Document mqygZ7wqrwo9J5gpDb7ooVpnJ

icosis and eilico-'' ouri State Med. lary asbestosis. 931). .. me, S. R.: Pul- ancet, tl8, 445 3is--Review of -nd prevention. Septs., 49, 595 HE dangerous dust diseases, are the cause of the distinctive pul silicosis and asbestosis, are be monary fibrosis called asbestosis. ing widely studied at present. Gardner writes that "these asbestos It has been estimated that there are particles are phagocytoscd as they are more than 750,000 silicotics in the caught on the irregular walls of the United States while there are only terminal bronchioles. The phagocytes ^%'u35*000 to 40,000 persons engaged in for the most part migrate directly into the asbestos industry in the world. the substance of the adjacent walls " W.v. bi the United States in 1929 a total and there stimulate growth of connec of 9,237 persons were said to be em- tive tissue cells. There results a . ployed in the manufacture of asbestos collar of fibrous tissue about the ter products other than steam packing minal bronchioles which contracts and and pipe and boiler covering. While constricts the tubes. The constriction ; it employs a relatively small number produces collapse of the distal alveoli - . - of persons, the asbestos industry has (atelectasis). The collapsed area be ;. had a remarkably rapid expansion and - by reason of the widespread and varied 'TV 7. uses of its products which include . "matches, filter pads, paints, roofing, ; high pressure jointing, electrodes, brake linings, clutch rings and insu. luting material in a great variety" v:c..;ythe industry occupies an important, comes fibrous from mechanical causes (collapse induration). In asbestosis unlike silicosis there is little or no transport of dust into the lymphatic system and no nodule formation." "Intervening units (between the af fected lobules) not being involved still contain air and permit the passage of ^creasing, and permanent place in x-rays. Consequently the roentgeno our economic establishment. gram fails to show massive homogene ... : > v Asbestos is described chemically as ous shadows." The appearance on the VS a hydrated silicate of magnesia con- film has been frequently likened to taining little iron and almost no ground glass. . calcium. It is a fibrous mineral which This paper reports the results of a :i ; ca^ he split up into flexible fibers for survey of 210 persons exposed to - .. spuming and weaving. When it is asbestos dust. The conditions im processed some of these fibers are fragmented. The fine fragments are mhaled by the workers. It is the ' V-. Articles smaller than 10 microns which posed upon the survey did not permit the thoroughness of study to be desired, but all of the employees were given a brief, general clinical examina `Received for publication January7,1930. tion which included taking their past 229 ( 230 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Apr., m$ health and occupational history and a physical examination. No labora tory examinations were made. AH had a single him made of the chest. The dust concentrations are not equal in the various departments. In the preparation department the proc esses of grinding, crushing, and mix ing are carried out. Here the quantity of dust is greatest and consists almost TABLE 1 HCM* n> bik C*NT Total examined.......................... Normal lungs.............................. Pulmonary fibrosis, linear type. Heavy linear shadows in tho cardiophrenic anglo................ Cardiovascular pathology......... Pleural adhesions....................... Azygos lobes............................... Bony pathology.......................... Pleuro-pcricardial adhesions... Bronchiectasis............................ Asbestosis questionable............ Asbestosis moderate.................. Asbestosis advanced.................. Primary pulmonary tubercu losis: Primary foci............................ Calcified lymph nodes........... Secondary pulmonary tubcrcu- losis: Minimal.................................... Moderately advanced............ Far advanced.......................... 210 123 0 11 24 7 2 4 5 3 20 25 8 6 5 2 4 0 58.8 4.3 5.2 11.4 3.3 0.9 1.9 2.3 1.4 9.5 11.8 3.3 2.8 2.3 0.9 1.9 0.0 entirely of asbestos particles. In the other departments the material proc essed is a mixture of asbestos and cotton. Here the proportion of as bestos particles is less and the total dust is also less. Table 1 summarizes the various types of pathology noted in the films. Of the 210 persons examined, forty-five were negroes. The films of one hun dred and twenty-three, 58.5 per cent, were regarded as showing lung-fields that were normal, except for a primary tuberculous focus in small one. * * Of the 210 films, fifty-three, 25.2 per cent, were regarded as showing definite or questionable evidence of asbestosis; of the fifty-three, 20 films were classed as questionable. Had stereoscopic re takes been allowed, it is believed that this number could have been greatly reduced. The indispensability of a competent roentgenologic technic needs to be emphasized. Thirty- three films, 15.7 per cent, showed definite asbestosis; in twenty-five, 11.8 per cent, the process was moderate in extent; and in eight, 3.8 per cent, more advanced. In the remaining 34 films various types of thoracic pathol ogy were noted, none of which were ascribable to asbestos dust. ' Table 2 presents the normal lung group and shows the distribution of the group in the various age-periods; the incidence of cardiovascular abnor malities seen in the films and dyspnea according to age-periods; the number with chest expansions averaging ap proximately inch, 1$ inches, 2\ X3 inches and 3} inches; the total number of