Document V33N7Nw1jx1LNd4GzxO84KN54

Volume Xn JUNE, 1930 Number 6 THE JOURNAL OF INDUSTRIAL HYGIENE WITH ABSTRACT OF THE LITERATURE Mih (um| SsI.ZMUi.JLS.SJi. Immm CamUat SbTXmu JLLmo.>U3.D^JL XdilM. Caii ***! . t. Coca. JLP. U TCI. Personal Qualities in Accident Cassation Total Heat Difference as a Measure of Wet Kata Cooling The Infectivity of Silicotic Tubercnlosis The Occurrence of Pulmonary Fibrosis and Other Pulmonary Affections in Asbestos Workers (Omdudai) 1 Published at Mount Royal jl__ Guilford Area, Baltimore, Ml by HARVARD SCHOOL OF PUBLIC HEALTH i U'crrJ m hc.iuW iu mm,m U* for OCtT it CiauMM. J:ir]^rB< u^0 Mt tl iUak L Oejrngta. ItM, kf tanwtf Uniat Sdul Veda a tia UxiicJ Slaia if America 0132 S PLAINTIFFS i EXHIBIT 1. SO 4/9 I l i1 > THE OCCURRENCE OF PULMONARY FIBROSIS AND OTHER PULMONARY AFFECTIONS IN ASBESTOS WORKERS ' (CotMti) E. R A. MniWLTHH, MJD. H. it. Mt&cal Imrptdar tf fuctorU* Mourn Ahatout Professor M. J. Stewart of Leeds has Madly supplied me with a detailed description (dated March 28, 1929) of postmortem appearances of several nan From this account the follow- Tha totally fibrosed areas of long show grayish-black mottling, owing to immobili sation of carbon. This tissue is excessively dense aad completely airless; but then is no evidence of ralrifiration Other por tions of long show varying grades of tha nai process, and even tha least affected parts art definitely tougher than normal. he points an extracted: In sons of tha easts was then any evidence of on active tuberculous lesion Tbs gras morbid anatomy of this Itrioa, as seen is persons who have booa at work for Hstoloot many 7an in tbs dusty Unophtr of aa sshwfts factory, eonaiats in a widespread polmonary fibroma affsetinc capseisUy tbs basal icgiaa of both luaga. Tbara an xtaamva, daaaely fibrous adhesions through The essential lemon is a chronic interstitial fibrosis of ths long. In ths earlier stages, there is fibroblastic proliferation in the alveolar walls, out tbs pleural sacs, which may, indeed, bo- which become increasingly thickened earns completely obliterated. In particular, the baees of the hup an firmly adberaat to the diaphragm, and between these two sUruetuies than is often a thick, homo- ptsws layer of fibroua tiaaue, la in consequence; and there is catarrhal desquamation of ths alveolar epithe lium. At this stageof thediseasepecu liar golden-yellow "asbestosis bodies" appearance and eooaiatcaee to yellow fibre- an found in varying, usually con cartilage. Aa a result of thsao two preoases pulninmry fibrosis and pleural aas ebiitsratioa--bronchiectasis dseelopa in ths midst of tha more grossly diseased tiaras siderable numbers, both in the alveolar paces and In ths thickness of their walls. Detached portions of bodies aad may go on to the formation of multiple ' may often be seen engulfed by alveolar abscesses with unooth walla. phagocytes, or a large unbroken body Tha distribution of ths fibrosis, apart from tha extensive basal lesions, is rather irregular, tha peripheral, eubptcurml regions of tha lungs being mon affected than tha Central areas. In ooe ease in which the pa may be partially surrounded by these cells. In the more advanced stages of the disease, the fibrosis of ths long is complete. Alveoli can no longer be tient had been away fromwork for four yean made out; but the asbestosis bodies (fallowing nineteen yean in the mill), ths. areas of dsnao fibrosis wen extraordinarily sharply areumaeribed. Tha char- actor of tha lesion which is so striking a fatten of silicosis in its earlier stages is not .till remain embedded in the fibrous tissue. Varying Hunntities of carbon am also present, chiefly belittle masses ss though ft had been contained with met with in this disease. in phagocytes. Chrome bronchitic TAB lk( 23C i 1 1___ 0id46 I I t 340 THE JOURNAL OF INDUSTRIAL HYGIENE changes ace present and all grades of bronchiectasis may be seen, in cases oflong standing, from simply bronchial and bronchiolar dilatation, with walls still more or lea intact, to large spaces filled with pus in which the original bronchial walls have become converted more or less completely into fibrous and granulation tissue. Many of the arteries show obliterative end arteritis. Reversionary metamorphosis of alveolar epithelium is frequent, and each alveoli are often filled with albuminous fluid, in which dumps of "bodin'* may be found. Aaaxaxos Dm or m Loses Dr. W. E. Cooke has supplied (under date of June 25, 1929) details of his researches oa asbestos dust in the lungs, end oa the constitution of the curious bodies, which have been freelyused in the following notes:-- Sections of Hmg and the results of digestion of the lung with trypsin bow an enormous amount of fine black granular dust, much of which is carbonaceous. In addition, there are taro striking features. The first is the almost complete absence of the fine tanabaent spicules of fiber which make up a great proportion of asbestos . duct in factories. The second feature is the presence of large fragments vary ing is length from 10 to 360 microns. They an found is fibretic and necrotic areas, singly and is groups. The particles axe ao large masses of them are seen is some sections--that they must have occluded small bronchi and resulted In fibrosis of the surrounding axes. - Compering these laxge particles in the lung with those found in asbestos / dost, doa&esemblanee in sizes, shapes, and eolonjs apparent. There are the same black, blue, brown, and trans lucent fragments. In fact it ia easy to take such a single particle from the hmg and immediately find its brother in a slide made from the dust. Curimu Bodiu Tw to the fine granular dust and larger fragments of asbestos, sec tions of the lungs show curious bodies. They axe found in alveoli, bronchioles, fibrous and necrotic areas, and in phagocytes in sections of both lungs. If a portion of lung is teased end extracted with water, or digested with trypsin, or, as Professor Stewart pointed out (1928), if a smear is made from the cut surface of the fresh lung, theee bodies are seen in myriads. The larger bodies measure from 20 to 100 microns or more in length, and are of a golden-brown color. They may have single dabbed ends or may appear aa elongated dumb-bells; some are filamentous, while others suggest a aeries of disks. Single eoccal and spore-like forms, and aggregations at these, and strepto coccal forms are not uncommon; the color varies in the smaller types from a very pale yellow to a yellowish-brown. The bodies do not stain with any of the aniline dyes, but in chrysotile workers, they give the Prussian blue reaction