Document rpQVLyrQpdEZrGzerkv6d622G

FILE NAME: General Motors (GM) DATE: 1940 Feb DOC#: GM077 DOCUMENT DESCRIPTION: Journal Article - General Motors Corporation Medical Conference [Industrial Medicine] This magazine it published to promote sound thought upon and eoncarning industrial medicine and traumatic surgery. To that end it will contain articles, news items, reports, digests, and other presentations, together with editors' comments. The editorial pol icy is to encourage franlc discussion. O n this basis contributions are invited. The editors will exercise care in check ing on the accuracy of data printed, but in all other respects articles and opinions of which expression is allowed are the opinions of their authors-- the editors reserving in all cases the right to comment on the same, in the cur rent or any subsequent issues, as they may be inclined. The Journal of Occupational Diseases and Traumatic Surgery With which are consolidated " The Industrial D o cto r" and "International Journal of Medicine and Surgery." The Science, the Law and the Economics of Industrial Health Volume 9 _____________ FE B R U A R Y , 1940 Number 2 General Motors Corporation Medicai Conference -- Dayton, Ohio, November 2 and 3, IQ3Q-- T HE recent Medical Conference of General Motors P hysicians, held at the Biltmore Hotel, Dayton, Ohio, November 2 and 3,1939, comprised five meetings and 18 presentations. The Program was as follows: Director, Fisher Body Lansing Division, Lansing, Michi gan. 13. "Study of the Factors of Employability, Especially Disabilities and Infirmities of the Elderly, and Problems Arising from Employment of the Same," George A. P aul, M.D., Medical Director, Hyatt Bearings Division, Harrison, Thursday, November 2: New Jersey. JV/TORNING Session: Chairman, M. M. Shafer, M.D., 14. "Early Diagnosis of Acute Appendicitis," C. Rush i,VA Medical Director, Frigidaire Division, Dayton. McAdam, M.D., Medical Director, Fisher Body St. Louis Division, St. Louis, Missouri. 1. "Recent Developments in Relation to Silicosis," LeRoy U. Gardner, M.D., Saranac Lake, New York. AFTERNOON Session: Chairman, F. B. Wishard, M.D., 2. "A Plan for the Control of Tuberculosis in Industry,"-lA. Medical Director, Delco-Remy Division, Anderson, Max Burnell, M.D., Medical Director, AC Spark Plug Indiana. Division, Flint, Michigan. 15. "Relationship of the Length of the Inguinal Liga 3. "X-Ray in Industry," M. William Clift, M.D.m, ent to the Occurrence of Inguinal Hernia," C. M. Hill Hurley Hospital, Flint, Michigan. enbrand, M.D., Medical Director, Harrison Radiator Divi 4. "Preliminary Report on Hygiene Studies of Weldsion, Lockport, New York. ing," L. B. Case and V. J. Castrop, Industrial Hygiene 16. "Hernia in Industry; Review of the Cases During Laboratory, General Motors, Detroit. the Past Ten Years," R. L. J ohnston, M.D., Medical AFTERNOON Session: Chairman, A. L. Brooks, M.D., Director, Inland Mfg. Division, Dayton. 17. "Antiseptics and Their Action," R. M. Freeman, Medical Director Fisher Body Division, Detroit. M.D., Medical Director, Linden Division, Linden, New 5. "Recent Developments in the Occupational DermaJersey. toses," Marion B. Sulzberger, M.D., New York City. 18. "Management of Fractures of the Spine," R. W. 6. "The Course of Disabling Morbidity among IndusP oborsky, M.D., Medical Director, Electro-Motive Divi trial Workers, 1921-1938," William M. Gafafer, D.Sc., sion, La Grange, Illinois. U. S. Public Health Service, Washington, D. C. 7. "The Industrial Nurse," Harold M. J ames, M.D., Except for Dr. Sulzberger's address on "Recent Medical Director, Delco Products Division, Dayton. Developments in the Occupational Dermatoses" 8. George The Doctor's Part A. Coburn, Personnel Diniretchtoer, PDeerlscoon-nReelmPyrDogirvaim," all of the papers given at this Conference are in sion, Anderson, Indiana. cluded here in full text, in the order of their 'G'VENING Session: Chairman, Walter M. Simpson, places on the Program: M. D., Director, Kettering Institute for Medical Re search, The Miami Valley Hospital, Dayton. 9. "Relationships of Industrial Medicine to Private Practice," Stanley J. Seeger, M.D., Chairman Council on Industrial Health, American Medical Association. 