Document garoGn0kZN9RbJ96jqQB2o2Ea

PLAINTIFF'S EXHIBIT OCCUPATIONAL, PREVENTIVE AND LEGISLATIVE ASPECTS 393 process or group of industries or processes involving exposure to silica dust, who were certified to have suffered death or to tal disablement from silicosis or silicosis accompanied by tu berculosis, or who, though not totally disabled, were found on medical examination to be suffering from the disease to such a degree as to make it dangerous to continue work in the industry and were for that reason suspended from employ ment. The Act required that the scales of compensation fixed by any scheme, in the case of death or disablement from silicosis, should be those prescribed by the Workmen's Compensation Act. 1906, in all other cases such as may be prescribed in the Scheme. The Act further provided for the inclusion in any Scheme of 3 principles: -- ( i ) The establishment of a general compensation fund ( administered either through a mutual trade insurance com pany or society of employers ) to which all the employers in tiie industries should be required to subscribe and out of which all claims for compensation and all expenses arising under the Scheme should be paid. The burden of compensa tion would thus be borne by the industry as a whole and no question of apportioning the liability among different em ployers would arise ; further, there would be no tendency to dismiss particular workmen who showed symptoms which might indicate the onset of the disease. ( s ) The settlement of claims, and other matters arising under the Scheme, by Committees representative of both em ployers and workmen with an independent chairman. (3) The appointment of medical officers with special knowledge of respiratory diseases, who would cam- out peri odic medical examinations and have power to suspend any workmen from further employment in the industries; and die appointment of Medical Advisory Committees or Medical "Referees for the purpose of deciding difficult cases referred MET-442 S96 SILICOSIS AND ASBESTOSIS to them by the medical officers on whose certificate only com pensation could be paid. By the inclusion of these three principles the special diffi culties in the way of providing compensation for silicosis were met. These had been recognised and pointed out by the Com mittee on Compensation for Industrial Diseases in 1906. They found there would be difficulty in apportioning lia bility amongst employers for a slowly developing disease oc curring in workmen who had moved from one employment to another ; difficulty in diagnosis of silicosis from respiratory affections generally prevalent; and a possible tendency amongst certain employers to dismiss workmen showing any symptoms, in order to avoid liability. The first Scheme under the Act of 1918 was made for the Refractories Industries and came into force on February 1, 1919. This Scheme embodied the 3 principles outlined above. The medical officers appointed under the Scheme were gen erally the Tuberculosis Officers of the Local Authority ad ministering sanatorium benefit under the National Health Insurance Act. The duties of the medical officers laid down in the Scheme were ( x ) to make periodic medical examina tions of all workmen in the industries, except those em ployed over twenty years, at specified intervals of one year in the more dangerous processes, and two years in the others; ( 2 ) to examine newly engaged workers within three months of commencing work in the industry ; (3) to examine on the warrant of a Joint Committee any workman claiming to be suffering from the disease ; (4 ) to examine at specified intervals workmen in receipt of payments for partial disable ment. If at either periodical or initial examination a work man was found to be suffering from silicosis or silicosis with tuberculosis, he had to be suspended from employment in the industry. After a clinical examination a medical officer was entitled to have a roentgenological examination, if neces- OCCUPATIONAL, PREVENTIVE AND LEGISLATIVE ASPECTS sary. If still in doubt about the diagnosis he could refer the case to the Medical Adsisory Committee or Medical Referee, after which he issued a certificate in accordance with their decision. The medical officers forwarded their certificates to tite Joint Committee, whose duty it was to determine the awards of compensation. The Refractories Industries Scheme, igi.v was a new and interesting experiment in Workmen's Compensation, and it appeared to work smoothly and to give rise to no serious dis pute. A Departmental Committee was appointed by the Home Secretary in 1923 6'\ to inquire into the working of the Scheme and to advise on any proposals for applying the Act to other industries. This Committee found certain defects for which they suggested improvements, and they considered that the Scheme, if amended in accordance with their recom mendations, would form a basis on which to frame similar schemes for other industries in which a risk of silicosis oc curs. In particular, they referred to the absence of power to suspend persons suffering from tuberculosis without silicosis ; the lack, of uniformity in the medical examinations; failure to eliminate workmen showing early signs of disease ; and the difficult financial jvisitioii of the Fund. In their Report the Committee sought to remedy the de fects in the metlii.il |>i< (visions, by recommending that a Medical Board be established consisting of two whole-time Medical Officers who should be responsible for all medio, examinations; l;u ilities for roentgenologic examinations should be increased anti greater use made of this form of examination; the responsibility of suspending a workman on account of silicosis should not be entirely on one medical officer ; power should be given to medical officers to suspend ^workmen found to be suffering from tuberculosis of the lungs (although no compensation was payable); entrants to the 398 SILICOSIS AND A5BESTOSIS industry should reach a prescribed standard of respiratory physique. The recommendations of the Committee were adopted and included in an amending Act passed in August, 1924, and later in Section 47 of the Workmen's Compensa tion Act, 1925. In 1929 The Sandstone Industry ( Silicosis) Scheme was made on the lines of the Scheme for the Refractories Indus tries. The same principles were adopted for the provision and maintenance of the Fund from which compensation and ex penses were paid ; Joint Committees settled claims and cer tificates were given by members of the Medical Board who, with an increased staff, also made initial and periodical medi cal examinations. These two Schemes, for the Refractories Industries and the Sandstone Industry, are the only Schemes of that type. In 1927, the Metal Grinding Industries (Silicosis) Scheme was made to apply to workmen employed in the grinding of metals ; incidental svork in the same room ; and the racing of grindstones. In 1928 The Various Industries (Silicosis) Scheme was made to apply to workmen in a large number of industries and processes, not covered by the exist ing Schemes, in which the risk of contracting silicosis was recognised. The machinery under these Schemes, which at first were limited to cases of death and total disablement, was that applicable to diseases scheduled under the Workmen's Compensation Act, namely, examination and certification by the Certifying Factory Surgeon for the district in which the workman was employed, subject to a right of appeal to a Medical Referee. Except for certain occupations in the pot tery industry, no periodical medical examinations were made. A Departmental Committee was appointed by the Home Secretary in December 1928, to advise as to the medical ar rangements which could be made for the diagnosis of sili cosis in cases of claims arising under the Workmen's Com OCCUPATIONAL, PREVENTIVE AND LEGISLATIVE ASPECTS 399 pensation Act61, and for carrying out any periodical or other medical examinations of workers which may be prescribed for any industry or process involving risk of silicosis. This Committee recommended that the examinations and certi fications in the industries covered by all the Schemes be co ordinated and a Medical Board set up for the purpose, of which the Medical Board already appointed under the Re fractories Industries and Sandstone Industry Schemes would form the nucleus. They considered that where compensation was claimed in fatal cases, a certificate as to the cause of death should only be given after a post-mortem examination, ex cept where the deceased workman was in receipt of weeklv payments under the Scheme, and then only if the Medical Board were satisfied as to the cause of death without a post mortem examination. Power to carry out the recommenda tions of the Committee was obtained in the Workmen's Com pensation (Silicosis and Asbestosis) Act, 1930, which ex tends Section 47 of the Workmen's Compensation Act, 1925. A Medical Arrangements Scheme followed in 19312S, and the existing Schemes were amended to give effect to its require ments as to the Medical Board, Medical Examinations and Certificates, and Medical expenses and fees. The fees payable for examinations and certificates by the Medical Board are prescribed by the Silicosis and Asbestosis (Medical Fees) Regulations w. The Medical Board now consists of 9 members : the Chief Medical Officer with a head office and laboratory at Sheffield, and 4 panels each of 2 medical officers, situated at centres con venient to the principal industries to which the Acts apply. These are Sheffield, the centre of the Refractories and Metal Grinding industries; Manchester, dealing principally with the Asbestos industry in I-mcnshire, and the Sandstone in dustry of the North of England and Scotland ; Stoke-onTrent, the centre of the Pottery industry ; and Cardiff, a con 400 SILICOSIS AND ASBE5TOSIS venient centre for the South Wales coalfield from which most of the cases of silicosis occurring in the coal-mining industry arise. Besides the whole-time members of the Medical Board, a few part-time members have been appointed to act, es pecially in fatal cases, in areas at a distance from the centres of the Board. Certificates are issued on the authority of not less than 2 members of the Board, and are conclusive. The 1930 Act also extended the power of making Com pensation Schemes to the disease of asbestosis, and a Scheme on the lines of The Various Industries (Silicosis) Scheme was made for the Asbestos Industry and came into force on 1st June, 1931. The provisions of the Silicosis and Asbestosis ( Medical Arrangements) Scheme apply also to examina tions and certificates required for the purposes of this Scheme, and the examinations are carried out by the same Medical Board. TABLE 5 Number and Results of Examinations under the Silicosis and Asbestosis ( Medical Arrangements ) Scheme, 1931, DURING THE YEAR 1935. (A) Initial and Periodic Examinations. Initial Examina tions. Periodic Eliminations, Industry. Refractories industries..................... Sandstone industry.......................... Pottery industry.............................. Asbestos industry............................ Total for 1935....................... Total fee 1934....................... 1 1 1 S82 645 473 468 2188* 1639 33 44 31 24 132 100 iul3l 60S 2.028 1,394 1,099 5,126 6,451 117 385 215 150 867- 1,058 Number suspended. On account On iccount of the of tuber disease4. culosis. 51 22 15 -- X 32 " 74 2 65 12 + AO of these azaminations were mule by I ocal tuberculous officers, 23 brine referred to the Medial Boned for^rospensiou. OCCUPATIONAL, PREVENTIVE AND LEGISLATIVE ASPECTS 40 l ( B) Examinations in pursuance of applications for Death and Disablement Certificates. Industry. Refractories industries Sandstone industry........... Pottery industry............... Asbestos industry............. Coal mining industry.... Masons 4; stone dressers. . Metal prindinj industries Other industries................ * 1 2 3 4 * 6 7 DUablemeot. Death. Work men exam ined. Certified to be wholly or par* tially disabled by the dis ease.'" Applications dealt with. Certified to be aused by the dis ease.* n7 3 j 41 Ui 0 66 4 '2S 71 49 16 u 51 51 10 7 51 43 391 52 l 69 51 55 :s 10 * u to sJ6 459 22s 175 690 417 203 149 * The disease means silicosis or abestotis or either of these diseases accompanied by tuberculosis Home Office Workmen's Compensation Statistics of Compensation etc., in Great Britain during the year 1935. London. H.M.Stationery Office, 19J7. The scope and amount of work done by the Silicosis Medi cal Board can be gathered from the preceding Tables, which give details of the examinations in the year 1935, with com parative figures for 1934. REFERENCES 1. Colus,E.L. Milroy Lectures, 1915. p.2. Reprinted from 'Pub lic Health' by H.M.Stationery Office, London, 1919. 2. Statutory Rules & Orders, 1925, N0.904. H.M.Stationery Of fice, London. 3. Factories Act, 1937. 1 Edw.8 and 1 Geo.6, Ch.67 Cd.685. H.M.Stationery Office, London. 4. Statutory Rules & Orders, 1931, No. 342. H.M.Stationery Office, London. 3. Statutory Rules & Orders, 1925, No. 904. H.M.Stationery Office, London. 6. Statutory' Rules & Orders, 19*5, N0.1089. H.M.Stationery Office, London. 7. Report on the Grinding of Metals & Cleaning of Castings, 402 SILICOSIS AND ASBESTOSIS with special reference to the effects of Dust Inhalation upon lhe Workers. Macklin.E.L. and Middleton.E.L. 1923. H.M. Stationery Olficc, Loudon. 8. Statutory Rules & Orders, 1931, X0.343. H.M.Stationery Office, London. 9. Statutory Rules S: Orders, 1931, N0.359. H.M.Stationery Office, London. 10. Statutory Rules & Orders, 1931, N'0.345. H.M.Stationery Office, London. 11. Miudleton.E.L. Milroy Lectures. The Lancet, 4 July, 1936. 12. Ibid. locciL 13. Green,H.L. and "Watson,H.H. Medical Research Council. Spec.Rep.Ser.No. 199, London, 1933. 14. Sutherland,C.L. and Bryson,S. Rep.Occurr.of Silicosis among Sandstone Workers. H.M.Stationery Office, London, 1929. 13. Ferguson,T. Jour.of Indust.Hyg. 1934, xvi, 203. it!. Statutory Rules Sc Orders, 1931, N0.34G. H.M.Stationery Office, London. 17. Sutherland, Bryson and Keating,N. Report on Silicosis among Granite Workers. H.M.Stationery Office, 1930. 18. Read.T.M. and Holland.?. Pruc.Liverpool Geol.Soc.1898, vui. Part 2, p.293. 19. Sutherland and Bryson. Rcp.on an Inquiry into the Occur rence of Disease of I.uug> in Slate Industry. Mines DepL London. H.M.Stationcr\ Office, London, 1930. 20. Watson,H.H. Unpublished report. 21. Sutherland and I1rw>\. Report on an Investigation into the Incidence of Silicosis in the Pottery Industry. H.M.Stationery Office, London, 1926. 22. Statutory Rules & Orders. 1913, N0.2. H.M.Stationery Office, London. 23. Report of Departmental Committee on Compensation for Silicosis dealing with the Pottery Industry. H.M.Stationery Office, London, 1928. 24. Statutory Rules & Orders, 193*, N0.393. H.M.Stationery Office, London. OCCUPATIONAL, PREVENTIVE AND LEGISLATIVE ASPECTS 403 a;,. Committee on Indust.Pulmonary Disease. Medical Research Council. The Lancet, 193(1, 2.1178. 3(5. Statutory Rules & Orders, 1931, X0.341. H.M. Stationery Office, London. 27. Statutory Rules & Orders, 1934. N'0.889. H.M.Stationery Office, London. 28. Haldam:..Martin and Thomas. Report 011 the Health ol Cornish Tin Miners. Cd.aogi, 1904. H.M.Stationery Ofluc. London. 29. Thomas.Herbert H. Unpublished Memo, to Committee on Indust.Pulm.Disea.se. Medical Research Council, 1934. 30. Watson.H.H. Unpublished Memorandum. 31. Collis.E.L. Proc.Roy.Soc.Med. 1923, xvi. Sect.Epidem., 96. 32. Cro.mn.A.J. Jour.of Indust.Hyg. 1926. viii, 291. 33. Stewart,M.J. and Fallds.J.S. Jour.Path.fc Baci.1934 xxxix, *3334. Statutory Rules i- Olden, 1935, Nro.6g. H.M.Stationery Office, London. 35. Watson,H.H. Unpublished report. 36. Second Report o Royal Commission on Mines.Cd.4820, igog. H.M^tationery Office, London. 37. British Metl.J0ur.1934, i, 198. 38. Fisher.S.W. Trans. Inst.Min.Engineers, 1935, lxxxviii, 377. 39. Jones,T.D. Trans.Inst.Min.Engineers, 1935, lxxxviii, 406. 40. Jones,W.R. Jour.of Hyg. 1933, xxxiii, 327. 41. Cooke,W.E. Trans.Inst.Min.Engineers, 1935, lxxxviii, 393. 42. Annual Rep.King Edward VII Welsh national Memorial Association, 1930, Cardiff. 43. Harper,A. Brit.Med.Jour. 1934, i, 1920. 44. Clmmins,S.L. ibid. 1935, i, 287. 45. Spec.Bull.41, Commonwealth of Pennsylvania, Dept.of La bor 8: Industry, Harrisburg, Penn. 1934. 46. Bohme,A. Silicosis, International Labour Office, Geneva, 193. P-35447. Reichmann u. SchCrmann Zentralblatt LGewerbehyg.1935, xxii, 121. 404 SILICOSIS AND ASBESTOSIS 48. Cocrtois.R. Rev.Path.et Phys.du Travail, 19^3, x, 37. 49. Leclercq.J. La Med.du Travail, 1933. v, 222. 50. Macnin.J. Ibid. 1935, vii, 137. ji. Badham.C. & Tayi.or.H.B. Med.Jour.Australia, 1933, i, 511. 58. Statutory Rules k Orders, 1934, X0.1155. H.M.Stationery Office, London. 33. Memorandum on the Industrial Diseases of Silicosis and Asbestosis, 1933. H.M.Stationery Office, London. 54. Statutory Rules & Orders, 1931, ' M140. H.M.Stationery Office, London. 33. Watson,H.H. Unpublished report. 56. Departmental Comm, on Compens.for Indust. Diseases. Min utes of Evidence. Cd.3496, p.127. H.M.Stationery Office, 1907. 37. Alribault, quoted by Merewether.E.R.A. Tubercle, Jan. 1934, p.152. 58. Merewether.E.R.A. fc Price,C.W. Rcp.on the Effects of Asbestos Dust on the Lungs, and Dust Suppression in the Asbestos Industry. H.M.Stationery Office, London, 1930. 39. Statutory Rules 8: Orders, 1931, N0.344. H.M.Stationery Office, London. Go. First Rep.of Departmental Committee on Workmen's Com pensation for Silicosis, 1924. H.M.Stationery Office, London. 61. Rep.of Departmental Committee on Medical Arrangements for the Diagnosis of Silicosis, 1929. H.M.Stationery Office, London. 62. Statutory Rules & Orders, 1931, N0.412, and 1934, No. 1063. VII. PUBLIC HEALTH AXD ECONOMIC ASPECTS USITED STATES A. j. Lanza, M.D. ASSISTANT MEDICAL DIRECTOR METROPOLITAN" LIFE INSURANCE COMI'AM Introduction The occupational diseases and the health of industrial work ers present one of the important phases of public health. Ol the occupational diseases, none is more truly occupational than the pulmonary diseases due to the inhalation of in dustrial dusts. Lead, carbon monoxide, arsenic, benzol and many other toxic substances associated with industrial proc esses are also found in circumstances that have no connection with industry. The same cannot be said for the pneumo conioses. They stand as the most perfect type of occupational diseases. Recognized for centuries, only in comparatively re cent times have their wide-spread effects been disclosed and their importance to the public health appreciated. More lately still, the inclusion of these disorders in schemes of compensation for occupational disease has emphasized their economic importance and the necessity for thorough and ade quate methods for their control. Silicosis and Compensation Silicosis and asbestosis burst upon the amazed consciousness of American industry during the period 1929-1930. Previ ously, the terms "silicosis", "asbestosis", "pneumoconiosis", were practically unknown to industrialists except that in the hard rock mining industry, silicosis, tinder its various collo quial designations, was well recognized. Knowledge of these 40s 406 srLicosis and asbestosis conditions was limited to the small number of those whose investigations of pulmonary dust diseases had made them conversant with the subject. Arising out of the period of economic depression, the situa tion with respect to silicosis and asbestosis became manifest as a medico-legal phenomenon of a scope and intensity that was at once preposterous and almost unbelievable. Damage suits, under the common law, were instituted against em ployers by employees, alleging pulmonary dust diseases, in industrial centers all over the United States, to an amount in excess of 100,000,000 dollars. To understand this situation, both in its economic and public health aspects, it is necessary to review not only the history of silicosis investigations in the United States but also the status of compensation for oc cupational diseases in the various States. The reader is referred to the first chapter of this book. Briefly, governmental agencies began studies of silicosis in the mining industry in 1914 and these were carried on until they were interrupted by the entry of the United States into the World War. These studies had for their purpose the de tection of silicosis, the extent and severity of the disease in the areas studied and the establishment of methods of control. The question of compensation did not arise, which must seem strange to the non-American student of the subject. In almost every State of the Union, there is a State Depart ment of Labor and industry. These State Departments are charged with the administration of the laws