employees in each department whose lungs were normal, and the numbers and lengths of exposure to asbestos dust of those in the several departments. .'"siSsS--- Table 3 shows the incidence and extent of asbestosis from increasing periods of exposure in the several departments. In this table employees are placed in the department where they work at present. It is obviously a practical impossibility to trace the. transfer of each individual from de partment to department and as the vol. 18, no. 41 EXPOSURE TO ASBESTOS DUST 231 management states that something like 95 per cent of employees continue in the department in which they began, it has been assumed in the discussion that the employee has been at his present work throughout his exposure. From this analysis it appears that of 9 persons exposed for more than 15 years to dust concentrations effective in producing disease, four, 44 per cent, sufficient in a great percentage of these cases to produce asbestosis. Attention is called to the fact that in the same department, that is, where the concentration of dust is the same, some exhibit the disease after a short exposure while others, after much longer exposures, escape. Nor is the incidence of disease always as great among those who have been TABLE 2 Analysis op Group of Ewploytes wtrn Normal Lunos ACC 16-24 yean 25-34 years 35-44 years 45-54 yean 55-54 years TOTAL Number in each age period... Dyspnea................................... Cardiovascular abnormalities. Chest expansion...................... 36 1 0-1 Number in each grade........... Years of exposure................... 2 1-2 57 6 2 1-2 in. 67 2-5 22 1 3 2-3 in. 48 5-10 6 2 3-4 in. 3 10-15 2 1 2 Not recorded 3 15-20 123 9 9 123 Departments: Preparation.......................... 4 1 Carding................................ 6 4 4 2 Mule spinning..................... 5 1 4 1 Spooling................................ 3 2 4 1 Twisting............................... 11 1 5 1 Winding................................ 19 1 7 3 Ring spinning...................... 1 1 Weaving............................... 8 2 8 1 Maintenance........................ 4 3 2 Total................................. 61 14 35 10 5 16 2 13 10 18 30 2 1 20 9 3 123 escaped asbestosis; of 32 persons ex posed for more than 10 years to similar concentrations, fourteen, 43 per cent, escaped; of 70 persons so exposed for more than 5 years fortyfive, 64 per cent, escaped, and of 28 persons exposed for more than 2 years and less than 5, twenty-four, 85 per cent, escaped. Prolonged exposure to disease-producing concentrations of dust alone docs not seem to have been exposed for equal periods in depart ments where concentration of dust is greater as among those who work in departments where it is less. The incidence of disease increases with the duration of exposure and the concentration of effective dust, but not directly or constantly. No length of exposure or concentration of dust produced the disease in more than 60 per cent of persons exposed in any 232 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Apr,, 19S8 department. It seems to be true everywhere, that somo workers are not affected however long the exposure or high the concentration. These facts suggest differences in suscepti bility. As to what deficiencies in defense or possible reinforcements of the attack exist in those in whom asbestosis occurs, other than the recognized difference in the compe- were made to observe the behavior of respiration in response to the changing ventilatory demands of graded physi cal exercise. Dyspnea here means that the persons replied "yes" when asked, "Do you have any shortness of breath under ordinary circum stances?" This "yes" is understood as meaning that these persons when engaged in usual activities were with TABLE 3 Analysis or ErFscr and Duration or Exposure in Various Departments DURATION OP XXPOSCU 0-2 yc*r* 2-5 year* 5-10 ye*n 10-15 ye*rt 15-20 year* DEPARTMENT* 0$ l L. ** |i i 0 ZZ 3 .a8 sm 1 &a o8 | 1e |4 < is z 0 Z sA4ek s i &a 1 if fi <Z a Z0 3 a9 Q 3 a 1 a 1* V<t IS z o Z 3 a s 3 i ti &a of 1 a -to < is z 1 a Z jb A a0 1 9 O' S g a8 1 a to < i H Preparation... Mule spinning. Ring spinning. Maintenance... 33 87 55 33 15 15 20 20 11 10 10 66 1 80 2 33 22 11 33 11 54 i 54 i 7232 13 5 1 3 4 8G 2 G5 1 071 1 08 1 11 12 0 1 2 531 1 11 71321 32 1 321 32 1 G4 1 1 11 51 1 3 31 1 1 3 11 42 2 12 5 1 11 2 1 1 11 5 21 1 3 Total............ 71 70 1 28 24 2 2 70 45 8 12 5 32 14 7 9 2 9 4 2 2 1 33 Number with dyspnea....... Cardiovascular 1 31 3 2 7 23 2 24 21 23 251 1 1 24 24 greater or less frequency conscious of an unaccustomed sense of inadequacy attending the ventilatory process. This experience was not infrequent among persons with lungs roentgeno logically and by physical examination normal, occurring in 8.1 per cent. The experience was more than twice as frequent among those with definite asbestosis. Six of the 33 asbestotics ful. i (18.1 some 25 n more vane tory no c. of or their asbe.freqi age, 45 y< vol. 18, no. 4\ EXPOSURE TO ASBESTOS DOST 233 (18.1 per cent), stated that they had some shortness of breath; three of the 25 moderate cases and three of the S more advanced. But the most advanced cases showed no special respiratory effort during examination and of tiic twenty-four with dyspnea showed cardiovascular pathology in the films and also had high blood pressure, but none of the five had definite asbestosis. Dr. William S. McCann reminds us: "Respiration is Eic. 1.