Document Lg3oXzDRvprapKJVJR9km5pq7

a U.S. TREASURY PEPARTMENT ptKBV UORGEKTKA0. fa* &** PUBLIC HEALTH SERVICE BUGS s. COMMING, S*V** EFFECTS OF l`HE INHALATION OF ASBESTOS DUST ON THE LUNGS OF ASBESTOS WORKERS A. 3. LANZA AnuloM &ir*dof WILLIAM 2. McCOKNEi-L AuutonI Dituief AVD 3. WILLIAM KERNEL CA/nia< HffropoltWn Lt/< /rwu'OiK Ce, iI REPRINT No. 1665 FBOM TSE PUBLIC HEALTH REPORTS Vet. so, Kg i, f**v**r <, 2ws i-if; OWENS-CORNING FIBERGLAS CORP. LEGAL ft PATENT DZPT. KECO SEP 15)941 **> fc/tfa* owrrn> mm OOVtRNafE>T PREKTttG 0F7IC* V>.&EEU<GTQV * !>*. W^tta*** D.C.......................................frrkS**u 01 118 0232 aitrfs**.:,... EFFECTS OF THE INHALATION OF ASBESTOS DUST ON THE LUNGS OF ASBESTOS WORKERS 4 FreUatleer/ Stair By A. 3. L&KI&, A*t<44ft* Medical V%reticr, Wiujsk J. Meox**u, AtriA- eM Medited Director, a&<f J. Kttt-it* FtBVSi^ CfefaUl, MetrepoUian Life fnwretux Co. ' INTRODOCTIOW -. la 192$ the Metropolitan Life Insurance Co- was approached by officials representing tbs asbestos industry m the United States, who were desirous of ascertaining whether asbestos duet was an occupa tional h&s&rd is 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 m English medical journals describing a pneumoconiosis due to asbestos dust. While in one or two isolated instances the occurrence of this type of pneumo coniosis had been described in American journals, the industry.itself appeared to be quite uninformed of the existence of any stick occupational disease. The hazard of silica dust, with special reference to the lungs, has long been appreciated, and a great deal of study and research has been applied to the problem (in the metal miaireg and certain oiher iadustms) in Great Britain, the United States, the British Do minions, and in other countries. The nature d the effects of silica dust expressed in the term "silicosis", with the resultant extraor dinary predisposition to pulmonary tuberculosis, is well known. These effects hare beea associated with the inhalation of dust con taining free silica to varying amounts. The effects upon the pul monary tissue of dusts containing combined eilica--^licatee---are ecZi a fertile field for investigation, but evidence is accumulating that certain of these dusts produce pathological result* quite distinct from tree silicons. . . . .. The name "asbestos's" has been applied to the pneumoconiosis canned by asbestos dust ttnd it will be so used in this report. Chem ical!y, the asbestos of commerce U a hydrated magoeaiutn silicate consisting primarily of silica (combined silica) 44.1 percent, tssg- nceia 43 percent, and water 12.9 percent, while ferrous iron and nickel are present in email quantities, .This commercial variety of 01 118 0233 i*^' .>. - * - *' r*Sv. ~W~-, ' *'* ' *V */$ - . - .? : "VA* \ 2 svvects or asbestos dust ok the lokos asbestos most commonly encountered is designated as chjv60tile and is one of the four varieties of the miners/ eerpeatiae, is which it usually occurs b seems. It should bo home b Bund that uhcosia (and presumably aabes- iasis) develops vwy slowly, taking from to 15 and even 20 or 25 years to become established. This rate of progress is uafiueneed mainly by the dosage of ri/ica which the loags receive, and this dos age, in turn, depends upon throe variables--the amount of silica in the dust, the quantity of dust in the air, end the feagfh of exposure. Individual idiosyncrasy might be included as a fourth variable; however, little is known of the variations in susceptibility in those exposed to duet. It might well be assumed that similar variables would influence the occurrence of asbestosis. In places where asbestos is mined or fabricated in North America .there does not appear to be present the clear-cut. clinical picture which is so uneacapable in communities with a true silicosis hazard, .such ie herd-rock mining communities. It may be that some of the asbestos plants are of too recent origin for the typical effects of a e2icate dust to become manifest, but this would oot apply to the older mines or to all pi the fabricating plants. _ The industrial health service of the Metropolitan Life Insurance po. undertook the following `investigation during the period from October 1929 to danu&ry 1931, which included; 1. A study of dust conditions in asbestos mines and mills in Canada and in fabricating plants along the Atlantic Seaboard in the United States. 