pertaining to fac tories, mines, and workshops. Previous to 1930 only 3 or 4 Labor Departments included in their activities a division of industrial hygiene and these few were not established on a basis that made possible original studies or research. They were mostly concerned with routine inspections and also endeavored to enforce laws and regulations pertaining to PUBLIC HEALTH AND ECONOMIC ASPECTS 407 health, tv hose vague wording often made them almost nonenforceable. The Suite Dcpai unenis of Ilealih, although their functions might be thought to embrace public health in industry, uni formly ignored the subject altogether, with the exception of Ohio and Connecticut, where occupational diseases were made reportable. Following the widespread national atten tion focussed upon occupational diseases by the silicosis furor, this situation has entirely changed and at present ( 1937 ) State Divisions of Industrial Hygiene are, with a few excep tions, located in the State Departments of Health. The Federal Government embraces several agencies that concern themselves with occupational diseases and industrial hygiene. In the United States Department of Labor, the Bureau of Vital Statistics has been actively engaged in the field of investigation. In the United States Public Health Service, the Office of Industrial Hygiene and Sanitation has likewise been engaged in industrial studies and at the request of and in co-operation with the United States Bureau of Mines investigated dust diseases. These governmental departments have jurisdiction in industrial establishments of a govern mental nature only, except that by virtue of recent legislation, the United States Department of Labor may supervise condi tions under which work is done under a contract with the Federal Government. The Government officers enter a mine or a factory only with the permission of the owners and usually at their request. The Federal officials have no power to en force existing State laws nor to initiate new laws or regula tions. Reports of silicosis investigations, when published by the department responsible, might and did contain suggested methods for the prevention and control of ihis disease but they were addressed not to the State authorities nor to the in dustrialist but to the general public as contributions to the 408 silicosis and asbestosis existing knowledge. Both State officials and industrialists might profit by this new knowledge if they so wished. Usually they did so and a great many improvements were instituted hut these were largely confined to those industries that had been studied at first hand. In fact, during the period 1914-- 1929, silicosis was considered a serious hazard only in certain phases of the mineral industry, with the exception of a few specific occupations, such as sandblasting. Asbestosis was practically unknown. To summarize, the investigations of silicosis during the period 1914-1930, and of both silicosis and asbestosis for some time subsequently, were scientific ( embracing both medical and engineering aspects), informative and non-legislative, with the exception of the study of silicosis among rock drillers made in New York City in 192S under the auspices of the New York Tuberculosis and Health Association.1 In this in stance, definite recommendations regarding workmen's com pensation were made. Since 1912, in Massachusetts, occupational diseases have been compensated by court interpretation of the wording of the accident compensation law. In 1914, no other State had made provision for compensation for occupational diseases. By 1930, however, 10 States and 3 Territories had enacted laws making occupational diseases compensable.2 In addition, there were 3 Federal laws, affecting employees of or under the jurisdiction of the United States Government. At present ( November, 1937 ) , 21 States have some form of occupational disease compensation and of these, 16 include silicosis and other dust diseases. When the time came to enact legislation bringing occupational diseases within the scope of the com pensation acts, some of the States followed British precedent and enacted a schedule of the diseases which were thus made compensable. In the other States, occupational diseases were covered under a general description such as `diseases arising PUBLIC HEALTH AND ECONOMIC ASPECTS 49 out of and in the course of occupation,' without further desig nation -- the so-called `all inclusive' or blanket law.' The Federal Government followed the latter method in providing compensation for its employees. Between 1914 and 1930, the total amount of compensation paid for occupational diseases was very small, averaging not more than a minor fraction of the accident compensation cost in the various States. Interestingly enough, up to 1935, not one State operating under a schedule included silicosis, asbestosis. or pneumoconiosis in the list of compensable diseases, a situation difficult to understand, considering that silicosis is the most truly occupational of diseases, that reports of studies of silicosis in the United States had been forthcoming for twenty years and that there was available a vast amount of literature embodying the experience of England, South Af rica, Australia, and Canada. In the States having 'all inclusive' coverage, the number of awards for silicosis was negligible. The explanation of this curious state of affairs is, probably, that silicosis was considered as distinctly a hazard of mining. In those mining States, where hard rock mining w*as a major industry, there was no compensation for occupational diseases nor was there any pronounced demand for such compensation. `Eating dust' was looked upon by the hard rock miner as a natural danger of his trade. Mining companies usually pen sioned older emplosecs disabled with silicosis or saw that they were cared for in one way or another. Also, following the gov ernmental reports, the mining companies concerned started to put their mines in order, spending large sums of money on ventilation and dust control. Then, with dramatic suddenness, came the era of the sili cosis damage suits. lawyers who specialized in this type of law practice instituted suits for damages under the common law bn behalf of employees of various corporations for injury to the lungs due to the inhalation of dust. They were aided not 410 SILICOSIS AND ASBESTOSIS only by the general and increasing unemployment but by the almost total ignorance of industry -- aside from mining -- concerning pulmonary dust diseases and by the absence of silicosis in the compensation schedules which enabled them to bring suits for amounts far in excess of the limits of compensa tion. An interesting exception occurred in one or two States -- Ohio, for instance -- where the absence of silicosis from the schedule was held to bar suits or claims for this disease eidier under compensation law or common law. In those States where there were no occupational disease laws, claimants were at liberty to sue under the common law. Among the first claims for damages were those for asbestosis, a hitherto unheard of disease in the United States.3 Damage suits multiplied by hundreds, starting on the Atlantic sea board arid extending to the industrial States of the middle West and far West. The terms `pneumoconiosis,' `silicosis,' `asbestosis' were strange and unfamiliar to judges, juries, and industrialists and were enveloped in medical and pathological technicalities. Consequently, the claimant's witnesses and medical experts, as far as their prestige with juries was con cerned, carried as much weight as did those of the defendants. So great was the confusion and lack of knowledge on the part of courts, juries, and physicians that awards were made for silicosis to men tvho had never been exposed to the dust of free silica. Many of those seeking damages undoubtedly had sili cosis -- many did not. Damage suits were filed against cement companies and against mining companies whose operations were in limestone formations -where there could be no pos sibility of a silicosis hazard. All of this might be dismissed as a historical and medico legal curiosity except that it greatly modified existing com pensation laws in the United States and stimulated the passage of new laws. Commissions were appointed by several of the States to inquire into and recommend legislation for compen PUBLIC HEALTH AND ECONOMIC ASPECTS 411 sation of occupational diseases and especially silicosis. It was generally felt that it was not sufficient merely to add silicosis to an existing schedule or include it when a new schedule was planned but it was essential to make special provision for reg ulating and limiting the benefits to be paid for silicosis. Manv industries had acquired through the years considerable num bers of employees who had, or might be deemed to have, silicosis ; industrialists, insurance companies, and the State funds feared that simply to make silicosis compensable was to invite a deluge of claims that would exhaust existing funds and make insurance rates prohibitivelv high. In most of the enacted laws, a fixed period of residence within the State was stipulated to prevent silicotics from migrating from a State where there was no compensation to one where there was. The problem of compensation for a chronic illness as con trasted with an acute one presented difficulties, inasmuch as it did not seem that the insurance principle, on which all com pensation in the United States is based, could be successfully applied to disability or to diseases already existent and whose extent was problematical. With business conditions as they were, the industries did not feel that they should be compelled to establish special silicosis benefit funds to provide for ac cumulated cases which had occurred under conditions where there was no statutory requirement imposing an obligation upon the employer which he had failed to meet. Moreover, it was often evident that silicotics had not contracted their dis ease in the place of present employment but in a previous one and, perhaps, in another State. The attitude of the average industrial firm was that, being shown that they had a silicosis hazard, they were willing and anxious to clean up and en deavor to control dust and to pay compensation to those who might subsequently contract silicosis but that they should not , be required to pay for disability from a disease of