Document 5bvpr1Njrv0mBqj3KGaL01M5R

V AFFIDAVIT WASHINGTON DISTRICT OF COLOMBIA ) ) sa . ) BEFORE ME, the undersigned Notary Public, personally came and appeared MICHAEL RHODE, a person o the full age of majority, being of sound mind and body, who, after being first: duly sworn by me, did depose and say: I, MICHAEL RHODE, am an employee of che Armed Forces Institute of Pathology, Washington, D.c. I am custodian of the original archives of Dr. Arthur J. Vorvald. Pages 1 through V ~2_ attached hereto are true, correct and authentic copies of documents from Dr. Arthur Vorvald's archives. The pages attached are Revised version of ASBESTOSIS - Experimental Studies bv_ The Saranac Laboratory. Report to. the Johns-Manville Corporation, dated January 31. 1949 Dr. vorvald was the Director of the Saranac Laboratory of the Trudeau Institute. - Upon his death. Dr. Vorvald's archives were donated to the Armed Forces Institute of pathology by his widow. Dr. Vorvald's archives are in such condition as to raise no suspicion concerning their authenticity; they were received by the Armed Forces Institute of Pathology from Dr. Vorvald's widow after RHODE AFFIDAVIT - 1 of 2 V *$&?> %*&$>> ...- asbestos Exp*ijcfls'tal Studies by THE fiABiZAC IABORATQBX CONFIDENTIAL A *\ *>V ~ .{*] $r EXHIBIT Dr. Vorwald's death; they are presently on file as authorized by law in the National Museum ot Health S Medicine, Armed Forces Institute of Pathology, Building 54, Walter Reed Army Medical Center, Washington, ..D.-C, 20306-6000; and the archives ha*rs-bMKt.in existence for 20 (twenty) or more years. SWORN TO AND SUBSCRIBED before me, the undersigned Notary Public, on this the ?*? day of April, 1992. > l^ruLL My ^ominlspi^^Expires; NOTARY PUBLIC Printed Name: iS/ygxJi RHODE AfriCAVlT - Fc t of 2 5 Zhtrocuctioe Asbastoa liinersels Vr I. ASSTRA.CT A* .-- 4 * 5. Sbecsri acetal ICetJiodis IF. ECFERIMBtttL ASSGSTOSIS | T-< -'%. fc-u L *TT .6 Species Susceptibility i - reculler Characteristics of Asbestos a. Rate sf Tissue Reaction to Asbectos Fibers 9. Aabeetoais Bodies a** XT* . X. JRIAIAIlOiLgXPgaSCTS King's Floats .12 Ihisting Materiel 13- Dust Composition Ui. Dust Concentration $.1 Reaction in Arn.oa.1a .16 Guinea Pies 17- Rate and Type or Reaction IS Progression IS. Infection Coincident -aith. Dust Inhalation 20. Infection after Duat Inhalation 12 ggfaft __ fW AsWWi^f, 26. 2123. 29. 30. 313233. Dusting litoriel Dust Composition Dust Concentration 5iza-frequency of Duet Reaction In Animals Guinea Pigs Rate and Type of Reaction Progression lit -:r=-- Hi ---15 15 15 15 15 15 17 3li- Asbestoels Oodles 35. Rats 17 IB 36- Bate end Type of Reaction 16 37. 36. 39- Cate Rate and Type of Reaction X-ray Changes 19 19 19 o lil. Ii2. Asbeetosis Bodies Rabbits Rata and Type of Reaction 20 20 2C Ii3. Asbestosla Bodies 20 Hi. Summary end Interpretation _ .. r 21 10 PJ Wnt w*i t~n*T \n JLW5!}5Celi JfbA U6. ixisting uaterifil 21 21 L7. Dust Conposition 22 u8. Dust Concentration 22 L9. Size--frequency of Dust 23 50- Ttceetian ia A*i1 ifll-s ^1. C-nioea, Figs 52- Rate and Type of Reaction 53. Progression 5U- X^apti Node Involveoent 55- Asbestosis Bodies 56. Hats and Klco 57- Svomary and Interpretation ^ Uwmt UOMJf^W - Lw^g fiber-unbeaten Past . -- -- S9- Pasting Ua&erial 60. Dust Cospoeitian fix. Past Concentration 62. Si*c-fro<xuancy of post 63. Reaction la Animals 6L. Cnisuaa Pigs .65. Sato and Type of Reaction 66 Fl-ogresaian 67- iysph Rode Involvement 6Q. Anbestosis Bodies 69. Cats 70- Rate and Type of Reaction 71. X-ray Changes 72. Rats 73- Rate sad Type of Reaction Faee "23 23 2h 2k 2k 2k 25 26 26 26 26 27 27 27 27 28 29 29 30 30 v2 30 31 7m. flics 75- Pa't-i' r.rri Ty^*cl w_.vii 76- *ST.!T/ aai Cr-rr.j*'. -*i%v. .. -.on ixsvn..' -------------* - | r ~t i ?C, Intratracheal &7sri:wc.is 7?- OsOTsrisoR cf >'ihrou* r.r.1 ' 90. Cnrpariaon. of Various rr L'ists SI. Caeparlson of lor^j-OTibo.- --v 92. Intravenous Esperirssnts lutraparitaasai 2rporlrrits : H-cs 11 If2XIV- OTIIT'. 2KF2:a^SBTS Tf<--1 V' t as. Protective Action oil /-liticin'Jri Cospc/ustfi 56. Parsation of Asbeatosls fcdias La4|/ _________ Liarml /'thsoi LKUiairr Acrrica " *> 8?. Infection if COlfPIldLTIC^`1 -I--4 -V4 . 90. Susceptibility, to Tuberculous Infection 91. Susceptibility tc 5oi>-toJb*rsulaus Infaciicn fCjff. TaBLSS*V 32 32 32 33 31 3m 35 35 35 35 36 37 37 38 33 3? ho iij - 71 Asbestosis Is . pulmonary discabe caused the Inhalation of asbestos dust. In an-; ip.wl.a it is"characterize i by ^peribronchiolar'" fibrosis rh'ich s r > ^ fchV*"4* ,, /f seems to b4) the result AC Taochsnical, /Either than.chemical, irritation of >/v the tissue by asbestos libers. jQnlf the loos fibers produce & typical it *y \ reaction; short fibers (are relative y incrtjj The f\ lamented structure of the fibers is an essential factor/Ln th ..mechanism of irritation', dt-character- istic tissue response can he produc id by non-siliceons (as-*ell as siliceous) 7* ^^ fibrous nlnerals. Inhalation of asbestos dost raparentljr deee not alter H#-* CKfiA^ Wlf* BuU A *jkJ^ 4^''*^ significantly theuoorglfe of^erperia atal^tubercolosis in^guinetf pigs. Thec ashestosis body, trhian. is a specific conccaritapt of asbestosia and faros soon after the % prevent.further of the asbeapos fiber Into the lung, js UyilUVBPGT ^ s* ;a to the tissue by the fiber and thus W limit pro gression of the/raactloa vtwn exposes ceases. ATmrtnnn does not exert a protective action against the tiasuoj Irritation of asbestos fibers as it does 'that of quarts particle . 2. --introduction ~ ---- -.st-estcsis is a Hors. of pneumoconiosis resulting from prolonged i.'Jhala- tioo of asbestos dust. The name asbestos, literally ^tnburaEblOc " is ucrfc that of & particular mineral but Is a term applied to a number of different dnsrals wu>se characteristic ffeaturo Is a structure composed of long, par allel, flexible fibers- This structure is unique because the fibers are capable of repeated longitudinal subdivision to units of molecular proportions. In length the fibers vary from a fee- microns to six or mors inches. Scats varieties are stiffbr than others but many are sufficiently flexible to be spun into yarn and woven on modified textile machinery. 3- Asbestos Minerals The aabestoa minerals are silicates of variable composition and belong to the serpentine and the amphibole groups. Listed below are the mere common varieties Amphibola Orcup Anthophyllite Aeoaite Anphibole (Me, Fe) silicate (MS, Fe. Al) silicate (C3l, lSg, Fa, &X, Ba, X) silicate TranoUta <Ca, Mg) silicate Actindite (Ca, Eg, Fe) silicate Crocidollte (Ka, Fe) silicate Fe silicate Serpentine Group Chryectile ifg Llicite (hydrcu3) -2- m TnQ bulk of tha ss.-sstcs of cscsEcrsa is oniT-Ville, 3 .fsC.aSiOa-SiioC-, T7hioh is nined la the luetford region cf the ?rovInca r [Jisoec. Crocidolitj and aaosite are also used comurciHiy Vet in each. aculior amountsCfcrysotile occurs as veiny in serpentine, s. mineral similar in chanicai com position to chr^sotili i&t rtiich exists in massive form ai^ is nade-Aro sf _____ microscopic fibers vcLtr.cr.it the parallel orientation characteristic of chxysctile. The massive blue black serpentine, -which is smooth xasL soapy to the * touch, is traversed by veins of fibrous chrysotila varying in ridfch froa a baroly perceptible line to six or more inches. The fibers run across the vein and not lengthwise -with the formation- Attention is directed to the arinnral bruclte, KgO -H2O, -nhlch.is often found in the asms formations with serpentine and chrysotils and nay be' ftbreus In structure. It has no commercial value at preseat because its fibers ere not sufficiently flexible to be used in textiles but they are capable of repeated longitudinal subdivision. Unlike other asbesrtiibxm rdnarals, brucite is not a silicate and for this reason it has been a valuable tool in an experimental evaluation of the action -of fibrous minerals upon lung tissue. IV. EXPEaiHBSTAL ASSESTOSIS ----------f-f < rl Far many years studies have c*an carried on -by the Saranac Laboratory in an investigation of the cause, nature and developaeat of asbestosls. The present re port. is devoted to Experimental Asbestosls. In it are described the arrival ex periments with various >-**** of asbestos dust. Another report, to be prepared and issued later, vill bo concerned with aumeu Acbasto9ia sne cove.