for iron in varying degrees of intensity. These curious bodies have been found In every autopsy in pulmonary ashestosia. It would be unprofitable to retrace all the steps which led down many by-lanes during the course of the work, but I will zr. -a a few per tinent details of interest. Professor Stuart wrested to me i . '3 ' ua Jmm.au 01*47 PULMONARY FIBROSIS IN ASBESTOS WORKERS 241 that a better method then ample extraction of the longs with water or line would be to digest portions with trypsin. During this process it was found that if the specific gravity was kept at about 1,070, the black dost and larger fragments of asbestos, as well as the partially digested lung tissue, sank to the bottom of the tube. By decanting the apparently clear supernatant liquid, and by centrifugalhang, neutralizing, and washing the deposit, the carious bodies could be obtained in a pure state. This was fllH WfatWtl for X- ray examination was obtained. The were attached to a hair with gum and subjected to a seven-hour exposure by Professor Bragg's method. If the bodies were mineral, the X-ray film would have shown a definite translatable atomic pattern. The films, however, did not do so, and we were then able to exclude the sugges tion. that the bodies were altered asbestos fiber. The result definitely painted to the greater proportion of their composition being of nonmiacral The bulk of the curious bodies is rrityKfa in gtfTOg if the solution is observed under dark |nmind ffluxainatioa, tluur m aeen as extremely fine spicules some of which, by transmitted light would probably be invisible. Under a dis secting microscope it is possible par tially to fracture the larger bodies and to show a central fine eon. The greater portion of asbestos dust consists of slender translucent fibers. In sections and extracts of the lungs there is a remarkable paucity of these fine spicules. Ihe end-results of diges tion show the fine granular dust and VU.B KS J>e large black, blue, uuf brown par ticles and what appear ti be pieces of quartz. Relatively few3ine spicules are found; but curious bodies of all descriptions are present In enormous numbers. All these facts lead us to imagine the bodies to consist of a central nucleus of asbestos spicules, upon which colloidal aggregate of blood proteins plus, possibly, soluble frac tions of asbestos and, in the ease of chryeutile workers, an iron salt have been adsorbed and molded by currents in the bronchi and the alveoli. The method of formation would appear to be as follows: The fine spicules of asbestos cause, by mechan ical action on the bronchioles and alveoli, either "*""* extravasations of whole blood, or serous exudates which envelop them. Solution of any >lnhl^ fraction of iihistns takes place. The total amount of asbestos that- is soluble mast be extremely small, as is proved by the X-ray pattern of the eorioua bodies, but in the ease at chryeotile workers same solution is suggested by the free iron reaction. We must remember, how ever, that the Prussian blue reaction may be due to the iron of the hemo globin. Any surface in contact with a colloidal solution may act as an adsorbent, and in the present ease the fine spicules must be considered to do so. Interaction between the soluble fraction of ehrysotile and plasma proteins takes place, syneresia occurs, and, with the loss of water, the adsorp tion is rendered irreversible. The adsorbent is permanently rnshcathed with stable colloidal aggregates which became molded into thee familiar r ! 0Ui8 * i r*. 343 THE JOURNAL OF INDUSTRIAL HYGIENE dupes by alveolar sad bronchial car- lympha&c glands; in material obtained rents. by hugjjpuncture during life, first sug Support for this ides is found in the gested Sy S. A. Henry; in the sputa; fact that micro-organisms adsorb col and in smear preparations from the loidal material in the presence of blood cut surface of the long. In smear serum and colloidal asbestos. Staphy preparations they can be readily lococci so treated appear as large demonstrated. round yellowish-brown disks; in the The importance of these findings process their property of staining with lies in the fact that the bodies have aniline dyes is lost. The organisms never been found, as yet, in any other coalesce and form masses; and I human affection. That similar bodies think it probable that some of the may be found to occur in the lungs of eoccal and spore forms are similar workers exposed to other dusts, is organisms. quite possible, although they have not Finally, are the curious bodies been found in silicosis, nor were they diagnostic of pulmonary asbestosis? present, according to Simson (6), in Asbestos is unique among minerals in the fibrosed lungs of a hematite miner. being fibrous; sad its dust, generated . They appear within a comparatively doing manufacturing, processes, is short period of time after exposure to also unique. As can be imagined from asbestos dost; at tKe moment, their the formation of the carious bodies, presence in the sputa, in the absence thert is no reason why, green any of clinical or radiologic evidence of pul* siBcosis, afinespicule ofmineralshould manary fibrosis, eannot be taken as in not hare colloidal matter deposited dicating anything more than previous around it and become molded into a inhalation of asbestos dust. The pres curious body. But as no other min ence of the bodies, however, in the eral dost is fibrous, this occurrence sputa of persona with signs of a diffuse must be so rare as to be negligible from fibrosis, or their presence in numbers on a diagnostic point of riew. The con postmortem examination of a fibrosed ditions which, apparently, must obtain lung, has evident implications. for the formation of curious bodies are Professor Stewart, who is continuing the preeence of plasma proteins and his work on this subject, has devised fine spicules soluble only with diffi the following method of examining culty. These conditions are ideally spaturn for asbestosis bodies: found in asbestos workers; for this reason I believe that curious bodies, if found In any numbers, are pathog nomonic of pulmonary asbestosia.-- W. E. Cooks and also Roodhomm Gfoync (20) have independently dem Half an oases or so of sputum is added to aa squat quantity of undiluted aatiformia. . This to costly agitated until the sputum to completely dissolved, after 'which to to diluted with 2 or 3 ounces of water and allowed to stand in a Iar(e test tube for onstrated the presence of a mineral sore, evidently derived Cram asbestos fibers, in the carious bodies. The bodies have been found (Stewart and Haddovr (21)) in the. intrathoracic three or four hoars. The balk of the super natant Said having then been decanted, the remainder to eentrifnged at moderate speed for tea to fifteen minutes. Thewhote of the supernatant fluid to new poured off, and the daposit transferred to aa albumin- r I its. 01349 l ?5IiaiQNR.Y irmROSIS UN .