whose exist ence they were previously unaware. The various commissions 418 SILICOSIS AND ASBESTOSIS and legislative committees endeavored to iron out these com plexities as best they could, having in mind their own local conditions. Some years previously, the Province of Ontario had as sumed the attitude that, tuberculosis being a disease common to the human race generally, when silicotics contracted tuber culosis, their compensation benefits for disability should be diminished and such a provision was enacted into law.4 A similar economic point of view, regardless of its logic or jus tice, influenced those engaged in drafting legislation in the various States, so that when silicosis legislation was finallv en acted, in some of the States the individual disabled by silicosis' received less award than one suffering from any other com pensable occupational disease. Furthermore, several of the State Committees took the position that uncomplicated sili cosis, as observed in American industries, was not disabling and that disability did not occur until infection (tubercu lous ) had supervened and then the disability was considered total. Hence, in some otates, partial disability due to silicosis is not recognized. The New York law,* as in some other States, provides that compensation shall not be paid for partial disability due to silicosis or other dust diseases. For permanent disability or death, the awards are fixed according to a sliding scale as fol lows : For a total disability or a death claim, presented within the first month in which the Act becomes effective, not exceed ing $500; for every subsequent month thereafter, $50 is added, but in no event shall the compensation exceed the ag gregate of $3000. The maximum for total disability from other occupational diseases or from accidents may be con siderably more, depending upon the age of the deceased and upon the number of dependents. It was hoped that the sliding scale would have a twofold effect. It would safeguard the continuity of employment by PUBLIC HEALTH AND ECONOMIC ASPECTS 41 $ spreading the economic burden which was expected to result Irom these laws and it would also tend to induce the workman with an early silicosis to keep on working. In addition, it would stimulate the employer to vigorously attack his dust problem with the hope o averting total disability claims. In Pennsylvania, the occupational disease law 6 prov ides that for diseases which dev elop to a point of disablement onlyafter an exposure of five years (to be determined by the Workmen's Compensation Board), compensation costs for disability or death, arising during the period of ten years suc ceeding the effective date of the Act, shall be paid jointly by the Commonwealth and the employer as follows : In the first year in which the Act becomes effective, one tenth by the em ployer and the remainder out of funds controlled by the Com monwealth. In each succeeding year, the employer pays one tenth more, the Commonwealth one tenth less, to the expira tion of the ten year period. Partial disability for silicosis, anthraco-silicosis, and asbestosis is not recognized and the total liability of the employer for these diseases is limited to S3600. In North Carolina, the recently enacted compensation law 7 states that in silicosis or asbestosis, compensation shall be paid as provided in the Act but if either is complicated by tuber culosis, the rate of payment may be reduced one-sixth. While some of the foregoing might seem to lie in that realm of reasoning so difficult of comprehension to the non-legal mind, the underlying motive was not a desire to deprive work ing men of their just dues but a feeling that it was necessary to place a drastic check on the expected avalanche of silicotic claims. Undoubtedly, the common law damage suits confused and terrified industrialists and insurance officials. As a matter of fact, many of these suits were never brought to trial, many \vere compromised by settlements out of court, but those that did come to trial were won by claimants in sufficient number 414 SILICOSIS AND ASBESTOSIS to inspire dread among all exposed to this type of legal action. If these apprehensions prove to have been unwarranted it is probable that in the next few years. Silicosis Acts may be modified to make their awards more in line with die general trend of compensation. The North Carolina Act also stated that if an emplovee is affected by silicosis or asbestosis, he shall be taken out of em ployment and paid partial or total disability until he can ob tain other occupation. The State will train him for other oc cupation at State expense. If later he returns to a job with a silicosis hazard, he forfeits compensation benefits. The experience of Wisconsin is very instructive and for a description of the complexities of silicosis compensation in one State, the reader is referred to the informative article by Kossons and Fried,3 from which the following figures were obtained. Wisconsin is an important industrial State with mines, quarries, foundries, and enamel ware industries, be sides many others. During the seventeen year period-- 19201936 inclusive -- 8g3 claims for disability from silicosis were brought before the Industrial Commission. Of these, 469 claims were allowed ( one third of them were death claims ) and 55 per cent of these were filed during 1933-1934. A com parison of costs for the fifteen years--1921-1935 -- shows that for the entire period, the cost of silicosis compensation was 2.23 per cent of the total cost, including and in spite of the peak years of 1933-1934. when it was 9.40 per cent and 8.80 per cent respectively. Extent and Nature of Hazard It is not possible to estimate accurately the number of per sons exposed to the harmful effects of silica dust. Compre hensive statistical information, based upon accurate death records, is lacking. Silicosis is not included in the list of re portable diseases. Many of the deaths due to silicosis with PUBLIC HEALTH AND ECONOMIC ASPECTS 415 tuberculosis have been recorded simply as tuberculosis. Nei ther hospital records nor death records customarily give a tvorkmau's industrial ImMoia --indeed, it is unusual lot even die present or final occupation to be stated with sufficient clarity to be of value to the investigator. Morbidity records are of less avail than mortality records, and physical examina tion of new employees in industrial establishments, while fairly common, have rarely been of such a nature as to reveal early pulmonary disease. Even when industrial conditions are good, there is considerable movement of labor from place to place and from State to State. When times are bad, this migra tion is increased. Unemployment then drives men not only from place to place but into new occupations. Lanza and Vane 9 estimated that there were about 500.000 industrial workers employed in occupations exposed to silica dust. It is more than likely that this estimate errs considerable on the conservative side. This estimate does not take into con sideration the thousands of men who have been employed where there was a silica hazard and who are now scattered throughout industry. The menace in silicosis has always been tubercle infection. The evidence 10 here is overwhelming and has been stressed by investigators throughout the world. In 1927, WatkinsPitchford 11 stated : "In ascertaining, from our records, what the liability of the simply silicotic miner to become tubercu lous has been in the past, account has of course been taken of all instances in which the change has been detected during life; in addition to this, however, it has been assumed that, in those persons suffering from simple silicosis who have died of their disease without having been again examined, death has been the result of this change. This is an assumption which is warranted in practically every instance. Relying on this assumption, and also bearing in mind that, as already stated, the liability to tuberculous change has appeared less marked 416 SILICOSIS AND ASBESTOSIS in each succeeding annual batch of cases, one finds that the combined results of seven years' observations shmv that, In the end of the seventh year, a little more than halt of the cases of simple silicosis have either developed overt tuberculous changes or have died as a result of those changes." Collis also bears witness : "Silica dust alone possesses the further characteristic that it increases the liability to succumb also to pulmonary tuberculosis." Kettle lJ states the case very clearly : "The silicotic lung ap pears to be a more favorable medium for the growth of the tubercle bacillus than the normal lung, not because it is fibrotic, nor because its lymphatic drainage is interfered with, but because it contains silica." Much research and study have been applied to the question of infection in silicosis but in spite of the fact that the nature of the relationship between silica and the tubercle bacillus is still to be determined, the reality of this relationship is af firmed by recent investigators. Irvine 14 and his associates analyzed 543 deaths in 1923, cases originally certified as hav ing simple silicosis. Approximately 75 per cent of these deaths were due to tuberculosis. They note that this inherent pre disposition to tuberculosis is as marked in very early (anteprimary ) as in later stages ( primary). Simson and Strachan 15 state : `The importance of the in fective factor in many and ultimately in the late stages of most cases of silicosis has always been recognized in South Africa, as elsewhere.' They comment further that many cases are in fective from the outset, in others there may be a reactivation and local extension of pre-existing dormant foci of infection or there may be a new infection from outside. The experience in the United States is similar. Meri wether 16 states for the Picher, Oklahoma District `The pTO- duction rate of tuberculosis (exclusive of old cases that progressed) was 0.75 per cent or 750 per 100,000 population, PUBLIC HEALTH AND ECONOMIC ASPECTS 417 which, for 1929, is certainly higher than that of the general population of the country.' > The following is quoted from the United States Public . Health Service report on Anthraco-Silicosis among Hard Coal Miners: l* "Sevei-al surveys have shown that tuberculosis of the lungs occurs among 1 to 21/*> per cent of the general adult white male population of the