4 '. 2. Physical examinations of asbestos workers, including X-ray films. . 3. A study of dust exhaust systems designed to eliminate asbestos 'dust. ` JData on the fabricating plants only are included in this study and are designated In the report as plants A, B, C, D, and E. This is a preliminary report. A more extensive study of the asbestos industry js now under way. , .. BTJflT BTOniEB . Apparoiu* and rmUwU of eatnpfinp.--Both the impingor (X) and the electric precipitator (2) were used for the collection of sir samples for du6( at the breathing: levels and is close proximity to the workmen, oth of these forms of apparatus are adapted for this work, as they are transportable, easily set up and adjusted for the taking of the jsir samples at the proper level, and are extremely efficient, j.. The impinger collects the dust by aspirating the air end then imputing it onto a fiat surface covewl by liquid in s tontainer. The liquid used was distilled water, containing SO percent alcohol to 01 118 0234 EFFECTS Of ASBESTOS DUST OK THE LUKOS prevent die solution of some of the dusts, particularly any silica which might be present- The impinger was actuated by an ewetneally driven rotary pump and the rate of air sampled was measured by means of a resistance type of flow meter with an inclined manome ter for measuring the pressure difference. Each sample represents the dust collected from a volume of 100 cubic feet of air. ^ The electric precipitator is designed upon the Cottrell precipitator principle used for recovering dusts and fumes commercially. This principle depends on electrifying the dust particles by making them pass through an electrostatic field and thus causing them to setde out upon a sheet of celluloid. The electrostatic field is set up by means of a transformer operating from the lighting lines on120 volte, alternating current. Air is drawn through the apparatus by a email rotary fan, run by a motor, the quaarity being measured by a flow meter. . . ... Samples of dust brushed from beams and pipe hues near the ceding ako were secured for chemical analysis. Ail samples were shipped to the industrial hygiene laboratory of the Metropolitan Co., and the dust counts were made according to the methods accepted by the U&Jted Stales Bureau of Mines and the United States Public Health Service (1). Particles is are up to 360 microns in the greatest diameter were counted. Chemical analyses were made for total {free and combined) silica according to the accepted standard method of Hiiiebrand (3). ' la the first plant studied <A) only particles 30 microns and under b sire were counted. It has been demonstrated repeatedly that no silica particles exceeding 10 microns (a micron equals oae-tmlbonth part of a meter or one-thousandth part of a millimeter) in greatest diameter enter the lung tissu ; for this reason, the larger particles usually are not considered when determining dust counts. Later, as it appeared from some of the published articles (4) (English) that asbestos particles much larger in sire were found in lung tissue, it was decided to count all particles and make differential counts of ail those 10 microns end under.* . Total particles per cubic foot and the corresponding weight of the * dust in milligrams were obtabed. Since no relationship between the dust counts and the corresponding weights was found, the weights are not included in the tabulations in this report. Table 1 shown by plants and by departments the maximum and ynimrmim dust count* b million particles per cubic foot of air. Although the counts in plant A are of particlee 10 microns and under, pfotte* M 0*4UuM O*04l U* Of WOIT*n U *t*dO*M 01 118 0235 -***'; - -'V --A^v i*&f WgUS*&*k\*V*: * V ' ^*ZrmrT *- 't~5^s52k>- . ., .. .\r ; V . V: . ;.*, :.Wv:J .- v*\ :.* '. 'A^}*:*:i:r>'. ' , * .*./; .':.\*'v%?:,?