- tco aspects of uorkers nho have been exposed to eaheatoa dust in. an industrial -3- Although j.sbastoaie in'can la a chronic diabase *"v.ch reouirca years to develop, it is possible to reproduce in ono or awe species cf aai.v.al character istic tissue changes "nhiclii are similar to the ieaicna of human aabastosis. Since ' the life-span of the experimental animal in relatively short, it is not possible to'develop the characteristic lasione in anlrarl s vo- dar the usual -Sn5*tttrisi-uenditions- Consequently, to obtain a complete avaiu^.tion ci th-' tissue response to inhaled particulate and fibrous materiel, it is necessary to accelerate the reaction by employing highly concentrations of duut than vrouis ordinarily b3 en countered in industry* IThile conditions of exposure are thus different, the information yielded by experiments trltb amaals 1g invaluable in furnishing a better understanding of the reaction of the human organism tc inhaled asbestos duet. S- Itcperimental Methods Far investigating the biological reaction of the experimental nnia.i to the various asbestos minerals, tuo types of technique have beon employed, namely, the inhalation method end the Injection method. In inhalation experiments, groups of animals - up to 100 or mure guinea pigs and eoaetlmeg smaller numbers of rabbits, cats, dogs, rats or mice -- are kept for eight hours a day in a cubical duct room, eight feet in dimension. In veiich a cloud of asbestos dust is maintained. At intervals during the experiment, a fee animnla are sacrificed and the tissue examined to determine the nature end extent of the dust reaction. Some unimvla are exposed for periods up to three years. The Injection Kqjsrijssnts, in nhich the dust, either dry or suspended in fluid, is Introduced into the eni nwl by the intravenous, izifcraporitoceal or Intratracheal procedure, are used to determine otvathsr or not a. particular dost haa a potential capacity to produce tissue reaction. Long-tera inh-aia.ti.on experiments furnish iiifonaabion upon -which great reli ance is placed -when estimating the degree to xsiich a dust night be hazardous to industrial workers. Tihatber cr not atmospheric dust, even though potentially dangerous, can be inhaled, -pass the natural defense barriers and reach the pul monary tissue in quantities sufficient ta cause daraagq can be determined only by inhalation procedures. Injection experiments are useful because in then contact between the dust particles end tissues Is assured and the potential capacity of the dust to produce reaction can be estimated accurately, tfhen dealing with fi brous minerals like asbestos, the iatratraobasl method Is valuable since it per mits observing the effect of the fibers on pulmonary tissue. 6. 5pedes Susceptibility HnHVn free iHo>) asbeetos does not exert its specific affect in all organs of all species of animal ('Cable 1). Injection of fine quartz into various organs of the guinea pig, rabbit, silicotic nodules* However, cat, dog, chicken and even tadpole will produce A Injections of long or short fiber asbestos have resulted in a fibrous reaction In the lung and, to A lesser extent, in the peritonea* bat not la otter orpmie|'tU ^t/ M^/ *" ^ uAuSm. ju*X .-* mm**** ^niu9'3> <ua^eu*. -^1- ef 7. Peculiar Characteristics of Asbestos u ** ^ *r,*1,n^^ *' Experience baa demonstrated that most of the particulate matter ^whaled Into the lungs of men and animal ia IX) mlaroes or less in mfndLman diameter, larger particles apparently are crrrludffd by* the protective mechanism of tha upper respir atory tract. In the case of fibrous materials, however, this restriction does not apply and fibera 100 and even 200 microns in length have been found in the termin al air spaces of human lungs. In laboratory an1 male exposed to asbestos dust tha d" length of fiber found in the lung rarely exceeds Go microns. Not every kind of fibrous material is Inhaled with equal readiness3 for example. the synib-etic liters si' real. ^T-crcr-t'-"/ ti-?. toe rj^T-lAa'-bAa to pass easily through vhe nose, pharynx, traeres. a;xi bronchi and seldca reach tha terminal bronchioles and alveoli. Inhaled port.icQla.t-e matter coca*a to rest throughout the terminal air spaces (alveolar duct, atr4a,-al.veoli) in all parts ->f the Iuma>i irihsleS^aebaetcs-fibera are first retained in tha respiratory brsnstriclas- Thest very assail tubes are immediately distal to bronchioles lined by ciliated epithelium. .Their oun essen tial lining la a lev euboldal type or apitho*1 low hut, as their name iinplias, they actually function In respiration through lateral alveoli given off as pouches along their walla. Either these pouches, cr tha abrupt change in the character of the lining epithelium, or the decrease in diameter of the tube, or perhaps the combination of all three factors is responsible for local retention of the inhaled filler. Only after aabestosis is tell established are appreciable ambers of fi bers carried into the more peripheral air spaces. 6. Bata of Tissue Reaction to asbestos Fibers The rate of tiesue reaction to asbestos is ouch more rapid thin to an active dust like quarts. Evidences of tissue response appear as soon ae fibers have localised, in sufficient concentration in specific areas. In rata receiving asbes tos fibers by intratracheal injeotian this evidence is visible 2S early as two week* after injection; for quartz dust the latent period night be two mentbc or The behavior of the tissue reaction to inhaled dust after the termination of exposure 1b not tha sue in silicosis as in asbestosis. 7n silicosis, tha young rmrfrqoft becom larger; in asbestosis, young scar tissue,that nay have fsrned.contracts and becomes more dense but the area of fjrxvolvessnl decreases in size. Xf expocure to asbestos dust is terndnated after a brief period, the recently^nhaled fiber3 In the lung nay causa the fibrous tinsua response to continue for . abort tine, until the fibers hava been coated. This progression is of only a slight degree and of little significance. 9, Aabestosis Bodies _ fv .__ __ The peculiar structure known as the aebestosis body or curious body is a 3pedlc coacooltant of asbestosis. The typical body is a golden-yellctr, beaded or baustr&ted rod which nay be elthar straight or curved. Often one or both ends are bulbous like a dumb-bell. The bodies vary considerably in length, and di mensions up to 250 microns have been recorded. Xt is believed that aabestosis bodies are due to a deposit of protein and iron pigment upon the surface of Inhaled fibers. Xa guinea pigs they fora after about 60 d^ys of contact with the tissue. They acre abundant in ran and the guinea pig (see Table l) but ere rash larger in the farmer, probably because the larger- sised sir tubes admit fibers of greater dimension. In cats, rabbits and aloe there Is sn atypical coating of a fee of the fibera after such longer residence in the lungs. In rata and dogs no bodies could be discovered. Although the evidence Is incomplete, it appears that the narration of the asbestosls body prevents damage to the tissue by the fiber. VaiV'i-1 -- -tti. /?4 X. .VMLAXTm EXPBOUEKIS * in* 'i '"%'*%* 1x Four cuBipiehensive Inhalation experSasitts have been conducted at the Saranac Laboratory with various forms of asbestos dust. Xa each of these Investigations rare than 160 nniwala rare used and the experiments -sere carried on fbr periods ranging from 2 to more than 5 years. The four kinds of asbestos dust employed are Identified as King a floats, abort fiber, 100 par cast hall,-mill ad, and long-fiber asbestos dust. Inh3ia.t|Lon Egpqjruaqpt Tri-th^ "Ejng |3^ *25*^1" ^sbagtog ^Du^t, The first inhalation experiment conducted at ths Sanmac laboratory vith asbestos dust was ba^un In 1928. An-it^iy the dust for periods up to nearly three years and Goae guinea pigs lived for about four years after -their first exposure to dust. A preliminary report giving observations afte-r 29 months of exposure appeared In the February, 1931 issue of THE JOURNAL OF INDU STRIAL HTGIEHE.-a it that time observations covered a period of only 2-1/U years and the conclusion* as to the ultimata effects of inhaled asbestos dust were provisional. Results of the oooplated study show that most of the conclusions drawn in the preliminary report were substantiated. A complete review of this experiment follows. 12. The dusting material, vaa a cattiuercial variety of asbestos dust taoesn as Sing's floats and -was composed of short fibers and particles of variable size. Corporation of 13. The dust composition. (Table 2) reveals that the amount of fibrous ebrysotile vu only Hi per cent, a rather low value- However, there eas suf ficient fibrous material, to produce a characteristic fibrosis. lb. The dust concentration at first ues quit* low and for Iwplnger rumples taken soon after the experiment was started, the average light field count.