Document rpokEmGzQM9k1nOwKdoYNbb5V

FILE NAME: CERAMICS (CER) DATE: 1940 Feb DOC#: CER021 DOCUMENT DESCRIPTION: Published GM Medical Conference Presentation by Dr. Gardner - Recent Developments in Relation to Silicosis This m .g .iin . 1 publiih.d to promoto sound thought upon ond concerning industritl modicin* end treumetic surgery. To thet end it will contein erticles. news items, reports, digests, end other preientetions. together with editors' comments. The editoriel pol icy is to encourege (rent discussion. On this besis contributions ere invited. Rrc. U 8 Fsl. Off. The editors will esercire cere in check mg on th eccurecy of dete printed. but in eli other reipecti erticlei end opinioni of which espresiion ii ellowed ere th opinione of their euthori-- th editore reierving in eli ceies th righi to comment on th seme, in th cur rent or eny subsequent itiuei, et they mey be inclined. The Journal of Occupational Diseases and Traumatic Surgery With which are consolidated The Industrial Doctor and "International journal o l M adicint and Surgery." The Science, the Law and the Economics of Industrial Health Volume 9 FEBRU A RY, 1940 Number 2 General Mntors Corporation IVIedical Conference -- Dayton, Ohio, N o v e m b e r 2 and J, IQ3 Q_____ 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: Thursday, November 2: Director, Fisher Body Lansing Division, Lansing, Michi gan. _ .13' , y tudy ot the Factors of Employability, Especially Disabilities and Infirmities of the Elderly, and Problems iurIrflni?i j m ^ P l o y m e n t 0f the Same," Georce A. P aul M.D., Medical Director, Hyatt Bearings Division, Harrison' New Jersey. ' TVTORNING Session: Chairman, M. M. Shafer, M.D A Medical Director, Frigidaire Division, Dayton. ' r J ' "Recent Developments in Relation to Silicosis " LeRoy U. Gardner, M.D., Saranac Lake, New York. 2- A Plan tor the Control of Tuberculosis in Industry," Max B urnell, M.D., Medical Director, AC Spark Plug Division, Flint, Michigan. 3. "X-Ray in Industry," M. William Clift M D Hurley Hospital, Flint, Michigan. ' 4. "Preliminary Report on Hygiene Studies of Weld 14. ``Early Diagnosis of Acute Appendicitis," C. R ush McAdam, M.D., Medical Director, Fisher Body St. Louis Division, St. Louis, Missouri. AFTERNOON S ession: Chairman, F. B. Wishard, MD 7 j. Medical Director, Delco-Remy Division, Anderson' Indiana. * 15 "Relationship ot the Length of the Inguinal Liga ment to the Occurrence of Inguinal Hernia," C. M. Hill enbrand, M.D., Medical Director, Harrison Radiator Divi sion, Lockport, New York. ing," L. B. Case and V. J. Castrop, Industrial Hygiene Laboratory, General Motors, Detroit. AFTERNOON Session: Chairman, A. L. B rooks, MX)., 16. "Hernia in Industry; Review of the Cases During the Past Ten Years," R. L. J ohnston, M.D., Medical Director, Inland Mfg. Division, Dayton. Medical Director Fisher Body Division, Detroit. 5. "Recent Developments in the Occupational Derma toses," Marion B. Sulzberger, M.D., New York City. 6- The Course of Disabling Morbidity among Indus trial Workers, 1921-1938," William M. Gafafer, D.Sc. U. S. Public Health Service, Washington, D. C. ' M n ' `w n] isepti,s and Their Action," R. M. F reeman M.D., Medical Director. Linden Division, Linden New Jersey. ' 18. "Management of Fractures of the Spine" R W P oborsky, MX)., Medical Director, Electro-Motive Divi sion, La Grange, Illinois. 7. "The Industrial Nurse," H arold M. J ames MD Medical Director, Delco Products Division, Dayton ' 8. "The Doctor's Part in the Personnel Program," Georce A. Coburn, Personnel Director, Delco-Remy Divi sion, Anderson, Indiana. Except for D r . S u l z b e r c e r 's address on "Recent Developments in the Occupational Dermatoses'' all of the papers given at this Conference are in cluded here in full text, in the order of their E ' S Ni?iGTv-SESf I0N: Chairman, Walter M. Simpson, places on the Program: M. D., Director, Kettering Institute for Medical Re search, The Miami Valley Hospital, Dayton. e;."R. f i tionships of industrial Medicine to Private Practice, Stanley J . Seecer, MJD., Chairman Council on Industrial Health, American Medical Association H>. "Unfinished Business," C. F. Kettering, Director Recent Developments in Relation to Silicosis ueneral Motors Research Laboratories, Detroit. L eR o y U . G ard n er, M J)., Friday, November 3: TUTORNING S ession: Chairman, G. L. Bird, MX) Medi 1 Director General Motors of Canada, L td . Osha- wa, Ontario, Canada. Director, The Saranac Laboratory for the Study of Tuberculosis, Saranac Lake, New York Practical Approach to Supervision of Mental Tnrfi!c>T-!n, industry, F. S. P arney. MX)., Chief, Division of HHeeatlitnh^, OnttttaHwyag, ,^Onne.t'ariDo,e?C!a' nadi a.Pensions and National a3 ,of industry's Participation in the Anti-Syphilis Campaign,' P. J. Ochsneh, M.D., Medical WHEN your Chairman asked me to speak of new developments in the field of silicosis I was perplexed because all but a few of the pathological, clinical and diagnostic aspects of this disease are now well established. I realized liNL/UbiKlAL MEDICINE F e b r u a r y , 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. 