Document NGpkO58OjeDM1e4Ed12JX4ezw

FILE NAME: Metropolitan Life (ML) DATE: 1930 DOC#: ML039 DOCUMENT DESCRIPTION: Met Life Study - Effects of the Inhalation of Asbestos Dust Upon the Lungs of Asbestos Workers T0?3W0?D The authors wish to express their sincere thanks to all those who aided in casing this study possible, especially the officials and employees of the asbestos companies ho cooperated to the fullest extent and gave every facility for securing data. Also to Dr. Pancoast of the University of Pennsyl vania for his interest and valuable advice in interpreting X-ray films and to Ur. J. V. Meriwether, united States Public Health Service, Surgeon in Charge of the United States Bureau of-Mines Cooperative Clinic in Picher, Oklahoma, whose interpretation of all the X-ray films listed in this report is followed. Also to Ur. W. Atsar Smith, and Ur. Kenneth lynch of Charleston, S.C. for in formation and advice, particularly as to the pathology of asbestosis;* to Ur. If. If. Wild of Charleston, S.C.; to Ur. Joseph E. Wyatt of Ifcwark, K.J., and Ur. E. E. Bellows of Kew York, for assisting in interpreting X-ray films; to Ur Paul 0. Snoke of Lancaster, Pa.; to Ur. E. E. Stevenson of Uanville, Quebec, Canada; to Ur. L. U. Gardner end Mr. Ucnald E. Cunnings of Saranac Laboratory, who have undertaken the study of the pathological effects of the inhalation of asbestos dust through animal experimentation, with the aid of a grant from the Metropolitan Life Insurance Company. * "AsbestoBis Bodies in Sputum and Lung, Kenneth ii. Lynch, E.U. and W..Atsar Smith, li.U., Charleston, S.C., Journal of American Medical Association, August 30, 1930, Vol. 95, Eo. 9, pp. 659-661.  2 & iffisonucTioy 1 In 1525 the ISetropclitan Life 2n.surs.nce Dchpanv was approached "by 'firms representing the asbestos industry in the United States frith the request that a hygienic study he cade of that industry. The officials representing these firns were desircus of ascertaining if asbestos dust was an occupational iztard in their establishments and, if so, what was the nature of this hazard and what should he done to prevent or control it. About this time several articles had appeared in English medical journals describing a pneumoconiosis due to asbestos dust. Irhile in one or two isolated instances the occurrence of this type of pneumoconiosis had been described in American journals, the industry itself appeared to be quite un informed cf the existence of any such occupational disease. The hasard of silica dust with special reference to the lungs has ,long been appreciated and a great deal of study ana research has been applied ;to the silica dust problem, primarily in the metal mining industry, in Great *1 iaritian, the United States, the British Dominions, as well as in other countries. The nature of the effects of silica dust expressed in the term ''silicosis", with the resultant extraordinary predisposition to pulmonary tuberculosis, is well 9. r . * hnown. These effects have been associated with the inhalation of dust contain ing free silica in varying amounts. The effects upon the pulmonary tissue of dusts containing combined silica - silicates - are still a fertile field*for investigation, but evidence is accumulating that certain of these dusts produoe I , pathological results quite distinct from truB silicosis. , l . he name asbestcsis has been applied to the pneumoconiosis caused by asbestos dust and it Trill he so used in this report. Clerically, the asbestos * cf comaerce is a hydrated nagnesius silicate consisting primarily of Silica 44.l Eaenesia 43.Cj^ i later 1 2 .9 g :while ferrous iron and nickel are present in snail quantities. This ccnsercial variety of asbestos most connonly encountered is designated as chrysctile and jis one of the four varieties of the mineral serpentine, in which it usually i occurs in sears. ? It should be borne in Bind that silicosis (and presusably asbestosis) develops very slowly, taking iron five to fifteen and even twenty or twenty- five years to be cose established. This rate of progress is influenced mainly ;by the dosage of silica which the lungs receive and this dosage, is turn, de- :pends upon three variables: the amount of silica in the dust, the quantity : of dust in the air, and the extent of exposure. Individual idiosyncrasy i ; sight be included as a fourth variable; however, little is known of the varia . . . . . X II fcnlM n il.