&`-*-' _*.,.><: v .- :.?.,>/;:y/ v 'v /.! ,V*-,*V* ." * `Vr .rV-.- .:. ;ti^. .V,T-V'r`" -- -.*,;-Ha*,'-1*<* <x >^.\V^ 'i '.'* .4;r*^v.;*n> *::;u-v'/r-*5 -- / ', -w.-<*,***"\"*:.c;*&1 K r- > . >v ^ ,*t ^vr;Vv:v->;^ WSK* ..--~WL l_ < *rfe5 4 EFFECTS OF ASBESTOS DOST THE tOKOS <ujd is the ether ftiants sre for aS p&rtlclee> direct cozapftflsoQ ia posable, ui&'do semple taken we?e the number ot particles 19 microns and under less than 94 percent of the whole. ' * . * ** ' > '* /*,' l. .' ' . . * .. ,'ii. T^BfX 1.--Afaxfmum ni mirnmvm tfiof einU nHZwm p*rtiel** p*r eiMe ftai .v ... *ir, by V*cxi and dtpertmerU , FWrtA ruws FfestC ...................... Fkw p ' HftB'E DopartaMni Kom> boot MBS* ttm UJUjj UOUc* UMtf ifecw BOb* MU IB > Kbb> trfTOf a*** pi* uka MtUte Ke fit. k*e4 euM toot of pte tit Ults T MSfea Jtt. ryh* tow ol Ur N*t. br( Pt> UktB Na. MSfec b0f Ml- Sr V* to* of eMfcc toot M U/ MStoB fiSi suftK tool Bf ob CFvwepdwmMo................... 2U& {mm ipt&BiBi ' nea.......... Mpi tp$&ajjK...--... TFevuJ/inOutp*e.|e....x..a...t.e...r..t...^...--........ EHbuotUttiiia*oS*iia*. t-*d `Iacrt*<? wptoaw. % H-IH * h-1H j tt-fc t sur t ISk HH 5* * W 4 H-H 3 -a c B1VJ4H *1 iii- 4H 8 -m *U-ic >+* ' to S - li 1 -4 i JH-ft '8M- ? B toy*-K ................. ............. t *iMtflCt SfMfl MB VMTU4. ............ - Whereas the duet is the preparation room is practically all due to asbestos, the contrary U the case in the other departments. In the carding, spinning, and weaving rooms asbestos comprises about 25 percent of the material used. On special jobs the percentage of asbestos may be higber, but in general the figure quoted U approxi mately correct, the other material consisting principally ol cotton. In the insulating departments of plant A, asbestos is but 5 percent ol ihe total material used. In the molded brake-lining and clutch division of plant D, asbestos comprises about 25 percent of the total material. The actual exposure to asbestos dust, therefore, is consid erably less than is indicated in the dust counts in table 1. CONitlTiOXO is TSS TlASTB Tbe processes in those planU were very similar to those in cotton nsiUa in general. For illustration, tbe process in the preparation room of plant B is here detailed at length: . * :. ' . Asbestos is race*vd in bag*. These are emptied upon the floor and the asbestos U shoveled into pug miSis and run for about 5 minutes in order to crush and open the fibers. From there tbe asbestos is .shoveled into trucks and wheeled to hoppers with either horixontal Tor vertical openers, similar to those used in textile mills. After passing through the opener, the material is discharged into trucks. Waste manufacturing material is first run through a garnet machine and 01 118 0236 EFFECTS OP ASBESTOS DUST OH THE HJKOS 5 discharged into trucks, which are wheeled to the openers, sod the material is fed into these in the seise manner es is the new materiel. After being discharged from the opener, the material is put onto a vibrating or shaking screen, where the long fibers are picked off by a suction hood and blown into a bin to be used again in textiles. The short fiber* falling through the screen are either sold as such or used in making an asbestos cement. The cotton is received in bales, opened, sod also run through vertical openers. It is discharged into trucks. The filled trucks from the vertical and 'horizontal openers codtaming dtlier the asbestos fiber, the cotton, or the waste material are taken to separate storage bins. As needed, these materials are weighed and dumped onto the floor in proportion to the mixture desired, and the resulting mixed materials are then passed through a mixing picker. As this mixture is discharged from the picker, it is sprayed with a light mineral oil. The materiel is then taken by a mechanical conveyor to the storage bin in the card room. Two of these miring picker* discharge onto this conveyor system, while a third machine is equipped with a suction device which coovey6 the material to a storage bin in the card room. The object of the two systems ie to facilitate the handling of two grades of material