Document RJYQ5gvxpy24R8EMQgXm6bOOE

FILE NAM E: Texaco (TEX) DATE: 1935 DOC#: TEX006 DOCUMENT DESCRIPTION: PA D ept o f Labor B u lletin - Asbestosis Part 3 Ss5-.' JA COM M ONW EALTH O F PEN N SY LV A N IA D e p a r t m e n t -o f L a b o e , a n d I n d u s t r y r j O P H M . B A S H O R E , S*cr*uxr> I A ^ Special Bullet* Ho. 42 ^73 //!<* // w a iu im s - F u iW a s b e s t o s is Part II. Part IH. *6-i 'lie Nature and Amount of Dust Encountered [in Asbestos Fabricat ing Plants. The Effects of Exposure to Dust Encountered -in Asbestos.Fabricat ing Plants on the Health of a Group of Workers.' & bureau of ind ustrial standards JOHN CAMPBELL. Director Harrisburg, P en n sy lv a n ia S ep tem b er 30. 1935 X^x__ r ----* : . ' ^ r '.v*^ - T 'i M."ml si- .* . _______ Sfefttf & BU* 111n ssg ss W  # * '7 3 O V- COMMONWEALTH OP PENNSYLVANIA Department op Lahor and Industry I Part II. I * Asbestqsis t The Nature and. Amount of Dust Encountered in Asbestos Fabricate ing Plants. Part III. The Effects of Exposure to Dust Encountered in Asbestos Fabricate ing Plants on the Health of a Group of Workers. W illia m B. h' Fulton, M. Ej }., Chief of ludtuirtol HygUnt A lla n D ooley, Chemifi1 . Julia L. M atthew, Pit. )., Chemin Ro u it L. Houtx, Chemin 1 INDUSTRIAL HYGIENE SECTION BUREAU OP INDUSTRIAL STANDARDS ) ASBESTOSIS--PA RT III.--The Effects ol Exposure to Dust Encountered In Asbestos Fabricating Plants on the Health of a Group of Workers. Complete physical examinations were made of sixty-four persons (48 men, 16 women) employed a t the time Irt the plants listed in Part II of this report. Of this number seven men without previous exposure were used as controls. Selection of the workers was re stricted to those employed in textile manufacture. Those workers longest employed were chosen because the necessity of including a sufficient number from this group is evident. A ttention was also paid to the group with exposures of siiortcr duration and to the particular operation at which the worker was employed. Table V III shows their age distribution. TAIIUC VIII. DISTBIUUTIOM DY AOS OF AU PEBSOXS EXAMINED (Irons Humbtrol r c n o M K naM U m lcr Muabtr to A* Croup 4 40-41 SOI *u4 m Control* . -- --------------- t I 1 - 1 * A*b*alo*l* II - 1 a IS IS hj * * T o ta l* ...... ............ ............. M M | Il 1 ` 9 Asbcstosis was found in fourteen' persons (12 mcu. 2 women), or 25 per cent of the exposed group. Forty persons were diagnosed as negative and .the remaining three doubtful. Of the latter group, ouc individual had previous exposure to silica dust which may have been tlic primary or contributing cause and. as a result, has been eliminated from auy further consideration. The cases having as- hestosis were divided into those having slight and moderate pul monary fibrosis, no advanced cases having been found. The esti mation of the degree of involvineiit depended on the amount and extent of fibrosis seen rocntgcnologically and in the clinical find ing. flic present, past, and family medical, and previous occupational histories were secured from each worker. Direct questions, which might influence the individual's replies in regard to Ins subjective -> iii|iloniK, were avoided in obtaining chief complaints. The pre*l*iiuintiit|r subjective symptoms iu the positive group were cough and dyspnea. Other mujor subjective symptoms were drv throat ml frequent colds. *utptoiits. One individual in this group hud nflfcih`jrctivr 19 Objectively, the major symptoms were again cough and dyspnea. Thirteen persons of those diagnosed positive for asbestosis coni* plained of cough, and eight of