country. In a study of tubei-culosis in Framingham, Mass., it was found that about 1 per cent were suffering from the disease in an active form, and an other 1 per cent were classified as having arrested tubercu losis.18 Physical examination of 100.924 adult white males made by the Life Extension Institute indicated a prevalence rate of about ii/2 per cent when suspected cases were in cluded.19 A somewhat higher percentage, namely, 214 percent, was found by the Public Health Service from the examina tion of 10,000 male industrial workers.20 "Among the anthracite workers examined, the clinical tu berculosis rate was below normal in the younger adult ages, but at ages 35 to 44 clinical pulmonary tuberculosis was diagnosed in about 5 per cent of the hard-coal mining em ployees ; at ages 45 to 54 in 10 per cent; and at ages 55 to 64 in 20 per cent. No such rise with age occurred in any general population group for which comparable data are available. "The prevalence of tuberculosis was greatest among the rock workers. The next to the highest rate occurred among anthracite workers who had changed more than five years previously from very' dusty to relatively nondusty occupations in the industry. The third highest rate was exhibited among persons who had had appreciable exposure to harmful dusts in other industries. Among the regular miners working at the face the rate was definitely higher than in the control group which showed a prevalence rate of less than 1 per cent. "When the term of service exceeded twenty years, more *than two or three of which involved exposure to heavy concen 418 SILICOSIS AND A58ESTOSIS trations of rock dust, about 37 per cent of such employees ( classified as rock workers) showed evidence of pulmonary tu berculosis. Service of twenty-five to thirty-four vears was as sociated with a tuberculosis rate of 8 per cent among non rock workers employed in the haulageways, of 14 per cent among the regular miners, but with a rate under 2 per cent among men exposed to less than 5,000,000 dust particles per cubic foot of air." As has been pointed out on numerous occasions, the severity of an individual case of silicosis depends upon the extent ol dosage of silica ; that is to say, upon the duration of exposure together with the intensity of silica dust concentrations in the air. The early investigators of silicosis in the mining industry in the United States were confronted by working conditions of the utmost hazard -- that is, a maximum amount of silica dust in the air with no provisions for its control nor for the protection of the men exposed. Hazards of this severity have happily disappeared except, perhaps, in isolated instances ; certainly such conditions are no longer industry-wide. Some recent investigations reveal a degree of exposure which is manifested as a disabling illness after middle age has set in -- characteristic of certain phases of the foundry in dustry'. 21 Again other studies have shown the existence of silica hazards sufficient to produce characteristic roentgenray appearance but without disability that can be directly charged against pulmonary fibrosis. It seems fairly certain that the industrial hygienist of the future will not see the typical cases of far advanced silicosis, presenting roentgeno grams with "snow storm" appearance and areas of massive fibrosis described by early investigators Ijoth in this country and abroad. ' On the other hand, tiie tendency to minimize the silica dust hazard which has been manifested on recent occasions is not justifiable. If there is one thing that stands out with con PUBLIC HEALTH AND ECONOMIC ASPECTS 419 spicuous regularity in the vital statistics of this and other countries, it is the high incidence of tuberculosis and other respiratory diseases in the silica dust trades.'22 We know that where silica has been inhaled in sufficient quantity to produce its characteristic effect, a definite condition of susceptibility to tuberculosis has been established. We should hesitate to infer, therefore, that exposure to silica dust to an extent in sufficient to produce characteristic nodulation may not carry with it implications in terms of tuberculosis and other respira tory diseases. From a public health standpoint and for the promotion of healthful conditions of work, there is demanded constant attention to dust hazards in industry with the utiliza tion of every practical method for the prevention of atmos pheric pollution. Asbestosis Asbestosis was first described in the United States by Pan coast, Miller, Smyth and Landis in igi8, but its impor tance was not realized until it was introduced into the damage suit situation which led to the first comprehensive study of this disease in the United States.3 Recent yean have seen an immense increase in the use of asbestos, both for brake lin ings of automobiles and for heat resisting and insulating materials. With relation to public health, asbestosis is not nearly as serious a problem as silicosis. The number of persons in the industries using asbestos is very much less than for silica and in the United States amounts to about 12,000 factory workers, of whom approximately 25 per cent are women. Not all of these are exposed to dusty processes. Most of the asbestos used in the United States is imported from Canada. It has been suggested that the various types of asbestos differ in their ability to cause pulmonary disease, but so far no proof of this is forthcoming. Much of the industrial exposure arises from textile proc 420 SILICOSIS AND AsBESTOSIS esses in which dust control measures can be readily instituted. As soon as the hazard was realized, industrial firms fabricating asbestos took energetic steps to control the dust so that it is probable that cases of asbestosis will become uncommon. A recent report from the United States Public Health Service details dust control methods instituted in an asbestos textile plant which illustrates in a striking manner what can be done to alleviate dust.33 .Asbestosis has not appeared to be as serious a disease in the United States as it has in England, judging from the various reports from the latter country. .Asbestos "mattress making," mentioned in the British reports as a serious hazard, is a process not found in this country. The role of infection in asbestosis is not as clearly defined as in silicosis and the clinical evidence available indicates that tuberculosis does not have the intimate relationship with asbestosis that is so conspicuous in silicosis.24 23 Effects of Silicosis upon the Families of Silicotics From the earliest times, when silicosis was first described as a disease of miners, the fact that the wife did not contract tuberculosis from the husband was mentioned and the many recent investigations have not upset this general conclusion. Hoffman24 stated in 1922, "The frequency of pulmonary tu berculosis among immediate relatives of granite cutters, but particularly wives, daughters, and mothers, is much less than, as a mere matter of probability, would be assumed to be the case." This was borne out by the later studies of McFarland27 and Russell.3* Cummings of the Saranac Laboratory, who investigated this subject in connection with the Picher Clinic, commented on the fact that, despite die wretched living conditions, and the lack of cleanliness and sanitation in many homes of advanced silicotics whose sputum was loaded with tubercle bacilli, no PLBLIC HEALTH AND ECONOMIC ASPECTS 1 adult type tuberculosis was found among exposed children up to the age of sixteen. Nevertheless, these various testimonies do not exclude the necessity of treating tuberculo-silicosis as a communicable disease and of making follow-up investigations of members of families of advanced or disabled silicotics, to determine the presence of tubercle infection or the desirability of segregat ing contacts from the diseased member of the family. Sound public health procedure should be the rule and reliance should not be placed upon the supposed immunity of the family because the tuberculosis is complicated by or conse quent upon silicosis. Control and Prevention of Silicosis The control of silicosis is both an engineering and a medical problem, as are so many other situations that concern the public health. Both the engineer and the physician, with their technicians, have their parts to play. In some instances, the medical phase may predominate : in others, the engineering, but it is seldom that they can be separated or be independent of each other iE a thorough job of prevention is to be done. Engineering Control The development of silicosis is dependent upon the dosage of silica and the matter of avoiding a dangerous quantity might be thought simple. The lay mind, familiar with the definiteness of the hazard of carbon monoxide, and other toxic substances producing acute effects, usually fails to appreciate the inherent difficulties of establishing a threshold limit for a substance producing a chronic disease whose development is measured in terms of years rather than hours. jC From time to time, critical comment is directed toward the industrial hygienist by the engineer because the former has failed to inform the latter of the safe or threshold limit of 42a SILICOSIS AND ASBESTOS IS silica dust in the air of working places. That is not an un natural criticism from those whose profession involves dealing with definite and measurable factors. Unfortunately, neither physiology nor pathology in their relationship to the incidence and progress of chronic disease has yet advanced to the point where they are susceptible of expression in terms as definite as those used by the engineer. The circumstances under which silica dust is introduced into the air of working places varies to an extreme degree. Furthermore, these circumstances and others that, in turn, affect them, vary from day to day and from hour to hour ; they are affected by wind and weather, by dryness and humid ity. All this would be complex enough if we were dealing only with the dust of pure silica, but in actual practice, the silica dust is frequently combined with other substances which may modify its action and about which little is known. Some industrial processes lend themselves to dust control measures ; others do not, and in these latter, an entire change of the process itself may be necessary to overcome the hazard. Dust Sampling To deal with any health hazard