* by the standard technique vma only 6.0 million particles per cubic foot of air. An appreciable umber of large particles (or fibers) also were present, as STUDIES ON HFEXDJENTAX. PNEUMOCONIOSIS. VX. Inhalation of Asbestos Dust-, Gardner. L.U., and Cunnuigs, D.E. J. Ind. Hyg., 13* 65--81, 97--Uli, 1931- Qhown by an average count of c.5 rai.liJ.oc for T-JU-txcLes jjvsater than 10 aicrous. After the inhalation experiment had been under way Tor afccu+- two years, the apaed of the rotating paddle in the dusting rachitis was increased and for tha remain- T\g j or lO months of tb* experiment considerably* nor* dust was dispersed into the-atmosphere- Average dust counts for impinger samples`dollecteeTrt^^KQ1^ change were 53-7 million for tha usual light-field method, and 1-c million for particles larger than 10 microns. 15. Reaction in Aniwtq to Inhaled "King*s Floats" Asbestos Punt. Results of the investigation; briefly snanazrized. in Table 3, obov that inhala tion of King's floats asbestos dust produced a typical peribronchiolar fibrosis in guinea pigs but not is rabbits or rats. 16. Pigs, Seven groups of guinea pigs mere used. In three groups the effect of a continuous and of an Interrupted dust exposure uas studied} In two other groups the relationship between infection, and dust exposure was investigated. The remaining too groups were infection controls 17. Rata and Type of Enaction. Guinea pigs inhaling this duet for periods up to 33 months developed a characteristic fibrosis occurring In conical patches about the respiratory bronchioles- Curing this exposure the peripheral alveoli ware not Involved. The particulate elements in the dust mere transported to the lymphatic system share they caused oo signi ficant reaction; the fibrous elements remained fixed el the site of original localization and -ware seldom detected in tha lymphoid tissue. Pleurisy and fi brosis in the septa were observed only Trisen infection conpli.ca.ted the process. After exposure of approximately a year, a small amount of cellular reaction hut* been produced about oapjr respiratory bronchioles- As more dust was inhaled. It continued to accumulate in the sane location and later stages of the disease I T`~ consisted cf extensions cf tha original lesions. Kasr ersas were not involved. Apparently, the inhaled fibers ^ere caught in the pocket-llica alveoli that arc given off iVom the lstersl nails of the respiratory bronchioles. There tlia-r wara hoocytized and many of them -cere carried into the util by isigratoiy ceils. ^Kaanuclear leucocytes'attracted to the area canoed an appreciable ~r the bronchial rail. After 16 months a daljiata fibrosis Dado its appearance. The praeecs evolved so gradually that mitotic division of fibroblasts could rarely be discovered* nsrartheloss, the number of fine intercellular collagenous fibare (fibrosis) steadily increased. As thin fibrosis contracted, it partially closed the alveoli, and with this Atelectasis the lining epithelium assumed its embryonic cuboids! fora. The result was the adenoma-llka appearance that 'mills described in guinea pigs inhaling silicon carbide. The longer expoeuros resulted only in more thickening of the walls of ths sir spaces, largely due to an in crease in the amount of fibrosis. Cm fibrous tissue always rceeioed cellnlar and never shooed the hyallnication characteristic of silicos3.fi. 18. Progreaeion. The reaction produced in aatpueod guinea p&ge did not pro gress glgrri flcantly during a subsequent period of 37 months when the lived Is a wraal ataospbere. Between 8 and 11 months after exposure ceased, the ^-eVtnTai* reaction had been completely replaced by thin strands of fibrous tineas. Observed atdll longer, the scar tissue decreased in Moount but in the last aaerifieed, 37 nontha after dlscontiauins dust exposure, soma fibrosis was still visible.' 15. Infection coincident with post -Inhalation. Of the group of 1*0 guinea pigs infected with atten uated tubercle bacilli (R^ strain) 31 died oar were sacrificed before two years of dust exposure and were reported in the paper by Gardner arid Cunnings mentioned above. Saventssn of thss-c died from iatsrcurrent pneumonia. Briefly, the re sults mere as fallows: 10 revealed seme evidence of spread of the tuberculous oroeess; In 6 of these It mas confined to tha longs and In the other k the ebdoxtnai viscera also ware involved. Usually a slight local extension of the tuberculous infeelion-hob occurred but cobsaquent. he? ling had -Tes^rtbed-in-fi> brosis of both tha pulncnary lesions end the secondary lesions in other organs. The pulmonary lesions shoved noire fibrosis than is characteristic of * either tuberculosis or esbestesis alone. The 9 shiah were ali.ll alive after teo years of dust exposure were sacrificed at intervals daring the fallowing year. In It of them the primary foci of Infection had healed with fibrosis and even calcification and there was no evidence of progression. In the other 5 the tuberculous fod shoved evidence of basing previously spread locally: In k of them it had healed, by tha tine of autopsy, with aseatlw fibrosis; in the other animal there was a generalized chronic tuberculous pneumonia in one lobe and isolated primary tubercles, diieh mere still active beet had not spread, in the other lobes. Evidence of extension of the infection mas first seen after 7 months of dust inhalation; during the next 20 months more than half of the animals shoved on actively spreading tuberculosis and in 3 of them small cavities had developed. Durine the last 8 months so animals exhibited any evidence of active infection although In half of them the healed fibrous sears of previous extensions ware ob vious. Sixty per cent of the guinea pigs with opreading pulmonary tuberculosis showed tuberculosis of the spleen and liver. 20. InfectionSupariaposed Upon an gatahlinhed Aabeatoeia. Twelve guinea pigs, after in haling asbestos dust far nearly 26 months, mere infected with tubercle haHHI and then rmored to normal air. Tha subpleural tubercles in the dusted animals more -11- no core numerous than in ncji-dustad covitrola - b-vt. a considerable raider vare found in th depths of tha lung about foci of tisbestosic. The reaction. to infec tion showed only alight local extension about the original sites in the lungs and tracheobronchial Jyxiph nodes. The ht-iatincl viscera oars involved in odly ofio animal. Caseation -j*as found in tubercles 1-1/2 nonttio old"1 hefty 5-1/2~ noBthfi it had coeaalstel-- rU.-r.7pw-u--'.. r-~- s-^-.r tic.-1-- ''"-v :-*ttr.r still persisted in the last animal, which -ras ki lied ll* ^nirtha alter inToction. 21. Aabastosis Bodies. Moderate numbers cf asbastosis bodies occurred in the lungs of the guinea pigs., ba^ccine more numerous and tsore distinctly segmented in later months. 22. Rabbits. Rabbits exposed to the acbeato3 dust far periods up to 19 nonthg developed a law- grade fareign-toady type cf reaction but no fibrosis. Although their lungs contained particulate elements of the dust, fibers me not present, indicating that the upper respiratory mechanism of the rabbit la adequate to exclude fibrous foreign bodies. Ten rabbits, after f dost for 6 and Id months, lived in normal air far more than too year*, it autopsy neither animal showed aay evidence of cellular reaction or fibrosis In tbs term inal bronchioles nor mere there axy ashestesla bodies. 