dyspnea. Other frequently elicited objective symptoms were frcuuent colds, nalpatation, weakness, precordial pain, and pharyngeal dryness. No objective symptoms could be obtained from one Individual in the positive group. Occurrence of acute respiratory infections was particularly ok* served in the past medical history. Frequent coryza or other upper air*passage infections which did not result in a loss of time of three or more working days, yrere listed' as objective symptoms. Pneu monia during the course of employment occurred in three of the positive and seven of the negative group. The past medical his* - ! tories were otherwise negative except for an attack of pleurisy in one individual of tills exposed group diagnosed as negative. Family histories and. In particular, tuberculous contacts were noted. Two workers with asbestosis had roentgenological evidence of healed tuberculosis and negativte family histories. Two others who showed evidence, of healed tuberculosis, and who did uot have asbestosis, also had negative family histories. Physical examinations were made with the workers stripped to the waist. Mean variations in the present and greatest weight were less in the asbestosis group than in the group diagnosed as nega* live and in the controls. Five*minute oral temperatures showed a maximum elevation o( O.S*C. Four persons having asbeatosis had an elevation of temperature and eleven in the negative group showed it. Ulevatiou of body temperature in the control group was absent. j The mucous membranes of the noije and throat of the entire group ] were essentially negative. The coiijimctlvae did not appear to be I irritated. Tenderness over the antra and frontal sinuses was not found. Deflected nasal septa were common, and diseased tonsils were noted in a few cases. The external auditory canals did not show evidence of plugging or irritation. Clinical examination of the thorax included inspection, palpation, percussion, and auscultation of the' heart and lungs. A tendency to increased anterior-posterior diameters of the chest in the positive exposed group was noted. In the positive group the respiratory murmur and vocal resonance were impaired in five cases. Crepitant, suberepitant, sibilant, and sonorous rales occurred in nine of the asbestosis cases, the two latter types being predominant. The recognition of cyanosis presented a difficult problem. 'When it occurred tiic skin had an unhealthy leaden hue, with variations in the degree of intensity in the three individuals in tuc positive , group showing this physical sign. Roentgenological examination*,' made of all workers, included fluoroscopic examination, stereoscopic anterior-posterior aiid oblique skiagrams of the chest. In addition to noting gross chest pathology, the movement of the diaphragm was measured in cehtimetcra dur ing kite fluoroscopic examination; Right and left oblique exposures of the chest aided in the interpretation of the films and particularly hi the ilclcctiou of thickened pleura. The Itila, trunk, and lung ^m arkings of tiie fibrotic lungs were increased in prominence. JhL P sonic films the lung fields showed`a slight tendency toward ml undulation. A small area in the distal third of the lung in V film suggested atelectasis. Increased aeration, such as one sees in emphysema, occurred-in a lew cases. Thickened pleura and ad-, iiesioiis were noted in a lew cases. The average movement of the - domes o! the diaphragm of the positive group was less than that of the negative exposed or control groups. Three' of the positive and two of the negative group were found with roentgenological evidence of healed