^JSBESTOS workers 243 ;bsd slide, by mum ot either platinum ..loop at a pipette. Alter thorough dryiae oa ;o hot plats mad final fixation over a boaaen burner, the film la very ceatly washed.in water, dried, and mounted in Canada balno. Alter a little experience -the tehee- (39.9 per cent) and of eaadetone workers (58.1 per cent). | The precise significaneejof the lower figure found in this inquiry is not easy -to determine. At first sight it seems tone bodice are readily picked np with-th* law power, and their true nature ia then eooArpad-with the i-ineb or oil iouneraion lane. .As-Xul* they are preaeat ia veryemail num bs, perhapa only one or two ia a whole .film. Ia the mm e! aorae el the older to indicate that asbestos dust is less -potent as a cause of pulmonary fibrosis then sn the dusts containing free silira. Other factors, however such Mt the measure of exhaust ventilation, lereriura, however, aaaeroaa bodiea, op to ^pa or two per field ia eertaia portiona oI 4b* film, .have been found. It ia obviooaly praepry -to oleaaaa thoroughly all <liaaerpra, ,sto, need .ia -asking tfaaaa evemmatfaaa; otherwise there ia a riak of eoatami* or other means of reducing the eoneen-tration of dust, in the several indua-fcries; differences in the average length of employment of the comparable groups in the samples examined in the nation ofsubssqusnt speeunsaa. The filma eaa be treated with hydro- aUerie acid and lemeyaaide of pntaah to .demaaatrate the Proaeian. blue reaction jpvopbythebodiee. respective inquiries; and the relative numbers employed in the more dusty and the less dusty processes--will scSeet -the ends incidence rates ex pressed by-these percentages. iwRpatii Occotaxxowai. Irian comparison of the amounts of ' Wf#a*w dust evolved--determined visually sad Oat of a-total of 374 workera cxnav by means of dust counts--in dusty Jbed, 105, or23.1 per cent^.ven found asbestos processes, uncontrolled by 4p bp.affected with fibroma of the lungs, local exhaust ventilation, with obvi jp greater or lesa degree. Rut when ously defective exhaust ventilation, theaefiguree an corrected by the exclu and with comparatively good exhaust sion of cases in which previous work in ventilation, there can be no doubt that dsurtyoccupations (.?., quarrying, coal this preventive measure, which has BttBtog) may hare been the prime, or a been applied in some degree for more PPBicbtttory, factor in the develop than seventeen years, has been a posi ing* of tho Sbroeia, ninety-five, or2&2 tive factor in minimizing the produc per pent., pf 353 workers wen found tion of fibrosis--probably in the direc to be effected with pulmonary fibrosis do* to the inhalation of oabeatoa dust, pod a further twenty-one, or 5A per pent, ahowed pneumve aigna of this tion of lengthening the period before the fibrosis becomes fully developed. Consideration given to tbs distribu tion of the workers both according to length of employment, TUe percentage nay well be com pand with the corresponding figures found by Middleton (22) in hie exami nation of metal grinden (46.9 per cent.) POd by Sutherland and Bryaon (23) and according to age, together with the incidence rates of fibrosis in each ease, indicates the outstanding importance of length of employment (arid hence length of exposure to dust), and the negligible effects of age, on tj|e produc (24) In their examinations of potten 4M. Nat tion of fibrosis. Thus age groups 30 to i s r1 344 THE JOURNAL OF INDUSTRIAL HYGIENE 39 and 50 to 59 have incidence rates of 30 per cent, and 37.9 per cent, respec tively--not a vide difference, since the groups inchide workers in various processes exposed to different concen trations of dust. Moreover, the over sea length of employment in these two groups, errindrng the cases of fibrosis. fibrosis in age group 20 to 29, has been shortened by increased susceptibility at ages under 20.1 As, however, the average age of this group of cases of fibrosis is 28.7 years, and also because the establishment of fibrosis does not necessitate immediate retirement from work, this is largely discounted. TABLE 5.--DISTREBCTION OF WORKERS EXAMINED WHO HAD BEEN EMPLOYED FOR FIVE YEARS OB OVER, TOGETHER WITH CASES i OF FIBROSIS, ACCORDING TO PROCESS IN WHICH WORKER WAS LONGEST EMPLOYED ciaascvfasou Amin mots or MMTUOmaxr XV T*S. i ------------ IO.BE* iwno No. hr Cent, of Group Group Lrn Cue* of Fibrosis Csresof Fibrosis QniUtt apftwy, dittftt#* grating, sad wiring X Cardiag.................................. X Spinning. twisting, doubling plaiting te_..................... A Malfnw making................... A Wsariag aad swnristod proa- f |p. |f a. Oath weaving.................. a b. Baad Tearing................... a a Cloth and baad aad a- riei'rtsd. Teasers............. 14 A Warpers, bssasra, loom ksftdjp aad others sasoriatod aTith Tearing.................. A IGseellaaeous protism aad lWttiniAg QftBlMBfisd a 39 IS <2.9 41.0 ir 13 ur 13.9 4s.r u 49.9 a 73.0 4 19.0 4 a.o U 4A0 94 U 4S.I 1.9 9.1 10.1 7.3 10.0 9.5 10.9 7.3 11.2 . 5.9 .9 13.3 19.7 12.0 12.7 14.1 U.5 9.5 10.5 13.1 TotaL.......... ............................ 374 H 3A7 9.5 13.5 Is also similar, but considerably less than the average length for all the caaes of fibrosis (13A yean). Ho speeal susceptibility to the development of fibrosis is shown by young persona, unless it is considered that the figure of 8.7 years, the average length of employment of the eases of Tbs effects of length of employ ment are such that after five years' exposure, the incidence rats of fibrosis mounts rapidly, and after ten yean increases almost in geometric progres sion. iuie aj uuwai u_ie. u_u.u_w__u_u_u__a of 274 workers examined, and of those with fibrosis, aceordijig to the process tin. JwmXM 0 AG 51 i / . I I ' m I l] 4 / PULMONARY FIBROSIS IN ASBESTOS WORKERS 245 in which tier were longest employed. This was a compromise necessitated by the common customs in the indus try of having several different processes going on in the same room, and of workers transferring from one process to another. Since the intention was to obtain some measure of the rdaiiM Incidence of fibrosis in workers in the various processes enumerated, and since no ease of fibrosis dearly due to asbestos dust was found among eightysine workers examined, who had been employed for less than five years, in