10. "Unfinished Business," C. F. Kettering, Director Recent Developments in Relation to Silicosis General Motors Research Laboratories, Detroit. LeRoy U. Gardner, M.D., Friday, November 3: Director, The Saranac Laboratory for the Study TV/TORNING Session: Chairman, G. L. Bird, M.D., Medi- J-V-L cal Director General Motors of Canada, Ltd., Oshawa, Ontario, Canada. of Tuberculosis, Saranac Lake, New York W 11. "A Practical Approach to Supervision of Mental Health in Industry," F. S. P arney, M.D., Chief, Division of Industrial Hygiene, Dept, of Pensions and National Health, Ottawa, Ontario, Canada. HEN your Chairman asked me to speak of new developments in the field of silicosis I was perplexed because all but a few of 12. "An Example of Industry's Participation in the the pathological, clinical and diagnostic aspects Anti-Syphilis Campaign," P. J. Ochsner, M.D., Medical of this disease are now well established. I realized Page 46 INDUSTRIAL MEDICINE February, 1940 that you had become better acquainted than I with the practical problems of diagnosis because you were dealing with them every day. After some deliberation I decided to tell you of some of the experimental work in progress at the Saranac Laboratory and to permit myself to speculate as to its significance. These experiments are incom plete and no conclusions are possible now, but perhaps they may ultimately lead to a better un derstanding of the action of irritant dusts upon the lungs. As far as I have been able to discover, it is still true that only certain forms of free silica and the group of fibrous silicates known as asbestos, are capable of producing fibrosis in a normal lung. Many other silicates have been incriminated by roentgenologists, but when autopsy specimens have been examined it is discovered that there is associated chronic infection or that the inhaled dust contains significant quantities of free silica. I shall first compare the action of chrysotile as bestos with that of quartz upon experimental ani mals and review considerable evidence bearing on their respective modes of action. A few of these observations now have practical significance; others may prove to be quite unrelated to the pneumoconioses found in human beings. FOR the last year or two we have been coming to the conclusion that -inhaled asbestos fibres are irritating not because they are silicates but be cause they are stiff fibres which mechanically ir ritate the lungs. Unlike the free silicas, these minerals will not stimulate fibroblasts in any part of the body; only those in the lungs are affected. It was inferred that these organs were affected because the movements of respiration are so much more rapid and continuous than those of other viscera. Then it was discovered that if asbestos was ground very finely so that few of the fibres were longer than 2ju in length the irritating prop erty of the asbestos was practically destroyed. In halation experiments with such fine chrysotile asbestos have now been continued for three years. No fibrosis has developed in spite of the fact that an average atmospheric concentration of 125 mil lion particles per cubic foot of air has been main tained. In contrast I would point out that in a previously reported experiment1 one third this concentration of long fibre asbestos dust produced well marked fibrosis after about two years. If the effect of asbestos were chemical, one would expect that a decrease in size would ac celerate tissue response. With free silica large particles have little effect, but as their size de creases cellular reaction becomes more vigorous and even constitutional symptoms may ensue.2 With fibrous asbestos the reverse is true. The histology of early asbestosis does not sug gest a chemical injury. Even under the most ex treme conditions that can be created by artificial injection there is no preliminary phase of tissue necrosis with infiltration of leucocytes as occurs with high concentrations of very fine quartz. The connective tissue cells merely multiply very slow ly in areas where the asbestos fibres are caught in the bronchioles. As collagen forms and con tracts, the air spaces are obliterated by scar tis sue. In experimental animals, at least, this change is not a progressive one after cessation of exposure to the dust as is the case in the response to quartz. Perhaps the reason is the deposition of the pe culiar iron-containing coating on the surface of the inhaled fibres giving rise to the characteristic "asbestosis bodies." Dr. Timothy Leary consid ers3 that the resultant smooth rounded ends of these bodies are no longer capable of scratching the delicate surfaces of the air spaces. Finally it is most suggestive that among dozens of different silicate minerals only the five known as asbestos, which are unique because they are fibrous in structure, should be commonly recognized^ as pulmonary irritants. The variation in chemical composition within this group is greater than that between them and many other silicates. In fact chrysotile asbestos has the same chemical formula as a non-fibrous silicate, serpentine, which is physiologically inert. Obviously irrita tion would seem to be associated with the physical, rather than the chemical, composition of these minerals. One point of practical significance may be indi cated by these observations, namely, that very finely ground asbestos is not dangerous. This conclusion has support