tuberculosis. Further evideuce .of pulmonary disease iu four of the positive group was clubbing of the fingers. The occurrence of asbestos bodies and the presence of 0. tubercu losis were determined in a single specimen of sputum obtained from each person. Each employe was instructed in the proper method of obtaining the sputum specimen, and was requested to collect a morning sample. An equal volume of antiformin was added to each sample. After complete digestion of the mucus, the mixture was centrifuged for three minutes at approximately 2000 r.< p. m. and the superuatant liquid decanted. Distilled water was added to the solid centrifuged portion, and the mixture rccciitrifugcd (or tlircc minutes. A drop of the deposit was transferred to a micro scope slide and examined for the presence of asbestos bodies under both 8 mm. and 4 nun. objectives. . * The greater percentage of sputum specimens were of a whitish culiir, but a few were muco-puriilcnt. Tlie asbestos bodies were a |Khf yellowish brown color and varied in sire, shape, ami number. Hie largest asbestos body found measured 117 microns in length. Iiie InkIich occurred singly, clumped, and as fragntculs. W hen present singly or in clumps, they presented a bcad-like appearance 'r u diiinlt-bcii shape, with bulbous ends tapering into a narrow Mrnml at a position midway between the cuds. Figure 3 iu iib u lo mirrugrapli of a single asbestos body. In one specimen ^H ycrngc tun nr three ashestos bodies or fragments of bodies w c ^ ^ e c u in eticli lw power told. while hi others. hnly one or two bodies were found in the entire specimen. Table} IX gives the occurrence of asbestos Itodics in a single specimen from each person. Merewcthcr (74) reports that the presence of asbestos bogies cannot be taken at present as hulicating anything more than previous exposure to asbestos (lust. This is in accord with our findings for it will be noted that they were found in a specimen obtained from one of the controls who at the time was suffering from an acute bronchitis, productive of a inuco-purulent sputum. Tills worker had been em ployed as n packer forcmait in the magnesia department for fifty years. His only exposure to asbestos dust was a rare visit to other {arts of (lie plant. - ( TAIII.K IX. O r c t'UlIKKCK OV ASUKHTOH HOtHRH IN SPUTUU - .. r* --serT*87r--ntATurr.et-yeBtr-asng'.rsirv.i ..*ii F n iU |i ( IlMrtH MiiMbrr 0 S is 4 ea T ot.l Humber of FtrtoM Baittl oa Spedbum KumUMl Ariwv- N-- C o * - X t b n i- x**- Goa- Aibr*. Mrs- ConIw h Hr* Irol i c o UN troi Intlt Itw Irol lUvIlr ih iw ii 1 1 1 H.S aa.s IM HA 0 .1 UA .VciNfltMi lltallni aluvtit s II a i - ' H .l 4M. IM HA n.* N'ti SlirriMrlM . . . . . . . . . . . s SI ? I u BA . -- .... Tull ........................ 1 1 T1 * i A single sputum specimen obtained from each Individual was stained and examined for the presence of D. tuberculosis.; Both direct smears and centrifuged nntiformhiizcd specimens wtre found to lie negative. Clinical examination of the heart showed the apical impulse to lie displaced in a few cases. Apical 'systolic murmurs were heard in . five of the positive atid two of the negative groups. The blood pressure was determined with a standard mercury, sphygmouauometcr. Hypertension, although present iu a few cases in each group, occurred only iu the older workers. Roentgenological evi dence of enlargement of tiic heart was not found. However, the cardiac silhouette in two individuals having asbestosis was found to l>c top normal in size. electrocardiograms of fifty-six 6f the workers were made follow ing n thirty-minute rest period during which the suhiect was in a Ireclining position, while chrht were taken with the subject in a Hit ting iiosilioii following a short rc.st period. The most consistently positive eleetro-cardiograpliic finding in the entire group was voltane. 