at the same time. The third machine h not equipped with an oil spray. The object of the oil spray is pri marily to entrap the small asbestos fibers and hold them enmeshed in the cotton fiber throughout the processes of carding, spinning, and weaving. Incidentally, it U apparent that It also diminishes the amount of dust. The material is saturated with about 4 percent of oil at this point; but by the time it reaches the looms, the oil had diminished to less than 1 percent. * While mineral oil wiis used in the preparation room of pl&ot C, it apparently was not as efficacious as in plant B. In plant E 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, ventilating, and beating system, while plant B depended on natural humidity. In plant E the carding machines were equipped with a dust-exhaust system, but it was not efficiently used. In plant C carding was done in 2 buildings, 1 of which wee equipped with an air-conditioning system, and in both buildings the machines bad exhaust equipment. Two plants, B and C, had artificial humidity installations in their spinning rooms. In the former the temperature waa 76 F., relative humidity 76 percent. One plant, C, had a humidification system in the twisting department and also in the weaving department, where the relative humidity was 76 percent with a diy-bulb temperature of 69* F., as compared with a relative humidity of 44 percent in the weaving room of plant A. 01 118 023? (Wf-1sa&x+i'. )e* : fc*rv 6 EFFECTS OF BUST OS THS BUKOS ,w* -*'.1 l&Sfc* Aside from plant E it would `>^fo" Stf excessive except m *h prep^onroo P^^ tf tu| dust counts ere interesting, permissible standard for gr" wskk by lie United^ A_ .bout 10 million psrtidea^ trrMtt=*r" sss%. S3 dust- dust cokthob Various measures, such as effing. for rs She basis of comparative dust count*, redudtB 3 &**?. ,. Zi Kith further alterations In this case such a SSffitS equipment'^ practicable nor econom.caUy desir eo" ^ defensive mechaaao3 SSr^SS5i| is such that it is not possible to apply down^ratt 0B ^ *X It is desirable to install a needle aspendbiyturdeuostf cmeuon.^rgj FBTSICil. EXaU3*ST10HS '' '.'ij in asbestos plants in tbe Vt* Beleetod more <x**h pven physical examination^years of employ| at random from among those bartog di&gncss| ment in the industry- It -- ^ on X-ray pictU of *1 ll^Celriy 2^3 em-is, the clinical aymp^ll 01 118 023S . * W' JEPPECT6 or AHBEST06 OUST OH THf. L.T7KG8 7 others experienced is this field. The differences of opinion were of minor nature, aed there was general agreement, as to interpretation. The films Were read conservatively, taking into account the physical examination and the ago of the individual, and were classed aa positive only when there was no major disagreement. All examiners C were guided by their experience In silicosis and other typesof pneu moconioses. The films classed a? negative for ashestosis wpre further subdivided into doubtful and negative. Only time can tali n whether the individuals classed as doubtful are progressing toward a definite asbestosua. .Particular attenlion was focussed on the presence 4 or absence of indications of tuberculosis, and in this respect all the reviewers of the films were in accord. With the unhappy experience of silicosis in mind, it was felt that a great deal of care should be devoted to ascertaining, if possible, whether or not aabestosb pre disposes to tuberculous infection. The oases of asbestosis were divided into two classes, first stage and second stage. The first stage embraces those who ehow by X-ray examination definite lung pathology sufficient ia extent to warrant ft diagnosis of pneumoconiosis, but who have no definite symptoms. The second-stage cases exhibit more extensive Jung pathology and also definite symptoms. All these individuals * were actively engaged in factory work, end it was not practicable to make any distinction on the beaU of working ability or disability. Had any individuals been found who exhibited extensive pulmonary involvement end marked physical disability or total disability, they would have been classified ea third stage, but no such cases were found. Of the total of 12$ X-ray examinations, 4 were diagnosed as second-degree asbestosis, 63 as first degree, 39 & doubtful, and 20 as negative. There Is a definite increase in the percentage diagnosed as positive in relation to the years of exposure, as shown in table 2. Small cumbers make it impossible to determine how far the factor of age enters into this increase. Tasue 2.