--Moderate usbestosis. Heavy pectoral muscles exaggerate the apj>barniiee of fibrosis. no cyanosis and none declared lack f or impaired ability to carry on at their jobs. Among the thirty-three asbestoties, dyspnea was twice as frequent in those under -15 years of age, 42.1 per cent, as in (hose over 45 years of age (21.1 per cent), l-'ive not a function of the lungs alone but of the heart, blood and tissue ability to absorb oxygen, and also to undergo oxygen want surh as tiie trained muscles of athletes withstand oxygen want." Decreased chest expansion may be 231 joi'kn u. i>r j x i u s i i: i a 1. inui.M. .wii n\K oi.iha .1/" . r.'-.r, said to be the cardinal sign of as-be>to>is. Among the normal lung group, 56 jkt rent had an expansion umlrr 2 inches, `14 per cent above 2 inches. In the group with definite asbestosis, 09.0 ]M"r cent, had a chest expansion of less than 2 inches, 30.4 per cent, had an expansion above 2 inches. The proportion of those with the lower degree of expansion was increased about 24 I>er cent among the ashestotics. Chest expansion depends not only on lung distensibility but on the mobility of the bony and soft tissues of the thoracic cage ami of the dia phragm. It is often astonishing how training and practice can rapidly in crease chest expansion. The indi vidual learns to exercise fully anatomic capacities which were present prior to the training. Worn the foregoing findings it ap|>ears that the assumption that a sense of air want and restricted chest expansion are due to tut existing asbestotie involvement of the lungs roentgenologiealiy manifest, should not be made too hastily. Studying the compatibility of as bestosis with length of life and work it is to 1h> noted that: One employee with advanced asbestosis above the age of 55 who had worked in dust more than 15 years was still able to work. One employee, 51 years old, with advanced asbestosis who had worked in dust more than 10 years was still aide to work. Three cm* ployccs with moderate asbestosis and above the age of 44 who had worked in dust more than 10 years were still able to work. Of this group of 5 asbcstotics above the age of 44 (three with moderate asbestosis and two with advanced asbestosis), one com plained of shortness of breath. Of the eleven with moderate asbestosis and the three with advanced asbestosis who had worked more than ]() years, one, (7.1 |ht cent), complained of shortness of breath; these fourteen men hail chest expansions winch com pared favorably with the normal lung group. Sixtv-six and two-thirds per cent of these 14 asbcstotics bad a chest expansion under 2 inches, whereas 50 j>er cent of the normal lung group had the same limits. But 7S.9 per cent of those with definite asbestosis who bad worked in dust under 10 years bad chest expansion under 2 inches and 26.3 per cent complained of shortness of breath. The older jiersons, whether with mod erate or more advanced asbestosis, appear better adjusted to the disease. 'Hie average exposure for the entire group with asbestosis was 10.2 years, for those with moderate asbestosis 10.3 years, and for those with ad vanced asbestosis, paradoxically, 10.0 years. If the entire group with as bestosis is divided into those below ami those alxive 40 years of age, the exposure of those with moderate asbestosis below 40 years of age was 9.5 years and above 10 years of age, 12.4 years. For those with advanced asbestosis the corresponding averages were 9 and 11 year.- respect ivciv. Advanced asbestosis may exist in late age-jienod.s with working ability not impaired below the level of con tinued employability in the depart ment where the disease was incurred. Xo very rapid development of the disease was noted. Only 2 eases occurred where the exposure had been less than 5 years. As a rule o or more years of exposure was required 4 ;,.! to c orali in si! po.-ei east's in lh Ti effee in L Apic note then I'l pr., i$se breath. Of ite asbestosis cod asbostosis ban 10 years, miplaincd of .esc fourteen s which eomnormai lung vo-thirds per ofies had a 2 indies, the normal nine limits. with definite ked in dust 't expansion -.3 per cent of breath. r with mod ! asbestosis, the disease. >r the entire 10.2 years, ' asbestosis e with ad* iically, 10.0 ;p with ashose below of age, tlie moderate of age was ars of age, h advanced :g averages ively. '.y exist in ing ability el of coil in' rleparts incurred, ut of the 2 cases > had been rule 5 or s required vol. 18, no. 41 KXPoavRi: to a.shk.stos di\st 235 to cause the disease. No conglom erate or massive lesions such as occur in silicosis where infection is superim posed were found in these asbestosis cases. The progression of the disease in this group was very slow. losis seen in these films. If it ran be assumed that most of these infiltra tions formed in the late 'teen age or before 25 years of age, then exposures to asbestos (lust varying from 5 to 15 years had produced no evidences of Fid. 2.--Advanced asbestosis, emphasized at left base. Fpper lung fields emphysematous. The evidence presented as to the effect of asbestosis upon tuberculosis in this survey is somewhat limited. Apical tuberculous infiltration was noted in the films of 17 employees; there was no other evidence of tuhereu- aetivatiou to be seen in the films. Four of these apical tuberculous in filtrations were found in asbestotics, two with moderate and two with more advanced processes. Six lesions with clinical significance were observed: 2 Jof) .KH'UNAt. <>!' IN |l <n:l \I. HYCII.Ni: AND T<>\|( ol.ocY ..I/>r,, ww. minimal and -1 moderately advanced (American Sanatorium As>ociat ion Clas>ifieation). One moderately ad vanced lesion was found in a man 21 years old who had been exposed to asbestos dust in the winding depart- gardrd himself as in good health. One of the moderately advanced le sions was found in an employee 37 years of age who hud worked in the winding department for 9 years and showed no evidoneo of ashestosis. A Kio. 3.