the impression of whorling, but not like the
"lie change from coal to oil as a fuel for ips' boilers has brought with it another liilem. The dust from oil-fired boilers :uses symptoms of bronchospasm or asthma : a high proportion of cases, and it is likely at this is due to the presence of vanadium
appearance of silicosis. There were, in addi tion, many "curious" or talc bodies, resem bling, but easily distinguishable from, asbes tos bodies. Much dust, which proved to be talc, appeared in the sections, and it was thought at the time that the particles were all
n the oil soot. Williams (1952) has published fibers. More recent work on the lung by
.:i interesting series of cases illustrating tin's Nagelschmidt X has shown that the bulk of point. My colleagues and I are at present the dust is in the form of plates with oniy a xnmining (with clinical, radiographic, and few fibers.
environmental details) the boiler scalers
At least three other autopsies on cases of
I i-oine 300 of them) in the port of South talc pneumoconiosis (all from rubber works)
ampton, where the boilers of ocean-going and large passenger liners are cleaned. The invesligation has not been completed, but up to the
have been made, and they show similar fea tures to the first published case. Small sur veys have been made on workers exposed to
present we have not found as much lung talc dust in various industries, but larger
damage as was shown in a previous inquiry ones have been planned to take place shortly.
tcs, ; r/Ot ro
in the port -of Hull, where the boilers of lishing trawlers are mainly scaled. So far we have found three cases of compensable
It is clear that talc dust, though fibrogcuic. is not so active as asbestos in damaging the lungs.
ust pneumoconiosis among 50 workers and one Leather Dressers' Pneumoconiosis.--Co
die case of cancer of the lung, together with a operation between the directors of chest clin
proportion oi cases with lower degrees of ics, the mass radiography units, anti the
pneumoconiosis and disability.
Medical Inspectorate of Factories has been
Talc Pneumoconiosis.--A great deal of instrumental in bringing to light hitherto H'l wurk on talc pneumoconiosis has been done unsuspected causes of pneumoconiosis. Since
m in the United States and Canada (Dreessen, the mass radiography campaign was begun
"r 1933; Dreessen and Dalla Valle, 1935; in 194S for the early detection of cases of
cs Uitldell, 1940; Siegal, Smith, and Green- pulmonary tuberculosis, some 13.000,000 per
it burg, 1943, etc.). Merewether (1933-1934), sons have undergone examination. Many
i- in England, studied the x-ray and clinical factorv populations have been surveyed, and
:e
it
features of rubber workers exposed to talc
t Nagelschmidt, G : Personal communication to
dust. But it was not until 1949 that we were the author.
McLACCHUN
included among them have been factories where there is a dust risk. The workers at one leather factory were examined by Dr. Hugh Ramsay, of the Wanstead Mass Radi ography Unit. He drew our attention to the fact that in one department a high proportion of the workers showed abnormal x-ray changes, whereas in- other departments, where there was no dust, no abnormalities were seen. In the department with the high proportion of x-ray abnormalities, skins loaded with china clay and calcium carbonate are dressed on rapidly revolving felt wheels covered with a layer of fine Carborundum powder. The job is very dusty, though it is done under exhaust ventilation. The dust is composed of much fine leather dust, with smaller proportions of china clay (kaolin), calcium carbonate, and Carborundum. It was found that the dust contained about 5% of free silica. The x-ray films showed all stages of abnormality, varying from early reticula tion (micronodulation) through nodulation to massive shadows. In a few cases there was clinical evidence of disability. One man with an x-ray film showing massive shadows had died from "asthma and pneumonia" a year before the investigation began, and there was no autopsy. In spite of the fact that up to the present time no pathological evidence has been available, it is likely that the condition will fall into the group of the mixed dust pneumoconioses. The dust of china clay, which for years has been thought to be com paratively harmless, is becoming more and more suspect. Even apart from china clay, the presence of a small proportion of free silica is prima facie evidence that the dressing of such skins is a hazardous occupation.