*--ClajtxjicaUon ofoat** fcy V<ort ofos-potur* FereABUn jxeU*** VoUti** HqdMt T>AiUu) N(C^*t 0gr i* nut...... ............ ....................... ......................... W <d ............................................. ...................... 4U>39 *._,,................ ....................... ........ .1............ vMu 6 y*n............ .......................... ....... .................. ... r M 'a a 1j 7s to u 17 Ift foul......... ................... VI * a a u to * .jeutiot*. , * ' `OwwbMUBworker(moosc!*U*jrU*d hU o-e U u* RM;. Ml it n0< *?W (ir4#a. * t >ot mttu&aj x* **s bwm ef old **. W mn mnn *5 - T%.y. c S EFFECTS OF ASBESTOS OUST OS 53B LOKOS Of the 64 persons given physical examination and diagnosed as having positive ashestosis, only 6 were entirely free Worn symptoms, while 10 out of 37 with doubtful and 7 out of 20 with negative diag noses were free from symptoms, Dyspnoea and cough were the symptoms most complained of, but none of these cases exhibited tbe urgent or evident type of "short wind " eeen in true silicosis. Several of those classed as negative stated that they were "short winded'* end were so recorded, but too much emphasis should not be placed on statements of subjectve symptoms. During tbe progress of the study, physicians who were practicing in the communities where asbestos workers lived were questioned and stated that they did not find an unusual amount of tuberculosis among these workers. The contrast between this state of affairs and that found in a community with a silicosis hazard is noteworthy. The incidence of tuberculosis {based upon X-ray films) is given in table 3; 40 of the 67 examined bad loss than IS years of employ ment in the industry. Tasle 3.--Incident* of tvbereuioru MUn DoatUaJ Kr>t!c TvWcvtosU HsmM)................................... ................... . Tubercutows <***>..................................... ToUtiM3lawd.................................. .. 1 7 V e K TbU <m* *u u pteMMj tMU(UtiXir Table 4 gives information as to physical signs of chest trouble. S l to Tasi.s 4.--CU*t findinft ttoafcWi*! KflVktlT* .......... ...................... Mamin*! ............... ............................ . TsUl....... ...........................................................................-- <f U SB 1t ? IS 13 0 r> at tout e c/teM &*i tMiodwataMdiurf tu> uMtatfi * Jorf not Mxiat3 -ua <uu*} rx>* found wits tsbeturt. fl f i&tM DOt *4*9Clt Witt Q9U) lije* 4* liWtOllt. What significance, if any, can be attached to tbe presence of "asbestos coma" on tbe hands of workers appears doubtful, as 18 percent of tbe positives (12 out of 64) and 15 percent of the others (doubtful, 7 out of 37, negative, 2 out of 20) showed such corns. Each roentgenologist who reviewed the X-ray films called attention to (he fact that these films indicated a very unusual incidence of enlargement of tbe heart. It ia probable that this is a compensatory enlargement duo to tbe additional work put upon the bean in efforts 01 11H OS/in JL ;c*j>. l*g; tm nr tM EFFECTS OF ASBESTOS 5PSTOK THE 2.TJNGS 9 to pump blood through the fibrosed lungs.* It Is posable that not sufficient attention has been pud to the effects of the pneumoconioses upon the heart. Many workers had changed from one department to another and from one plant to another during their years of employment in the asbestos industry. Since only the amounts of dust collected at the time of this surrey in the various departments are known, there is no way of knowing the average amount of dust in the atmosphere inhaled by these people over the years of their employment. Conse* quently, it is not possible to correlate individual cases with definite amounts of dust exposure. INSURANCE Cl/AIMS To throw