successfully, its nature and severity must be understood. For silica dust, the two factors involved are the proportion of silica in the particular rock or mineral substance from which the dust originates and the amount of dust present in the air breathed by the workmen exposed. A great deal of study and research has been con i centrated on this subject. It is customary to define the extent i of exposure by stating the number of dust particles, under ten microns in greatest diameter, in millions per cubic foot of air. Various methods of counting the dust particles in the air have been devised, later to be discarded, until at the present time in the United States reliance is chiefly placed on the impinger method as defined and practiced by the United s PUBLIC HEALTH AND ECONOMIC ASPECTS 4^3 States Public Health Service and the United States Bureau of Mines. The merit of the impinger is that it takes large samples, over a considerable period of time (one-half to one or two hours). The objection to the impinger is that it is cumber some, time consuming, and demands expert technical skill if the results are to be trustworthy. Simpler devices consisting of smaller portable instruments, taking a small quantity of air -- "grab samples" -- and necessitating less skill are also used. The objection to these devices is that due to the smallness of the sample, the margin of error is considerable. Both methods have their place, but when serious studies of dust hazards are involved, it is probable that reliance will continue to be ? placed on the impinger method until a more satisfactory one e is evolved. Small electric precipitators, modeled on the Cot h trell precipitator, are in use but are mostly restricted to labora e tory practice and to standardize the impinger. Other devices are still in the laboratory or experimental stage. e To summarize : While no one method of sampling air for the purpose of making dust counts has proved entirely satis factory, up to now the impinger is accepted as most reliable in field work. No two methods are quite comparable; even d samples taken by the same method in the same location and s at the same time frequently show marked differences. r State Departments of Labor are naturally desirous of es c tablishing standards of air dustiness for the control of the dust ii | hazard and for the guidance of factory managers and factory i- inspectors. To a very limited extent, such standards have been IC suggested as a result of various government investigations.38 n However, much caution is needed here and too much reliance r. should not be placed upon the formulation of "standards" of ir air dustiness and the enactment of factory codes setting forth it ,, permissable limits of dust counts. Such threshold limits as have been worked out have very definite value as a guide in endeavoring to secure better working conditions but their 1 C. n 1 i 1 [ V 424 SILICOSIS AND ASBESTOSIS limitations and possible transitory nature should be well understood. They should not as yet be enacted into law, other wise a situation analogous to that of school ventilation may be repeated. Some of our State laws and regulations controlling ventilation in schools provide for an air change of 30 cubic feet per minute per occupant -- a highly expensive and troublesome provision. This standard was based on what was thought at the time these laws were enacted to be a correct conception of 'pure" air and "bad" air. Our present knowl edge of ventilation and atmospheric control has proved the in adequacy of this carbon dioxide standard but it is the law in many places. If history repeats itself in formulating threshold limits of air dustiness, the result will be not only vexatious but costly. The first and basic principle in dealing with a dust hazard is to remove the dust at its point of origin and thus prevent its dissemination into the air. This is the only procedure to which the term prevention may be properly applied. Once the dust is in the air, the protection of the individual becomes difficult and often unsatisfactory. The removal of dust at the point of origin may be accom plished by suction devices working on the principle of the well known vacuum cleaner. In certain processes, such as drilling, water may be used to advantage. In some instances, water and air suction may be combined. So great is the variety of industrial processes from which silica dust may arise that a detailed description is not feasible. Each type of process usu ally presents its own problems and difficulties to the engineer I! and what will work satisfactorily under one set of circum stances will not always be successful in another. : Once the dust has been disseminated into the air, its re moval may present serious engineering difficulties. Water may be employed, either as a spray to increase the humidity and facilitate the settling of dust particles, or water blasts may be ell erbe 'nsf bu nd vas ect ivlinin )ld Hit nd nt to ice nes m:he as es, ety .t a sn eer .m- remy nd lie PUBLIC HEALTH AND ECONOMIC ASPECTS 425 used to accomplish the same results more rapid!v and thor oughly. It is obvious that this method is limited in its applica tion. The dust mav be diluted by increasing the qiiamirv <>l air through forced ventilation -- again a method not alwavs applicable and apt to be expensive. The two methods may be combined. Both methods, either singly or in combination, have been widely applied in mining operations. Some experimentation has been done with the use of hygro scopic substances applied to the surfaces of mine usages to prevent dust from being continually stirred into the air. It has also been proposed to add to silica dust other kinds of dust with the hope of inhibiting the action of silica in the pul monary tissues. While this method of combatting silica dust may be both practical and valuable under certain conditions, it is not likely that it will be accepted as a final satisfactory solution. The effects of long loutinued breathing of such mixed dusts are unknown. Boiling or chlorinating infected drinking water may be a necessary procedure but satisfactory hygienic standards require that the community be supplied with water from reasonably pure sources and enormous sums o money are spent to secure such water. Likewise the air that industrial workers must breathe should be reasonably pure. Air containing harmful quantities of an injurious substance plus a counter-acting or antidotal substance would seem to leave much to be desired with respect to purity and proven harmlessness. The industrial age has seen too many miracles of achievement and too many evidences of inventive genius to maf- one believe that satisfactory dust control is beyond our resources. It is essential that where dust control devices have been in stalled that check tests be made from time to time to de termine their continued efficiency'. Such equipment tends to lose its value unless continuously supervised and maintained in good working condition. It is the common experience of 426 SILICOSIS AND ASBESTOSIS investigators to find installations of ventilating and dust re moval machinery that are of little use due to failure to keep them in proper working order while at the same time tliev continue to give a feeling of unwarranted security. Face masks, helmets, and respirators have been developed to protect the individual in dust polluted atmospheres. Their use is justified when the exposure, or the dusty process itself, is intermittent and of short duration. Filter type respirators, which are approved by the United States Bureau of Mines as adequate for protection against silica dust, can be relied on. They may be uncomfortable, especially when the temperature is high, and their continued use calls for a degree of co-opera tion from the individual workers which experience has shown is difficult to maintain. Positive pressure helmets and masks are generally efficacious when used under conditions for which they are suited. The adequate supervision and maintenance of protective equipment is all important. A faulty device or one improperly used will give a false sense of security that will eventually betray its user. Medical Control Pre-employment physical examinations, where a definite health hazard is involved, are an essential public health pro cedure, definitely important in controlling the incidence of occupational disease. The benefit should accrue impartially to the individual, the industry, and the community. It is also important that the function of the pre-employment examina tions be understood so that they may not be abused. It is desirable to place men in types of work for which they are adapted. It is equally necessary not to bar, needlessly, employ > ment to those seeking it. Much of the dispute and ill feeling ^engendered during the last few years on the subject of physical examinations, both pre-employment and for those already em ployed, as related to the silicosis furor, might have been A ) c s l / f > % I PUBLIC HEALTH AND ECONOMIC A.M>ECTS 427 avoided if the basic reasons for such examinations had been understood and if employers and others concerned had thought their problem through. Some misunderstanding was I inevitable under the general circumstances. It is not practicable to lay down definite rules or to assume a dogmatic attitude. Circumstances vary in different occupa 1 tions and different parts of the country and economic con siderations always stand well to the fore and must be recog nized. Obviously no one with active or recently active tuberculosis should be exposed to silica dust, nor anyone suffering from other pulmonary disease, especially if of an infective nature, which would tend to increase the hazard. On the other hand, there is often no good reason for rejecting an applicant who already has silicosis, if the silica hazard in the work place in volved is under control and if the workman's physical condi 1 tion is properly supervised thereafter. This is an important consideration where the industry is a dominant one in its locality and other opportunities for work are limited. Here is where the experienced industrial physician must bring his judgment to bear both upon the individual and upon the work he is to do. I In connection with the recent compensation laws passed in some of the States, the attitude toward pre-employment ex aminations is interesting. The New York5 law states, "It is hereby declared