Beryllium Pneumonitis and Granulomato sis.--It is remarkable that British experience of beryllium pneumonitis and granulomatosis is not as extensive as that in the United States, though many workers have been ex posed to the dust of fluorescent lamp powders containing beryllium oxide and also the dust and fumes from the alloys. Only one death has occurred, and the Factory Department has collected clinical, x-ray, and environ
mental details of five nonfatal cases, one of whom is now very ill. The other four cases are either recovering, or their condition is stationary. It is also remarkable that five out of six affected workers were chemists en gaged in the development of the beryllium lamp powders. At the factory where the fatal case of beryllium granulomatosis occurred, 150 of the other workers were examined clinically and radiographically and no more cases were found, though there had been con siderable exposure to the dust of the lamp powders in the early days. It is undeniable that beryllium oxide is toxic, but examina tion of the histology of the lungs of the one fatal case has led nie to hold the unorthodox view that beryllium was not the sole cause of the condition. There were two types of le sion : one of a granulomatous type, in which there were giant and epithelioid cells, and the other in which were many fibrotic nodules indistinguishable from silicosis. Under polar ized light many doubly refractile particles were seen in the nodules, and an eminent crystallographer stated that these were cristobalite, one of the most active forms of free silica. This is not surprising, because one of the ingredients of the lamp powder is silica gel (25%), which in the preparation of the powder is heated up to about 1100C. The changed methods of preparing the lamp pow der have eliminated both the beryllium oxide and the free silica, so that the risks both o: beryllium granulomatosis and of silicosis have also been eliminated.'
"Pneumoconiosis" jrom Vegetable Dusts. --Apart from cotton, not a great deal of work has been done on the vegetable dusts. The illnesses noted among cotton workers include mill fever, a transitory illness which affects nearly all new workers in cotton, flax, and hemp mills and also in malt houses; "Monday fever" (or feeling) ; weavers' cough, and byssinosis.
Byssinosis develops after about 20 years as a natural progression from "Monday fever"
and in its final stage has the characteristics of chronic bronchitis and emphysema. As Schilling (1954) savs, though it was tie -
94
'/ CHUN
nica [he
The nv of ove .<Yv.
if is.
T>
I'll
X.
.1ST DISEASES IN GREAT BRITAIN
..rilier] by Greenhow nearly 100 years ago, - i-iiulogy is still obscure. It presents an odd ' ;i characteristic history of chest tightness
Thirty of these men had pulmonary tubercu losis, but 11 others had x-ray changes sug gestive of the presence of pneumoconiosis.
:j hrenthlessness on Mondays, which grad- Fourteen had normal x-ray films. Analysis
''v extends to other working days as the of the dusts from various grains showed
:i<c progresses. "In its later stages these small percentages of free silica: oat dust, for
upturns are very distressing, but usually instance, had 5%. No autopsies have been
inin worse on Monday than on any other carried out, but it seems that a case has been
It causes no S]>ecific x-ray changes in made out for an extended investigation of
lung fields." In the main, the workers larger groups of grain dockers: `
lie cotton card and blowing rooms suffer -t from the disease. Strippers and grindwho clean the carding engines are especiati'ected. As mentioned previously, workwith hyssinosis are compensated under a .ini scheme.
ngossosis.--Only one factory in the coun. handles bagasse (or sugar cane without sugar), and bagassosis has occurred inly in those workers who were grinding gnsse in a dry state. The condition is an .ute bronchiolitis, with high temperature, ere dyspnea, and x-ray picture of the lungs owing generalized miliary shadows. Fifvn cases of this acute disease have come to
Graphite Pneumoconiosis.--It has been found by some observers in England (Dan ner, 1945, 1948, and 1949; Gloyne. Marshall, and Hoyle. 1949, and Harding and Oliver, 1949) that workers e.\|>osed to the dust of natural graphite develop radiographic changes in the lungs and disability. The range of x-ray abnormalities closely resembles that seen in coal miners. Pathological and experi mental studies (Gloyne and others, 19-9. Harding and Oliver, 1949) show that the condition falls into the group of the mixed dust fibroses, the fibrotic nodules having a linear and radial pattern as opposed to the whorled fibrosis of the classical silicotic
lie notice of the Factory Department; some f these have been described by Castleden and Hamilton-Paterson (1942), Gillison and Taylor (1942), and Hunter and Perry l 1946). The last case occurred in 194S. Since we got the firm to grind the bagasse under water, there have been no further cases.
Fanners Lung.--Farmers', or threshers', lung was first described by Campbell (1932), and after that Fawcitt (1936 and 1938) did a great deal of work on the condition. It has features similar to bagassosis, but, since it occurs mainly among workers who have been handling moldy hay during a wet summer, it is regarded as being caused by a fungus. Fawcitt was firmly of this opinion. Single cases of the condition are described from time to time by physicians in the agricultural districts.
