Document 93de465jj3jZx0Vx28OEMQQgp

1412 Monthly Life JUNE *. tMO Ire Weekly Underwriter Department Underwriting Aspects of the Industrial ' , Dust Hazard By A. J. Lanza, M.D., Assistant Medical Director, and R. J. Yane, Statistical Bureau, Metropolitan Life AddrtJi Btfort iftdual Section of American Lift Convention, Colorado Springs, Colo., June 6 UR knowledge of health hazards re wool, silk, sugar, flour, starch, wood, tobacco, quality. Their lungs become pigmented freo O sulting from exposure to various and leather. kinds of dust-'in industrial .occupa It is true that some occupations in which tions is based, on .observation and cliniiscainl volved exposure to organic dusts mani coal dust, but they do not develop a tree. fibrosis. For anthracite miners, the picrcre is quite different and (he reason is that u- studies oi workmen exposed to these dusts, fest a tuberculosis mortality .rate higher, thradte mining includes exposure not ociv - and upon noting .the-results of the action of than the average. Formerly, it was thought to coal dust but also to silica. Disabling these same dusts upon experimental animals. that this undue prevalence of tuberculosis miner's asthma was shown by the Unhed The former method goes back for centuries was due to the occupational dusts but the States Public Health Service study oi 193S and oar earliest conceptions of the harmful dust studies of recent years have demon to be a type oi silicosis, to which the tea properties of.dust were based on first hand strated that, mostly, organic particles are too aiuhraco-sUicosis is properly applied. Anth observation. large to penetrate to the pulmonary tissue racite seams are often found in country rock Many of these conceptions were erroneous. and when they do, they are absorbed without which contains a considerable amount of It is only in the past twenty- years that any producing any specific inflammatory reaction. free silica and. as in other silica dust ex thing like a comprehensive knowledge of Nor is much credence given nowadays to the posures. the development of pulmonary dust diseases has been attained-ldue first to idea that organic dust particles convey tub fibrosis was found to be proportionate to the the perfection of the X-ray as a means of ercle bacilli to the lungs and thus cause amount of silica in the coal dust and the diagnosis, and the development of successful tuberculosis. length of exposure. The incidence of tuber laboratory technique, for conducting tests on Metallic'Costs culosis among anthracite miners is very high. experimental animals. - . ..... . Here the sittation is not unlike that of Qinical pulmonary tuberculosis was found in. . ; Now we have arrived at a point where in organic dusts. The prevalence of pulmonary IS per cent of those with early anthtaeo-- tensive studies, both clinical and experi disease among workers in certain occupa silicosis and in 43 per cent of those with mental, conducted in this country and in tions exposed to metallic dusts gave rise to advanced anthraco-silicosis. Service upwards other countries, have resulted in a crystalixa- the theory that metallic dust was a fruitful of twenty to twenty-five years was asso tion of our ideas. In the English speaking source of tuberculosis. Such diseases as ciated with a tuberculosis rate of 14 per cent world, (he outstanding contributions to our "grinder's ret" were recognized clinically among regular miners and 37 per cent among knowledge have come from the South long before the era of modern diagnosis and those with a number of years as rock work African Institute for Medical Research: and - laboratory research. Metallic particles in ers. Animal experimentation, with both the Miner's Phthisis Prevention Committee the form of fumes may cause such reactions bituminous and anthracite coal dust, free in.Johannesburg; from various official agen as zinc chills or brass founder's ague, which from associated silica, produced no specific cies in England and Australia, in Ontario, are more in the nature of an allergic reac reaction. Canada, and m this country, especially the tion. The. pulmonary disease which afflicts Non-Siliceous Minerals United States Public Health Service; the grinders and buffers is silicosis and not in There is no evidence that non-siliceous United States Bureau, of Mines, and the any way a result of exposure to metallic minerals produce any pulmonary disease. Saranac Laboratory. "7 ' dust. Metallic