to be the policy of the legislature of this State, in enacting this article, to prohibit, through every lawful means available, any requirement to employment which com pels an applicant for employment in any occupation coming within the purview of this article to undergo a medical ex amination." As contrasted to this, the North Carolina7 law states, ( where the Industrial Commission has found an occupation to have a hazard of asbestosis or silicosis) "it shall be the I V  .1 V t (I I I' 428 SILICOSIS AND ASBESTOSIS duty of every employer ... to provide prior to employment necessary examinations of all new employees tor the purpose of ascertaining if any ol tliem are in any degree affected In asbestosis and or silicosis or peculiarly susceptible thereto ; and every such employer shall from time to time, as ordered by the Industrial Commission, pros ide similar examinations for all of his employees whose employment exposed them to the hazards of asbestosis and or silicosis." At least one mem ber of the Advisory Medical Committee or other physician designated by the Industrial Commission shall make such ex amination or be present when such examination is made. Further on, the law continues : "The refusal of an employee to submit to any such examination shall bar such employee from compensation or other benefits provided by this Act in the event of disablement and or death resulting from an ex posure to the hazards of asbestosis and or silicosis subsequent to such refusal." Particularly to be commended are the control methods set up in the Province of Ontario. A co-operative agreement is in force between the Workmen's Compensation Board and the Provincial Health Department. Examination centers are estab lished where necessary and pre-employment and periodic physical examinations, with the use of the roentgen ray are made by a physician of the Health Department for the Work men's Compensation Board. Examination certificates are is sued to acceptable workers. Claimants for compensation come before a Referee Board of Physicians of the Health Depart ment. This Board works in co-operation with the industries concerned and the Compensation Board. Where workmen are exposed to a silica hazard, medical supervision goes hand in hand with engineering control of the dust. Indeed, it is the industrial physician who must finally determine whether the dust control measures in his establishment are efficacious. Annual, or perhaps bi-annual, PL'BLre HEALTH AND ECONOMIC ASPECTS 429 medical examinations with the roentgen-ray are usually suf ficient with more frequent examinations of those individuals "ho, the industrial physician feels, need more constant super vision. As in any other circumstance where an occupational health hazard is involved, no mechanical method of preven tion can be taken for granted. BIBLIOGRAPHY 1. Smith,A.R., FehnelJ.W. and the following Committee: Colling,J.J., Emerson, Haven, Greenblrg. Leonard. Hop kins,H.L.. Lanza.A.J.. McBirney,R.S., Platt.P.S.. Smith. A.R.. Goldberc.J.A. Silicosis among Rock Drillers. Blaoccrv and Excavators in New York City, Based on a Study of 208 Examinations. J.Ind.Hyg.i 1:37, 19*9* 2. Savers,R.R., Lanza.A.J., S.mith.A.R., Havhi rst.E.R..-- Committee on Pneumoconioses of the American Public Health Association: Workmen's Compensation for Silicosis. Assocof Cas.and Sur.Exec, New York, N.Y., 1933. 3. Lanza,A.J., McConnell,W.J., FehnelJ.W. Effects of the Inhalation of Asbestos Dust on the Lungs of Asbestos Work ers. U.S.Pub.Health Repts., ton, 1935. 4. An Art to Amend the Workmen's Compensation Act: On tario, 25, Geo.V, 1933. Chap.yo, assented to Apr. 18, 1933. 5. Joxes,F.Robertson. Workmen's Compensation Law of the State of New York as Amended with Supplementary Laws to August, 1937. X *v York, N.Y., 1937. 6. Act of General Assembly, N0.552, July >, 1937. Supplement to Compensation Act of 1913. Harrisburg, Pa., 1937. 7. Amendment to the Compensation Act Covering Occupational Diseases Adopted by the General Assembly, March 26, 1935. N.CIndus.Com., Raleigh, N.C. 8. Kobsons,M.D. and Fried,O.A. Experience with Silicosis under Wisconsin Workmen's Compensation Act, 1920 to 1936. Mo. Lab.Rev., May, 1937. 9. LanzaA-J. and Vane,R.J. The Prevalence of Silicosis in the i S 43 SILICOSIS AND ASBESTOSIS General Population and Its Effects upon the Incidence of Tuberculosis. Ain.Rev.of Tuberr.. 29:8. 1934. " 10. R.R.Sayers. Chairman : Report of the Committee on the Prevention of Silicosis through Medical Control. Chap.on "Infection in Silicosis." U.S.Dept.of Lab., Xov.20, 1936. 11. Watkins-Pitchford.W. The Silicosis of the South African Gold Mines and the Changes Produced in It by Legislative and Administrative Efforts. J-Ind-Hyg-gnog, 1927. > 12. Collis,E.L. The Statistical Characteristics of Dust Phthisis ( Pulmonary Silicosis). J.Ind.Hyg.8:457, 1926. 13. Kettle,E.H. Experimental Silicosis. J.Ind.Hyg.8:49i, 1926. 14. Irvixe,L.G.. Simson.F.W., Strachan,A.5. The Clinical Pa thology of Silicosis. International Labour Office Report Series F. Johannesburg Conference on Silicosis. (Industrial Hygiene) Geneva, 1930. No. 13. 15. Simson.F.W., Strachan,A.S. Observations on the Origin and Character of Silicotic Lesions as Shown in Cases Occurring on the Witwater""tmd. Pub.Xo.XXXVI, S.African Inst.of Med.Res.Apr., 19. .. 16. Meriwether,F.V., Sayers,R.R., LanzaA-J-, and Adams,W. W. Silicosis and Tuberculosis among Miners of the Tri- State District of Oklahoma, Kansas, and Missouri. II. U.S. Bur.of Mines Tech-Paper 552, 1933. 17. Sayers,R.R., Bloomfield.J.J., DallavalleJ.M., Jones,W.R., Dreessen.W.C., Brundace,D.K., Britten,R.H. Anthraco-Silicosis among Hard Coal Miners. U.S.Pub.Health Bull.221, 1936. 18. National Tuberculosis Association: Framingham Commun ity Health and Tuberculosis Demonstration. Framingham Monograph No. 10, July, 1924. 19. Sydenstrtcker, Edgar and Britten,R.H. The Physical Im pairments of Adult Life. Am.J.of Hyg.n:73, 1930. 20. BrittenJLH. and Thompson,L.R. A Health Study of Ten Thousand Male Industrial Workers. U.S.Pub.Health BulL 162, 1926. 21. Papers and Discussions Presented before the American .{ e n n c is a- rt ll .d of W S. L, 1 liit. n* m I1 1 in- II en 11. an 1 iI PUBLIC HEALTH AND ECONOMIC ASPECTS 431 Foundrymen's Association Annual Convention, Toronto, Can., Aug.21-23, 1935. Reprint Xo.35-22. 22. Hoffman.F.L. Mortality from Respiratory Diseases in Dusty Trades. (Inorganic Dusts) U.S.Bur.of Lab.StaLBull.231, 1918. 23. Page.R.T. and Bloomheld.J.J. Dust Control Methods in an Asbestos Fabricating Plant. U.S.Pub.Health Repts.52:1713. 19S7* 2 {. McPheeters.S.B., A Survey of a Group of Employees Exposed to Asbestos Dust J.Ind.Hyg. 18:229, 93625. DonnellyJ. Pulmonary Asbestosis. J.Ind.Hyg. 18:222, 1936. 26. Hoffman.F.L. Problem of Dust Phthisis in the Granite-Sr^ne Industry. U.S.Bur.of Lab.Stat.Bull.2g3, 1922. 27. McFarland, W. Silicosis and Tuberculosis as Seen in the Granite Workers in Barre, Vt.: J.Ind.Hyg.g:3i5, 1927. 28. Russell,A.E., Britten,R.H., Thompson,L.R., Bloomfield, J.J. The Health of Workers in Dusty Trades. II. Exposure to Siliceous Dust ( Granite Industry) U.S.Pub.Health Bull. 187, 1929. V IXDEX ABRASIVES 17j1.33.110.i8J.347. 349-39* Agate 35 Air Hygiene Foundation of America Asbestos corn 60.172439 Ashescosis definitions of 57-58.233,385 disability from 60.175.391400, *3 Alkalis 3441.61 jo 1.223.248487.389. 401413-414 stages of 173-190 35-3*o Almandite 373 Aluminum 11.1843.3841400402, Asbestosis bodies 13.60-61,167,169, 170.173439433-344,350.352. *74.3*4.336.327 267 470486.323,349.353 "37. S75-376-39* American Foundrnnen's Association Asthma 4.1948.346 Australia 14-1645409 Commonwealth Department of so American Public Health Association Health -- 15 New South Wales 14.15.384 -- Committee on Broken Hill (N.S.W.) Pneumoconiosis 31 Amethyst 33 Amosite ts3.173j76.386 *4->5-4j Veu- South Wales Department of Health Amphibole 173 Analcite 273 Anemia 17 Anorexia 60,171 Anthophyllite s73.a75.a76 5 Sydney 14.15 Victoria t4 Western Australia 14 Autopsies 5,11,12.18.39.63.127.136, Anthraco-silicosis 1941,111,113.154. 881.3834134*7 Anthracosii 148,154.155.170411436, 148,162,164,165,167-170,188, 302403405-146,249-253480, *83491,308-311.314.3*1.331, t 828,384 341384-599 Anenic 163,165405 Asbestos at-tj^7-6*.i 18,166-190, BALL day 371 198400403-105,2*3.225-346, Baritosis 90,137,139 161471473-177491,296.297, Barium 137.139 } 3,S-3*7-33-335.383_39l -399" 401.319-410 Barytes 347 Beryl *73 duration of exposure to -- 58-60. Belgium 383 167,171,173.175,179-188403, Benzol 405 138475,313-325.335,388 Biopsies 164 extent of exposure to -- 58-60. Biotite 273 166-167.386419 Bismuth 165 mechanical action of --239-144. Bohemia *74-3*4-3*7 Joachimstal mines 161,163-163 types of--13,58413473.385.387 Brake linings *3,386.389-391419 u-orkers exposed to -- 58-60,118, 1*0,167,173.175.179-188401, Brick workets 5,8,17,3440,349,355. 356 *15439.386-391.399400419 British Factory Inspectors 5,9 i 1 V i W t / i I 434 INDEX British Home Office 8.365-369.401 Bronchial catarrh to; Bronchiectasis 47.107.163,190.214, 228445 Bronchiolectasis 47 Bronchiolitis 202.301 Bronchitis 47,69402.207414444. 346.329.3*2.384 Broncho-pulinunary diseases < in general) 16.163 Bronze 38 Buhrstone cutters 3.34.311-3211 CALCITE 270 Calcium 21*419463 Calcium carliomue 26348*489,306, 878 Calcium fluoride 288.a89.306 Canada 17-18.2341.58.386409.419 Alberta 17 Ontario 1743,106,116.117412.1a* Cobalt 17 Kirkland Lake 17 Porcupine 17 Sudbury 17 Ontario Health Department 174*8 Saskatchewan 1; Carbon 2014044114*8429494 Carborundum 34.36.157.158481, *97 Carcinoma 136,161-165415-217445 Cardiac diseases 1048.504gB2.123. 1*4.148,165,168,174.185,188. 190409.* 144*8,304,331,384 Castings deaning 9-S47-5-49-39* Cement 355.366.387410 -- industry 16.1740 Chalcedony 32,34458478483486, *91492-301 *335 Chemical industries 34,386 Chert 33-35491-493499.306,307, 309-S3.33-3S5*4 China day *01,37* China stone 372 Chrysoprase 33 Chrysotile 584i5-*73-*7-l-*75-*7<j, 3*3-8*7.330,386 Cigar makers 163 Clav 41,167.355 Coal 11.1941.154.155,158,199.201, 270,294.297 anthradte --19.384245,1324*1, 381-384.417 bituminous-- 19-297,383 -- miners 10.1942.108.109,114. 118.119.120.138,142.154,163. 2*1,229.380-385 -- mining 8.11434445.119.132, 347.336.380-385400401 Cobalt 164.165 Cocddiosis 291 Commission of Enquiry (South Africa) 7 Committee on Compensation for Industrial Diseases (Great Britain) 396 Committee on Mortality from Tuberculosis in the Dusty Trades (VS.) 20 Committee on the Prevention of Silicosis through Medical Control ( UA.) 4347 Compensation laws 7-9.11-13,15, 17,31.106,116,117,151-153, >99-35.355.337.359.38s-365. 