in clinical observation, for it has long been known that at the Thetford mills there was no clinical asbestosis even though in former years the atmosphere was very dusty and the dust was extremely fine. The fact that fabri cation of fibres of the same mineral in American plants could produce disease was one of the puz zling features of this disease. But these experi ments offer a plausible explanation. The fine dust in the mills is composed of serpentine and ex tremely short chrysotile fibres; that in the spin ning and weaving mills contains many more long fibres. IN THE case of free silica everything points to a chemical form of irritation although the solu bility hypothesis as now conceived is not com patible with all th observations that have been made. In experimental animals inhaling or in jected with excessive quantities of pure quartz or flint in exceedingly fine state of subdivision, it can be observed that tissue reaction takes place in two stages. First there is an acute inflamma tion resulting in necrosis. Following it there is healing with fibrosis in the form of a granuloma whose end product is the silicotic nodule. The collagen laid down by the connective tissue cells is modified in a peculiar way analagous to that in the tanning of leather, and this is responsible for the characteristic hyalinization of silicotic fibro sis. Incidentally, leather has been tanned with silica and sections of such leather reveal that the collagen has undergone a similar hyaline trans formation. In human subjects only cases of rapid ly developing silicosis show evidence of a twostage reaction. In those with ordinary chronic disease, degenerative changes are slight and over shadowed by the formation of connective tissue. Vol. 9, No. 2 INDUSTRIAL MEDICINE Page 47 The solubility hypothesis is based solely upon indirect evidence. It is known that colloidal silica is toxic and that quartz will dissolve to some ex tent in slightly alkaline fluids of the same pH as those of the body. But it has never been possi- tides of larger size and it has not been observed on injecting suspensions of several other minerals ground to the same particle size. Symptoms are initiated even before completing bie to prove that silica has dissolved within the ?set of raPid>lab<>red respir- body, because the soluble material is immediately combined with local tissue elements. It is now generally accepted that the soluble silica detected m the urine and blood probably comes from in nal % Skln -f t}ie face and extremities becomes pale. The animal displays uncoordinated mus cular movements and sporadic convulsions ter minating m death if the dose is sufficient. When gested food and drink rather than from inhaled t^ e s p la c e 6S ^ administered complete recovery dust. Autopsy of fatal cases discloses an intense en T 1 T E have made a good many experiments whose results are difficult to reconcile with the solu bility hypothesis. They do not necessarily invali date it because we may not have all the facts and do not know how to interpret them. For example we have found that cellular reactions begin within 15 to 30 minutes after injecting fine particulate silica. In the test-tube traces of dissolved silica are only discoverable by an exceedingly sensitive coionmetric reaction after 12 to 24 hours. Possi bly vital factors may accelerate the process, but no means of evaluating them has yet been dis covered. No one has ever produced fibrosis by single or repeated injections of the various forms of soluble silica. The effect is apparently not due to the quantity of silica dissolved, for many of the inert silicates in vitro are more soluble than quartz or flint. Evidences of alteration of the surface of quartz particles long in contact with living tis sue have thus far escaped detection. In years of experimenting to discover the mechanisms by which free silica exerts its pe culiar effects upon living tissues we have re peatedly observed evidences of a specific toxicity. Guinea pigs, injected intraperitoneally with large doses of fine quartz particles are often obviously gorgement of the spleen, omentum and subperitaneal tissues which are deep purple-red in color. ; i 1! u T 'Jand. m iact Practically all the remainder of the body, is almost bloodless. Counts of earvein blood show only about half the number of leucocytes present just before the injection and a corresponding reduction in red blood cells. The blood no longer clots. There is no hemolysis. Animals that have recovered from one reaction seem to acquire a tolerance so that in some in stances at least twice the former dose may be in jected without symptoms. The degree of toler ance, however, varies widely in different indi victuals. These symptoms are not influenced by the in jection of adrenalin. They are not reproduced by