dust particles are mostly large Gardner, at the Saranac Laboratory, tested In presenting this discussion of industrial and heavy (that is, comparatively speaking), upon animals such substances as diamond, dusts, their effects on workmen'exposed to consequently do not penetrate to the lung, aluminum oxide, rutile, marble, gypsum, ga-- them, and the bearing that this subject has in many instances, and when they do they are lena. chalcopyrite, iron sulphide, tine sul on life insurance underwriting; we. have at either absorbed or remain fixed and inert in tempted to summarize `what should be the , the tissues. From' an underwriting stand insnranrr attitude, based on the present state point then, the hazard of-metal dust is the of our knowledge.. Briefly, the present con hazard of such silica dust as may be asso cept regarding industrial dust hazards-is as ciated with it. phate, fluorite, and dolomite. The sulphides and dolomite proved toxic but this affect a outside of our present discussion. Non-silkt.ous minerals proved inactive in animals and there is no clinical evidence of specific dis follows: Organic dusts, of which the dust. . . Coal arizing in textile operations is an'example, For many-years there has been a belief do not cause any-specific pulmonary disease. that coal miners had less, tuberculosis than ease among workers exposed to this type of dust. Artificial Abrasives There is no clinical nor experimental evi the average for wage earners and, on the Experiments with artificial abrasives dence to the contrary. Coal, which is an or other hand, miner's asthma has been recog demonstrated the incorrectness of earlier ganic substance, is considered in connection nized as an occupational disease of coal ideas that dust caused injury to the lungs with mineraSrdusts.. Organic dusts at times miners. Here again, recent studies have proportionate to the hardness and sharpness may cause an allergic reaction and also irrita clarified the sittation to a considerable ex of the particles. Artificial abrasives, arc tion of the upper air passages. They do not tent. among the hardest substances known. Neither cause protrabted disability nor death. In Bituminous or soit coat miners do not have silicon carbide nor aluminum oxide produced this classification may be included cotton. an occuptional pneumoconiosis of a disabling any reaction resembling silicosis in expert- er. ungs V June.8, 1940 1413 mental animals nor co workmen exposed to these dusts show any clinical symptoms or X-ray apjicaranccs suggestive of silicosis. Silicates A considerable number oi silicate. dusts have been studied and their effects upon ex asbestosis, but most of the fatai cases nave been complicated by other disease such as cancer and diabetes so that the extent to which the asbestosis was responsible for death is not clear. Titc pathology and X-ray appearance of asbestosis are entirely different from silicosis though cases wiii be seer. occasionally that j'rccccd to a tatni termination without tniccttert. Exposure to moderate amounts of silica dust where titc parttcic counts are in excess of ten million does not occur frequently a: the present time, though it is oniy in the iasi perimental animals, both by inhalation and and in the absence of a definite history of few years that stiica industries have en injection, noted. They produce little or no exposure over a considerable period of time deavored to cope with their dust problem ar.d reaction in the body tissues and what little to asbestos dust, the diagnosis is difficult. A reaction some oi them do produce does not great -'~?1 of success has been attained in tend to progress. An exception should be controlling dusts in the plants where asbestos noted here regarding asbestos, which is con is fabricated so that it is not likely that as- sidered separately. bestosis will ever become an important in Nor is occupational exposure to silicate dustrial disease, as far as the number of dusts accompanied by any such clinical pic cases is concerned. ture oi disability and death as is. found in The scarcity of clinical data on asbestosis silica dust exposures. The Public Health makes the prognosis doubtful We have had Service studied some talc mines in 193S. a small group of cases under observation ior Only 66 men were exposed. Tuberculosis about ten years and some of these show a morbidity and mortality rates were very high . definite but slow progression as far as can