clusion of this group of workers would only have introduced a varying source of error. The protests differ, some very materially, in the amount of dust which they cause, and consequently in the amount inhaled by the operators (30). The outstanding point brought out by Table 5 ia the relatively low incidence rate of fibrosis in "spinners'* (group 3), as compared with each of the other groups. They are corrobo rated by counts of the dust partides in samples of air, a number of which have been taken and are discussed under Dust Risk. There is also some indication in these figures that not only are "spinners'' less likely to devdop fibrosis, but when they do, it takes longer to devdop. Study of the radiograms suggests that in such cases (*., in the less dusty processes) the resulting fibrosis is, for a considerable period, much more linear in ita radiologic features, and shows less mottling. The history and dinieal features in these cases, and the com parative dust counts, all contribute to the view that with comparatively low concentrations of dust, the resulting fibrosis is longer in developing and *LU Mat . remains longer in the milder, and radiologically linear stage, i This view is evidently of; consider able practical importance since it sug gests that in such eases, the rate of accumulation of dust in the hug has not greatly exceeded the rate of elim ination, the changes still being centered in the main lymphatic system. If this hypothesis is accurate, it should follow that in order to prevent the full development of the disease, among asbestos workers, within an average working lifetime, it is neeessvy to reduce the concentration of dust in the air of the workrooms to a figure somewhat below that pertaining to spinning at the present time. Fortunately, also, the spinning group is the largest individual group in this section of the industry--*.?., out of over 400 workers employed by one firm, this group acoounti for more than one-third. Although all workers examined who have been included as spinners have been engaged in spinning, or in simi lar processes for convenience termed "spinning," for a longer time than on any otherprocess, only a few have been employed solely on spinning, and in workrooms'where no other, and more dusty processes, were being carried on. These two factors, prior work in more dusty processes and present work in proximity to more dusty proc esses---especiallythe latter---have had, it is believed, some effect in raisingthe incidence rate of fibrosis for this group. Dust Risk in an effort to obtain additional data on the influence of concentration of dust in workrooms, a number of sam ples of air were taken and the dust con k -! i. * 0id52 246 THE JOURNAL OF INDUSTRIAL HYGIENE TABLE 4.--SUMMARY OP DETERMINATION OP dAsT CONTENT OP ATMOSPHERE OP WORKROOMS AND OTHER PLACES sums BO. nooscinioviaor Anns LOCAL BXSAVST xjcniA- TZOJf TO nnciii OB MOT otm FftOCBUS SB IAMX BOOM \ mo. or raaw> FUA^T* PAS* AOS ACS TirLCI 2* Ajrs 7.5a ura rsmc.Ce OBDBS nsta L 1/3 2. 1/S A 1/3 A 1/7 A VS A VS T. 1/1 A 3/11 A 3/1 EL 3/14 1L 3/10 a. vs a. vr u. v Cudiac; paaaacamy batmen uda Oath marine, dry Opening Sirri&c; tbareUfic fiber oa to nrre Plaitinc Office Office Goth meTine Spto&i&C Mattmc wcHne; Sniac Mutm mahjnc; baatinc, (bttp Motreee malrint; bcatinc. dry Maitmamakinc;alter SUiaf Yes No No Yaa No No No No Yaa Yaa Yea Yaa Yaa Yaa Yaa Yaa Yaa No oo ooo Yaa Yaa No No No No 3,139 1.4SS 1,736 3.3S4 3,839 1,687 901 l.0 1,788 1.073 983 TO 1,829 A304 S1.3 85.9 84.1 80.9 S3.0 99.0 98.8 98.7 88.8 98.3 93.8 8S.9 <8.9 88.8 93.1 100.0 96.7 93.7 87.6 98.0 100.0 100.0 98.8 100.0 98.1 85.8 98.8 98.4 1R VI 1A V4 a. s/s a vs 19. 3/3 30. VI 3L VI a 4/s a V4 a vs as/so a vs v. vr a vs a 4/io a vu AVB a i/12 as/i at/a a s/s as/v a. vs Band marine, *tt * Opening Cardiac, batman carda . Cardiac; laadiae card Office Maltreat making; SOiac Maflraaa uakinc; fiOinc baakat Emptyinc tattliaf chamber Same - Tnanlatinc aaetioaa; fetaliac fiber Cardiac; tide of dirty card Cardiac; aad at data cud Cardiac; faadiac card Gath marine, rery clichtiy ffiUBp fnij^ 4snp Brnidiac Spiosisi Office Band marine, dry Goth marine, dry Bead marine dry Opeaiac Cardiac; feeding card No Yaa Yea ' Yaa oo No No No No Yaa Yaa ooa Yaa Yaa No Yaa No Yaa No Yaa Yaa No Yaa No Yaa No No Yaa No No No ooo * No Yaa Yaa Yaa Yaa Yaa Yaa Yaa ooo Yaa No No Yaa Yaa 808 3,313 LS 1.321 1,049 1.838 1,390 A401 4,711 LS38 1.402 1,092 1,889 2,033 738 SOS 884 880 A302 885 701 843 sst 88.8 77.7 82.5 SAB 98.3 80.1 OO O 0 100.0 . 08.8 97.4 98.4 100.0 90.1 at oooo ooo ooo 0*0 oooo oooo oooo oooo ooo ' oooo i ALB. FCXMONARY FIBROSIS IN ASBESTOS WORKERS 247 TABLE 8.--Coan'mud a ftiiffu arc nocase am term or sauna .toeAS, tXXAVR TXNTILA- TIOHTO OTXZX noc* tun oriiaa Oft HOT aoon * HO. OF rXXCZHT- Ftxciwr- m aox* AflX TTCLM 2* Airo 7.5* aho race. mu OHBSH a. /4 Carding; enter of room SB. S/S Carding; grinding reilaxa Tan T Tea Tea 830 540 OOO ooooo 40. S/7 Spouisf L S/8 Office No Taa 630 oooo ooo see oooo 1 83.7/2 doth wearing, dry Taa Taa 4,888 oooo i1 43.7/1 Opening; (hoveling fiber into box Tea Taa 4,880 ooo 44.7/3 Opening ` Taa Taa 8,334 oooo % S3. 7/4 Band weaving, woe No Taa 8,333 ooo i 40.7/S 3pisaio( No Taa 8,044 oooo 47.7/0 Carding; batwen cards Taa Taa 4,807 0*00 40.7/7 Office ooo oo 3,413 0 0.0 40. U2 doth weaving; dry 10. S/3 Band weaving; dry n. a/s Carding No Taa 1.S7 M.a 84.8 No Taa 1,233 78.2 83.7 Tan Taa 1.183 07.2 84.8 tent u determined by means of air of the workroom, the majority of I Owens' jet apparatus. Hen also the the particles are, just as dearly, undetermined effect of dost from crystalline particles of asbestos, toneighboring processes most be noted. (ether with, frequently, some cotton Nevertheless some information ofprac fibers and numbers of black and brown tical valae was obtained. ish particles, some adherent to asbestos Reference to Table 6 shows that the spicules and some free. Most of coasts ranged from 50<S to 0,324 the latter an iron containing and are particles per cubic centimeter in the derived from the asbestos, and then air at workrooms, and from 660 .to are relatively few smoke particles. Iso 3,413 per eobie centimeter in the air of lated golden-brown scales or plaques, offices associated with the factories. also derived from the asbestos, an In some eases there was a smaller count scattered about the field. fat a workroom than in an office of the The asbestos fiber first fragments same factory; this was due either to longitudinally, and apparently this thenbeingmuch fewer smoke particles process can go on indefinitely, since in the air of the