23. Rate. All the white rats bad acquired an infection, resulting in the formation of pulmonary abscesses, before they cose to autopsy* Apparently, so much haavy mucua obstructed tksir bronchi that vary fev fibers could have entered their lungs. In a fee of the rats, an occasional asoeetosia body van discovered but there vas no fibrosis. -12- 2k- Suroiarr --^ Interpretation of infra* *ton Experiment ?ric.h King1 s Floata Dust. The find Inga in thus crparlaictit with Jdng's floats dust pan oe summar ised under three headings. A- Effect of the inhaled dust on nonai animals. The King's ilcata dust Cansad a charge s' ieristic peribronchiolar fibrosis in guinea, pigs but not in rabbits or rets. The fibrosis did not progress after the dust orposure tas discontinued and the guinea pigs transferred to noroal air. B- Effect of the inhaled dust on tdber^^^^e In gulnaa pips. In guinea. pigs in fected nith attenuated tubercle tv-s and then, placed in the dust room, the k results were nors variable than is usual in an experiment of this type. A few nWi< shoved no sign of, progression; in most of then there uao evidence of tem porary progression rith subeequent healing; in tme animal there vraa continuous progression to death. In contrast, when guinea pigs, after being infected, are exposed to quarts instead of asbestos dust, the infectious process continues to progress and eventually causes tha death of the animals. On the other hand, ex posure of infected * to a harmless dust like ealexte cr gypsum does not s ~i<-wd to any progression of tha Infection. Guinea pies Infected vitb. attenuated tubercle Hatrrm following the termination of about two years' exposure to asbestos dost not develop progressive disease. The coaly modification of the infection was in its localisation, a fear haing retained in tha fi'orons terminal bronchioles th^ forming tubercles there in addition to the ujnfftl fooi beneath the pleura. ' In view of this variability, tha unusual nature of the response and the high proportion of deaths from intercurrent pneumonia it is felt that definite conclu- &M\x.Vp'S* " aions as to the influence of tols-dust on the course of tuberculous Infection are not justified. c. EfXi dust to prodPi lesion -ran ^SxTy&UbAhAWi az. fky* iSI*-* to i abdflad a ad thhee J^eodenca the wbathoryor not the/'bacterial Inh^tion Experiment with t-riber'i^WtoeJDuat. Since tuw-irdotis dusts like quarts are nast affective In producing fibrosis ohen the particles ce 3 Bicrons sad less in sise, an inhalation, expcrlsmt sss carried on to determine whether this condition is true also for asbestos dust. It was tteugbt that hr using a short-fiber asbestos dust consisting almost entirely of fibers and particle* smaller than 3 nicrona an accelerated tissue reapoose sight be Initiated aod an advanced reaction obtained la a short Hue. The previous experioeant with Kang's floats asbestos, which contained fibers froo 1 no. to 1 aicron or less in length as well as a great deal of particulate natter and which produced a typical peribronchiolar fibrosis in exposed guinea pigs. served as & basis of comparison. 26. Ths dusting material for this expwrdaent was forwarded from tbe UanrlHs plant of the Jotas-Haurllle Corporation. It wad the rBasins of fibers collected in dost tad no attar a carding operation and screened to pasa 200 wash* Since the material ae received coBtaluedmany long fibers. It vu grand in a steel to reduce practically all the particles to 3 microns. or loss in. aise. *hen used in. a standard dusting machine, this flnely^grouad asbastoa tmaded to TBck in the hopper and it became necessary to adz one toIsbb of the on ground material with three -volsnaa of the ground to generate a satisfactory dost cloud. The addition of tha email quantity of wngrouad asbestos was -unfortunate *N because it confused ths interpretation, of results. Probably the minor amount of reaction that developed was due to the long fibers in the mixture although the data of this experiment do not prove the point. 2?. The composition of tho short-fiber asbestos as received is disclosed by the chemical and petrographic analyses given ia Table ii. Samples taken before and after grinding yielded about the osa valnas.^p analyst that there vu no contamination from the skill or loss of vrater content. 26 The dost concentration varied Borawhat during the ssperiaent acd light field counts for atmospheric sanplev collected inside the animn, cages with tha lmpingsr apparatus ranged from S3 million to 1&2 million. The average of counts i*as 130 million, for the first year of the experlmsirt, 13U dVLinu for tbs saoood year and lliO inHm for the third year- 29. 3lae-frequency measurements of air-floated dust from inside the cages at a magnlf**--l-n of 1300X revealed a great preponderance of fine par ticles (Table 5)- Hearly 90 per cent tha particles seen were smaller than 3 olcrona. 30. Reaction In Aniaala to Inhaled Short-Flher Asbestos Oust. Fbur spades of ** -- guinea pigs, shite rats, cate and rabbits -- mere used In this experiment. The results of the dust exposure, Which are summarised in Table 6, mill be considered more in detail below. 31. Guinea Pigs. Eighty guinea pigs mure originally pieced in the dost room but 21 of than were later eliminated from the experiment and killed because of enlarged lymph nodes. Of the other 59 animals, hB remained in tha duet room they were sacrificed or died from natural ceases and 13, after being exposed to dust for 20 months, sure transferred to a normal atmosphere. 32- Rate and Type of Reaction. The type of tissue reaction to the inhaled sficrt-fiber asbestos -wl* aasar.bisllr the sera as thst already observed In the experiment -with Kind's floats sa'oeatcs. The rate of reaction also was approxi mately the asm but the extent of involvement rrith the short-fiber dust was very much less and after 16 to iL aonths of exposure only a very few s*ia~H foci of reaction, which generally raqsired microscopic examination fdr fiet5fcton`~ir9ra produced in the guinea Figs. Until exposures had continued for apprasdnartely one year, there was little tendency for dust--containing tiugoeytu to collect into clumps, By l months phagocytes had begun to collect About the walls of a few of the respiratory bron chioles with a little proliferation cr infiltration of mononuclear cells in these walls, there were also some multinudeated cells but they were always of the Inert foreign-body type, ft 2C to 2U oonths the cellular clumps were sometimes quite marked end somatimos changes In the epithelium resulted in the adenoma--like or "adenomatoid" appearance previously described in Section 17. In most of the subsequent members of the series, the reaction remained cellular In type. Xh a few, however, fibrous elements dominated the picture. In the latter ease, the collagen was pals in color and tenuous with no heavy swollen tyali iri satjon. s in the rate described below, the alveolar walla might be made up of a band of collagen supporting a leaner of epithclixaa, but with no contained capillaries. In the tracheobronchial lymph nodes the reaction was more pronounced in this experi ment than in the previous ossa with, King1 floats asbestos, probably because of the transportation of an excess of fine particles to the nodes in animals inhaling short-fiber asbestos. The reaction was essentially an increase in reticulum, rather than a fibroeia, with preservation cf the original Cells between the - thickened reticular fibers. Biffuse'chronic pleurisy without evidence of pulmonary infaction was present in a few animals. -lb- 33. Prograssign. In the 13-3/4 sontbs rollsiting tha cessation of 20 months1 exposure to dust, progression of disease was cot dafinitaly demonstrated but neither could it be absolutely disproved, owing to the varia bility or the response in different animals- At the end of the dust exposure of 20 ninths two pigs wsrer'read as and one as 2*. Among tSa" 13 reiwv3r?r5iii*det the findings were variable: in 2 the reaction waa i; in ii it was +5 in 3 it ms 3*; in 3 it was L+; and In one animal it was +. It is quite possible that those with the most marked changes had already developed more reaction than the remain der by the tioa exposure ceased. Since the more severe reactions occurred spora dically' end bore no relationship to the length of time after cessation of expo sure the differences were attributed to variation in individual susceptibility. TVta witrw received support from the analyses (Table 7), which often re vealed ccagmrable amounts of ash and silica in lungs with widely different amounts of tissue change. Far sample, the ash and silica values ware quite similar for three in dost 20 months and than In normal air 13-3/Zt months, yet the tis sue reaction ihr one animal was h*} tar another, *J and for the third, only . 3U. Aebeetoeie Bodies. The formation of asbaetosia bodies mas at first ex tremely limited. After months' exposure only a vexy rare short body could be found, usually inside of cells. Around the finest Intracellular particles there were yellow deposits baring the same color as the ESbestosle body. Exposure of one year permitted ea accusailatxon of aexjy longer fibers about which the aabestosls-bodf coating developed, lfost of these were still short enough to be partially or entirely within phagocytic cells. By the 20th rww*g>i uv thereafter, they ware comparatively mnmrous although still rare in comparison with the findings in the King's floats expaxinmt. 