in the county where the mines were located be judged from the X-ray films. However, and the dust exposure was. exceedingly se what the outcome may be remains to be seen. vere, running into_hundreds of millions of These men are alt working and showing no effectively reduce the amount. Such ex posures produce definitely disease in from, eight or ten to twenty or more years, i.n pro portion to the actual quantity of dust. The incidence of tuberculosis is high and of those who die of their pulmonary condition, 75 per cent are tuberculous. It is also possible to find degrees of silica exposure which, white producing definite sili cosis evident on X-rays, will not produce dis ability or death in an average working life time. Morality statistics are not broken down by industry to an extent sufficient to make available definite figures by degree of exposure. We must rely then on the clinical particles. Eight men showed advanced pneu moconiosis but tuberculosis was also present in most of them. It is conceivable that ex posure to tremendous quantities of any min eral dust, regardless of silica content, might so overwhelm' the lungs that they could not deal with the invading substance. Irrita tion, inflammation, and probably infection would follow with disability in proportion. Such isolated instances do not invalidate the condosions stated in the previous paragraph. Asbestos ' signs of any disability. results obained in industrial investigations Silicosis which are conclusive enough for those indus tries studied. Our own impression is that It may be said that there is a very general, even where the silica hazard is of a mild accord among the leading investigators and . type, the incidence of tuberculosis wiil be research authorities in the opinions and con higher than the average. It has been sated clusions presented in the international con that where silica dust contains caustic alkalies ferences on silicosis. Such differences of also, the action of the silica is intensified opinion as .may be expressed.from time to very considerably. The evidence here is time do not seriously affect the general meager. " Other substances apparently have agreement on the basic factors affecting the some inhibiting effect upon the action of cause, incidence, effects, and prognosis of silica, affecting the pathological as well as silicosis. the clinical picture. 1 Asbestos is the only dust of combined silica which is known to cause a definite pulmonary fibrosis which may result in dis ability and death. Most pf the asbestos fab ricated in the United States comes from the mines in Quebec. Asbestosis, however, is not' found among asbestos miners, most of The effect of silica upon the lungs depends on the nature and extent of exposure. That is to say, upon the quantity of dust in the air breathed by workmen, the amount of free or uncombined silica in the dust, the site of the dust particles, the presence of other substances in the dust which may modify Prognosis The prognosis is fair for a silicotic whose lungs are not extensively damaged and who is free of infection. Such persons have an increased, susceptibility to infection and if brought into intimate conact with a case wham work in open quarries or pits, nor among men engaged in milling operations whereby the asbestos is prepared for ship ment and bagged, but among workers in fabricating plants. Only recently has an ex planation been otiered for this anomaly. It the action of silica, and the length of time or duration of exposure. The individual himself must also be considered. Previously existing disease of the lungs, especially a tubercle infection, will influence his reaction to inhaled silica. There may be other phases of tuberculosis are very apt to became tuber culous also. The outlook for the tuberculosiiicotic is poor. Many cases are essentially chronic and may live for years. Others show rapid progression and die in from one to two years after their infectioc becomes active. would , appear that not only is asbestos an of susceptibility about which we know little The importance of tuberculous infection exception in that it differs from other sili or nothing but in the main, it may be sated among persons exposed to silica dust brings cate dusts in its ability to cause structural that individual susceptibility to the action of up a very important underwriting considera changes in the lungs but its action appears to silica dust is an acquired rather than a con tion, that is. where the worker in a silica be mechanical and not chemical like the ac genital condition. , occupation is in contact-in his home with an tion of silica. If asbestos is crushed to fine particles. it will not cause asbestosis in ex perimental animals nor will asbestos produce any reaction elsewhere than in the lungs.