transfusing the blood of an animal dying in shock into another one of the same species. Thev are only exhibited on injecting suspensions of quartz particles less than 3/* in diameter. Thev arf. Produced by injecting the supernatant salt solution from which the quartz particles have been removed by centrifugation. The severity of the reaction does not vary with the age of the par ticle suspension, although the amount of soluble silica increases on standing. The toxic effects of quartz can be more or less MMrr. Rp erd^lSm0T ewhe0rUerSs' eeWkinhegn aMn r-aCveunmume infogrs athnde quantitative introduction of silica they tried in travenous injections into rabbits and discovered the method which we now use as a standard for comparing reactions to different dusts. But in cidentally they found that these animals would effectiveiy neutraliZed by adding small amounts of different substances. Colloidal aluminum hy- nf nXn s t glVeu ?,01?Plete Protection in a dilution of .03%; colloidal ferric hydroxide is much less effective. Animal charcoal cannot be injected, beCciuse it flocculates with the quartz and produces die very promptly if the unit dose of quartz par ticles were too large. These deaths were not em bolic because they did not occur with large par ticles but only when the quartz grains were 3a or less m diameter, and they did not develop on in jecting suspensions of other minerals ground to the same size. Mr. Dworski and Mr. Delahant have extended these early observations in a long series of ex periments that have yielded interesting though puzzling information. They have shown that fine m in te d into the left side of a guinea pig's heart acts like a strong poison. Symptoms of shock followed by death within a few minutes to one hour occur when a 400-gram guinea pig receives an intracardiac injection of 3 used by nDTeHnney, RobsognroaunnddIrmweinta4lliinc thaelumprienvuemn, tion of silicosis has no influence upon acute in toxication. Further experiments are in progress to verify the conclusion of these authors that Muminum coats the surface of the quartz particles with insoluble material.* Recent observations indicate that all species of animals are not equally susceptible to intravenous injections of quartz. Dogs, which develop sili cotic fibrosis very slowly and under conditions not yet defined, tolerate intravenous injections of comparatively large doses of fine quartz without symptoms of any kind. Rabbits, guinea pigs and white rats all die of shock. Soluble colloidal silica in dispersed phase is also V cc- of a 1% suspension of 1 to 3Mquartz par ticles m physiological salt solution. The reaction is specific in that it is n o t nrr.Hn.-wi w --*_____ * Subsequent experiments have shown that sterilizing suspensions of metallic aluminum by heat destroys their power of neutralizing the action of silica. TTnhoato^ Page 48 INDUSTRIAL MEDICINE February, 1940 toxic, and intravenous injections produce the re actions just described with extremely small doses. With larger ones death occurs promptly with symptoms referable to the respiratory tract. The lesions are then confined to over-distention of the lungs and subpleural petechial hemorrhages. THE results produced by injecting particulate silica into the circulation all suggest a rela tionship to a large amount of mineral surface sud denly brought into contact with the blood or tis sues. This is borne out both by the absence of reaction to large particles in excess of 3p in diam eter and possibly by the observations on neutral ization. Any effect due to preformed soluble silica liberated in the suspension before injection has been eliminated, and no active soluble silica could be demonstrated in the blood of an animal dying in shock by transfusion into a second host. Everything now suggests an effect taking place very rapidly at the interface between the quartz and some element in the blood or tissues. Whe ther this is due to the very rapid production of colloidal silica in this location or to unique elec trical properties of quartz is still a fascinating subject for speculation. In the same category is the demonstration of the tolerance conferred by previous injections. The manifestation of acute toxic symptoms by those species of animals which develop silicotic fibrosis most readily and their absence in the dog, which appears to be much more resistant, sug gests that these immediate reactions may have some bearing on the etiology of silicosis. Until more is learned about the reactions in the dog no inference is possible. The influence of particle size is just as signifi cant in the production of advanced silicotic fibro sis as it is in eliciting acute symptoms of intoxica tion. Many injection experiments have convinced us that quartz particles over 3/n in diameter are of little or no physiological