35- TShite Rata. Seventy-tia,res -shite rcto were exposed to atsespheric shoe-t rieai` asbestos duct ltr periods up to 32 nantbs- Sacrl- fioinga during tho first 10 souths were n&ac bimonthly and for the remainder of the^aeperiaeot at less .Arsqaenh in.tcrrsj.e- ,.*. .:. _.t=--, --. 3S- Rata ard Type of Baactioo. 'fha drat cells until G months were widaly scattered and existed in fofci only sporadi cally- Reaction -mas. Halted to occasional slight thickenings of the septa abort mall accwnliitlaag of dust calls, rn a fecr rats at 10 months, there was a erzg- ^Taatloa of early fibrosis but the change was so slight that it would probably be overlooked without the clump of dust cells to attract attention to the area. Only 10 an1-main were exposed from 12 to 32 onotbs. In each of them the lnz^e Showed ad ante patches of weHrdeflnod fibrosis distributed like that of asbastosia but without asbestosis bodies. The lesions, visible only at a "c,yf of 1$0 disasters or more, consisted of patches along alveolar ducts in which the wan-a of tbs air spaces were very thick, due to smllsn collagen fruseuork. Comeetive tissue al Foct-BLelsabowski silver preparations revealed cosplete loss of capil lary bed locally. Outside the collagen was a tbla l^ru* of epithelial oalls. This did not rwaodale the "adenomatoid" change characteristic of guinea pig as- bestoala. Kb pleurisy was present. Hear the lesions the air spaces wera with phagocytes containing grey to yellow particulate dost and a rare long naked asbestos fiber. Careful search failed to reveal even a suggestion of an asbosto ads body. The tyx-b^rtht-mn-Mai nodes Iiiipi il ooopect focal aolleetioas of mono cytic cells at 12 sooerths and, at 20 months, sobs diffuse thickening of the rwticulm. In a few rate tbere was definite fibrosis along the aarglns of the node and extending Into the med.1 astiral areolar tissue. Compared with the response to active dusts T'lm quartz and chert the reaction to short-fiber asbestos sue negligible- HesiiLts of cheraicai ansle/ser: sei-s t.>e rrhiwa rats sre given in Table 3 nd `the. average Tallies have baen tabulats.:: 5ji Tail s for ccopuriscn -with similar ^iiw ibr rat* inc other dust*. The concentration or atmospheric particles to which tc animal-3 "aror* ezpcsed was *pproeiina.teljr tlia u*ne ior asbestos id quarts; for the gypsaa-quart* xixfcure, it was about twico aS i'-igli aja^ar~eKS^T n-ra tints' as high. It Kill be noted, that the percent&sac for aassstos are loner than those for quarts or chert but are siaalar tc those for tJio Rjjpauffi-qnarta nixfcure, in which ataospheric agglutination tanned to reduce the saocni of dust inhaled. It might be inferred that the total quantity of asbestos duet inhaled was low or that it had been eliminated from or dissolved within, the lnsga. In the present state of oar knowledge evaluation of these hypotheses is not possible. 37. Cats. Twenty cats mera used in this inhalation expsriOGut with the short-fiber asbestos. Eighteen mere leapt in the dost room until death| +>n exposure period ranging frea one month to nearly 1:--1/2 years, and two, after a dost exposure of 31-1/2 months, were rasorved to normal sir* One of these was sacrificed $ months, and the other 2li months, later. 38. Hate and Type of Enaction. The reaction was essentially that to an inert dust, even after more than U years of expo sure. The tissue response in this species was confined to microscopic fod of fibrosis In the walls of groups of eubplsural alveoli, rather than in the peri bronchiolar areas. In one animal the change was extensive enough to be visualis ad on gross inspection of the section. 3?. X-Bay Ch*ngp- Only in. the prriroT with the longest exposure did the X-roy reveal definitely abnormal shadows. After 29-3/1: norrths the picture wan negative; after h*> months a faint mottling could be detected throughout both lungs. It autopsy. 5 aoi'.t.ha lat<r, thsrs oa? only microscopic fSbroris in the rrofcrcl&prai tota piv^i hasty lyjtohocytic iryj.lw'aW-r.r* eba-.it swX3. brcnehiolss- JiO. AgboaHoclfl Eodlrs. On rsrolanged ssareh a jferw ye'icw e.typi.ar.2. u?be3tools -- beelas, smooth and haugt-.ra.t.if*--. -r-rc .fp.jjpd in ben -3Triirta.~L exposed far more than a yonr. 111. Rebblta. Sigrvb rabbits -sera exposed to dost far periods crtasdlns Cron oae to cars than fiva tqvs. Tbs last- eni-sal -raws renovea frea the dust roaa and loft In unreal air* 6 months before being sacrificed. )|? _ Rata and type of Reaction, There was ner*r enough fibrosis to be de tected grossly end there vps no chronic adhesive pleurisy. Microscopic evidence of alveolar wall thickening was first detected after about 3 years of exposure and was --> in ell five errfaaals eosndaed thereafter* In one that died of paralysis after nearly fora- years, of ex posure the reaction was extensive enough to be visible on gross Inspection of tissue sections. Ibe possibility of pulmonary Infection in this amaal could not be excluded. However, In another antral dying two years later tho focal fibrosis was not nearly as obvious or e advanced. Areas of invtiLvsaestj which were largely visualised bcoaaaa of phagocytic reaction within the air spaces, tended uzicrascoploally to beoeea rare fibrous with the passage of tin but there wee never h encroachment upon the Inarm of air spaces and the architecture of the lung was preserved. Ii3. Aabestosia Bodice- Asbestos bodies were not detected in rabbits that died early in the ta^ertaaafc cut were seen in all anircals that bad been exposed to the duet fear more than throe ysera. nr*. LUt* ftyranary and . 713a cs-i^lTvsl purposn er tbs eqsriseai was to evaluate the chcsical theory of the pathogenesis of a&'oastosis. Xt vas fait that if tha tissue r<*ao-- wloa te asbestos ver-e crveoical in crifjin -*11 accelerated or accentuated response Kotild result frau cscposvre to finely-divided asbestos, as in the case with quarts. This cgporiaant, in fniich the reaction leas deter and lees extensive than -Kith Slug's floata, iadlcstas that tha reaction (jw ottgg^ is not prloarlly oheoical in 1/ nature. Of the four species* exposed. in this experiment only the guinea, pi end rat reacted -Ith characteristic peribronchiolar fibrosis. The cat reacted with atypical sub-planral fUrosia end in the raWait the fibrosis which occurred could not be positively attributed to the dust because of a strong possibility of pducagry infection. xuyx^HfcUii4TtaM- S-r H -'' l ^ .tioo. ^Derfjn^nt^ei^h 10 P^r Cen^ BaXy-IlLl^gd Aalfestoi^Puss. Tti tbe ciperiaBlt with short-fiber asbestos dost a quantity of unground asbestos was n-H trlth ground material in order to produce a suitable dust cloud, then evidence of a dust reaction appeared in the guinea pigs during the azperinsnt, it was not dear whether this was a tissue response to tbs small number of long fibers in the tuagruuud eebectoa or wee a delayed effect of the store abundant Una dust. Consequently, another inhalation axporiaeaxt was started in which no ungrouad materiel was used. 1*6. The dusting material too tha ground short-fiber asbestos used in the previous <3ia+-lpn experiment bat no ungrovnd material was raised with <*v^nr? XjO tne uexidancy oi *:;g <7^*6tt.^ j. l-c . scall spherules iihich prevented Each of til fibrous portion fron fi.cs.r-in>; cut of the hopper, ih2 -dlsporsai of the dust -eras cot entirely satisfactory and cuter 7 souths ef operation, tha dust ing machine was reconverted tc its criminal design. To prraat "pilling" or the foraition of spherules of asbestos, Ctnel sire brunfaas ncre attached t-o the in- % side surface of the hopper and to tha rotating padels - ^bis ^rv?Uiforueni gave satisfactory results and was used for the rcasinlaj 11 --antbs of th* exserteeefc. ii7. The cogpositicn of the rau natori.il i Chert-fiber asbestos) and of atmos pheric dust liberated fron the fcali-isHlad product in the dusting ma chine is given in Table 10. These values are based upon petrographic study and X-ray diffraction analysis. The aiaccphnrie oaixde vac collected with an elec trostatic precipitator efter wire brashea had been installed in the dusting machine. Previous to this, the chrysotile content of the air-suspended material mas undoubtedly less than the 15 per cent value given in Table 10. In an inter im report, it was stated that the air-borne dust contained about 5 per cent of chrysotile before the wire brushes were csss end up to 6 per cent afterwards, but these values were probably low. Quantitative estimates on balXesilled asbestos dust may be somewhat inaccurate because it is difficult to determine how much of a dust sample is fibrous chrysotile and how such is non--fibrous serpentine. IS. The dust concentration for the first 7 Booths of the experiment was about 100 pillion particles per cubic foot of air. After the wire brushes had been installed, the dust counts were a little higher and the overall average for the first year was 106 nilliob. The average of counts for tha second year vas 163 nil'llon and for the third ytsar lltS ail.li on. i>9. The oise--frequency of tfm ct:nnc-r.6nis oi atasc spheric cuat collected inside the .te-sa?. czes tilth ths electrostatic apparatus is reported in Table U Two samples -mare taken, one before the vrire brashes mare iuatailed and one After. It -will be noted that after the wire brushes wore in use a greater proportion of rery fine particles anc also of lohsar fibers was released into the air. jj0,, Reaction in Animals to Inhaled 100 Par Cent Bail~X1lisa Asbestos Duat. Guinea pigs, rate and nice were used in the Inhalation experiment with the ICO per cent ball-milled asbestos dust. The results arc suosarited In Table 12. 