Pneumoconiosis in Grain Dockers.--Dunner, Hermon, and Bagnnll described in 1946 the clinical features and abnormal x-ray ap pearances in a group of 55 grain dockers.
nodule. Natural graphite contains small per centages (of the order of Sfc-IOfo) of free silica. There is as yet no evidence that pure graphite will produce a similar condition.
Manganese Pneumonitis.--A few cases of manganese poisoning affecting the nervous system occurred in the middle 1930's in workers grinding manganese dioxide for use in lamp batteries. In 1946, Lloyd Davies re ported a high incidence of pneumonia in a group of workers exposed to manganese di oxide dust in the manufacture of potassium permanganate. Animal experiments by Lloyd Davies and Harding (1949) confirmed that manganese dioxide irritated the lung tissue and caused intense infiltration of the alveolar walls and alveoli. Later granulomatous changes developed in some instances. These results are in line with those described by workers in other countries.
Vanadium Pneumonitis.--Wyers (1946) recorded his observations on workers exposed to vanadium pentoxide dust, and his results
S3
UcLAUGHLlX
are similar to those described by Sjoberg (1949) in Sweden. The effects are a combi nation of systemic poisoning and irritation of the pulmonary tissue, leading in some cases to bronchospasm and pneumonia. Doig and Williams (1952) have described the marked bronchospasm occurring in workers exposed to the soot of oil fuel, which is thought to be caused by the high percent age of vanadium in the soot.
SUM MAR Y
The position as regards the dust diseases in Great Britain may be summarized as fol lows :
1. During the past 50 years, the risk of sili cosis in most of the major industries has been firmly established. Until the late 1920's, free silica was the only dust which was thought to damage the lungs. Asbestosis, caused by the dust of a combined silica mineral, came into prominence about that time. In the mid dle 1930's, attention was given to the effects of other dusts on the lungs, such as iron and its oxides, and of radiopaque dusts, china clay, sillimanite. kieselguhr, talc, and mixed dusts containing free silica.
During the middle 1930's also, the effects of coal dusts on the lungs were given increas ing attention, and extensive surveys were carried out, culminating in the formation of the Pneumoconiosis Research Unit of the Medical Research Council in 1945. The coal miners numerically constitute the greatest problem of dust disease in Great Britain.
2. Despite the combined efforts of inspec tors of factories and mines, physicians, chem-
/sists, engineers, and research workers, the deaths from pneumoconiosis have continued to rise yearly. The reasons for this increase may be found in more accurate diagnosis of the condition and in the publicity given to occupational diseases of the lungs, leading to more frequent mention of pneumoconiosis by physicians on death certificates. But a more likely cause is the urge for increased speed of production, and the introduction of machines
Doig, A. T. : Unpublished data.
06
which make a dusty process more dusty and cause a lag in dust-control methods.
3. Compensation for industrial pulmonary disease began soon after 1918, and gradually most of the processes and industries which damage the lungs are being brought under the provisions of the various Acts of Parlia ment. The Industrial Injuries Act of 1946 removed the responsibility for compensation from employers and insurance companies to the Government. Since then cases taken under Common Law against the employers have increased rapidly.
4. Numerous legal provisions, contained both in Acts of Parliament and in Regula tions, have been brought into force. Routine inspection by inspectors of factories and mines has been instrumental in limiting the numbers of cases of disability and death brought about by inhalation of the dangerous dusts.
5. It is expected that more accurate infor mation about the incidence of the dust dis eases will be obtained in the near future, when statistical studies of the information obtained by the Pneumoconiosis Panels have been carried out, and when the report of the Registrar-General about the occupational incidence of disease at the time of the 195! Census becomes available. At the present time no reliable information exists about the populations at risk in each industry and process.
6. Surveys of the population by mass radi ography to detect early tuberculosis are bringing to light information about the ef fects of dust in some hitherto unsuspected occupations.
7. Many problems about dusts and the lungs are still unsolved, and some would say that we have only just begun to attack the fringes of the problem. Nevertheless, a great deal has already been accomplished.
Assistance in compiling the Information con tained in this paper was rendered by Dr. P. K. Walker and the members of the Pneumoconiosis Panels of the Ministry of Pensions and Rational Insurance: Drs. E. R. A. Merewcther, A. T. Doig. and G- 0. Williams, o! the Factory Department,
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DUST DISEASES IN GREAT BRITAIN
Ministry of Labour and National Service; Dr. H. E. Harding, lately of Sheffield University, and Dr. G. Nagelschmidt, of the Safety in Mines Research J.aboratories, Sheffield.
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