11 was found to be present In seven of tiie positive a ! ^ ^  eighteen ( Ike ui`|$itlive groups, compared with (our of llic conIrols. Right predominance was not present in the tracings o( th e . control croup, but did occur in two tracings, of individuals with iwbcstosni and three of the negative group. Left predominance was most frequently fouud in the tracings of individuals in the ad vanced ace croups. Katz and Slater (62) found eighty-six per cent of individuals with a second positive wave of the Q-R-S complex to have changes in the heart muscle. O ur findings show that six of the exposed group had a second positive wave of the Q-R-S com plex ; two of these had asbestosis, and four were negative, a s com pared with an absence of this finding in the coutrol group. The I'-U interval was increased in the tracings of two exposed per sons found to be negative. A functional test of the individual's response to effort was per formed by having Idm place one foot on a chair and then raise his body twenty-five times in thirty seconds. The pulse rate was de termined immediately before and after exercise, and again at the end of a two-minute rest period. The respiratory rate was deter mined immediately before and two minutes after the exercise test. Table X gives the results of the functional test. Greater variations were seen in the rate of respiration following exercise in the ex posed group as compared with the controls than were seen in the pulse rate. Individuals with a pulse rate of 10 above the normal resting rate, two minutes after exercise, were considered abnormal. TAIILK X. VUNOnONAL TEST OF KESPOSSE TO E P rO ItT Pulw > Respiration * Nmotor h n n l t n Mumtor P crcto U rt COSTSOLS VeiHib -- - t u.c -- - MKOATIVB 1 US 1* it.3 T n u k . . -- ___ ______________ __ t II.S 4 ta.ft AHIIKfjrOHIIft 1 l.t Fciook _________________________ - - ci.a I to. 1 nla It ibovi MtMil mltttf till two mtauUi alter tamlse* * Nrtpkfttorjr vata I above normal featlat vale Iwo Mlmiiea alter carrels. Asbestos warts arc thought to be produced by a fiber of asbestos ' which has become lodged in the skin, largely through the irritation and overgrowth of the horny and matphigluan strata (27). These growths are usually found on the hands but may also develop on the feet. Forty per cent of the exposed group had ouc g ^ o r c of these papillomas oil their hands. \ . Tim* IiImhI ruiitilit ami iirinnlyHCM were innile on each Individ c r ; uni iminnl. Ilnenuiglitbhi wan determined by the Haden and llniiiw r culiirinu tric Method and expreased a gram of lincttiog|ul>in per 100 cc. o f blood. Smear for dilTcrential counts were stained with Wright's Inin and 200 cell studied microscopically using a 2 Him. oil immersion objective. Practically no change was observed in the blood picture of the three groups. Comparable average variations did not occur in either the erythrocyte or leuco cyte count. In two individuals with moderately advanced pul monary fibrosis, the total leucocyte counts were 10,800 and 11,400 with corresponding increases in the percentages of polymorpho nuclear leucocytes. Changes in the percentages of other types of wliitc cells were not observed. I Urine specimens were collected from each worker at the time of physical examination.' Specific gravity, albumin content, and the presence of sugar \Vcre determined and a microscopic examination made of a centrifuged portion. Urinalyses