- If its action were in the nature of silica, the effect would be more pronounced with smaller partide rises. Consequently, Gardner condudes that the relatively long spicules of as bestos produce their effect because the lungs are never at rest and the constant movement ' provokes the fibrous reaction. Like silicosis, asbestosis devdops slowly, presenting the characteristic symptom of shortness of breath. The number of cases of asbestosis that have come! to autopsy is ' small but there are several cases on record in which death .was due entifdy to the as bestos and not to any associated infection or other condition! There does not seem to be any pronounced tendency to tuberculosis in In industry we find different types of silica hazards. The severity of a silica hazard is estimated on the amount, of dust in the air and this is expressed in millions oi particles per cubic foot. The particles counted, are those under ten microns in size, though the present opinion is that it is the partide be tween one-half a micron and three microns that is mostly responsible for causing the disease. Exposure Co excessive quantities of pure silica dust, that is, where the dust count is in the hundreds of millions of partides per cubic foot, is now rare. Isolated instances may be found as. in the case of a sand blaster improperly protected. Such exposure produces a severe type of silicosis in upwards of five years, even sooner in extreme cases. With such extensive silica damage to the lungs, tubercle infection is almost ineviable. open case of tuberculosis. The question is frequently asked whether men who had worked in silica dust at one time but later changed to a job in which there was no exposure to silica might be considered, standard risks for life insurance if they passed the usual insurance physical examination. While there are no insurance statistics to prove the point one way or the other, there is every reason to believe that a group of such men will not give a stand ard morality. The usual type ot physical examination will not detect silicosis. The only way to be sure is to secure X-rays of the lungs of such applicants and have them interpreted by some one who has specialized in reading films of this kind. Silicosis is gradually coming under control. The aggravated cases seen twenty years ago (Continued on Pagt 1417) 54 1420 INDUSTRIAL DUST HAZARD (Continued from Page 1417) error, nevertheless it is interesting to ob serve that they were quite uniformly high for copper miners, gold and silver miners, and lead and zinc miners. The situation as regards iron miners is interesting because it was thought for a long time that they had little or no exposure to silica. More recent studies show that there is actually a moderate degree of silica hazard which produces silicosis in upwards of twenty years. However, .- in both insurance studies there were too few deaths from respi ratory tuberculosis to permit definite quan titative conclusions therefrom. A gTcat many workers in mining occupa tions, it must be borne in mind, are common laborers among'whom we should expect a much higher, mortality from tuberculosis than among standard ordinary policyholders. From the limited data available for unskilled workers,-from these studies it would appear that the tuberculosis' death rate for this class of workers runs between two and three times the rate of standard ordinary business. Thus it is clear that even when allowance is made for-the important factor of social-economic class; the death rates for the metal miners are extremely high. - Coal, miners' in different sections of the country present an interesting contrast Among the bituminous miners, exclusive of the Pennsylvania miners, the mortality from tuberculosis was over 1J4 - times that on standard ordinary miners, a low ratio for this -type of worker. .Pennsylvania miners, da the other hand, most of whom were em ployed in- the anthracite field, had a very high'ratio of actual to expected deaths-- 'well over 300 per cent Anthracite miners, as we have' stated, are exposed to an appre ciable amount of silica