^ .1. . . IV*~i t - ,-- *1 . tions is susceptibility is those exposed to dust. There does sot appear to be present, is places where asbestos is nined or fabricated in Worth America, the clear-cut clinical picture which is so us escapable is coaaunities with a true silicosis hazard, such as hard rock . sini:.g communities. It might be thought that sose of the asbestos plants are of too recent-origin for the typical effects of a silicate dust to becone . manifest, but this theory would sot apply to the older nines or to ail of the w fabricating plants. * The Industrial Health Service of the Jeetropolitan life Insurance i f lV f fts ' .'.ls I r t . \n :::?ar-7 undertooh the following investigation during the period iron October, 25 to January, 1531. This investigation included: A. A study of dust conditions in asbestos tines, tills, and fabrieating plants. 2 . Physical examinations o f asbestos worhers, including 2-ray Tiles. C. A study of dust exhaust systems designed to eliminate asbestos dust. Asbestos fabricating plants located along the Atlantic Seaboard were included in this study and are designated in the report as plants A, 3 , C, D, and 2. Asbestos tines and tills In the Province o f Quebec are designated as 7, G, E, and I. The Canadian portion of the investigation was conducted Jointly with the Industrial Eygiene Division of the Departsent of Public Health of the I'edical School of hc&ill University. The results will be sutaarired in a report which will foil the present one dealing with the investigation in the United States. e - s - * . DUST STUDIES . ipparatus and Methods o Sampling: Both the impinger (2) and the electric precipitator {2) were used for the collection of air samples, ior dusts, at the breathing levels and. in close Iproximity to the worhmen. Both of these forms of apparatus are adapted for this uorh, as they are transportable, easily set up and adjusted ior the taking :i the air samples at the proper level, and are extremely efficient. The impinger collects the dust by aspirating the air and then im pinging it onto a flat surface covered by a liquid in a container. The liquid used was distilled water, containing .50 percent alcohol to prevent the solution of sore of the dusts, particularly any silica which might be present. The impinger was actuated by ar. electrically driven rotary pump and the rate off air sampled was measured by means of a resistance type of flow meter with an inclined manometer for measuring the pressure difference. Bach sample repre sents the dust collected from a volume o f .100 cubic feet of air. The electric precipitator is designed upon the Cottrell precipitator principle used for recovering dusts and fuses commercially. This principle depends on electrifying the dust particles by mahing them pass through an 1 electrostatic field end thus causing them tc settle out upon a sheet -of oellucioid.' The electrostatic field is set up by means of a transformer operating Jirom the lighting lines on 120 volts, alternating current. Air is drawn through ithe apparatus by.means of a small rotary fan, run by a motor, the quantity being |(1)"Comparative Teste of Instruments for Determining Atmospheric DuBts", public Health Bulletin Do. 144, Treasury Department, Washington, D.C. I g(2)Determination of Suspensoids by Alternating-Current Precipitators*,' Philip Printer and Bobert H. Thomson, Journal of Industrial Bygiene, Vcl. VII, Do. 6 , pune, 1925. leisured by aeons of a flow seter. Samples of dust brushed from beans and pipelines near the ceiling also F tre secured for chesical analysis. All samples were shipped to the Industrial :Eygiene Laboratory of the Metropolitan and the dust counts made according to the t (L) ethcds accepted by the D.S. Bureau cf Mines and the 13.S. Public Bealth Service. t articles in size up to 360 sicrons in the greatest diameter were counted. Chemical analyses were Bade for total (free and combined) silica accord ing to the accepted standard method of Eillesrand.(3) 'Percentage Precuensy of Particle Size; In the first plant studied (A) only particles 10 microns and under in size were counted. It has been demonstrated repeatedly that no silica particles exceeding 10 microns - a Bicron ecuals one-millionth part cf a oeter or one- thousandth part of a Eilliaeter - in greatest diameter, enter the lung tissue, and for this reason the larger particles usually are net considered when deter mining dust counts. Later, as it appeared, froa soae of the published articles(4) (Bnglish) that asbestos particles aush larger in size were found in lung tissue, it was decided to count all particles and aehe differential counts of all these I !10 oicrons and under. Both sasples collected by the iapinger and the electric preeipitator sere counted. Itiorphotographs of these dust particles were further enlarged by ;celag projected upon a screen by'aeons of a lantern slide.projector, the enlarged particles being aeasured with a ruler, Knowing the entire enlargeaent (by actual (1) "Comparative Tests of Instruments for Determining Atmospheric Dusts", Public Kealth Bulletin 3io. 144, Treasury Departent, Washington, D.C. |:z*) "The Analysis of Silicate and Carbenate Eechs", W.P. Eillebrand, Bulletin 422 fJ.S. Geological Surrey, Washington, D.C. i4) "Pulmonary Asbestosis", W. E. Coohe, British Medical Journal, December 3, -2 ?. - 7 - measurement), it was easy to calculate the original particle size.