51. Guinea Plea. The experiment was started with. 100 guinea pigs, as the duat exposure proceeded, there were 39 accidental deaths. 32 of in an epidemic. After 26 months of dusting the 16 surviving guinea pigs were transferred to normal air. 52. Bate and Type of Reaction. For the first year of exposure practically the only reaction to the duat was the pre- Bence of scattered phagocytes and an occasional urinate ee'oeatoels body. at lfi aod 20 months no gross response mas visible on the tissue section but microscopically peribronchiolar fod of Inflawtory cells could be seen. At 2h snaths there mas still no change large enough to be seen with a hand lens although microscopic fuearjnation revealed cellular accumulations about terminal bronchioles end many more asbetrtoais bodies, chiefly within cells. Ctvemical analyses of the lungs (Table 13} reveal that In spite of the limited tissue reaction Considerable duet had- been retained In the lung. 53- TYogresaion. The lungs cf anlaals exposed for the full dua-xrig -period (2E months) and than living In normal air for 2 months revealed the changes described above and also veil' alight peribronchiolar fibro sis. After Q nontks in normal air the findings more similar bat at 22 montha 3 ofh. anirealfi showed grossly-visible characteristic peribronchiolar fibrosis with* adeaonatoid change. 0| - lymph Bode InrolTOsmt. The tM***-**TM"^ v nodes ere essentially negative until exposure had been cantim^rt for acre than a year and & half. it|1bp1< sacsd fiend at 12 months and 16 months revealed a fee minute collections of phagocytes oontai n1.ng porticlea but prac tically no fibers large enough to be recognised aa such. After 20 souths of exposure many monocyte* filled with yellow granules were present. At 30 months there had been a slight Increass la reticula but Bo fibrosis, Ko further changes occurred in the nodes. Asbestosis bodies were not aeon in the nodes of any of the guinea pigs. 55. Asbestosis Bodies. Kumte asboatosis bodies wars observed as early aa 3 BOBtha after exposure began, but they did not be came numerous until 16 months had elapsed. The bodies were short and practically all wera intracellular, although at 20 months some were long enough to project beyond, the cell borders. It 1s important to note that in the later months of exposure there was a dis tinct increase in the uuatoer of long fibers (ftp to 70 microns In length)in the lungs end that after exposure ceased characteristic long asbestosis bodies were seen. 56. White Rats and Klee. In this experiment UO rets were exposed for periods op to 20 months end 2li mice for periods up to 12 norths. Neither species developed arap a suggestion of csbestosis and reaction, mas to phagocytosis of inhaled particles by tridely-acatter.Qd dust cells renained ires in air spaces or were transported to the tracheobronchial lymph nodes. So asbestosls bodies were fbund in the rata but in the nice there were a very few snail non-4uuistr&ted forms within phagocytes. In 21 mouse lungs sectioned there were 3 instances of pulmonary adenoma ClJLiS). % $7. Siapoary and Interpretation. The tissue reactions observed In this experiment ware much less extensive and slamer in development than in the previous Investigation with short-fiber asbestos. Since presumably there were fewer fibers longer than 3 axLcrona in the material used in this experiment, the results tend to confirm the interpretation made in Section hh of the short-fiber experiment that the reaction pswMRy is not primarily chemical in nature. The finding of long asbestosls bodies in animal a Inhal ing the ball-colled material, is an example or the difficulty of completely eUadnating long fibers from an. asbestos preparation. In regard to progression of reaction after newel from dust* vtoich was ob served in this experiment but not in the others* the following interpretation is offered: then the reaction is veil-developed at the termination of exposure,tha contraction of the fibrous tissue would obscure any possible progression. In tivii experiment* however* since only the earliest stage of reaction was present at the time of removal from dust, its subsequent progress use apparent. It should be noted that the degree of progression was so slight that It can have little, if any, practical significance.  UK u xa. & : xInp.ta'tier Eygariraarat Tth Lonfr-fibgr > plyajfcp^ Ihyt. After ajii naJ-a ir^ullny chert-fiber aabcstoa dust Tor more thou a, yaar bad failed to develop significant reaction, tbs hypothesis that asbeatoexc in pro duced ty the mechanical irritation of Ions fibers ns given added support. Since the King's floats asbestos used in the first inhalation experiment had a rather low content of fibrous duysotUa and contained considerable serpentine * asd other impurities, it was decided to conduct a new inhalation experiaant with a purer fora of ehrywotlle which would be richer in long fibers. 55- The dusting material employed in this investigation was obtained fro* the UanvUla plant of the Johns-Jienville Corporation. Samples of se veral varieties of asbestos dust were first submitted to the Saranac Laboratory for pagination and one kind. Identified as lot D, which was low In magnetite and chrosdte and bed a fibrous content estimated to be about 75 per cent, was selected os most suitable. Steel wire bnndiea ware fastened to the Inside sur face of the hopper and to the rotating paddle in order to open the bundles of asbestos and liberate more fibers into the atmosphere. 60. the composition, of the long-fiber asbestos used in this experiment la . indicated by the chemical and petrographic analyses given in table lk. It appears that this material was a much purer farm of asbestos than the short-- fiber dust used In other eogierlaaats. This Is borne out by coopering the approx imate analyses of the long--fiber end abort--fiber ldnat In Table 15. l. The dust concentration as revealed by landager samples taken inside the animal cages was mch lower than the concentration for the experiments with short--fiber or ball-milled dust. Far the first year of the experiment with long--fiber ubeatoa the average of the light field counts was 32 mill ion; for the second year, u8 nUlior.; rc-r the third year, 3i*' ailiionj vaa. fcr ts? forrch year, L.3 million. Sxssdnaulon of the loplrger senpiso tTitr. dark field iHvcsin- C-tlon disclosed that nany fine particles l^sa thea one rgicron in size accompanied the larger particles end dark fisld counts were, on the ff'-'srags, about 5 cr" ^ larger than the light field counts. ' "" --------~~ 62. The 3ine*Crega'snc3r of atmospheric samples of ths IcnjT--flber asbestos dust sad of the ball-nlUad dust la show* in Table 16.' Both aenplcs mra collected "with the electrostatic precipitator- It was far mure fibrous material in the long-fiber dust. be noted that there 63. Firurtlon in Anl"*1* to Inhaled Iona-Fiber Asooetog Dust. Guinea pigs, cats, rats exvi sloe ware employed In the inhalation experiment -with long-fiber asbestos. Remits of the experiment, summarised in Table 17, ere described in greater detail boles. 