workroom, orto adher* then is no ultimate fiber comparable cnee of the smoke particles to the to a vegetable fiber such as cotton. inorganic dust in the workroom. The dust collected in the Owens appa The character of the dust in the two ratus contains numbers of these very esses is, however, entirely different. fine fibers--some about 0.5 micron in H- the air of the office almost ail the transverse diameter, many less--which particles an black, or brownish, and have fragmented transrertdy. Thus amorphous, evidently smoke; in the spicules of very diverse length--up to r ? Old 54 ****. US THE JOURNAL OF INDUSTRIAL HYGIENE a about 80 microns--bat about 0.5 the dus content of the atmosphere-- micros broad, are found in numbers on such sc. that produced by shoveling the sample, together with the black, asbestod fiber into a sack--can be brownish, and yellow particles already detected and estimated. This is of mentioned. The great majority of the great importance since short, but spieoles are found hroken down into repeated, exposure to massive concen particles of the order of 2 microns and trations of dust is agreed to be very less, many being about 0.5 micron and harmful. Counts Nos. 5, 22, 23, and more or less rounded. The proportion 43 in Table 8 are examples. Much of elongated to rounded particles seems useful work can be done by means of to vary hi the different processes; for serial dust counts in various dusty example, a greater proportion of elon processes in the same factory, and by gated particles is found in the sir near comparison of the results. dry doth weaving than near a spinning The counts set out in Table 6 are frame. Weaving damp reduces the derived from eight different factories, proportion of elongated particles. and It is a matter of interest to con This variety of microscopic spicules, sider whether counts from different particles, and frequently some cotton factories can be directly compared with fibers, found in the samples of dust col one another. Strictly they cannot, lected in the Owens apparatus, results since the content of amoks particles^, in a tendencyto dumping on the cover varies In each group. The difficulty I dip, making counting, especially of the might be obviated by counting only \ higher concentrations, a matter of the particles derived from asbestos. extreme difficulty. Occasionally, also, The method has been applied success pert ofthe slot of the apparatus choked fully to counts of crystalline silica op withdust. The effect of the dump dusts; but it is not so easily applicable ingis to reduce the counts of all except to counts of asbestos dust, which con-y the low concentrations. tains numbers of black and brownish Furthermore, this apparatus is modi iron containing particles, many of influenced by local air eddies and cur* which are not quickly distinguishable rents. It takes a grab sample, which from smoke and tarry particles. la accurate enough ss an indicator of To classify the processes acefirately the local conditions at the moment of on the basis of amount of dost evolved, sampling, but does not give a picture it is necessary to take serial samples at. of the average state of the atmosphere intervals corresponding to the details during a period of time, as does a and complexity of the processes. gravimetric apparatus. Moreover, With some straightforward processes, with high concentrations of dust, such ss spinning, few samples will be accurate counting becomes impossible. necessary; but in others, such as mat The apparatus has, however, many tress making, mixing, grading and advantages, including those of eon opening especially with old-fashioned ' fence, quickness in operation, and plant--in which the evolution of dust I direct examination of the nature of the rises and falls rapidly in a compara dost. By serial observations, too, tively short^space of time, many more temporary and local large increases in observations are necessary throughout ^ at.iL 0iv>53 i J PULMONARY FIBROSIS IN ASBESTOS WORKERS 249 a shift, to detcnnino the average eon* when asbestos tape weayiag dry, and castration of dust. Repeated controls only oncea daywhen wearing asbestos tie also required. wet 4 Comparative data show that the Nextin order comes ms^tressmaking, dustiest processes are opening (with without any precautions such as ex old-fashioned teasers), sieving (with haust ventilation, or damping floors, no local exhaust ventilation), and doth, and tables. Application of ex shoveling, or otherwise asbes haust ventilation and damping reduce tos fiber. The heaviest counts of all the count considerably, bat it is be werefoundin this group, in fillingsacks, lieved that the figures are too low, since by hand, with disintegrated fiber in a counts for some subsidiary processes settling dumber. The visual cloud of mch as buttoning, sewing, and catting dust was intense, and irritating enough out are not available. to provoke immediate coughing on the The figures for spinning, plaiting, part of the observer. The clumping of and braiding are believed to be rather thedust particles of the sample on the too high, owing to contamination of cover slip was very marfrad, with the dust from neighboring and more dusty result that the total dust count arrived processes, and further investigation is at was undoubtedly too low. With required here. counts of asbestos particles of this A number of the samples taken with order, however, the precise count is of the Oweaa apparatus were examined Stile practical importance, since the to determine the sue of the particles, dost concentration is far beyond the sad the percentages of particles 2 safe limit. - wiwaM And tinder, 7*5 microns Nest in order is doth weaving, dry and under, were ascertained. The 2- and without the application of local micron standard was retained for exhaust. This is undoubtedly a dusty purposes of comparison, and because process, and although local exhaust of its accepted importance in silicosis. reduces the oount at the breathinglevel The 7.5-micron figure was also adopted of the weaver, much dust still escapes because of the pronounced adcolar into the workroom. Further counts are character of much of the asbestos dust, necessary to estimate this. Weaving and because, representing the diameter doth wet, not merely damp, reduces of the human red blood corpuscle, it the dost count to a remarkable degree. is a standard easily distinguishable, The figure for band (.