--Lateral position. (Same case as pig. 2.) ment for G years. The lesion appeared "soft" and unstable; there was, how ever, no evidence of accompanying ashestosis. The disease in this mod erately advanced ease was clinically manifest, though the employee rc- ihird employee with a moderately ad vanced tuberculous lesion had worked in the twisting department for 10 years but had no ashestosis. The fourth, an employee 37 years of age who had worked in the weaving dc- r., 1036 health, ed le~ \'cc 37 in the rs and -is. A / ad- rked r 10 The ; do- ; ** 41 EXPOSURE TO ASBESTOS DUST 237 Apartment had moderate asbestosis. 'ir^The tuberculous lesion in this case f-could satisfy rigid criteria of a healed . lesion. Three of these lesions were .Tractive and were accompanied by clini- ' cal manifestations. The one lesion associated with asbestosis was healed and the employee apparently was in good health. One of the two minimal ^ lesions was in a man 24 years of ago who had worked 15 months in the twisting department and whose films did not show asbestosis; one in a man ` 37 years of ago who had worked 12 years in the winding department and The films were studied to discover any accentuating effect of a focus of tuberculosis on the surrounding as bestosis. No convincing evidence of such an effect was seen. Tuberculosis and asbestosis were coincident in only 5 employees. The average dura tion of exposure for the five was 10.4 years and for the entire group with asbestosis 10.2 years. No accelerating effect of tuberculosis on asbestosis could be inferred. Twenty-four films showed abnor malities of the heart and aortic shad ows (Table 4) and eleven of the TABLE 4 Group or 24 Emplotees With Abnormalities op tub Heart or Aortic Shadow 101 15-24 ytn 25-94 yarn 55-44 yan 45-54 yean 55-50 ymn Number of employees in each ageperiod ............................................. Dyspnea............................................. Hypertension.................................... Years of exposure............................ Number of employees...................... Asbestosis.......................................... 0 0 0 0-2 4 7053 12 1 0S43 2-5 5-10 10-15 15-20 299 32 had no asbestosis. One of these minimal lesions was apparently healed. It is felt that no evidence of an aggravating effect on tuberculosis by asbestos dusting is to be found in these cases. Only one of the six clinically significant lesions was ac companied by asbestosis and that lesion had every appearance of being healed. The incidence of pulmonary tuberculosis (2.8 per cent), is regarded 83 comparable to the incidence in many other industrial groups in which the association is close and prolonged and whose general standards of living and hygiene are not as good as might he desired. twenty-four abnormalities were found in the 45 negro employees. A Wasserman test was not allowed. Ten of these negroes were under 45 years of ago and one over 55 years of age. In this group of 24 employees with cardiovascular changes, three had a normal blood pressure and the rest had hypertension. Five of the group with cardiovascular abnormalities had def inite asbestosis, three of these were negroes under 35 years of age (Table 5). . _ Waring and Black in an admirable paper discuss, "The Syndrome of Ob struction in the Lesser Circulation" (Am. J. Med. Sci., A/ay, 1034) and 238 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Apr., 193$ give as its clinical features, cyanosis, dyspnea, polycythemia, and right ven tricular preponderance. The blood was not examined in the cases here described and no electro cardiograms were made. Cyanosis and dyspnea were not observed in any of the 5 asbestotics with cardiovascular disease. In view of tho pathology characteristic of asbestosis, namely, constriction of the terminal bronchioles with no perilymphatic or perivascular fibrosis as in silicosis, less obstruction tions in the group docs not appear to be excessive. To make a scientific appraisal of the effect on the employees in this plant of exposure to asbestos dust, it is necessary to know how many employees during the 15 to 20 years covered in the study have died or quit and how many of these had asbestosis. This knowledge is not available. Cer tainly it might add greatly to the gravity of the picture. The most that could be done was to note the effect TABLE 5 Asbestosis with Cardiovascular Lesions KMttOTta MO. SI XUPLOTSa xo.W runoTxi MO. 131 zwnorxB ho. 13S zunoTza mo. 197 Age............................ Race.......................... Blood pressure......... Years of exposure... Asbestosis................. Dyspnea.................... Chest expansion....... X-ray pathology.... 44 White 174/96 13 Moderate No 2.5 in. Enlarged aortic shadow 53 White 170/110 3 Advanced No 1.5 in. Enlarged aortic shadow. Enlarged left ven tricle 27 30 30 Black Black Black 158/104 130/92 134/90 7 10 7 Moderate Advanced Moderate" No No No . 1.5 in. 1.5 in. 1.5 in. Enlarged Enlarged Enlarged aortio heart aortio shadow. shadow. shadow Enlarged Both ven right and tricles en left ventri larged cles of the lesser circulation would seem to be expected in asbestosis than in silicosis and consequently less strain on the right heart. The frequency of respiratory infec tions was investigated. Each em ployee was asked, "Have you had severe colds, `flu/ or pneumonia and how often?" None said they had had pneumonia, six said they had had "flu," eight mentioned having had colds since being exposed to asbestos dust, and one spoke of having frequent colds.. The reported respiratory infec- on those now present in the plant, after varying periods of exposure. Summary 1. In addition to duration of expo sure and concentration of effective dust, it appears that individual re sponse to the inhalation of asbestos dust is an important factor in the production of asbestosis. 