dust, which accounts for their relatively unfavorable position. No dusty trade has received more careful .: Underwriters, i agency managers, \ _ home-office men: For the first time, the whole subject of safeguarding life insurance proceeds has been reduced to readable form and substance for easy assimilation end .. practical application. -Safeguarding . . LIFE INSURANCE PROCEEDS By W. J. Wheeler and T. I- Todd .. Here, in simple fashion, ere ex plained the desirable. objectives to be ; attained by safeguarding life insurance estates; as well as approved practical ' plans of distribution of insurance pro- * U | tetMM ( UUr, - BU7 if* T--1 t~~H laM rtmpto aWtt UtvtiAj frefhu Millmi wkUk tk |m7 mm uniH, MtpdlMtiea ( A**, <k Mi-a k It wilk fewfal m1IU Ideas far gvwy adarvrllaa ta aktark kto kie talat a^alpaaab 12.90 PfrftptoM 33) e ESttfclp Bntoertorikr ' 80 Maiden Lane . New York The Weekly Underwriter study in the United States linn that oi granite cutting. Long recognized as a dan gerous trade, it has been found lime and again to take a heavy toll in deaths from tuberculosis. The amount of free silica in the dust breathed by these workers is very is indicated fcy the higher x-.oriaiiry irc= tt-.bcrculosis among exposed workers r -- age 45. About all that can be tiiri point from the limited American lift ancc company experience, is that the . cuiosis death rates icr grinders, metal pol large In the years 1935 to 1936, the mor ishers. and buffers -,vr.o are exposed ta in tality from tuberculosis among granite and organic dusts, most oi which do not contzz sandstone cutters was the highest recorded a large percentage of sines, are not high, for any of the groups of insured lives having in mind the economic status of thee stuo.cu. There were more than 25 times as workers as compared with the average ordi many deaths from tuberculosis as expected, nary policyhoidcr. Lime, cement, and arui- whereas in the eariier years, there were ciai stone workers had a quite favorable nearly ten times as many deaths as expected, mortality. The very high ratio ior oartie based on a small exposure. Marble and lime and limestone cutters, however, may be sug stone cutters did not show anything like as gestive oi some untoward influence. Dr. high a ratio as the granite and sandstone cut L. U. Gardner at Saranac Lake, found that ters. There were ten deaths where one was animals dusted with marble dust by inhala expected in the years 1925 to 1936. tion, developed little reaction,. but became It can be but regretted that there are so few morality statistics for occupations ex posed to dusts other than silica. Grinders temporarily more susceptible to infecdcc with tuberculosis. The increased susceptibil ity was not marked. of metals, most of whom for many years have been using composition wheels in place of the old sandstone wheels, and consequently have had a little or no exposure to free silica, experienced a relatively low extra mortality from tuberculosis in both studies, based, however, on a small exposure. An interesting point to be noted here is that this occupation also offers exposure to- metollie dust. It would appear that neither the dust from the composition wheels ncr the mecal dust has produced excessively high death rates from tuberculosis. Buffers and pol ishers, a somewhat similar group, also ap peared to have a low extra mortality from tuberculosis in the years 191S to 1926. Cement and Lime Workers The three occupations in which there is exposure to organic dust had from two to two and one-half times the number of tuber culosis deaths expected- Even allowing icr the economic position or these groups as compared with ordinary policyholders gen erally, the mortality is high. It is difnrclt to see in the light o: present clinical knowl edge, how it is possible to account for the excess mortality on the score of damage u the lungs caused by such dust. Mortality findings, then, are still not is complete harmony with clinical and labora tory findings. But irem a practical under writing standpoint, it may be said that the only dust which of itself might y the total mortality, by increasing Cement, lime, and. artificial stone workers dence of tuberculosis, as to require a were reported upon in both the Joint Occu premium charge for life insurance, is free pation Study and the Occupational Study, silica. We have no mortality data for as but the number of deaths from tuberculosis bestos workers but, it