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 ers5 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 recog nized 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 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 2ft in length the irritating prop erty of the asbestos was practically destroyed. In 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. 5 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.5 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 I N 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 the 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 ble to prove that silica has dissolved within the body, because the soluble material is immediately combined with local tissue elements. It is now generally accepted that the soluble silica detected in the urine and blood probably comes from in ticles 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 the injection by the onset of rapid, labored respir ation. The skin of the face and extremities becomes pale. The animal displays uncoordinated muscu ar movements and sporadic convulsions ter minating in death if the dose is sufficient. When gested food and drink rather than from inhaled takesplaceeS ^ administered complete recovery dust. Autopsy of fatal cases discloses an intense en TXTE have made a good many experiments whose J !. rsults 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 colorimetric 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 subperitmieal tissues which are deep purple-red in color. / V! r,J3nd. m fact Poetically all the remainder f.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 viduals. 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. They are only exhibited on injecting suspensions of quartz particles less than 3i in diameter They are not 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. Redlin were Ss' ee^kihnegn aMn r' C"eunmume i"fgosr atnhde quantitative introduction of silica th w 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 die very promptly if the unit dose of quartz par ticles were too large. These deaths were not em- because they did not occur with large par- W * b? n y when the quartz grains were 3/* or ess m diameter, and they did not develop on in- the sameUsizenS1nS * 0t^er minerals ground to effectively neutralized by adding small amounts of different substances. Colloidal aluminum hy- rifn o t ^ P 1^ 6 protection in a dilution of .03%; colloidal ferric hydroxide is much less effective. Animal charcoal cannot be injected, be cause it flocculates with the quartz and produces ~The toely ground metallic aluminum, used by Denny, Robson and Irwin4 in the preven tion of silicosis has no influence upon acute in toxication. Further experiments are in progress to verify the conclusion of these authors that aluminum coats the surface of the quartz particles with insoluble material.* Dwiorsli! 311(1 Mr- Delahant have extended these early observations in a long series of ex p riments that have yielded interesting though puzzling information. They have shown that fine silica injected into the left side of a guinea pig's heart acts like a strong poison. P 8 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 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 or 4 cc. of a 1% suspension of 1 to 3,* quartz par Subsequent experiments have shown that sterilizing tie s in physiological salt solution. The reaction suspensions of metallic aluminum by heat destroys their is specific in that it is not produced by quartz par power of neutralizing the action of silica. Unheated sus pensions of the metal are just as effective as the hydroxide. " ' y, i J 7 V 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. peared to be quite uninfluenced by the ingested material. In the case of particles 3 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 HE 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 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. T sues. This is borne out both by the absence of HIS observation brings us back to the cause reaction to large particles in excess of 3/x in diam of these progressive changes. Apparently eter and possibly by the