2. Asbestosis is infrequently found before 5 years of exposure to industrial concentrations of asbestos dust. In pr., 1938 y- pear to '.' usal of rin this ,/-|f s dust, - '% many ) years ~j or quit estosis. ". Cer- .; to the ": st that : effect PLOTS* 0.167 30 lack 4/90 7 ierate Xo > in. rgcd rtic adow '** vol. 18, no. 4! EXPOSURE TO ASBESTOS DCST 239 this group even under dusting which continued 15 years or more, the disease did not progress to an extent of involvement attended by marked clini cal manifestations or disability. 3. Roentgenologicallv advanced asbestosis was not incompatible with ability to work at the process in which it was incurred. Continued work entailing exposure to disease producing concentrations of asbestos dust slowly increases the extent of fibrosis and so is to be advised against. 4. The evidence presented in this study warrants the opinion that with the reduction of dust concentration now feasible by available dust elim inating devices, the incidence of sig nificant asbestosis would in time! approach the vanishing point. 5. No activating or aggravating effect of asbestos dust or asbestosis on tuberculosis was observed. 0. The evidence of this study, as to the effect of asbestosis on the lesser circulation, is inadequate for forming more than impressions. It does not suggest any marked tendency on the part of asbestosis, with the degree of involvement ob.-erved to obstruct the lesser circulation. 7. No increase of respiratory infec tions was reported in this group. S. There is some evidence which suggests that asbestosis develops more rapidly in younger persons than in older. plant, expoctive d re- A SURVEY OP A GROUP OF EMPLOYEES EXPOSED TO ASBESTOS DUST* S. B. McPbzxttbs CXmrioUM, Xvrtk Csntiam HE dangrrou* dust diseases, are the cause of the distinctive pul Tiilicwiit .ind asbmturis, are beijtg widely studied at present. monary fibrosis called aabestosia. Gardner writes that ``these asbestos It has been imated that there apraerticles are phagocytoaed as they are more than 750,000 ailicotics in the caught on theirregular walla of the Uaitod while there are only terminal bronchioles. The phagocytes 35,000 to 40,000 persons encaged in for the most part migrate directly into the asbestos industry in the world. the substance of the adjacent walls In the United States in 1929 a total and there stimulate growth of connec of 9X17 person* wore said to be ea- tive tine cells. There results a pioyid in the manufacture of asbestos collar of fibrous taros about the ter product? other than steam pocking minal bronchioles which contracts and and pipe and boiler covering. While constricts the tubes. The constriction it employs a relatively small number produces collapse of the distal alveoli of prisons, the asbestos industry has (atelectasis). Ths collapsed area be* Had a remarkably rapid expansion and comes fibrous from mechanical causes by reason of the widespread and varied (collapse induration). In asbestosis lues of its products which indude unlike dlrcosis there is little or so "matches, filter pads, paints, roofing; transport of dust into tbs lymphatic high prearore jointing, electrodes, system and no nodule formation," brake lining, dutch rings and insu "Intervening units (between the af lating material in a great variety'* fected lobules) not bring involved still the industry occupies an important, contain air and pannit tbs passage of increasing, and permanent place in x-rays. Consequently the rowtgeno- our economic establishment. gram fails to show msarive homogene Asbestos is described chemically as ous shodows." The appearance on the s hydrated silicate of magnesia coo* film has been frequently likened to taioiug little iron and almost so ground {lass. calcium. It is a fibrous mineral which This paper reports ths results of a can be split up into flexible fibers for survey of 210 persona exposed to spinning and wearing. When it is asbestos dust. The conditions im processed some of these fibers are posed upon the survey did set permit fragmented. The fine fragments an the thoroughness of study to bo inhaled by rim worker*. It is the desired, but all of the employees were particles mailer than 10 microns which given a brief, g-- HeceiTidforpublication January7,1936. tion which included taking their past 230 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY Uf^n KW* health and occupmdonAl history and a physical examination. No labors- tory examinations were made, AH had a single film made of the chest. The dost concentrations are .not eqoal in the various departments. In the preparation department the proe- eases of crushing, and mix ing ore carried out. Here the quantity of dust is greatest and consists almost TABLE I sm> m Total cmained......................... 210 123 Pulmonary fibroma, linear type- 9 Boawj Ua*r ihadowa in the nnHuphwiifa Cardloremnlir pathology......... U 24 T Asycoa lotas............................. 3 Bony pathology........................ 4 PlmrcNfoneardial adtarions... 5 Broaohieetisa........................... 3 Aataetoeie qiwftonabto............ a Attartooia modems................. s Aetaetoria advanced................. 8 Primary pulmonary tubercu loma: Primary foes........................... 8 Calcified lymph nodes,......... S Secondary pulmonary tubercu loma: Mhrat.1 3 Moderately advaneed............ 4 Far advaneed......................... 