6U. Guinea figs- The experiment was started with 100 guinea pigs. After exposure had been carried on for a year, a severe epidemic of pneunonia arose In the dust room and about one-third of the anInals died or were killed. To replace them, 38 Boone guinea pigs were added to the surviving group in the. dust room. 65. Bate end Type of Reaction. Histological examination revealed grossly visible leaionn in the lungs after 6 months of exposure to dust, consisting of cellular infiltration about the terminal bronchioles. At 12 months, there ware adenomatoid changes in the air spaces and by the 16th month a definite fibrosis was present In these areas in half the anisals- The fibrous lesion could be seen aacroscopieally at 20 months. Prom this time on the reaction increased in- extent and in the amount of collagen and nout'.:, it ii&S. rer-r.tfJ cut into the paranctyt5* - *be lesions -rrare rethe? aharply ic~-al J.~ed and the extensions froa diferrant, fcronchialcc showed no tendoucy to fuso, even in animals exposed Tor the -arriema period (3 years). Although the Intra^pul nonary reaction sometimes reached the plcuijk*- there 'wssjao involvement af that membrane. No emphysKaa was visible at any point. Sons thickening of the larger bronchi with a chronic inflammatory infiltration was re- % vealcd, bat it probably ms no Ssoro than would be produced by & similar exposure to any dust. Par the first ? Booths the phagocytes consisted of monocytes or very ana'll giant cells j later, giant cell formation was more preadnent. After 16 months the giant cell a were large, filled with ysT'.lowiah-fcrosn pi{jTryK sometimes vacuolated. An occasional animal showed sn .\dmirturo of polyswrpho- ouclear leukocytes and, la guinea pigs exposed for a coatiderabla period, eoalnophiles. The reaction mas at first entirely cellular but by 16 ir~ arous tissue formation -bus definite* However, it never attained a stage of tga:iIni Mil on suggestive of silicosis. a moderate individual variation occurred, among the exposed axinals, both In the rate of developing lesions and In the stage of development attained at the end of exposure. Analyses of the l&nga (Table lfl) disclosed that although the tlasuu response was much greater In. these guinea pigs then in those exposed to either short-fiber or ball-milled asbestos, the amount of mineral matter in the lung ash wee lies. 66. Progression. In guinea pigs exposed to the dust fop 20 mouths and tLxa. removed to normal air, there was a marked tendency for cellular inflammatory reaction to clear. This affect, arm-nri'iqH by contraction of the fibrous tissue, resulted In & diminishing alxe of the focal lesions. Uous of these animals, klld at verioao periods -rp to 1L. aoistr-s after exposure, revealed lesions as large as those in the group eacrifieed at the end s the 20-month exposure period ox* those in animals Tiiich ycyainisd ir. the dust room for more than 20 months- Fotarteen months after cost exposure ceased, the foci, in four of the six remaining guinea piga rare so snail that they were visible only uith & hand lens. Reaction in the group exposed for 27 months and then transferred to a normal atmosphere mas quite similar to the response in the 20-oonth exposure animals mentioned above. However, foci -sere always visible on gross inspection of sections of all guinea of ths 27-month series hut in so instance u there evidence of extension of the reaction- 67. lymph Bode Involvement* Reaction in the tracheobronchial lymph nodes was first visible at the third month of ex posure. At the 6th sooth patches of cellular connective tisane began to appear in the medulla end by the Ihtb month most of the node had. been replaced by cellular coasectlvo tissue. This picture, which reseafelsd that in eerly silicosis, persisted to the end of the experiment. Some animals, as a variant, shoved heavy sheets of diffuse monocytes and large active giant cells but there was never any necrosis or hyaline formation. The spindle-shaped nee cells were yellowish in color from finn pigment granules that stained for Iron. Bb fibers or asbestoais bodies seen. 66. Asbestoais Bodies. Although asbestoais bodies wore seen.ee. early aa one A. month after exposure began, they were rare and hard to find. At 5 months mare were visible, chiefly coiled inside giant cells, and at 8 months amy bodies ware free In connective tissue. They became fairly abundant as oqjopire programmed although in some later mlrsls the asbestoais bodies ware only moderately numerous- 5?. Gate. Four cats totaled the long-fiber asbestos dust zor periods of 1L. 25, 33 and 1*2 jaonth3, respectively, and were Immediately sacrificed* Two other cate, after exposed to dost for 16 snaths, Used in a normal atcosphere tar an adrii ttonal 21*. months. 70. Rate and Type of Reaction. Exposure for 1L months was sufficient to produce cellular accumulations of phagocytes around terminal bronchioles and peripheral arterioles together with compact eollections of similar colls in the tracheobronchial lymph nodes* At that time there mare no typical asbestos!* bodies, bat smooth pointed yellow fibers were seen very rarely. With continued exposure, up to h2 months, reaction In the locations noted progressed to the formation of cellular connective tisane which Bade'well-defined sheaths about the respiratory bronchioles end arterioles. Barked lymphoid hyper plasia and lymphoid infiltration of bronchiolar walls. The bronchi alar epith elium was low and flattened, giving the tubes a euooth contour. Typical eshestosis bodies were not formed although there wee en occasional yellow, smooth, pointed fiber. Mb pleurisy was proseot. The reaction ws similar in location to that In the guinea pigs, but fibrosis was much slower in development end had not reached the same degree of maturity. fi.. A-day Changes. Roentgoiograms of throe cats were made after exposure periods of 25, 33 end L2 months, but tissue changes were not dense enough to be seen on an X-ray Aim. 72. Rato* Although 20 rats were placed In the dust room, many died from pneu monia and were not suitable for study. Five animals, of which one was exposed fbr IS months and four far 25 months, ware free from pulmonary infec tion end offer a basis for conclusions. 73- end Tms of Ugactivn- Alt ieur animals sacrificed at 25 months shewed a -Will-narked peribronchiolar fibrosis In the 19-month animal, reaction was Just beginning. Asbestosia bodies were practically absent at both 19 and 25 snaths although two small ssooth bodies were ,*fdtad in the 19-mnnth Tmira=l after a len.3 search. Thus these jualaol? exhibited fibrosis without asbestosls bodies. 7U. ISLce. Out of 20 white mice usad in this experiment, 11 lived a year or ore in dust and died or mra killed without showing as. appre- clable degree of pulmonary Infection. 75- Rate end Type of Reaction. Reaction was limited to phagocytosis by aaononaclenr cells. Usually- these were wide-- ly scattered through the air spaces; a limited nunteer were grouped about the ter minal bronchioles producing some thickening of their walls. There was no oug- Kanerous asbestosls bodies ware observed in killed late in the experi- nast. Thus, these animals exhibited asbestos!* bodies without fibrosis. 76. Suaparr'ahd Interpretation. The purpose of this experiment -was to evaluate the importance of long fibers In the tissue response to inhaled asbeetos. The results Indicate strongly that long fibers are chiefly responsible for the reaction. Thus, is guinea pigs reaction doreloped earlier and became sore ezCaasxvo than, in previous experiments in spite of a smaller concentration of atmospheric dust and a lover mineral con tent in the lungs. Furthermore, a typical peribronchiolar fibrosis was produced in cats although in a previous experiment)with short-fiber dust, it did not develop in thie specios. The cause of the ceUdar fibrosisyin the lymph nodes of the guinea pigs is not clear. Xt did not occur In other inhalation experiments with asbestos. zpctfxx. ajycnoy cptomms Xp order to determine to that extent the various fibrous minerals possess ' the capacity to produce tissue damage, numerous injection experiments -sera per- formed. In these experiments guinea pigs and rabbits were used and the arinaral dust was injected by the intratracheal, iatraperitonasl and intravenous tech niques. Far the purpose of simplification the findings in each series of teats hare been, condensed and reported in tables, to sfoich reference will be made lata*. 78. Experiments Using Intratracheal Technique. Since the asbestos minerals do not cause a typical advanced fibrosis in extra-pulmonary tissue, the intratracheal technique la the perferred way of in troducing fibrous dust into the experimental animal. la this method thrf dust suspension is injected by means of a special needle or catheter deep into the trachea. Item which it flam into the lungs. 