may well be that ex was in each instance less than the number posure to asbestos dust in large quantities required for separate tabulation. This fact will also be iound to produce a high tner- in itself is significant, although it does not tality. mean necessarily that the death rate from tuberculosis was. below the average. Never theless, from the facts presented in these studies, it is quite evident that the tuber culosis death rate for'this occupational class BALDWIN'S' New York Insurance Law was comparatively low. Annotated Three groups of male workers exposed to organic dusts art included in the table__ upholsterers, cotton mill operatives, and "PerptUial Revision Edition" is the one authority on New York woolen mill operatives. The ratios for ail of these, classes run about 200'per cent, based on small exposures. It must be admitted that these occupational Insurance Law. It contains: The Insurance Law mortality statistics are meagre and do not permit of very definite conclusions regarding the effects of specific dusts. So far as they go, they fully substantiate clinical and labora tory findings regarding the injurious char acter of silica dust. The death rates from respiratory tuberculosis for men in occupa All miscellaneous statutes relating to Insurance Exhaustive annotations Insurance Department rulings Attorney General opinions "Common-Sense" index tions where there is a serious exposure to silica dust arc so high as to leave no room Kept to date for doubt that silica is the offending agency. Price $20 Contrary to clinical and laboratory find Including 1940 Supplement ings, however, the mortality statistics, pre sented by Collis and Yule, suggest that long 2< Tfjc HMzekip kSnberfcr "'t continued exposure to non-siliceous inorganic dust has an injurious effect on the lungs as 80 Maiden Lane Ne> 1940 'SURPLUS FUNDS ?L Metropolitan .J309.717.567 l*JL *?rodcatialI .................... 209.492.460 *L New York Lite............. I23.6J9.022 ^LEouiublc. X. Y............ 90.762.653 Fs.*7aa . Hancock.................. 37.9tfl.JJ7 JltTraoelers ........................ 64.902.795 r/TT'Fcrthwesttro Mutual.. S7.I36.J4J ~&t. Mutual Lite. N. Y..... 31.152.202 J.l. Aetna Life ...................... J6.355.402 >11 Pena Mutual .................. J0.944.720 JlL Mutual Benefit ............. J0.J14.767 *12.`Western 6: Southern.. 23.J8J.92J fc 13* Mass. Mutual ............... 27.050.794 Jli Provident Mutual .... 19.374.230 *15* Sre Enfland Mutual. J9.010.80J 1147 Life oa. Co. of Va... 16.956.9JO l7jAner. Nat'l. Tex..... 15.533.244 Sit Coon. General ............... 14.423.687 If.'Conn. Mutual................. 1 J.020.498 9S. Union Central Life.. 11,348.155 ' JJl Bankers Life. Za......... 11.599.788 >21.National Life. Vt..... 11,224,492 t7aef4ea 3221,101,620 etntinfftney re* 2J. National Life 1 Aec... 24. Lincoln National .......... 25. Equitable Life. la.... 26. State Mutual ................. 27. Phoenix Mutual _.......... 23. Southwestern Lite ... 29. Kansas City Life.......... 30. Fidelity Mutual .......... Jt. Jefferson Standard ... 32. Bankers Life. NeU.... 3 3. Pacific Mutual ............... 34. Northwestern National JS. Guardian Life .............. 36. Reliance Life. Pa.......... J7. Great Southern ............ 33. Monumental Life .... 39. Home Lile. N. Y.... 40. Occidental. Calif............ 41. Life fc Casualty............ 42. Continental. Ill............... 43. Central Life. la............ aa, Columbian National .. 4 5. Acacia Mutual ............ ad. Callf. Western States. 4 7.' Provident Life Sl Ace. 43. Mutual Trust ............... '.9.45 1.570 3,941.163 J.777.602 3.623.391 7. 344. 962 7,340.000 7,205.984 .<68.839 000.000 5.799.129 5.672.956 5.457.913 5.269.459 5.171.696 4.733.020 4.569.1 J7 4.300.635 4.152.034 4,077.235 3.922.443 3.378,551 3.529.063 3.412.797 3.295.000 3.233.576 3,231,713 4l. Wiij, National ............ 33. Minnesota Mutual . . . 51. Sun Lite. Md................. 52. Columous Murual. O.. 53. Ohio National .............. 54. Guarantee Mutual ... 55. Midland Mutual .......... 56. 57. North A mcr. Reaaaur. 5S. 59. Western Lite. Mont... 60. Home Beneficial .... 61. 62. Mats. Sav. Dank.......... 6 J. 64 65. General American ... 66. Old Line. Wis.................... 67. Baltimore Life ............... 69. Ohio Stare Lite............... 69. Presbyterian Mm. . .. 70, Alliance Life ....... 71. 72. Farmers Si Rankers... 