*., narrow) and may conceivably represent. the weaving; wet, is not accurate since it limit sin of particles which can be con was raised by dust from a neighboring veniently engulfed by phagocytic cells, 4 dry doth loam; still the improvement which are somewhat larger. Among dne to wet methods is noticeable. One twenty counts from various processes asbestos weaver, who was formerly a (Table 6), in two, between 60 and 70 4 cotton weaver, and who has to wear per cent, of the particles were of sixes glasses, stated that whereas he used to 2 microns and under; in two, 70 to dean his glasses about three times a 80 per cent.; in tea, 80 to 90 per cent.; day when ootton weaving, he has to and in six, 90 per cent, and upward. dean them about five times a day When the counts were ^nalyxed so VO.WMat t r ! j Old 56 250 . THE JOURNAL OF INDUSTRIAL HYGIENE cording to the 7.5-micron standard, all twenty showed 90 per cent, or more of the particles to bo of this size or less. With regard to the effect on the hugs of different varieties of asbestos, no evidence was found to indicate that any one of its varieties is more potent in producing fibrosis than the others, other factors, soeh as concentration of dost, being equal There is now no doubt, however, that both chrysotile and erocidolite will produce fibrosis; while the third, the comparatively newly discovered amosite, resembles eoddolite so closely in its chemical constitution, and in the characteristics of the dost, that there can be no reasonable doubt, also, with respect toifi. % Dmgik cfDust Ezposun Ho ease of diffuse fibrosis dearly due to asbestos waa discovered with under 5 years' employment. Three eases were found with 3, 3}, and 4$ years' work, respectively, who showed clinical signs of fibrosis. Definite confirmatory radiologic evidence was obtained in the first, definite but slighter radiologic changes in the sec ond, and indefinite suggestive changes in the third. The previous occupation fat the first case was flax weaving for 18 years; In the second, coal hewing for 16 yean; and in the third, work in an iron foundry for 1 year. All these occupations are dusty; and in the lost two there may be some exposure to free silica. Also increased silica conteat has been found in the lungs, after incineration, of Sax dressers. For these reasons, these three case, .uld not be certainly ascribed to asbestos dost, although it was, probably, at least a contributory factor. Among the cases of^fibrosis found, thirty-six had been employed in asbestos for periods ranging from 5 to 10 years; two of these cases, one employed for 9 yean and the other for 7 yean, show that a considerable degree of fibrosis may occur with less than 10 years' exposure. F. W. Simeon (6) examined the lungs of a guinea-pig which had been experi mentally dusted by Mavrogordato for two hours a day on each of fifty days between February and April, 1925, and which died from other causes in December, 1927. He states that his tologic sections showed a slight gen eralised fibrosis. This observer also examined portions of the' lungs of two native asbestos mill workers; one had been employed for twelve months and had died from a miliary tuberculosis, and the other, employed for two yean, had apparently never recovered from an attack of lobar pneumonia a year before death. In entnmutfag on fo* amount of fibrosis found, he states that "a com parison between the human eases and the experimental animal showed that the fibrosis was more rapid and exten sive in the human cases, than in the experimental animal," and, again, that "the amount of fibrosis in two of the human eases .... was quite definite, and, if due to the presence of asbestos dost, the initial rate of pro duction was rapid when compared with present-day non-infective silicosis on the Hand." Experiments by Professor Beattie, In 1912, demonstrated that the lungs of guinea-pigs exposed to asbestos dust for forty-threa and sixty-seven hours showed "definite cellular proliferation, though not very extensive, and this is 1* J.LX. 01357 I J T1 PULMONARY FIBROSIS IN ASBESTOS WORKERS 251 certainly a preliminary itage in the production of fibrosis." These pathologic and experimental pwrlingii auggest that the inhalation of asbestos dost rapidly causes some changes in the lungs. But no evidence was obtained that asbestos dust can produce an sente type of fibrosis com parable to that formerly noted in South Africa after repeated exposure to massive concentration of free silica, a few eaaes of which have occurred recently in Great Britain, causing death in from two to four years. The amount of disablement pro duced by the development of pulmo nary fibrosis in these workers is surpris ingly slight for a number ofyears, even more so than is generally the cue is alieoeia. The nature of the work, however, in the majority of the processee does not involve mUch physical exertion--in fact, in this respect it is "light work." Tha effected person may, and often does, continue at work --with occasional Intermissions, lat terly, due to exacerbations of bron chitis--until the condition is advanced, although he suffers increasing incon venience from shortness of breath on the slightest exertion. Usuallythese cases cease wor* a year or more before death, but sometimes a terminal bronchopneumonia, or other acute infection, commences while they are still at work, and there is no long period of invalidism. Particulars of eight deaths have been collected, and are summarized in Table T. In six of these, advanced pulmonary fibrosis was the primary reuse of death. In the remaining two eases, pulmonary tuberculosis was a contributory factor. In^ six of the eight eases the diagnosiejjru verified by postmortem examination; in the other two eases, confirmatory radio graphic evidence wu obtained. Information has recently been ob tained in regard to three other esses, in which death occurred in 1929. The details of one have been published by Wood and Page (25). Postmortem examinations have been made in all three eases, and in all, the presence of pulmonary asbestosis, without tuber culosis, wu verified. In one ease, the pulmonary fibrosis wu the primary cause of death; in one, information u to the extent of the fibrosis hu not yet been obtained; sad in the third case, a lobar poetzmonia wu superimposed on the fibrosis. It le not suggested that these few fatalities, in which the reuse of death hu been verified by strict inquiry, are any criterion of the true effect of the disease on the mortality rates of asbestos workers. Others are known to have occurred in which the exist ence of the asbestos fibrosis hu been determined in life, but no postmortem ersTninition hu been possible. DiffieuUia m Diagnotin Marry factors have contributed to impede both the recognition of indi vidual eases of this disease, and the establishment of asbestos dost u the determining reuse. These factors are consequent, partly on the nature of the disease, partly on the nature of the dust, and partly on the industry itself, its rapid growth and internal condi tions. Difficulties ' - diagnosing the disease. Us prints of resemblance, in its latest stages, to fibroid tuberculosis, and the liability of thou affected to be \' Q; ' Mas . 