0 38.8 4.3 5.3 11.4 3.3 0.9 1.9 3.3 1.4 9.5 11.8 3.8 2.8 2.3 0.9 1.9 0.0 entirely of asbestos particles. In the other departments the material proc essed is a mixture of asbestos and cotton. Here the proportion of asbestoa particles is leas and the total dust is also leas. Table 1 summarises the various types of pathology noted in the films. Of the 210 persona examined, forty-five ware negroes. The films of one hun- dred and twenty-three, 684 per cent, were regarded as showing hxng-fieldn* that wen normal, except forra email primary tuberculous focua hr ona*`*** Of the 210 films, fifty-three, 254-per IT V cent, were regarded aa showing definite^^ or questionable evidence of asbestosia*; of the fifty-three, 20 films were classed as questionable. Had stereoscopic re- V.vj takes been allowed, it is believed that . ~ this number could have been greatly t reduced. The indispenaability of .a competent roentgenologic technic needs to be emphasized. Thirty- three films, 15.7 per cent, showed definite asbestoda; in twenty-five, 114 per cent, the procue was modem** in extent; and in eight, 34 per cent, more advanced. In the remaining 34 films various types of thoracic pathol ogy were noted, acne of which were tecribahle to asbestos dot. Table 2 presents the normal hmg group and shows the distribution of the group in the various age-periods; the incidence of cardiovascular abnor malities seen in the films and dyspnea according to age-periods; the number with chest averaging ap proamateiy } inch, 1} inches, 2| inches and 3$ inches; the total number of employees m each department whose luB^ were normal, and the TMinben and lengths of exposure to asbestos dost of those in the several departments. Table 3 shows the incidence and extent of asbestosa from increasing periods of exposure in the several departments. In this table employees are placed in the department where they work at present. It is obviously a practical impossibility to trace the transfer of each individual from de partment to department and u the KX70SUBE TO ASBESTOS DUST 231 ajaoagwaeot states that something fog 95 per cent of employees continue in the department in which they began, it has been assumed in the discussion tbat the employee has been at his -reseat work throughout his exposure. From this analysis it appears that of 9 persons exposed for more than 15 yona to dust concentrations effective introducing disease, four, 44 per cent, sufficient in a great percentage of these cssss to produce asbestosis. Attention is called to the faet that in the same department, that is, where the concentration of dust is the same, some exhibit the disease after a short exposure while others, after much longer exposures, escape. Nor is the incidence of /finesse always as great among thoarwho have been TABLE 3 Akaatsis ov Oaoev or Exnom wrrx Noams. Lmraa MB IHIfW a hi-- o-Mtm (Mm IHli dumber ia *ocb period... UvupoM.................................. t rjniwraaeuUr iboocmaHtior 36 1 04 Yriim f ttporuw................... 3 1-2 57 a 2 1-2 ia. 97 2-5 22 1 3 2-3 ia. 48 5-10 5 2 3-4 ia. 3 MM3' 2 1 2 corded 3 15-20 123 9 9 123 IXnrtfMBU: Prrpwadoa.......................... 4 1 5 (ardinj................................ 6 4 4 2 16 Mule spiaaiag...................... 3 1 4 1 2 13 Spooling............................... 3 2 4 1 10 T*i*tiaf............................... U 1 5 1 13 19 1 7 3 30 Kins jpiaaiag...................... 1 1 2- UVavtaf............................... t 2 8 1 1 20 Maiuunaae*........................ 4 3 2 9 ToUi................................. 61 14 35 10 3 123 MRiped asbestosis; of 32 persona ex[XMcd for more than 10 years to dmilar concentrations, fourteen, 43 per cent, escaped; of 70 persona so < sp<*ed for more than 5 yearn fortyfive. 94 per cent, escaped, end of 28 t8oos exposed for more than 2 yearn and Ives than 5, twenty-four, 86 per *nt, neaped. Prolonged exposure to liMrt^rodudng concentrations of alone does not seem to have been exposed for equal periods in depart ments where concentration of dust is greater as among thoae who work in departments where it is less. The incidence of disease increases with ths duration of exposure end the concentration of effective dost, but not directly or constantly. No length of exposure or concentration of dust produced the diesesa in more than 60 per cent of pessoos expoeed in say 232 JOURNAL OF INDUSTRIAL HYGIENE AND TOXICOLOGY [Awn department. It seems to be true everywhere, thet some workers axe sot effected however long the exposure or high the concentration. These foots suggest differences in suscepti bility. As to whet deficiencies in defense or possible reinforcements of the attack exist in those in whom asbestosai occurs, other than the recognised difference in the comp^ . . ' " > were made to obeervwthe behavior of^-v*. respiration in response to the ebahgiat ventilatory demande*of graded phya- cal exercise. Dyspnea 'hero' means, that the persons replied "yes" when . _ asked, "Do yon have eny shortoees ; 5 of breath under ordinary drcua* - stances?" This "yml' is understood . ss mesning that these when ,, engaged in usual activities wen with ^ TABLE 3 Ahaitk* or Emcr ass Duxatiow or Exroscaa a Yahoos Daaunanm teney of the protective mechanisms in different individuals, no conjecture is ventured. As of silicosis, dyspnea may be said to be tbs characteristic symptom of sbestods. The dyspnea ben re ported does not refer to don fre quent, more forceful or embarraaed operations of the respiratory nisma objectively manifest. No tests greater or lea frequency conscious of an unaccustomed sense of inadequacy the ventilatory process. This experience was not infrequent among persons with lungs roentgeno logically and by physical examination normal, occurring m 3.1 per cent. The experience was mors than twice a frequent among those with definite asbestos* Six of the 33 asbestorics rU. KMnwrUK TO AMiKSTOS nrST 233 (]s 1 i> r statist that they had w*nt`- diortm-* of breath: three of tlx* j.) in- -i-ra'i* axe ami three of flu* 8 iuon* advanced. Bur (he iiiifi ad- v.,l(r!..i i dum-ed nospeeiai respira- . iVorf -luring examination :uui of tin* twenty-four with dyspnea showed itmliova^eulaf pathology in the film* ami also had high blood pressure, hut none of (he five had definite aslK-stosU. Or. William S. MeCanu reminds us: "Respiration is fo *M4 ^ wm m '.sag pi V > V: .