(5) By the use of Eazer's (6) logarithmic probability paper, tbs logarithms of the ** [Unction to be measured - in this case microns - are plotted as ordinates against the probability of occurrence as abscissae. Since the line is straight, exterpolatior. and interpolation of any desired region is facilitated. Th6 analyses are reported in total particles per cubic foot and also in the corresponding weight of the dust in milligrams. There is no indicated relationship between the dust counts and the corresponding weights. Con sequently, the weights are not included in the tabulations in this report. Table No. 1 shows by plants and by departments the dust counts in million particles per cubic foot of air. The plants included are all in the :United StEtes and are mainly of a textile nature. It will be noted that the counts in plant A are of particles 10 microns and under, while in the other plants all the particles were counted. Nevertheless, direct comparison is possible, as in no sample taken were th6 number of particles 1 0 microns and I-mder less than 94 percent of the whole, which makes it evident also that i :Ln regard to dust control we are concerned only with the smaller sizes. It is also important to'note that whereas the dust in the preparation room is practically all due to asbestos, the contrary is the case in. the 4 jsther departments. ;' In the carding, spinning and weaving rooms asbestos is about 25 per ient. of the material used. On special jobs the percentage of asbestos may be * ______________ ______________________ ;_________________________________ ,________________________________________________________________________ i 5) Green, E. *A Photomiorographic liethod for the Determination of Particle 'size of Paint and if:6) TThipple, G.C. n 4 Rubber Pigments", Journal Pr&nklin Institute, 1921, 192, 657. - Vital Statistics, John filey & Sons, N.Y., 1925, p. 451. % % i 1 . .i.l tMt IADLEI )opt. ----------------------------- .----------------------------------- -- .. . -- ... ... ... PLANT A *i 1 PLANT B Ho.... Samples Taken Million taSrloAT|> per cu.ffe. of nir Ho. Samples Taken l Million Particles per cu.ft of air . PLANT C > - (/> ------------- j No. Samples Taken Million Particles per cu.ft* of nir ation 6 | to 1 | 9 \ to 0 8 2 to 43 oora 'rame ng room 5 2 \ to 1 2/5 | to f 5 $ to 4| -- l 0 5| to 15^ -- -- ipinnJr- Z 2/3 to 2| 6 1/5 to 1 5 1^ to 4| PLANT D ( I PLANT E No. Samples Taken Million Particles per cu.ft. of air Mo. Samplos Taken Million Particles por cu.ft. of nir 5 50 to 02 -- 5 20 to 70 -- -- -- -- 5 5j to 1 0 .ng 10 1/3 to if -- J Included In spinning 8 1 to 3if (includos broad loom weaving) B 0 1/3 to 7 (Includes broad loom , weaving) 4 'ept. 0 ln- 5 ing 1 / 2 0 to 2 . 4 1/3 to 4 4 1 1/3 to 4 1/3 to 4/5 . - 8 3| to 10 -- ' . -- 15 1 to 7 3 -- -- -- -- ---- 10 to 19f ------------- 4^ brake and h t i l . 2 \ to 3/5 t I r n i H f f O 1* * 9 A. 3352! . fi - ID - a mixing picker. As til mixture is discharged ires the picker, it is sprayed with a light mineral oil. The material is then paassed onto a mechanical oonveyor and taken to the storage his in the card room. Two of these mixing pick- ers discharge onto this conveyor system, while a third machine is equipped with a suction device which conveys the material to a'storage kin in the card room. Tie object of the two systems is to facilitate the handling of two grades of material at the same tine. This third machine is not equipped with am oil spray. The object cf the oil spray is primarily to entrap the. small asbestos fibres and hold them enmeshed in the cotton fibre throughout the processes of carding, spinning, and weaving. Incidentally, it is apparent that it also diminishes the amount of dust. The material is saturated with about A per cent, of oil at this point, but by the tine it reaches the loons the oil has diminished to less than 1 per cent. While Eineral oil was used in the preparation room of plant C, it apparently was not as efficacious as in plant S. In plant 2 oil was not used, nor was there any attempt at humidification or any system of dust exhausting. Carding machines were fed by hand. In plant A there was a humidifying, ventil ating and heating system, while in plant B natural humidity sufficed for the process. . In plant 2 the carding machines were equipped with a dust exhaust system, but it was not efficiently used. In plant C carding was done in two ^ b u i l d i n g s o n e cf which was equipped, with an'air conditioning eystem,-^nd in i f :. ............. : : - - - ........ * ;both -buildings the machines had exhaust equipment. Two plants, B and C, had artificial humidity installations in their ii {spinning rooms. In the former the temperature was 76*2., relative humidity I ipB per cent. One plant, C, had a humidification system in the twisting department TT - 11 - * re possible* The corral, defensivemechanism of the bo 7 takes care of a fair curt cf atmospheric pelletion. It is when the body is exposed to an excess= amount cf dust over a long period of time that this-defense mechanism eaks down. The application of exhaust equipment to textile machiner/ involves -siderable difficulty, especially where the construction of the plant is such at it is not possible to apply down draft suction to the looms. It is desirable tc install exhaust apparatus in any plant on an experintal basis first, and then check its efficiency by dust counts. This practice 1 1 result in saving the needless expenditure of much coney. PHYSICAL" 1XA2II1ATI0HS It was soon obvious that the diagnosis of asbestosis must rest mainly X-ray films of the chest. As in the early stages of silicosis, the symptoms th asbestos workers were usually indefinite and inconclusive. The foilowg tables are based on physical examination, together with X-ray films of 126 rsons actually working in asbestos plants in the United States. Ho Canadian suits are included here. These cases were selected more or less at random cm among those having more than three years of employment in the industry. 5. interpretations of these films all are based on the readings of one compeut roentgenologist, but they have been studied by several others experienced thi> field. The differences of opinion were of a minor nature, and there 3 general agreement, as to interpretation. The films were read conservatively, s X-ray findings took into account the physical examination and the age of s individual, and only those were classed as positive about which there was \ IS $ > major disagreement. All concerned were guided by their experience in sili- :sis and other types of pneumoconiosis, hence the films classed as negative :r asbestosis were further subdivided into "doubtful*1 and "negative". Only ime can tell whether`the individuals classed as doubtful are progressing .o-- ard a definite asbestosis. Particular attention was focussed on the presence ;r absence of indications of tuberculosis and, in this respect, all the re- iewers of these films were in accord. With the unhappy experience of silicosis n Bind, it was felt that a great deal of care should be devoted to ascertaining, i possible, whether or not asbestosis predisposes to tuberculous infection. Table II exhibits the diagnostic, classification of these 126 ndividuals, with their symptoms and specific occupations. Pive of these per- ions were not physically examined. The cases of asbestosis are divided into two classes, first stage uid second stage. The first stage embraces those who show by X-ray examination :efinite lung pathology sufficient in extent to warrant a diagnosis of pneuao- :or.iosis, but who have no. definite symptoms. The second stage cases exhibit lore extensive lung pathology and also definite symptoms. All these individuals* were actively engaged in factory work, and it was not practicable to mahe any distinction between them on the basis of torhing ability or disability. Had any individuals been found who exhibited extensive pulmonary involvement"and marked physical disability or total'disability;-they would have been classified as third*stage, but no such were found. Jne asbestos worker (2 nd degree stage) retired of his own accord and because of >1 d ten ye&rs previous to this study, but is still active about his garden. - <* --------------------------- ... It will be seen fros Table II. that of a total of 126 Z-rey examina- ns four were diagnosed as second decree asbestosis; sixty-three as first ree; thirty-r.ine as doubtful; and twenty as negative. Table II also shows that only eight individuals out of sixty-four ,h positive asbestosis were entirely free of sycptoss, while tea out of rty-seven with doubtful and seven out of twenty with .negative diagnoses were s of syrptotts.' dyspnoea and cough were the syxptoBs Best coaplained of, but none obese cases exhibited the urgent or evident type of "short wind" seen in e silicosis. Several of those classed as negative stated that they were ort-winded" and were so recorded, but too such esphasis should not be placed these stateaer.ts of subjective syEptocs. Table III shows th6 occurrence of pnoca and cough.