73. Business Men's. Mo... 74. New World Li/e............. 1417 3.253.323 2.066.705 3.045.994 2.7C3.J93 2.6 72.773 2.573,074 2.570.341 2.500.000 2.413.961 J33.35S 2.350.000 2.348.435 2.321.712 2.293.596 2.285.976 2.244.524 2.244.449 2.211.27$ 2.154.771 2.074.617 1.363.971 1,859.77$ 1.340.913 1.334.663 1.308.949 1.799.790 : Amtf. Mutual, .'i .... 76. Coiamai L.:c ... .. Industrial L. 5. ;i . Ca. 73. Protective Lie. 79. Country L.ie................... SO. American atafinara . .. 31. indunauoiis L:;c .... 32. Aimcaolc L.ie ............. 3.1. Paul Revere L;:< ----24. Franklin L.;u. ......... Si. Caoital Lu'c. Co.o .... 36. Union Laoor Lite.... 37. Orezon Mutual ........... S3. Monarch Lute. Mata.. $9. Leva! Protective ......... 90. Southland Lite ............ 91. National Reserve .... 92. Illinois Bankers ............ 93. Volunteer atare ......... 94. Atlantic Lite. Va..___ 95. Girard Lufe. ?a................. Ww Great Amer~. i ctu. . 97. United Lu'e i Aec... 93. Northern Lite .............. 99. Mass. Protective ......... 100. Lutheran Mutual .... :.7;T.;o5 i.'.al.M* l.; ./1. I. ill. 333 1.l21.:-5 235 1.5:2.306 1.450.457 1.440.42S 1.-*9/192 1.273.363 1.244.335 1.313.523 1.209.124 !.231.507 :. 201.167 I.ICO.377 5.294.333 ;.:s9.:?9 1-226.652 1.242.320 I.174.J23 1.093.817 1.332.901 1.363.910 1.352,766 INDUSTRIAL DUST HAZARD (Contintud from Page 1413) culosis.- is considerably higher than among persons in the higher income groups. The selection of certain kinds of work by the less 139.8 and 164.2. Eut the summary figures conceal interesting changes with age. A glance at the figures (shown on Table 4 of rarely seen now and the clinical picture robust workers is reflected in the high mor their study), shows that in the Silica Group jj^tas changed with the .progress of dust con- tality from tuberculosis of men in other the ratio of mortality to the normal, though .-trol measures. The' trend is towards a callings. Racial and nationality groups tend greater than unity even in the lowest age ^ Jessened incidence of new cases of silicosis. to enter certain occupations, with the result group, rapidly increases as age advances. In fe.This improvement- depends upon the main- that the peculiar susceptibility or relative the Non-siliea Group, the comparative mor l^ tenaivce of constant vigilance in detecting un- immunity to tuberculosis of these stocks, tality is actually below normal up to age 35; juspected hazards and in supervising the colors the mortality picture of men in such It rises just above normal in the following & efficiency of dust control methods after they occupations. These are but a few of the age group; but as ages over 4a. it is con & have been put into effect: It cannot be cx- many circumstances for which allowance spicuously above normaL" jl pected that this improvement will be reflected must be made before conclusions can be The facts regarding tuberculosis were not cj d insorance mortality until a considerable drawn as to whether a particular dust is or published in this report for each of the six 'period of time has elapsed. ----- ------------------ -is not the responsible agent in the high mor silica occupational classes included in the The conclusion seems warranted from tality found among men in a dusty trade. study. We have, however, determined by ;6dU6e* 26X4201 i7Fm X M ;k. *i| /nrjnz n6s3.j*Jn2 *iw iMjt 443X09 , 573*4223 !3f`,J79^ *50.1 USSST 61ur '*0474; I3.U : 99.926 .9C.07 113,40 4C41S 99.UQ 37^1 S9.497k 4042 074291 00.403V 64,434 TUfIC 1o7r4.i9z9s1l 994626 43.2233 44J165 lt.97l5 53,1574 40.1324 19J047 11.459.1 17J71?. 32.472S S14C722 72.7532 29.641? 19.0990 23.973 :< 59.472 3 4 7.493-^ 27,3012 N4lS'i 4*489/ 20.667 1W7.9.t9l9lW4J 0.760t^ tj). clinical and laboratory experience, then, that ^5' the only dusts which of themselves might Et*. have sufficient effect on the mortality of A. workers exposed to them, so great as to reIgi. tprire an extra premium charge for life in- w'rance, are silica and possibly, asbestos, ijr;. Life insurance men naturally will turn to Eft mortality statistics for* confirmation of a jK'finding So at variance-with the common beFh -Gef, Tong held, that exposure to all kinds of [yV llusts is productive of a . high incidence of ^^respiratory tuberculosis. To .the'layman it i only reasonable to suppose that the ^- difficulty in breathing he experiences when ^'exposed to large quantities of dust must Sri in some way affect bis health, and that filling Johjthe lungs with foreign particles' must have jj&.'injarious effects on them. The writings of '-'sniaeat students of occupational mortality _ ^statistics have served to strengthen this beNearly all such statistics, show the X~ynoTialiry from respiratory, tuberculosis among ci-workers exposed to a wide variety of dusts ''.to be well above the average for all workers .included in the study. But, when these fig- &'-ures are refined so far as is practicable to jp.i'.