significance. The fact that the lungs of persons exposed to most dusts contain few particles larger than 10/i in diameter has been responsible for the establishment of this size as the maximum important in dust counting. As a m atter of fact we know that with some dusts there may be many larger ones. While it would be just as well that any large fragments should be excluded from the lungs, it is felt that only ones 3p or less in diameter are responsible for causing silicotic fibrosis. We have long maintained that particles of this size are irritating because they present a suffi cient surface of silica to the fluids. Recently Mr. Dworski decided to test this reasoning further by injecting graded doses of different sized quartz particles which would all present the same total surface area. He found, however, that regardless of the total surface, silicotic reaction only de veloped when the size of the particles was 3/i or less. On examining his material it was discov ered that with particles 4 to 5y. in diameter or larger there were only two to four visible in a thin section of each phagocyte. These cells ap peared to be quite uninfluenced by the ingested material. In the case of particles 3n or under the number inside each phagocyte was countless, and there was marked evidence of degeneration of the cytoplasm of these cells. In other words, the ef fect of surface area had to be exerted inside of the cell and not upon the body fluids as a whole. Ex tracellular quartz seemed to have little influence, and even intracellular particles of a large size produced no visible evidence of irritation. THIS observation brings us back to the cause of these progressive changes. Apparently they are initiated with degeneration in the pri mary phagocytes, an effect which is exactly paral leled in the histogenesis of tuberculosis. Some years ago I published a paper calling attention to the similarities between silicosis and tuber culosis.5 In both of these diseases the primary irritants, quartz grains or tubercule bacilli, as the case may be, intoxicate the phagocytes. In tuberculosis the cells thus poisoned are commonly designated as "epithelioid cells;" in silicosis the morphological effect is similar. Visible fat droplets accumulate in the cytoplasm and the elements stainable by supravital dyes undergo rearrangements in characteristic patterns. Giant cells of the Langhan's type are produced in each disease by stimulation and repeated multiplication of the nucleus. In each disease many cells die and their degenerated products are liberated in the tissue spaces. Incidentally it is the pabulum of necrotic cells in silicotic lesions on which tu bercle thrive so well, an effect which is responsible for the high frequency of complicating tuber culous infection in silicotics. In the tubercle it is in the necrotic or caseous tissue that tubercle bacilli are most frequent. Perhaps they not only cause such caseation but they themselves thrive on it. Coincidentally more cells migrate to the area and proliferate to form the granulomatous nodule that is characteristic of each disease. Finally the production of necrotic tissue, high in lipoids, by two very dissimilar primary irri tants recalls the experiments of Fallon8 and his hypothesis that it is these lipoids which are di rectly responsible for the formation of the granu loma. He showed that the injection of such lipoids, freed at least partially of contaminating silica particles, was capable of producing a granu lomatous nodule. Such mechanisms may be involved in the pro duction of both silicotic nodules and tubercles. It still remains to demonstrate the nature of the primary injury by each of these irritants, and it is this problem that will probably engage our at tention for some time to come. Bibliography: 1. Gardner, L. U., and Cummings, D.E.,: Studies on Experimental Pneumoconiosis: VI. Inhalation of Asbestos Dust: Its Effect upon Primary Tuberculous Infection. J. Indust. Hyg., 13:65-68 and 97-114, February and March, 1931. 2. Gardner, L. U., and Cummings, D. E.: The Reaction to Fine and Medium-Sized Quartz and Aluminum Oxide Vol. 9, No. 2 INDUSTRIAL MEDICINE Page 49 Particles. Silicotic Cirrhosis of the Liver. Am. J. Path., 1933:9, Supplement whole number 54, 751-763. 3. Timothy Leary: Personal Communication. 4. Denny, J. J., R obson, W. D., and Irwin, D. A.: The Prevention of Silicosis by Metallic Aluminum, Canad. M. A. J., 37:1-11, 1937. 5. Gardner, L. U.: The Similarity of the Lesions Pro duced by Silica and the Tubercle Bacillus. Am. J. Path., 13:13-23, January, 1937. 