0i358 rs --1Arrangemaot of iloUa follow* Iho American auctoni * Eatloatad. month, day o f month, year. - : PULMONARY: EIBHOSEj IK JLSBESTOS'WDKKZRS 0253 r carried off by aotne internment dis* . asbestos only for comparatively short < ease--which alone is noted on the death : periods, snd af theprocessesionsideied eertifieatc--are all of importance. o far, the less dustyspinnii^ group is ...A concrete example encountered - at the same .time the largest. .Thus sduripg the inquiry will illustrate one of coaly nowthercmsteace of a health risk ..these points. J. C., Case No. 7 in ::hr.the.:industry is beginning to be "Table 7, was known by his own doctor * recognised. _fnd bythe Chief TubcrculosisOfficer of _ . _ - .the town to be affected with advanced Dod Asbbtos Dotx tom : fibroma of .the lungs. Tour or fire *>" ?" P"0!,UT Mppaths before his death it was thought ^Xtoxasia: tJhat_a...change of. air would be..of TIhe ..important question as to s.#dy*ntog to. him. `Through the gea- ^whether, asbestos workers show,sxuio- i-emaity of the firm with which he had . creased liability to other , diseases of .-been employed, he was--transferred -.the lungs, such as pneumonia, pleurisy, from the town to a farm in the country, end'pulmonary- tuberculosis espec where he died. The death certificate, ially the latter--requires further in* ; given locally, stated that .pulmonary - vestigatinn. t Johereulosia. was the cause of death. A history o pleurisy war given- by 1jit another ease chronic bronchitic-eras ten workers,-in-cghtsince pgiyen as the causa of death. rwork .ia. asbestos;.dn addition, one jn .the less advanced stages of the -worker bed a alight pleural effusion at .-.disease,- the -symptoms ere sounob- -thertime of rramination, and.one rtousive that the worker rarely consults - showed signs of old pleoray, but no Jlia doctor.; jn the later stages,. broa- ihistory -was obtainable. .Of-the two '.chitia, or- the. supervention of-acute Twith attacks-prior to wurkin.asbestos, .bronchopneumonia, pulmonary tuber- . ooe.had.narmai lungs,, and .the other fuiosis, pr other acute infection,.aQ so showed signs, of.*.bronchiectasis. -.'Of -{qach more common, masks theunder- :Jhe right:giving.histories: nt pleurisy, ;jyj?g.fihrosi3;.and tho torminaleondi* :'three< showed - signs; ofufibrnris,: four rjtlon<is'noted as.the cause of.death. * ishewed-aigna. ofithe oid-pleurisy only llAAheserandploco, tho silicate-duets (onerbdogeidue; to_angniahotv.wquhd -a^pf-.whicb. asbeatos.dustis onerrepse- ciduring -.the n?ax), tend -.the righth tfgnfog silica jn ihe-combined form as showedsigu atan old inactive tuber- copposed to free- silica, have.oatanlly ceuloiui'icsion--ofr iherrightuppet Jobe. been overshadowed by tbe silica,dusts, A ..bietory - of pneumoniav.was ob f/gnoe they dp not produce.the picture -. tainedin sixteen-workere--in ten prior of silicosis and have not been shown to -.to commencing-workin.asbestos, and be associated with an increased mor- in six since. Of these six; two showed tality from pulmonary tuberculoaia. signs of r thickened- pleura only, one Moreover, although the asbestos in- .showed merely enlarged hug-roots, ..dustry has very rapidly expanded, it-is - two had diffuse- fibrosis, andin one the f0tSU comparatively small, and scattered .Jungs werenormal. 0 the-remaining cover the country. A large proportion - ten, one had a thickened pleura,* two ipt theworkers have been employed in - bronchiectasis; twodiffuse fibroma, one t VL IS . Jkl _? o.id';so J I 2S4 THE JOURNAL OF INDUSTRIAL HYGIENE commencing fibroeia, and la four the and are of no importance unless it is hup were normal. shown that the inhalation of asbestos With regard to evidence of bron- dust is associated with pulmonary AM| gad bronchial and pulmonary tuberculosis to an increased degree, catarrh, fifty-eight of the 363 workers when such eases, ss indicating a group (16 per cent.) showed signs of one or of workers with a latent infection, other of these conditions, all being would assume a greater significance. quite mild. Of these, thirty-one also No close association is apparent, how showed signs of diffuse fibrosis, repre ever, since only thirty-seven, or 9.9 senting 32.6 per cent, of the fibretic per cent of the 374 examined, showed group, and eight were in the prefibrotic evidence of this disease, excluding eases stage (38.1 per cent, of that group). of old inactive hilar tuberculosis, even The fact Hth'hi1 aTamirtatinna when those showing the minor changes were conducted during the wanner mentioned above are included. In months of the year, no doubt operated only four was there a family history of to reduce the incidence of these com pulmonary tuberculosis; and three out plaints. Underthe rircnrnstances, the of four active eases belonged to this preponderance among the cases of group. Thirty-three eases were inac fibrosis is the more noteworthy, as In tive, of which twenty-one presented no dicating persistent irritation resulting evidence of dust fibrosis, and twelve from the dust. presented evidence. Of other diseases, ei^rt gave his Out of the 374 persons examined, tories of rheumatic fever, and of these, fourteen, or 3.7 per' cent., gave a two had definite valvular disease of the family history.of tuberculosis. Evi heart. In addition, valvular disease of dence of active pulmonary tubercu the heart was noted in one worker, but losis was present in three; is two of no history of rheumatic fever was ob these three the source of infection tained. appeara to have been a near relative. With regard to pulmonary tubercu Thus, no outstanding susceptibility losis, so definitely an added risk in sili to pulmonary tuberculosis was dis cosis, this disease group has been closed, either among asbestos workers drawn up to include all workers pre aa a class, or among those with fibrosis, senting signs indicating s past or pres considering the frequency of old healed ent pulmonary tuberculous infection, apical lesions among the general but excluding cases of old Inactive hilar population. tuberculosis. Under this heading are We have, however, by no means dis included not only workers with definite posed of the question. The superven dinieal signs of active tuberculous tion of a tuberculous infection on a hmg infections, or of old inactive long already the subject of fibrosis pro lesions, equally definite, but also those duces an increase in symptoms, pre workers showing signs of old apical col viously unnoticed or disregarded, and lapse, usually attributed to a past causes the worker to scck his doctor's tuberculous infection. advice. He is th& appropriately Signs of the latter arc not uncom advised to give up lys dusty employ monly found in quite healthy persons. ' meat, migrates fromjhc industry, and XX.S. JaafeKS OioGi 'i i PULMONARY FIBROSIS IN ASBESTOS WORKERS 255 nay or may not accept sanatorium treatment. Thus there tends to be a drift of such eases from the fibrosis producing industry. * produce a serious and even fatal degree of pulmonary fibrosis. . 