were essentially negative except for a trace of albumin in fo ir of the positive and thirteen of the negative exposed groups, as co npared with two of the controls. A brief summary of the clinica findings of three asbestos mill workers and the accompanying il ustrations (Figure; 4 to 7 inc.) arc presented to show the two st< ges of asbestosis c countered in this study. I Case number A-87J0--While male; seed 30 years. Olici complaints--Coligli. Objective symptoms--Occasional front d headache (2) Epistaxls rare (3) Dry unproductive cough (4) Coughini ; attacks precipitated by strenuous exerelse. Past Medical History--Usual diildhc id diseases. Traumatic orchids. 1934. Occupational History--Began working at 16 years of age. Milkman. 2 years. Mule sjtiiuicr. worsted mill, 2 years. Ice men, 1 year. Mute spinner, as bestos fabricating plant, 9 years. Physical Examination--Apparently healthy adult male. Height 62 inches. Weight 122 pounds (greatest weight 122 pounds). Slda clear. No cyanosis. Asbestos warts on both hands.. jPuIsc rate before. Immediately after, and two minutes alter exercise, >4, 100, 72. Respiration rate immediately be fore and. two mluutcs alter cxctcise, 20, 22. Cheat, normal shape; per cussion normal; breath and voice sounds normal; sibilant sad sonorous rales both bases. Heart, epical Impulse, Stb interspace mid-ctavkular line; no murmurs. Illood pressure 134/90. i Fluoroscopy--Diaphragmatic movement, right dome, 2.5 cm.; left dome, 1.5 cm. X-Ray--Thoracic cage is negative. The trachea is in the midline. The cardiac silhouette is within normal lioitta of the. The arch of the aorta is not widened. The domes of die diaphragm, are somewhat irregular on the left side but fairly irregular on the right. The pleura appears to be slightly thickened on the left side,.and Is more clearly shown in the oblique view. In tile rigid spex there it possibly an old healed tuberculous process giving the appearance of an apical Cap. The hila are increased bt prominence. The trunk markings and linear markings are Increased fat prominence. FIGURE 4. CASE NUM BER A 8 7 3 0 . X V r* \. I\krtrnciuilii*gntiii- -Cardiac rale 11 P-R interval 0.16 tccuml. Voting..- 4 mm. I>iii|ttuin--Admtlmd, rliglil. Case NihiiIkt 447- AVIillr nude; aged 47 year. Oiirl Coiii|>laiiM-r(l) Cough; (2) Slmrtne uf hrvallt. Part Medical llUlory--Uual diildlwod dUcascl. Gonorrhea, 1922.( Occupational llUlory--Parmer until 29 year* of age. Laborer atcfl work, lailairer grain mill, 1 year/ Prt|>aration room. ailKitoi mill, IS i ^ F IG U R E 0. ELECTROCARDIO G RAPH!1C TR A C IN G O F CASE NUMBER AS7SO FIGURE 7 . ELECTROCARDJOGRAPJttC TRACING OF CASE Phyiical Examiiulion--General appearance (air. Slciu dear. Height 59 indica. Weight 120 poumli (greatest weight I2S pound). No dubbing ol finger. No aibcato wart. Nail lied not cyanotic Cheat, normal liapc; per* ruubm normal; re|dratnry murmur wltlifai normal limil; vocal rruawnce iNinlicriil; alhilant and wumriuii rale. Heart, im apparent enlargement mi uiiiriiiiirn. PuIh- rale M ure, (nuiwdlatdy after, and two minute a f t e f l ^ 20 J * liwcllnml cxcrcUe ltd , 76, 118, 76. Rc>|>lratlotl n tc ktiwc and lw*> initt. utc alter functional excrcltc tcl, I t, lit. Ulood prruurc IJt/VO. Rlikirniu-npjr--Oiapliragiualic cxcurtkiu} right dome, 17 rut.; k it Ionic. 2.$ cur.. X-Uay--'Tlte lltoracic cage I* negative. *The Iradica Is in lltc luiil-linc. The carillnc illmucUe la within normal limit. Tltc ilmtic of Utc lia|>|iragui are regular, lltc hila and trunk marking arc lucres*! in prominence. lltc lung marking arc al*o incrcaed In prominence. 