observations on neutral they are initiated with degeneration in the pri ization. Any effect due to preformed soluble mary phagocytes, an effect which is exactly paral silica liberated in the suspension before injection leled in the histogenesis of tuberculosis. Some has been eliminated, and no active soluble silica years ago I published a paper calling attention could be demonstrated in the blood of an animal to the similarities between silicosis and tuber dying in shock by transfusion into a second host. culosis. In both of these diseases the primary Everything now suggests an effect taking place irritants, quartz grains or tubercule bacilli, as very rapidly at the interface between the quartz the case may be, intoxicate the phagocytes. In and some element in the blood or tissues. Whe tuberculosis the cells thus poisoned are commonly ther this is due to the very rapid production of designated as "epithelioid cells;" in silicosis the colloidal silica in this location or to unique elec morphological effect is similar. Visible fat trical properties of quartz is still a fascinating droplets accumulate in the cytoplasm and the subject for speculation. In the same category is elements stainable by supravital dyes undergo the demonstration of the tolerance conferred by rearrangements in characteristic patterns. Giant previous injections. cells of the Langhan's type are produced in each The manifestation of acute toxic symptoms by disease by stimulation and repeated multiplication those species of animals which develop silicotic of the nucleus. In each disease many cells die fibrosis most readily and their absence in tne dog, and their degenerated products are liberated in which appears to be much more resistant, sug the tissue spaces. Incidentally it is the pabulum gests that these immediate reactions may have of necrotic cells in silicotic lesions on which tu some bearing on the etiology of silicosis. Until bercle thrive so well, an effect which is responsible more is learned about the reactions in the dog no for the high frequency of complicating tuber inference is possible. culous infection in silicotics. In the tubercle it The influence of particle size is just as signifi is in the necrotic or caseous tissue that tubercle cant in the production of advanced silicotic fibro bacilli are most frequent. Perhaps they not only sis as it is in eliciting acute symptoms of intoxica cause such caseation but they themselves thrive tion. Many injection experiments have convinced on it. Coincidentally more cells migrate to the us that quartz particles over 3/t in diameter are area and proliferate to form the granulomatous of little or no physiological significance. The fact nodule that is characteristic of each disease. that the lungs of persons exposed to most dusts Finally the production of necrotic tissue, hign contain few particles larger than 10/i in diameter in lipoids, by two very dissimilar primary irri has been responsible for the establishment of this tants recalls the experiments of Fallon* and his size as the maximum important in dust counting. hypothesis that it is these lipoids which are di As a matter of fact we know that with some dusts rectly responsible for the formation of the granu there may be many larger ones. While it would loma. He showed that the injection of such be just as well that any large fragments should lipoids, freed at least partially of contaminating be excluded from the lungs, it is felt that only silica particles, was capable of producing a granu ones 3/t or less in diameter are responsible for lomatous nodule. causing silicotic fibrosis. Such mechanisms may be involved in the pro We have long maintained that particles of this duction of both silicotic nodules and tubercles. size are irritating because they present a suffi It still remains to demonstrate the nature of the cient surface of silica to the fluids. Recently Mr. primary injury by each of these irritants, and it Dworski decided to test this reasoning further by is this problem that will probably engage our at pinajreticctilnesg wghraicdhedwodousldesaollf pdreifsfeenret ntthesizseadmequtoatratzl tention for some time to come. surface area. He found, however, that regardless Bibliography: of the total surface, silicotic reaction only de veloped when the size of the panicles was 3/t or less. On examining his material it was discov ered that with particles 4 to 5/i in diameter or larger there were only two to four visible in a thin section of each phagocyte. These cells ap 1. Gardner, L. U., and Cummings, D.E.,: Studies on Experimental Pneutpoconiosis: VI. Inhalation of Asbestos Dust: Its Effect upon Primary Tuberculous Infection. J. Indust. Hyg.t 13:65-68 and 97-114, February and March, 1931. 