369,371,376.377.380.385.390. 394-401405-4144274*8 Construction industry 33.35.347. 360,365.370.386-387 Copper 34.347 Corundum g Cottrell predpitator 4*3 Cough 164849,53,60,156,171,176 Cristobalite 33,278481483 Croddolite **5431473,386 Cutlery factories 18.352 Cyanosis 50,60,148,168,172,176405 DIAMOND *70 Diatomite (diatomaceous earth) 3*-33.34-38,265478483.339 Dickite 273 Digestive system, complications in 1050 Dolomite 263470 i INDEX 435 Dust (see specific type) Germany u-i4.359 antidote duM 11.18.30.4041.133. Ruhr District 383-384 >' t67-3*3-I*3 classification of -- 198.363 Sthneeburg mines (Saxony) 161.163.164.165413 dust counts 7-9.13.a1.3343.59, Glands, compilations in io.to6. 60.137-138-01.383,293,396, 1334164*8 303.303.305.308-3 it .314-317. 3'9-3*3-S33-36o-361.367.370. Class 33-35-347-348-S49 Glaziers 347 373 -379-361,3874114s particle size measurement of -- Glauconite *73.174476 (.old crushing 18 9-37-39-45-38-1 98-soo.*so. *34-*i7-26'-a6747*-*78.*8o*8*493493.308-310.316-318, 3ao.315.361.387 Gold mines 6.14.17.45.115493.347 Grauite 9.t3.3*-33-34-'37-*s9-*93. *99-306307.320-3*3.331.341 -- industry so.384045.365-369. threshold limits of dust 39* concentrations 7-'5-43"46-39. -- workers 9.11.17,115.118.120, 39x411-414 Dyspnea 133.' 18.136. 140.3*2.347.365-3694*0 {.rain uorkers 4.17 1 7` (.rave diggers 347 Gravel 33 EDEMA 50.168.1711463 Great Britain 5.8-1 *. 18,23.58.59, Emery 9 167.198-156495.3*8.346-404, l Emphysema 1747^9.110.186,1*7, It3,i44.i48-i3ol69-t76,i90, 105.107 413414-**8.333-384 409 England 8-1 *.346.350,338,361. 3S9.370.379.388 Empyema *18445 Birmingham 353 Enamel ware 347.349414 Bristol 38* / Erythremia 148,149.190 Cannock Chase $8* FACTORY inspection 389-390407 Cheshire 381 Feldspar S67471473J75-*7748g, Cornwall 840.363.377 Cumberland 365,378.379.38* *9**93-3*3 Ferrosilicon 34 1 Fertilizers 35 Derbyshire 40,35* Devon 365 Durham 38* i Fireclay S47-37-37* ` Flint 4^.ii,S*-35-3|6.318.349.331, 37'-376 Fluorspar 187488.306.347 Foundries 10.34.38.13a.305,347.351, Forest of Dean 38* Kent 38s Lancashire 378,379.381.383, 386.399 Leicester 365,38s 33*4I448 worker* in --17.18.347,351 France 384 Charleroi 384 Condi-sur-Nolreau 388 London 386 Manchester 399 New Castle 4.35* North Derbyshire 38* North Staffordshire 38* French chalk 1C7 Fungus diseases ( see Mycotic Stoke-on-Trent 371.383, infections) 399 Northumlrerland 38* CARNET *67473476 Nottingham 38s Canister 34-355-357 Sheffield S3*-353-399 * 436 INDEX Shropshire 38* Somerset 381.382 Insulating materials 25.35.58.386. 389-391419 South Derbyshire 382 Intermittent employment 40,305, South Staffordshire 38a South Yorkshire 382 3`3-359-393 Iron 23.61.167,198.199.202432435. Suffolk *37438.270487,294.297.308, Brandon 346.348 312-316,323,324.331.370.378- Warwickshire 382 380,386 Westmorland 365.382 -- mines 1140492 West Yorkshire 38a Worcestershire 382 Italy 16-17. '39-386 Cornacchino 16 Yorkshire 386 Sardinia 16 Scotland 10.356.365,369.382.383. 399 Ayrshire 382 Clackmann 382 Fife 382 Lanarkshire 382 Lolhians 382 Wales 8,10421.346.350.362.369. JASPER 35 KAOLIN 167473 Kidneys, complications in 10,170. 210483 Kotze konimeter 7 Kyphoscoliosis 148 370 383.338 Cardiff 399 LEAD 18.37.43.163.347403 Monmouth 10.381.38a Leather dressing 347 North Wales 370.38a Limestone 16470410 Penrhyn 370 -- workers 5.16 South Wales 10,11,356.381, Lithographers* graining sand 34 382,383.399 Liver Crinding 4,8,9,16484.352-355.362, cirrhosis of 278491 i 37S-377 Grindstones 34.35t-355.360.398 other complications in 10,170. 262470473 478.279480482, Gypsum 270491494W-S'S-S*0- 283488494499 I 323,328,330.331.335 MAGNESIUM 23,38.198.386 HALLOYSITE 273 Harvard University Department of Geology 272 School of Public Health 22 Hematite 291493497,307-310,312, S*S-S9-3*0,3S.378-38o -- miners 11422,312,347.379 Hemoptysis 49.156 Hepatitis 282 Hypernephroma, raetastic 133 Hyperplasia 163404 Manganese 165 Marble 34.38424470.297.328.330 -- industry 1740 Mattress-making 386-391420 Medical Board (Great Britain) 396-400 Medical referees (Great Britain ) 395-397 Medical Research Council (Great Britain) 375 -- Committee on Industrial Pulmonary Disease 381 Medical Society of Hamburg 23s Insecticides 35 Metal Impinger (Greenburg-Smith ) 21. *95-3>7-3'944*3 -- grinding 5,9,11.12.1741.346, 347.352-335.39* -398.39940 ` Is 1 o. > ) rent INDEX 437 -- milling 3.14.15.18.1 iit.i 19. i'livsiial examinations 7.9.13.13. 346.408409.414 -- polishing 17.33 iii. 17,1943 4348-56,58-62.89. 139.167.173-176,187,314.315, Metastases. malignant 134,145,14.8. 190 Metropolitan Life Insurance Company 19.20.22 3s*-337dj9-30'-3<>3-3G7-369- 37,-374-373-37,S79-31_34388.390.393.395-401415417, 426-429 Mica *71.273.289.292.293.323 Plaster 16.314 Micro-incineration method 1S.251 Pleurisy 47.49.71407.226 Microline 573 Mineral fillers 35 Pneumatic tools 9.363.367 Pneumonia 15. >6.47.59.129.129.130, Miners (in general! 4.3.6,12.15, 16.17.118.164.165 131,132.145.158.159,164,167. 214.217.218226^28444.273, Miners' Phthisis Medical Bureau (South Africa) 6.7.206.3*8 Miners' Phthisis Prevention *94-399-33 304-3*8-335.341 Pneumomycosis 139 Pneumothorax 97.145445 Committee ( South Africa ) 6.7 Mines ( see specific type) Polarised light 5.17434.247.293,321 Tolycvihemia 148,149,190 Potassium 11.200 Mining engineers 7.347 Montmorillonire *73 Potter-Bucky diaphragm 70.143, 149.150,151 Mortality rates 10.1s.15.19-40.59. Pottery industry 8.9,11.1240.33, 157,164.165.188.346.347.350, 346-350.371-37; ,392.399-401 I S33S36-338s6> -39-37.37' 374-377-379-38i-33*-388-44- Preventive measures 74.1543.23, 40-43-48.59.'61.185,347,349- 416 351 S54-35fi,359-S6*-369-37' Muscovite *73-*93 375*379-S84-389-3944094'9. Mycotic infections (fungoid 4204*1-422-429 infestations) 90.135-163 Pulpstones 34.360 Pumice 167.357 NERVOUS system, impairments Pyroxene 273 in 10 Xeuburg challt 359 QUARRIES (see specific type) New York Tuberculosis and Quartz 6.8,11,11,13.184041.31.3*. Health Association 408 33S4-35-'37.`38.'99.aoo4o6. Nickel 163 ***447 43145*463478481, OCCUPATIONAL histories 4S-46, 534034*3.313-415 Oilstones 34 Onyx 35 Owens' jet dust counter 9.370 Opal 3*'33-33-s65'78-3S s83.285-s94.301,307-309.3 is, 316.319-3*3.331.335.360,370, 376378 Quartzite 3* 33 34-35.357.358 Quarttose sand 199.349-33`359.376, 3/8 PAINT 34 Petrographic determinations 9.231, *5*47147*476478487.305. 308-31* Phagocytosis 96,158404 RADIUM 163,164.165 Refractories industries 8,11,34.347, 335-357.396-401 Rhodonite *73 Rock crystal 35 438 INDEX Rock driller* 3.7.16vj36.36s.377, 381.383408417418 Royal Commission (Great Britain) 54.15 Royal Commission Mines (Great Britain) 381 Russia 386 Moscow 339 Rutile 3711.309 SAND 9.3334-3j ` 53-3*4.355. 39* -- blasting 9.17.33.38.1*3.133, *84.303.347-331.393.408 -- paper 33 -- pulverizers 118.133.133.133. 34* Sandstone 58.9.13.32.33.3 (.133.34(1. 347.35*-355.337-3S,-3l -- industry 11,154043.163.353- Silica Gel 378484 Silicates 11.17.31.33.33.166.198.199, 3*3 439-* 77.386-3*7.336.384 types of *73 Silicatosis 199459471 Silicic acid it.13.14.203448,*78, *80481483484 Silicosis acute 4t.**3-**5 definitions of 31.117,1*3,198, a 17-320 disability from 10.1s4s.53.55, 36.116-118.12*.149,155.161, 3*8.351.355.357.359.380.38*. 381-395-401409-414418 singes of 7.1548-53,105-13*.206, s 13.301-304 Silicosis Medical Board (Great Britain) 381.399-401 Silico-iuberculosis 117,151-154.335, J55.360-363-S^SS8-)00 Saranac Laboratory for the Study of Tuberculosis t L'-S.) *0. *'337-34*-4*o Sardonyx 35 Schist 33.377 Scoliosis 69 Sculptors 16.360 Seridte 11400453467473475476. *77879.*3J93^94'383 Serpentine *73474.3*6.S85 Sewers 14.15.19.303 Sewer Works Ventilation Board (Australia) 14 Sideio-silicotis 114**493.309.311- 3i3d35S4i Slderosis 11 Silica chemical action of 10,36,158, 103411-313401-304.337 duration of exposure to 3940. 43-46,134,1564*34*4485, 89-a99.30a.30s.307-3JS.335, 350458,361^83417-419 extent of exposure to 33,364*1- **5448*350.353.358<358.3o. 370477>378-381 >38* -383415 metallurgical uses of 34 types of 3S-35.199478 339 Silicon i7-34470.33`.340.353 Sillimanite 373 Silver 165 Sinus infections 47 Slate 8.38,347,370-371 Smelting and refining 34.33.34 Soaps and powders for scouring (abrasive) 33^*3487.357- 359 Soapstone 38.167 Sollas separator *5* South Africa 6-7,18434045,106, 115.116-118.1*9406413418, *33493-*94.303.3*8.348.347. 409416 Cape Province 386 Rhodesia 386 Transvaal 377 Witwatersrand 6 South African Institute for Medical Research 6,7 Spleen, complications in I704t8, *44461470475478479480, *83489491494 Steel 350,355 Stone masons 4,17,31,334064**, *5*,346,347,360-365401 Sulphur 165 INDEX m Susceptibility to dust diseases - animal 268-269.340 *L_ human 47.107,134402-2113.311 j/Syphilis 163 C onnecticut 30,21407 Kansas 18 Lake Superior District 292 Muvachusetts 3041408 TAR 163 Talc 17.38.1G7j67.371.273.373.370. Framingham. Mass. 417 Michigan 30 Missouri 18 *77 Technical Commi--ion (Australia) 13 Textile industry' 23.38-00.3811-331, 4'94*o Tile makers 349-37'"377 Tin 165.347.337 Senaca. Mo. 358 Nevada 18 New Jersey 31 New York 408412437 North Carolina 413-414.437 Ohio 407410 Oklahoma 18.139 -- mining 8.11.10.377 Picher Clinic 1940,139416. Tooth powders and pastes 34 Topaz 273 Trap-rock milling 38 Trauma 165.260 Tremolite *73 Titanite 273 Tridymite 33463.278481.283.283 4*o Pennsylvania 45-383413 Pennsylvania Department of Labor and Industry 19 Vermont Barre 43.115489.310.323 West Virginia 31 Tripoli 33.34.33,265 J78.283.358 Tri-State Producers Association Wisconsin 20414 United States Bureau of Mines (U.S.) 18.19 Tube mill lining and grinding pebbles 34 Tuberculo-iilicosis 117,152-154. 218-2*1.250 Tuberculosis 3-22.324049.52-57, 59.61.67,102,109-112,116118,1*2-1*4.128-161,187-189, 206414-2* 1.1*4425444447, 249,304.307.3* 1.3*2.3*7-342, 346,355.357-359-377393~399412-4*14*7 18.19414*.*7*4<>74*S4*6 United States Department of Labor *1407 United States Public Health Service 18,1940414*4341, 46.59.3834074164*3 University of Rochester (U.S.) ***74 University of Toronto ( Canada) 17.18 Uranium 165 Reactivation of healed lesions 57-`59-333-t'6 Tunneling 15,33.303.347 VITREOUS silica 334784B1483 WHETSTONES 34 UNITED Mine Worker* of Wood polishing and finishing 34 America 19 United States 18-22j358.105.303, 3*8.367405-431 ZEOLITE *73 Zinc 1845,165