2. Hie type of fibrmhj produced, however, exhibits a number of diverg During the course of the inquiry, ences from that caused by the inhala information eras obtained of a number tion of free silica dost, and the outcome of persons, previously employed in of these variations is not yet apparent. asbestos, who were either at home or in 3. Hie divergences noted so far. are aanatoriums, suffering from ehest com exhibited in the radiologic picture, plaints. Where an examination of and on postmortem examination of workers is confined to those at work, a the affected hings, both in the gross certain number of advanced eases of morbid anatomy and in microscopic fibrosis, and a certain number of eases sections. of pulmonary tuberculosia, with or 4. In the latter case the appearances 4 without an asbestos fibrosis, in persons of the asbestos fibrosis seem to be who have either given up work, or who sufficiently distinctive not to permit are off work temporarily, will be of confusion between it and silicosis. miaeed. 5. The radiologic appearances of the It is necessary, therefore, to leave asbestos type of fibrosis, even la the this question of increased susceptibility more developed stage, are more deli i to pulmonarytuberculosis in abeyance cate, softer, and more diffuse than the pending further investigation. ailieotie fibrosis. Withrespecttoany increased suscep ft. It follows, therefore, that an tibilitytothe superventionofotherlung opinion as to the degree and intensity diseases in workers with an asbestos of an asbestos fibrosis, based on a com fibrosis, the data obtained were insuffi parison of the radiologic changes with cient to lead to any conclusion, except those shown in standard silicosis films, as to bronchial catarrh. There are in will be an underestimate. dications, however, that when pneu 7. In the absence of a full medical monia or bronchopneumonia super and industrial history, possibilities of venes on a fibrotic lung, the prognosis confusion of the two types of fibrosis is grave. will arise in the interpretation of redio- grams. AnxsTosa and Srucosts Coxnusm 8. There is evidence that other in In view of the relationship between organic dusts, containing no free silica, 4 the asbestos fibrosis and silicosis, since may be productive of this fine type of they are both varieties of fibrosis of fibrosis in varying degree. the lungs caused by the inhalation of - dusts, it seems desirable to stunmarine SointuKT shortly the main points of similarity L There Is * definite risk wf -tbs ud dissimilarity between the two dis devefopment of a diffuse pulmonary eases, so far as has been ascertained. fibrosis in persons exposed to the in L Inhalation of asbestos dust, under halation of asbestos dust. favorable conditions of concentration 2. This risk varies directly as the of dust and length of exposure, will length et employment (and hence MS at r I i Oio'62 \ 358 THE JOURNAL OF INDUSTRIAL HYGIENE length of expoaun to dost), and is unaffected by the age of the worker. 3. There is a considerable difference between the least dusty and the most dusty processes investigated, and there is a corresponding variation in the rela tive risk of. the development of fibrosis in the workers in these processes. 4. With continued exposure to high concentrations of dust, the disease may be fully developed in seven to nine years, and may cause death after about thirteen years7 exposure, exceptionally ta a shorterperiod. 8. fibrosis as it occurs la asbestos workers differs considerably from the disease as it occurs in workers exposed to free crystalline silica dust; it differs in the radiologic picture, and also on postmortem examination of the affeetcd lungs. 8L The mare dusty procesou are those involving the preparation and manipulation of the raw asbestos (other than crashing), dry doth weav ing, and mattress making. 7. The less dusty processes are spin ning and similar processes, and proo- esMs, other than dry weaving; in volving the manipulation of the spun yam. - 8. Further investigation is required to determine whether there is any in creased susceptibility to the superven tion of pulmonary^ tuberculosis asso ciated with the development of the asbestos fibrosis. Much generous assistance has boon re ceived from maar eoureet during tin course ef this inquiry, and for this acknowledgment is gratefully tendered. In addition to thoos already referred to, the writers beholden especially to Dr. S. A. Henry, who did much to facilitate the inves tigation, particularly by his detailed reports on various relevant matters, and by aoeh organiiatiou sad liaison work; to many others of his colleagues in the different dis tricts, to a number of directors and officials of various firms, foremen, tad employees; to Dr. W. . Cooke of Wigan tad Professor M. J. Stewart of Zeeds for pathologic mate rial and for much information aa to the progress sod results of their oara researches into the gross anatomic and tbs histologic features of the asbestos fibrosis, sad the eooetitation sad location of the carious bodies; to Dr. MacGregor, Medical Officer of Health for Glasgow, for various clinical aad radiologic facilities, and for his ever present readiness to lead the aid of hie Department, and especially to Dr. H. E. Seder of hie staff; to Dr. J. C. Robertson for the loan of a radiogram, together with detailed clinical notes of ooe patient aad other valuable Information; to Dr. W. H. for tbs loaa of a radiogram, for tome 1 histories, far obtaining aad examining several specimens of sputum, aad for other aid; aad to Dr. J. Rennie, Chief Tuberculosis Officer at Sheffield, for a aeries of radiograms showing various stages of riUsoniw BIBLIOGRAPHY L Departmental Committee on Compet estion for Industrial Diseases. 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