<o 14 m r\i U*i tu. I.--Mil#rate a>besr<m. Heavy peeroral mtavien ftiemf die appearance or lihmaift. vaiesis ami mine deelared laek >r mwdrrd ahility fo earn* cm at - o. Among tin* thirty-din-e dyspnea was twin* as i m under 45 years i ' |ht as In those over i- rJi | |ht ii-tii). fr*tve not a funetiou of the lung* alone l>ut of the hrntrt, blood and tissue ability to aiieorli oxygen, ami also to undergo oxygen want such as the trained twwh of athlete* withstand oxygen want." Decreased ehest exjjausion may be SB 3Jv IkfrEl - ifi * * *2*1 JOt.KN \|, (>K INDCHYttlAI. IIYCJKNE ANT) TOXICOLOGY [Apr., im tti lx* iIk* cardimd sign <>( asls^to- ,>i>. AniiMitf 1he normal lung group, Mi |x*r cent hud :ui exclusion under 2 meins*, 44 |J**r n*l above 2 inches. In I he group with definite asls-stoniM, l*0. jier <*ent, luul a chest expansion of lew rJuia 2 inrhftj, 30.4 per rent, luul an (>x|tmMon above 2 inches. 'The proportion of those wil h the lower degree of exjxjiWMon wax inemustd aiKMit 24 per among the asl***- pities. Che*! expulsion depends not only on hmff distensiliilily hill on the mobility of die Imnv mid *>fl (issues of llte llmmcic note and of (he dia phragm. Il is often asiuoishtug how (mining and practice ran mpitHy in crease c1h*si expansion. 'Hie indi vidual learn* to exercise fully anatomic ettimrilies wliieh were twvsetM prior lo the (minims. 1`roto the foregoing Ihtdinte* it appears that the assumption ilrnt a x-tiiM* of air ant ami restricted du*st exjiansion are due to an existing its- U*siotic iuxolvrmem of the lungs r*ntii,uoh>tti*ailly manifest, should not U* made tin* hastily. Studying the rmutmtihilitY of as* lM-*tMU* with length of life and work ii is to Is* noted that: (hte employee with ad\:me<*d :isl**stosis almve the age of Vi w ho laid worked in dust more titan In years was still able to work. One employee. .VI vt-tr* old. with aihaneml asU**i*is who Itad worked in dust more ritan 10 year* was -till .J*le to work. Three em ploye- with moderate a*le*tt-is ami :ds*ve f:v aite ot H who i,;.d wo"k*d m h:**t :*.;ore that* til \,.sr* \vr:v -till .d*le o w *"k t ** this sitvp of n -lot* ,, ':;e age of 4t thrH* w; ...Hurate as** two w,-:* ;uh . **.i iie.n- plained nf shortness of breath. Of the eleven with moderate Mbestossi and the three with advanced asbestosis who iuitl worked more than 10 years; one, (7.1 per cent), complained of shortness of breath; these fourteen men hud client expansions which com pared favorably with the nonnal lung group. Sixty-oix and two-thirds per cent of these 14 asbestotks had a chest expansion under 2 inches, whereas 36 per cent of the oormai lung group had the same limits.* But 78.9 per cent of those with definite aabestois who had worked in dust under 10 yean had chest expansion under 2 inches and 26.3 per cent complained of shortness of breath. The ohler person**, whether with mod erate or more advanced osbestosis, appear better adjusted to the disease. Tit* avenge expoeure for the entire group with ashestoaia was 10.2 yean, for thorf* with moderate asbestosis' 10.3 yean, aud for those with ad vanced asbestesis, paradoxically, 10.0 years. If the entire group with asbesUM* is divided into those below aiul those above 40 years of age, the exposure of those with moderate aslx*stosis lieiow 40 years of age was 9.3 years and above 40 years of age. 1*2.4 years. For those with advanced aslvsttwis tin* corresponding averages were 9 and U years respectively. Advanced aid**tuw may exist in hue agc-pcrunl# with working ability nut iupwred In*low the level ot con tinued employability in the depart ment where Hie disease wa incurred. No \-rv rapid development of the di.-en-* was noted. ("hily 2 eas** f-i-.irrnl where the exposure had i-~*n .i*s- titan 3 years. As a ruie 3 <-r mure years of exposure was rey ure-l r;I. t.t, no. *\ KXPOSURfc TO A^HKSTOM l)i>T r-t -auad the No congiom- i mrc or massive lesioua such as occur iu *iliccis where Infectiou is superiru- l*H*d were found in th*o aebentoeis case*. The progression of the disease in this group was very slow. !oei* jmtii in (hex* /ilm-. If if mn ) that mosr >i thx> inrtifm- rions formed in fin* luh* **% aw ir hrfore 25 year* of aw. then ixpo>un*s to o.-*l>e*tow du>t varying from 5 to l*> year* luul prdMHi{ no mdcm-i* ot Fxo. 2.--Advanced asfeotoevi, cmphieued at left bane. Upper iua* eW tmphroomatom. The evidence presented ae to the of aebeaton upon tuberculosis thk survey.is somewhat limited. Spiral tuberculous infiltration was ttoteil in the filTM of 1? employees; there u no other evidence of tubercu- actiration to lie w in the films. Four of these apical tuberculous in filtrations were found in asia^totir*, two with moderate and two 'nth morv advanced process**. due ledonn with clinical significance were oJwervrri; 2 2M JOIHINAI. OK INIM'HTRfAL IIYUIKMK ANJJ TO*lCOLOaY Mpn, ISM;,? minimal and \ moderately advanced (American Sanatorium Association Classification). One moderately ad vanced lesion was found in a man 24 years old who liftd born ejqxwed to uxix*toN ditHt ill the winding depart* girded himself as is good health,]*.. One of the moderately advanced lesiotw wax found in tui employee 37 years of :ige who bad worked in the.; winding deportment for 9 yean and-, showed no evidence of aabestoaic. A v Fig. 3.