light on the relationship between aabestosis and pulmo nary tuberculosis, an analysis of death claims and total and per manent disability claims was made in regard to companies carrying group insurance and haring available figures. There were 2,099 lives involved, with a total exposure of 7,019 lifeyears. The death claims are so small in number that reliable con clusions cannot bo reached from auy subdivision of the figures. The same is true of the sickness claims under health insurance. The number of claims for respiratory disease* is high in two of tbo plants studied but low for the others, as compared with the Metropolitan experience of 1927. However, during the latter part of 2928 and the first part of 2929 there was an epidemic of influenza. The records of one establishment (plant B) showed that 6 of 36 death claims end 8 of 20 permanent and total disability claims were listed as due to pulmonary tuberculosis. This appeared to be an in ordinate amount of tuberculosis from this plant. However, many of the employees were Negroes, and also tuberculosis claims are gener ally high in this section of the country. Realizing the difficulty in diagnosing pneumoconiosis and the tendency to confuse it with tuberculosis, these claims were studied individually. The physicians who had treated the individuals were interviewed, and the hospital and sanatorium records, including available X-ray films, were investigated, with the following results: Death claims: 1. A typist, not exposed to dust; died of pulmonary and intestinal' tuberculosis. 2. Colored male, age 27; worked in asbestos I year and 8 months; died of pulmonary tuberculosis following a hemorrhage; was in sanatorium 20 months. Also bad a four plus Wrssctmann. No evidence of asbestoais. 8. Colored male, age 32; worked in asbestos plant 2 year and 7 months; died of pulmonary tuberculosis alter 1 month in hospital. Cavitation both lungs; no evidence of asbestoais. 01 118 0241 rW'wiiliiT % fcatfwa;-", **?* ? ....c- 10 EFFECTS OP fi-BBESTOS DUST OX THE LCKGfi 4. Colored male, age 34; worked in asbestos piact 2 years and 0 months. His physician behaves this was a case of uncom plicated tuberculosis- Was not inmate of hospital or sanatorium. No Information could be obtained on the other iwo cases.' Total and permanent dUaKXty daimt: 1. Male, employed la asbestos plant 3 years. 'His physician states that he first came under his observation with an old estab lished case of tuberculosis about 2 years after asbestos employ ment started. Also had tuberculosis of the kidney and cervical glands. 2. Male5 employed in asbestos plant 8 months. His physician stated finding of old fibroid tuberculosis with tubercle bacilli in sputum. No X-ray available; but according to physician, as bestos bodies were found in sputum. 3. Male, 10 years' employment. Two physicians who treated him at different times are now inclined to bdieve this man is not tuberculous, but has ashestosis. 4. White male, was reexamined at time of investigation. His rP* 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 lunge. No evidence of tuberculosis. .Probably a second stage ashestosis. . 5. White male, 13 years is asbestos plant. Is now in sanato rium. An interesting case. His physcion states that he has ex tensive esbestosis and pulmonary tuberculosis; cavity in right lung; sputum loaded with tubercle bacilli and asbestos bodies; believes tuberculosis long antedated asbestosis. This patient is progressing in a satisfactory manner. It was not possible to locate the other three cases of total and permanent disability who had been diagnosed as having pulmonary tuberculosis. On the basis of the information obtained, the deaths in death-claims cases appear to be due to uncomplicated tuberculosis; three of them were Negroes, who were probably tuberculous at the time their employment in the asbestos plant commenced. Of the 8 disability claim cases, 1 was uncomplicated tuberculosis and 2 were uncomplicated asbestosis who were put on disability because of a mistaken diagnosis of tuberculosis. In this same com munity we know of one death due to uncompliceted ashestosis in an individual with many years' employment in the industry.1 CONCLUSIONS t. Prolonged exposure to asbestos dust caused a pulmonary fibrosis of a type different from silicosis and demonstrable on X-ray films. Clinically, from this study, it appears to be of a type milder than silicosis. "" . J " / **. * 2. Cases of definite cardiac enlargement were frequently found to be associated with esbestosis. . *' i '>' 0.1 118 0242 EFFECTS OF ASBESTOS DU6T OK THE hVHOS 31 S. A predisposition to tuberculosis due to asbestos dust waa not indicated in this study. 