2. G ardner, L. U., and Cum m incs, D. E.: The Reaction to Fine and Medium-Sized Quartz and Aluminum Oxide :i i i i f! 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. T imothy L eary: Personal Communication. 4. Denny, J. J,, Robson, W. D., and Irw in, 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 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 of the Lesions of Silicosis and Pulmonary Tuberculosis Tuberculosis Association, states:* "85% of adult Canad. M. A. J., 36:223-228, 1937. ' 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." A Plan for the Control of Tuberculosis in Industry 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 M ax R. B urnell, M.D., Medical Director, AC Spark Plug Division, General Motors Corp., Flint, Michigan 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 I T IS a proud day when it can be stated that testing in industry has many disadvantages. He one of the safest places to be in this country is states that* "the individuals must present them at work. Statistics from the National Safety selves at least three times--there is considerable Council seem to bear this out. The reduction in disruption of work--even after most careful ex the frequency and severity accident rates in our planation as to the meaning of the test, the em industrial institutions has been nothing short of ployees who react positively are greatly dis turbed." remarkable. Prevention has been the watchword. With such improvements, the consideration of Applicants in whom active pulmonary tuber the medical departments in industry has more re culosis is discovered are sent to their family physi cently been drawn to the general health of its em cian. Our roentgenogram is at his disposal, but ployees. Attention to the control of tuberculosis must be returned to our files so that we can later has been a very major issue. We believe that in compare the progress of the disease and determine no adult group throughout the country can so at what future time those persons may be pro much be accomplished in prevention and early nounced employable. recognition of this disease as in our industrial in Applicants with arrested or quiescent tubercu stitutions. losis are placed at work after being informed of Legislation varies in the different States regard their condition and instructed to return for pe ing occupational disease but the ultimate objective riodic examinations. These examinations .or new of this legislation is clear: The general health of employees, in this classification, are conducted the employee must increasingly become the re every three months. sponsibility of the employer. While the status of It has been increasingly evident that our re tuberculosis has been debated by many legisla sponsibility does not end there. We.explain to tive bodies, silico-tuberculosis is definitely com the employee that while he now has an arrested pensable. In the state of Illinois the new occupa tuberculosis, it was once active. We encourage tional disease disability compensation law went him to have the members of his family examined into effect on October 1, 1936. Dr. C. 0. Sapping- by the family physician. We feel that not until ton states that "during the first year of the oper then has industry wholly discharged its duty to ation of this law, 10.9% of disability claims filed the community. were for pulmonary tuberculosis while silicosis 2. P eriodic E xaminations for Old E mployees. claims were 15% of the total."1 These examinations are made at different times The corporation that is looking toward the fu and(a)forUvpaornierdetrueransionngs: to work after vacations. ture with the best interests of its employees in mind certainly should be actively engaged in the (b) After absence caused by an illness. problem of the control of tuberculosis. Many of (c) Re-employment following seasonal lay-off. our industrial institutions have already shown, by (d) Transfer from one type of work to another. (e) Medical department requesting the exam tmubaerkrceudlorseidsu, cjtuiostn hoofwthtehiisncciadnenbcee oacfcpoumlmpliosnhaerdy, ination for some definite reason. uur own corporation has a very definite program (f) Volunteer requests by the employee for concerning tuberculosis. such an examination. Little comment is necessary concerning these '-T H E PROGRAM: 1. The P re - E mployment E xamination. Every prospective c c r i v o r i 3 t Vi r \T -r \y i rrV i r-vV, , , r- 1 examinations except to state that every employee comes into our medical department for a general physical check up at least once each year.