--faUrai pnttlion. (Same can* aa Fig. 3.) moot forrtvntrx. Tlit* lesion append'd '.*ou" and imstnlil**: tfw*n* woe, how ever, utt evidence f nerompanring The disease in this mod erately ad\:ttinil case was clinicnUy nmnifr-u, though tlie employee re- third employee with a moderately ad vanced tuberculous lesion had worked in the twisting deportment for 10 year* Imt had no asbestosu. The fourth, an employee 37 years of age who had worked iu the wearing de- tti* tit 41 EXPOSURE TO ASBESTOS OUST 237 partment had moderate aabestosis. The tuberculous lesion in this case could satisfy rigid criteria of a healed teaoa. Three oi these lesions were active and were accompanied by clini cal manifestations. The one lesion aooeiated with aabestosis was haaisd and the employee apparently wee in good health. One of the two minimal lesions was in a man 24 yean of age who had worked 15 months in the twisting department and whcea films did not show aabestosis; one in a man 37 yean of age who had worked 12 yean in the winding department and The films were studied to discover any accentuating effect of a focus of tuberculosis on the surrounding asbestosis. No convincing evidence of such an effect was seen. Tuberculosis and aabestosis were coincident in only 5 employees. The average dura tion of exposure for the five was 10.4 yean and for the entire gronp with aabestosis 10.2 years. No accelerating effect of tuberculosis on asbestoste could be inferred. Twenty-four films showed abnormiKtiee of the heart and aortic shad ows (Table 4) and eleven of tbs TABLE 4 Gaoev or 9ft fimma wrm AxxoauAuras or m gti"1 om Aoaxsc Saaoow -- tl My S4t|M a*4 raa 4M4yw Keabor of mplayw m cash ag^ period......... ................................. 0 7 9 9 3 Byspoea....................................... 0 1 3 1 1 Hypottonowm.................................. 0 9 3 4 3 Yean of iipaw........................... 0-3 3-ft 5-10 10-19 19- ftuber of oapfteyeM................... 4 3 9 9 ftohoinsM....................................... 33 had no aabestosis. One of those minimi 1 ktiocs was apparently healed, It is frit that no evidence of an aggravating effect on tuberculoma by asbestos dusting is to be found in tea cases. Only one of the sis eSnicaliy krione was ac companied by ashartnnis and that tem had every appearance of being healed. Ha pulmMary ^herriiliete (2A per cent), it regarded twenty-four abnormalities were found in the 45 negro employees. A Waaaer man tart was not allowed. Ten of thart negroes wan under 45 years of age and one over 55 years of age. In this group of 24 employees with cardioTaaouiar changes, three had a normal blood preamn and the rest had hypertenson. Five of the group with cardiovascular had def inite aabestosis, three of these wen negron under 35 years of age (Table 5). Waring and Black in an admirable paper discus, "Ths Syndroms of Ob struction in the Leaser Circulation" <Am. J. fifed. ScL, fifo?, 198$ and 238 JOCSNAL Of IOTCSTSUL HYGIENE AND TOXICOLOGY "fr. girt u its 1 features, cyanosis, dyspnea, polycythemia, and tight ven tricular preponderance. The blood was not Examined in the cases here described and no electro cardiograms were made. Cyanosis and dyspnea were not observed in any of the 5 aabestotics with cardiovascular disease. In view of the pathology rharaftwristit of tsbrntoaie, namely, constriction of tk? terminaibronchioles with no perilymphatic or perivascular fibrosis as in rificoab, Isas obstruction tions in the group doss not appearin' be excessive. To males a scientific appraisal, of the effect on the employees.in tlur.* plant of exposure to asbestos dust*,',/ it is necessary to know how many ' employees during the 15 to 20 yeas j covered in the study have died or quit * and how many of these had asbestos*. This knowledge is not available. Cer tainly it might add greatly to the ** gravity of the picture. Ihemostthat ^ could be done was to note the effect ^ ' '31 T11M.W 5 Aaasvona w**n G*nstoTAoem-Ln Lastoa* *5ssr aMm.Ur7a te.......................... Sees....................... Blood preenre........ Years of eeposare... Aebastorie............... Dyspnea................. Chest eepsneioa...... X*y pteoiofy.... 44 White 174/96 13 Moderate He 1.3 in. Ealergid orris bedew S White 17D/U0 S Advaaeed No 1.5 in. Soierted eortie bedew. Ealercsd left ven tricle 37 30 30 Bleek Stock Black 156/104 130/93 . 134/90 7 10 7 Moderate Advanced Moderate Ne Ne No 1.5 is. 1.3 in. 1.5 in. Satorsed Eotorod Enlarged eerie .hedn ortie bedew. bedew. bedew Enlarged Both van. ri(b* tad tneiaa &- left ventri- torced tiee L.'cAj'L -/ !. , 1 .' .V of the tear escalation would seem to ba expected m aabeetotie than in silicosis and consequently te strain on tbs right heart. The frequency of respiratory infec tions was investigated. Each em ployes was ashed, "Have you had severe colds, *fiu,' or pneumonia and bow often?** Now said they had had pnsumooia, said they had ^ `*80," eight mentioned having had colds rises being exposed to asbestos dost, and one spoke of having frequent colds. The reported respiratory infec- on those now present in the plant, aftar varying permds of exposure. SCIOUBT 1. In addition to dmatinn of exp^ sure and concentration of effective dust, it appears that individual re sponse to the .inhalation of asbestos dust is an important factor in the production of osbestosa. 2. Aihestosts is infrequently found before 5 yearn of exposure to industrial concentrations of asbestos dust. In 1 <1