6. Fallon, J. T.: Specific Tissue Reaction to Phos pholipids: A Suggested Explanation for the Similarity of the Lesions of Silicosis and Pulmonary Tuberculosis. Canad. M. A. J., 36:223-228, 1937. A Plan for the Control of Tuberculosis in Industry Max R. Burnell, M.D., Medical Director, AC Spark Plug Division, General Motors Corp., Flint, Michigan I T IS a proud day when it can be stated that one of the safest places to be in this country is at work. Statistics from the National Safety Council seem to bear this out. The reduction in the frequency and severity accident rates in our industrial institutions has been nothing short of remarkable. Prevention has been the watchword. With such improvements, the consideration of the medical departments in industry has more re cently been drawn to the general health of its em ployees. Attention to the control of tuberculosis has been a very major issue. We believe that in no adult group throughout the country can so much be accomplished in prevention and early recognition of this disease as in our industrial in stitutions. Legislation varies in the different States regard ing occupational disease but the ultimate objective of this legislation is clear: The general health of the employee must increasingly become the re sponsibility of the employer. While the status of tuberculosis has been debated by many legisla tive bodies, silico-tuberculosis is definitely com pensable. In the state of Illinois the new occupa tional disease disability compensation law went into effect on October 1, 1936. Dr. C. O. Sappington states that "during the first year of the oper ation of this law, 10.9% of disability claims filed were for pulmonary tuberculosis while silicosis claims were 15% of the total."1 The corporation that is looking toward the fu ture with the best interests of its employees in mind certainly should be actively engaged in the problem of the control of tuberculosis. Many of our industrial institutions have already shown, by marked reduction of the incidence of pulmonary tuberculosis, just how this can be accomplished. Our own corporation has a very definite program concerning tuberculosis. THE PROGRAM: 1. The P hysical E xamination. P re - Employment Every prospective tion. This is done with the intent of placing that individual in industry where he or she is best physically as well as mentally fitted. This exam ination is not done for the purpose of either pass ing or rejecting that person for employment. This pre-employment examination gives the examining physician the best possible opportunity to detect pulmonary tuberculosis. Dr. Robinson Bosworth, President of the Illinois Tuberculosis Association, states:2 "85% of adult pulmonary tuberculosis has its beginning in the age group 18 to 28. In the vast majority of cases there are no symptoms and no physical signs." It is exactly this age group that concerns us most in our pre-employment physical examina tion, for it is during this age period that most em ployees first enter industry. We therefore feel that such an examination is not complete without an x-ray of the chest. We believe, with Dr. Andrew R. Riddell, of the Industrial Hygiene Department, Ontario Depart ment of Health, that the wholesale tuberculin testing in industry has many disadvantages. He states that8 "the individuals must present them selves at least three times--there is considerable disruption of work--even after most careful ex planation as to the meaning of the test, the em ployees who react positively are greatly dis turbed." Applicants in whom active pulmonary tuber culosis is discovered are sent to their family physi cian. Our roentgenogram is at his disposal, but must be returned to our files so that we can later compare the progress of the disease and determine at what future time those persons may be pro nounced employable. Applicants with arrested or quiescent tubercu losis are placed at work after being informed of their condition and instructed to return for pe riodic examinations. These examinations for new employees, in this classification, are conducted every three months. It has been increasingly evident that our re sponsibility does not end there. We explain to the employee that while he now has an arrested tuberculosis, it was once active. We encourage him to have the members of his family examined by the family physician. We feel that not until then has industry wholly discharged its duty to the community. 2. P eriodic E xaminations for Old E mployees. These examinations are made at different times and for varied reasons: (a) Upon returning to work after vacations. (b) After absence caused by an illness. (c) Re-employment following seasonal lay-off. (d) Transfer from one type of work to another. (e) Medical department requesting the exam ination for some definite reason. (f) Volunteer requests by the employee for such an examination. Little comment is necessary concerning these examinations except to state that every employee comes into our medical department for a general Dhvsical check tin at least, once each vpar