1 - ' j ! I Electrocardiogram--Cardiac rale 60. P-R interval 0.16 ccond. Voltage J.S mm. 1-ow voltage of all Q-R-S complex*-. Diagnoili--AibcttoiU, moderate. I TAMJC X I. JMOIDKNOK AND DKOUKE 0 ASIIEUTOUta W ITH KKLATtOX TO OOCUfATtOH. I)UT CONOKNTtUTIOH. AMO TEAKS O P EXfOaUKE i ' Oeruiiftiloa ; Lvcract Camra* Aibrelaalt i iu te UlUlatu al elicle* VMM Vaiai reraubl* el Humber i loot Riparare Kxamlacd Negative Might Uotkratf A<lraacml| poubl l-U rttfo m till Canteri M 1 -It 1 4I.M . II--IS 1 M~M t ovrrto 1 Vaiai It t -- -- a t 1 1 1 1 -- 4 t *_ j . 1| *- ' -- -- -- -- V nw n Bit aiitaurr* IViailera, TVrlalera, SVatlteea, Ik. Total* -I 1 Ml 1 a . ,, .. ft 1 -- .. -- MM IJ-II 4 I- ft 3 -* i a * -- -- .. everta t t -- .. -- Total M 4 a i i .. ! a-- 4 ft--lft I i .. I -- i L 1 - .1 i t - ft i -- 1*~!0 1 . 1 -- i ~ -- -- 1 ` ** Vll over 4 4 -- -- i Total tl ti t -- - !i L I i 1 1 * Tiif principiti fuctora umv llumi'lit to ilctcrtuinc inrilt*m*i* an<l ilegree of tilt* |iiiciiiiiiinocoiiinxcii arc tinture nini co iic^^^lion of the dust, letizili of exposure, ami imliviiliinl xiixtTpliliilin^Pfhc in- ~X' \ V i\ ` T V cidcnre of ashcstosis with relation to occupation, concentration of tlic dn*t, and length of exposure in the fifty-six persons examined in tills study Is indicated in Table XI. Obviously the examination of such a relatively small group prevents the formation of definite con clusions as to the influence of these factors. Nor is it possible from our findings to establish tlic maximum safe concentration of asbes tos dust in the air. However, the results of tills investigation show the necessity of a reduction o f'th e dust concentrations in those operations, shown in Part I l of this study, where there is continuous exposure to high concentrations. Summary (l). The concentration of dust in asbestos fabricating-plants dc- [tends primarily on the grade of asbestos; mill fiber gives rise to a uglier concentration than crude fiber, i Operations arranged In de creasing concentration of dunt are preparing, carding, weaving, spin ning, twisting, winding, and warping, - (2). The average particle size of asbestos dust is stated hi two diameters, longitudinal and transverse. (3). Petrographic analyses of dnst encountered in asbestos fabri cating plants collected in the workers' breathing zone shows it to contain no free silica. (4). Fourteen^ oc 25% jot fifty-six^ both clinical- and r o d Ackmowijsoomrmts The Department of Labor and Industry of the Commonwealth of Pennsylvania wishes to thauk the nianagement and employes of the plants studied for their cooperation and interest which made the success of this study possible; Dr. H. K-. Pancoast and Dr. E . P. Pendergrass of the University of Pennsylvania, whose interpreta i tions of the films have been used; Dr. G. W . Grier of the University of Pittsburgh, for his interpretation, assistance, and advice in the roentgenological study; Dr. J. Evans Scbeehle, Secretary of the Pennsylvania Department of Welfare, in extending to the Depart I ment of Labor and Industry the facilities of bis department; Dr. C. A. Lnnbnch, roentgenologist and cardiologist of the Norristown Slate Hospital, for doing a large majority of the X-ray work, and iiis technicians for the routine laboratory examinations; Dr. J. D. Ilcnrd ami Dr. A. II. Fuller of the University of Pittsburgh, and Dr. C. C. Wolforth of the University, of Fehnsytvania, (or their as sistance niui interpretation of the cardiograms. Dini.iocsAhiiY Amiante. Hyg. du trav., 1:191-192, 1930. Anderson, H. V., and Clark, G.