*inake allowance for factors other than dust. -.'which may influence the' mortality from ?: 'tuberculosis of men employed in these oecu- 'pations, the importance of many, dusts as jiS .causative factors becomes less evident. ; .'There is a surprisingly large number of '.factors, other than dust, any one of which may be responsible for the high mortality I-'t 'from tuberculosis among men in dusty trades, fclj 'Some dusty occupations are carried oo by L. oo> recruited from the lower income classes, 1 ,'T -among whom it is now knosvn that apart en<V 'tirely from exposure to a specific occup- ' Unfortunately there is, for the United States, no considerable body of mortality statistics sufficiently detailed to permit of evaluating separately some of even the mast important conditions affecting the mortality of men. in specific occupations. Perhaps the .beat statistical demonstration of the effect of different, types of dust on mortality from 'tuberculosis is supplied by two British au thorities. Dr. Edgar L. Collis and G. Udhey Yule These authors selected for study, from the occupations reported upon in the -Registrar General of England and Wales', report on Occupational Mortality covering the years 1921-1923, two groups of occupa tions--one exposed to silica dust, and the other to non-silica inorganic dust. The groups were so chosen that each had, as far 'as possible, the same amount of dust ex-posure, physical effort, exposure to heat or to weather, or any underground environment. Part of the authors' comment on the results as regards respiratory tuberculosis is quoted: "For all ages (20 to 6S) the comparative mortality figure (this figure is defined as the number of deaths that would have occurred in the Standard Population at the rates rul ing in the occupation) of the Silica Group is no less than 592.2 against 163.5 for the Standard Population, i. e.. the mortality is 'more than three and a half times the normal. For the- Non-silica- Group, the Comparative Mortality Figure, although actually slightly higher titan normal, at first sight hardly scans to differ significantly from the normal: nor would one's judgment be much affected if, instead of making comparison with the Standard Population, one had used the 'Social Groups III and IV, for which the re reference to the report of the Registrar Gen eral, that each of the silica occupations had over twice the expected number of deaths. The extraordinary high ratio of 1,150 per cent was recorded for tin and copper miners, while sandstone masons, cutters, and dressers had a ratio of 441 per cent. On the other hand, only the limestone masons, cutters, and dressers of the five occupations considered in the non-silica group exhibited a high ratio. 191 per cent. Like the English tin and copper miners. .American metal miners are exposed to a serious silica hazard and have an morriinaze mortality from respiratory tuberculosis as will be seen by reference to Table 1. In this table are given the ratios of actual to ex pected deaths from tuberculosis for a num ber of occupations exposed to dust and re ported upon, in the Joint Occupation Study. 1928, and in the Occupational Study, 1937. both published by the Actuarial Society of America and the Association of Life Insur ance Medical Directors. In the period 19131926, the number of deaths from respiratory tuberculosis among metal miners was over eight times the number expected on the basis of death rates by ages prevailing among standard ordinary lives in the same years. In the latter study covering the years 1925 tc 1936. the ratios were even higher--over 11 timeq as' many deaths were recorded for metal miners as were expected on the basis of death rates among standard lives in these years. While the actual number of deaths tor each separate metal mining class was rather small in both investigations, and consequently the ratios are subject to a large margin of ii' Sibnal hazard, ' the death rate from tuber spective Comparative Mortality Figures are (Continued on Pagt 1420) mm