* TABLE III Dyspnoea Cough Kot examined . Total Positive 40 39 3 67 Doubtful 16 20 2 39 Kegative 6 10 0 20 The incidence of tuberculosis (based upon Z-ray films) as revealed Table IT is both interesting and icportant. TA3LS 17 Positive Doubtful V Negative Tuberculosis (healed) 'v''Tuberculosis '(active) Total Examined *7 1 2 1 0 1 67 39 20 Ti Tables III to ZI, inclusive, the division into positive, doubtful, end egative refers to the cases so classified in Table II. his case was diagnosed as probably active on the X-ray findings. During the progress of the study, physicians who were practicing in he ccmunities where asbestos workers lived were questioned, and stated that * r.ey id net find an unusual amount of tuberculosis among these workers. The ontrast between this state of affairs and that found in communities with a il'iccsiB hazard, is noteworthy. The following tables classify results of examinations by occupation . * n industry and by years of exposure. It is to be resenbered, however, that oese individuals are classified according to the partner.* in which they 5re working at the tine of examination or where they had spent most of their .me. liany had changed from one department to another and from one plant to other during their years of employment in the asbestos industry. Since 2y the amounts of dust collected at the tine of this survey in the various partaects are known, there is no way of knowing the average an our.t of dust 'the ataosphere inhaled by these people over the years of their employment, isequently, it is not possible to correlate individual cases with definite unts of dust exposure. TABI2 V By Departments Positive Doubtful Jfegati Teaving Carding Spinning Warping Spooling. . ^Trucking a -" *- * io on fixing Packing * . . Winding Picker .. Twisting Other Total exasined 22 13 5 IS A 1 9 2 3 1 0 2 s5 2 `I 1 ' ;0 s1 0 1 0 0 3 A 1 0 2 2 5 0 6 3 A 67 39 20 Over 15 years 10 to 15 years 5 to 10 years T3nc.gr 5 years Total exaained TA3IS VI Years of Exposure Positive IS 7 SO 17 67 Doubtful Negative 1 (part 5 27 T-j 59 tine} 5 2 5 12 20 (1 not continuous) The following tables are also of interest, but, lihe the two previous, U n i t e d value and little ir. the way of definite conclusions can be based n tnea. TA5I3 VII Age Groups 50 and over 40 to 49 30 to 39 20 to 29 Under 20 years Total examined - Positive 12 13 17 24 1 67 TABLE VIII Sex Doubtful 3 6 12 16 2 39 Negative 2 4 6 8 0 20 Positive -- hale (Total exaained 10S) 59 . Peaale .( * * IS) 6 *. *` ^ .CU;*-,-V'>. ; -.- '-: 1 to 2 Inches Z to 3 inches 3 Inches plus Fot exacined Total TABLE U . , Chest Expansion - Positive 28 31 5 3 67 Doubtful 32 . 7 Doubtful 13 21 3 2 39 Negative 17 3 Negative 7 12 1 0 20 JU T 17 - TABLE 7. Chest Tintags Physical signs of Ko physical signs Kct examined ' Total chest trouble Positive S3* SI 3 67 Doubtful 9* 25 2 39 2'egative 13 0 20 What significance, if any, can he attached to the presence of bestos corns'* on the hands of workers appears doubtful, as indicated in le 71: TABLE 71 Asbestos corns Bet examined Positive 12 5 Doubtful 7 2 ' Negative 2 0 Bach roentgenologist who reviewed' the 7-ray films called attention the fact that these files indicated a very unusual incidence of enlargement the heart. It is probable that this is a compensatory enlargement due to additional work put upon the heart in efforts to pump blood through the ;rosed lungs. In the first silicosis studies, published in this country 1917,**** Dr. S.3. Childs of Denver, .who interpreted the 7-ray plates of c study, consented as follows: "The heart in miners* consumption (silicosis) casts a larger shadow than ncn&al and in the early stages is probably caused by its increased musculature. The shadow of the heart remains larger than normal in he second and also in the third stage." 4At least six cf these showed no evidence associated with asbestosis. "Two cf these not associated with usual signs found with asbestosis. Six of these not associated with usual signs of asbestosis. 4 "Miners' Consumption", U.S. Public Health Service Bulletin #S5, January, 1917. 19 Teeth claims: 1 . Proved to be & typist, not exposed to dust; died of pulmonary and intestinal tuberculosis. 