-L .: Application of X-rays >In1.1^^ the Classification of Fibrous SiUcate Minerals C om m onlj^A ___ t Ind. and Eng. Chcm., 21524-933, 1929WF 3. Auribnull: Notes aur l'hygline et 1 curite des otivriers dans les filatures et tissages d'amiautc. Dult, de 1'lusp. du . trnv., j). 120*132, 1900. 4. Baader, . W .i Asbetoe mit Wnrzenbildung. llfmcliii nted.W chnsehr., 79*83, 1932. 5. Beger, P. I.: Ucber die Asbcutosis Krperchen. Virch. Arch., 290:280-353, 1933. 6. Beger, P . I.t More on Asbestosis Bodies. Virch. Arch.. 2`.V. 530-539, 1934. Abstr., J. lud. Hyg., 17:32, 1935. 7. Beger, P. I.: Injurious Factors in Asbestosis and Silicosis. Med. Kn., S c o t 14. 1934, p. 1258-1261; 1922-1927. Abstr.. J. Ind. Hyg., 17:32, 1935. 8. Beintker, .: Asbestosis. Arelt, L Gewerbepath. u. Gewerbchyg., 2:345-358, 1931. 9. Beintker, E .t Asbestosis Bodies. Virch. Arch., 293 : 527-529. 193*4. Abstr., J. Ind. Hyg., 17:33, 1935. 10. Bowles, Oliver: Asbestos--Domestic and Foreign Deposits. U. S. Bur. Mines Inf. Circ. No. 6790. June, 1934. 11. Bridge, J. C.: Asbestosis. In : Ann. Rep. of the Chief Insp. o f Fact, for the Year 1928, p. 95. H . M. Stnt. Oil.. Lou don, 1929. 12. Bromley, I. F., Wood, W . B., Eltiuan, P .: Pnciuuuuoconiosis --A Discussion. Part I--Silicosis; P art II--Pulmonary Asbestosis. P art I II --Pulmonary Asbestosis. Brit. f. Radiol., p. 262-295, 1934. Abstr., J. Ind. 11vg.. 16:1023. 1934. 13. Buttner-Wobst, \V. and Trillitzsch, C : Die Bcrgflachstuugc (asbestosis) und was der deutsche Arts von ihr wissen muss. Tuberkulose, 11:11-14, 1931. 14. Cirkel, F ritz: ChrysotHe Asbestos. Its Occurrence. Exploita tion, Milling and Uses. Mines Branch Bull. 69. Canada Dep't of Mines, 1910. 15. Clyncs: Asbestosis and Silicosis. Brit. Med. J.. 1-.379. l.tl. 16. Cooke, W . E .: Fibrosis of the Lungs due to Inhalation of Asbestos Dust. Brit. Med. J., 2:147, 1924. 17. Cooke, W. E .: Asbestosis. Brit. Med. J., 2:1024-1025. P*27. 18. Cooke. W . E .: Pulmonary Asbestosis. Brit. Med. J., 2:585. 1928. 19. Cooke, VV. E .: Asbestos D ust and Curious Bodies Found in Pulmonary Asbestosis. Brit. Med. J.. 2:578-580. 1920 Abstr., J. Am. Med. Assn., 95:1431, 1930. Ahstr.. f. lud. Hyg., 12:34, 1930. 20. Cnoke, VV. K.: Asbestos Dust und Asbestosis Bodies (nun I.unga of Asbestos W orkers. J. State Med.. .19:54-1.548 1931. j i i 21. l<Ktkc. W. K.: Siliro-AiitliracQHis Presenting Curious Bodies Similar to Those in Asbestosia. Brit. Med. J., 1:656-657 1932. 22. Cooke, VV. E., and Hill, C. F .: Pneumokonioaia due to As bestos Dust. J. Roy.' Micr. Soc., 47:232, 1927. 23. Cooke. W. E., and Hill, C. F .i Pneumokonioaia Caused by. Asbestos Dust. Brit. Med. J., 1890, 1927. 24. Cooke, W. E., MacDonald, S., Oliver T .; Strange Bodies Found in Asbestos Workers. Lancet, 2:136-137, 1926. 25. Cooke, W. E., and Hill, C. F .j Further Observations on Pul monary Asbcstosis, with Special Reference to Asbestos Dust and Curious Bodies found in the Lungs. J, Roy. Micr. Soc., 50:15-19, 1930. f 26. Davis, G. G., Salmonsen, E; U ,, Earlywine, J. L.: The Pneiimouokonioses (Silicosis). Bibliography and La vs. Ind. Medicine Inc., Chicago, 1934. 27. Dctvirtz, A. P .: W arts from Mineral Substances. Roussky Vestnick Derm. 1243-247, March. 1930. Abstr., J. Ind. Hyg., 13:125, 1931. 28. Dhcrs, V.: Amiantc et asbeitose pulmonaire. La nied. du trav., 2:147-172; 187-209, 930. Abstr., J. Ind. Hyg., 13:49, 1931. 29. Donnelly. J.: Pulmonary Asbestosis. Am. J. Pub. Health. 23:1275-1281, 1930. 30. Drinker, P .: Alternating Current Precipitators for Sanitary Air Analysis. J . Ind. Hyg., 14264-370, 1932. > 3 |. Drinker, P .: The Size Frequency and Identification'of Cer tain Phagocytosed Dusts. J. Ind. 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