4. Asfeestosis as observed in this series of cases bad sot resulted in marked disability in any case, 5. It is not knows bow much asbestos's may add to the mortality of pneumonia and acute nontuberculous pulmonary infections. 6. It is not practicable as yet to establish standards for the asbestos dust content of air. 7. The amount of dust in the sir in the asbestos plants studied can be substantially reduced. R ECOMMEX DATTON8 It is recommended-- 1. That the industry seriously face the problem of dust control in asbestos plants. 2. That new employees be examined physically, including X-ray examination of the chest, and rejected for employment if they show tuberculosis or pneumoconiosis. S. That employees be examined physically, preferably evy year, but at least every 2 years, this examination to include an X-ray examination of the chest. 4. That the industry sponsor studies on known cases of asbestosis, as well as studies on effects of asbestosis on the heart end circulation. ACKNOWLEDGMENTS The authors wish to express their sincere thanks to all those who aided in making this study possible, especially the officials and em ployees of the asbestos companies who cooperated to the fullest extent and gave every facility for securing data; also to Dr. Pancoast, of the University of Pennsylvania, for his interest and valuable advice in Interpreting X-ray films, and to Dr. F, V. Meriwether, of the United States Public Health Service, surgeon in charge of the United States Bureau of Mines Cooperalive Clinic in Picher, Okls., whose inter pretation of all the X-ray films listed in this report is followed. Ap preciation is also expressed to Dr. W. Atra&r Smith, and Dr. Kenneth lynch, of Charleston, S. C., for information and advice, particularly as to the pathology of asbestosis;4 to Dr, W. W. Wild, of Charleston, S, C.; to Dr. Joseph H. Wyatt, of Newark, N. J., and Dr. H. H. Fellows, of New York, for assisting in interpreting X-ray films; to Dr. Paul O. Snoke, of Lancaster, Pa.; to Dr. R. H. Stevenson, of Danville, Quebec, Canada; and to Dr. L. U. Gardner and Mr. Donald E, Cummings, of tbe Saranac Laboratory, who have undertaken the study of the pathological effects of the inhalation of asbestos dust * Aibu(s bodJ la iputua hun, B* Sn<wUi U. I.Tvct. W D.u4ff,*CBui 8WUi,U.D. low. Aia W*4. aOO.Au SO, IttVi.ioS.M, , pf>. 01 118 0243 EFFECTS OF ASBESTOS POST OK THE LUKQS through aaunal experimentation, with the aid of a grant from the Metropolitan life Insurance Co. REFERENCES (I) Greenburg, Leonard, and Bloomfield, J. J.: The Implogcr dust sampling ap paratus u used by tbe United State* Public Health Service, Pub. Health ftep^ vol. 47, do, IS, Mar. 18, 1632- Hepriat so. 2628. (2} Drinker, Philip, and Thomboo, Hubert M.: Determination of suspettsoids by Uematthg<<Qrre&t precipitator*. jour. 1ml. Byg,, voi. VH, do. 6, June im (8) HUJebraod, W. F.: Tbe analysis of silicate and carbonate rveka. Bull. 422, United Stales Geological Survey, Washington, D. C. Cooke, W. .; Fulr&onary aebericsia Brit, Med. Jour., Dec. 3, 192?. (5) Green, 8.: A pbotomkrographic method for the determination of particle also of paint aad rubber pigments. Jour. Franklin Institute, 1921, pp. 292,637. (6) Whipple, G. C.: Vital statistic*. Jobs WUey and Born, Kew York, 3925, p. 452. <7) Ruud, A. Britten, R- B,, Thompson, L. S., aad Bloomfield, J, L: The health of workers a dusty trades. It. ifsure Co siliceous dust (granite Industry). Pub. Health BulL No. 287. 1029. O s .. .* ; .it : >' A ' * i. . i i .s ., i ' j >'< ! * f' . ,> ** , , 01 118 0241