2. Colored Dale age 27; worked in asbestos one year and eight months; died of pulmonary tuberculosis following a hemorrhage; was in sanatorium ten months. Also had a fourplus Easserman. lio evidence of asbestosis. 5. Colored Bale age 32; worked in asbestos plant one year and seven months;' died of pulmonary tuberculosis after one north i in hospital. Cavitation both lungs; no evidence of asbes- tcsis. 4. Colored male age 34; worked in asbestos plant two years, and six months. Els physician believes this was a case of un complicated tuberculosis. Fas not inmate of hospital or i. s&natoriun. Sc information could be obtained of the other two cases except from the de?.th certificates which gave pulmonary tuberculosis as the cause of death. Total and permanent disability d a l e s : 1; Kale, employed in asbestos plant three years. Eis physician states he first came under his observation with an old established case of tuberculosis about two years after asbestos employment started. Also had tuberculosis of the kidney and cervical glands. 2. hale, employed in asbestos plant eight ccnths. Eis physician states old fibroid tuberculosis with tubercle bacilli in sputum. No X-ray available, but according to physician asbestos bodies were found in sputum. . i. ^ / ** ,u-'. 3. hale, ten years employment. Two physicians wbo treated him ,at different times are now inclined to believe this man is hot tuberculous, but has asbestosis. "'. 4. White male, was re-examined at time of investigation. Eis physician reports well nourished, husky looking, good color, \no cyanosis; no clubbing of fingers, diminished expansion, incessant cough; X-ray shows fine mottling disseminated through both lungs. Ko evidence of tuberculosis. Probably a second stage asbestosis. 5. Fhite Dale, thirteen years in asbestos plant. Is now in sanatoriua. An interesting case. Eis physician states he has extensive asbestosis and pulmonary tuberculosis; cavity in right lung; sputum loaded with tubercle bacilli and asbestos bodies; believes tubercu losis long antedated asbestosis. This patient is progress ing in a satisfactory manner. It was net possible to locate the other three cases of total and perm anent disability who had been diagnosed as having pulmonary tuberculosis. On the basis of the information obtained the death claims appear to be due to uncomplicated tuberculosis; three of them were Negroes. It was more than probable that these sen were tuberculous at the time their employment in the asbestos plant commenced. Of the eight disability claim oases, one was uncomplicated tubercu losis and two wer& uncomplicated asbestosis who were put on disability because of a sis taken diagnosis of tuberculosis. In this same community we know of one death due to uncomplicated asbestosis in an individual with many years employment in the industry.* CONCLUSIONS 1 . Prolonged exposure to asbestos dust causes a pulmonary fibrosis of a definite type distinct from silicosis demonstrable on 2- ray films. Clinically, it Is of a type milder than silioosis. 2; There is associated with asbestosis in a large percentage of cases definite --j.- . cardiac enlargement. __ * * V.v*l=. * ` * ' , . 5, ..Asbestosis does not involve an unusual tendency to pulmonary tuberculosis. -personal coanuaication. Details not yet published. iir*-''-t- . ' "" vT' < V 6 - 21 - Asbestosis as observed in this series of eases does not cause ar.y marked spree of disability. However, it is possible for uncomplicated asbestosis : result fatally. . It is not i u o n how much asbestosis may add "to the mortality cf pneumonia nd acute pulmonary infections other than tuberculosis. . It is not practicable as yet to establish standards for the dust content cf .ir and in view of the many low dust counts in this report, compared with the -.5. Hublio Health Service standard for silica dust, it is possible that asbestos ;*.y causs pneumoconiosis more readily than free silica (Si02). The amount of dust in the air in the asbestos plant3 studied can be sub stantially reduced. Bscoiaearomogs T.. That the industry seriously face the problem of dust control in asbestos plants. 2 . Shat new employees be examined physically and rejected for employment if they show tuberculosis or pneumoconiosis. "3. -That employees be examined physically every year or certainly every two years, this examination to include an X-ray examination of the chest. That the "industry sponsor studies on known cases of asbestosis, as -well as studies on effects cf asbestosis on the heart and circulation. -w--t.-? ... . ''T I. .... r. - -;ry . >... r ': . -- *