79. Comparison of Fibrous and Ifea-Fibroua Dusts. To 'demonstrate that the ability of asbestos to produce fibrosis resides In its fibrous character, the series of injection experi ments reported in Table 19 mere perfbrned. The tests were made with imhaated long--fiber chryeotile end with Chrysotile that had been ignited to destroy lie -32- r.y-<>i1a structure cr balH.-ai.llcd to reduce tbs lacfith -1 .'.'tber v-o Z mic.~s;;.n is;lcs3. At the cars tico -iov.trol testa vers swee with sorpt?nhiner which has ;li.< sens chismical opposition as chrysatiis but is con-fibrous. A ?z?rijg? ol t:ie findings r.evsals that only the unhea&ed long--Ilbor chrysfotilo produced nbraeis. libera subjected to ignxtica or shortened bjr baH-flr"ling had`lest frair capacity to causa a(crlcr^s tissue danege. Iscitlon produced important chenges in tha chiy- v s-stils fibers, among then being lose of water, an alteration Trot'- n fliixLfclp to a brittle structure end goesibly other changes. 60. Costparison of Various Long-Fiber Dusts. Some vary interesting fir-din^s are disclosed by the results c the experiments included r< Table 20. First, all the long--fiber asbestos minerals tested, with the exception of ehthopbyllite, produced e typical fibrosis. It is not entirely clear siby aatkophylllte behaved differently front the othar asbestos minerals. Unfortunately, of 8 animals died of p&auiaonla within the first two -weeks of the experijaanu and the remaining animals ears sacrificed at 1, S and 12 month* j thus observations uere not marie at the aptixum periods of 2 end U noothe. Second, -with, the mineral bruoite, -i&lcfr la eat a silicate but is e fibrous fora of ffagceausu hydroxide, a characteristic fibrosis like that of the asbestos minerals vaa obtained. Since the brueite used contained only 0.90 per cent silica (as an impurity), it is obvious that a siliceous component is not an essential factor in the development of aabestaslo. Third, so fibrosis resulted froa the injection of glass -wool fibers, even though glass wool resembles asbestos in some vayu. There are fundamental cliffor-- encea, however. A glass wool fiber 3 microns in disaster la a solid rod and, in short lengths, is fairly rigid, -while an adbeetos fiber of the sane diameter is a bundle of axtremaly fine filxmentfl which impart to the fiber a high degree of flex ibility- It would seam tlyxt this structure and too associated flaaohility ere f important factors governing the capacity of a mineral to produce peribronchiolar fibrosis. 8l. Comparison of long-Tiber and Short-Fiber Posts. Kith quartz duet It h*5 -. ' --- tvinn~dc5jnstt aLud^that the smaller the particles, the mare intense is the tissue reaction, end that there is little reaction to particles larger than 3 demos la diameter. In the esse I of asbestos, homever, the reverse is true and apparently only long fibers hate aiy specific effect, this is confirmed by the data of fable ZL, in mhich & series of tests mlth fibrous minerals is reported. Khen the Injected duet consisted of fibers 20 to $0 microns long, all the minerals tested (except aatbophyllite, as noted in Section 60) produced a fibrosi*; shoe the sateziol maa prepared by first grinding the fibrous dost until the length of fibers mas reduced to 20 microns ad less (or, in sons oases, 3 microns and leas), none of the injected adadsmL dnsts ceased fibrosis. 82. Experiments Osing Intravenous Technique. The experiments, described in Table 22, in mhlch the intravenous method of lnjeetioa mas es^loynd, shoe that the' asbestos mdsarals an far different from quarts In their action on tissue. It has bem repeatedly demonstrated that intra- tsdoos injection of quarts particles 3 microns and leas la diameter will a typical tissue reaction vith the development of(<fibroStt Ja extrupulmonary sites, sudi as the liver and spleen. Asbestos minerals, hoaover, on intravenous injection generally produce only an Inert type of reaction, as is revealed by the results given in tbe table. The reason for the early deaths in tbs experiment uLth ebryso- tils particles is not clear; it may have been caused by silicic add liberated by the finely-ground mineral. 33. Scpaarfjnants Using IatraparttODsal Techninoe. Tha results of Injection experiments elth tha lntrAperitoneel technique are. given in Table 23- It will be txited that the lone-fiber dust* produced a fibrous miction while dusts aaegnsed of particles 3 el crons and Isas in alza cosed only an inert type of response- These in^anih indicate si so* that the fibrosis initiated by the irritation of asbestos fibers is not restricted to the logs, forawrly assnsed, but can be produced in the peritonea as wall. ^L' twiv, S.\lTXtH ASWCatBS KD02U1S k miaber of additiaasl specific ptraan of tlis contacted to throw light on 8JT. protective Action of -Alneiinai Ccegmunds . Intratracheal Injection of a suspension of Isag^Ober chrjreotdle to which colloidal nliwrtmra ljyilrudds bad been added reveal ail that the addition of the jtiwwyiTw ix^pwiwd did not prevent the tisane irritation prndoc^ by chryaotlla. If eurthinca the acute fuflaeaatmy response to the injected fibroma aineral was accelerated. One r"iI,` after the last Injection of tha dost enspwurton the branchloll tin wee bteedfli fibrous 86. farertlea of Aabestssle Bodiaa. The iron In tha csatlic of the aabestosia body appears to be derived Than blood or tiaaoa donate ad not, aa has been suggested, from the odLneral fiber. Following subcutaneous injection of two kinda of Chryeotile into the groin of gains* pigs -- odd kind containing 2 par cent sad the other 0.2 por cant hjOjth aabestosia bodies were equally nwerata at both Sites of injection* , o'-' l" Vib An Attempt to produce asbestosls bodies in eui&ea pigs by implantation of three silk bags containing fibrous chryaotils was unsuccessful. ,, One bag planted subcutaneously in the abrtnarinal wall disappeared! the other two bogs, in the peritoneal cavity, produced a little foreign body reaction bat no asbestosls bodies in a year- . Intratracheal Injection into guinea pigs of asbestosls recovered from hianan lung tissue failed to produce the typical tissue reaction to afeMtiyg * fibers. The injected material vqs obtained by digesting with hypochlorite solution lung tissue removed at autopsy Aron an asbestos worker. The asbestosls bodies could be seen in the guinea pigs for at least a year after Injection. This experiment shoes that the aSbestosis body has a rather resistant. which Is not destroyed by Moderate hypochlorite titurtad and aay be in tIwo far a year or longer* n imuHi itpyi xy ramsHT-dcriPii or .asbestos jommior Two lypotbases have bean propoead to srwplsln tbs tissss Irrltatlca aid reaetlon aaaai ty asbestoe fibers* the chsvrical and the ----- In tbs rhnalral theory, dddk is based span experience with quarts. It is asaated that the u> bestoa ninsrals dissolve In the body fluids end that in this preoeea their baeee are laaCbedt saay to leesn silica in a fine capable of Irritating tiseuee. Accord* lng to this hypothesis, hestrwie, would be merely sa indirect alllcosls* Severe! facte aakw the chasdeal theory untenable i (1} intratracheal injections of brndte fibers, ubidi had a silica cootant of only 0.90 pw* cant, cenoerl a typical fibrosis like that produced by tbs-aebestos mlaarels} (2) free-oilica particles Increase in potency as the particle else becomes less, but Asbestos fibers shorter than about 10 to 20 sicrons are relatively Innocuous! (3) aluminum hydroxide neutralizes the irritatinc affect of quartz but not of asbestos; (la) aerpentino baa the sane Chssrical cor^osition as lonj-fiber chryaotile but it does not produce the seas v-inn of tissue reaction; (?) there is a ride range in tfr*> chemical composition of the sicurals which do cause asbestosls (see Table 2lx) Ih view oiTthis evidence it aeeas more lately that asbestoala is caused by an unusual mechanical irritation from long asbestos liberal Probably this irritation Ip Velated to the peculiar falmcanted structure of the fiber end tbe associated flexibility, which are possessed by no other foreign body. Far example, ignition of chrysotile fibers changed their structure and fade them inert while the sane fibers, before being heated, would product fibrosis (see Table 19)* Further support for tbe theory of mechanical irritation is that asbestosie occurs in an organ of high nobility - the lung - and that a fibrous reaction can be produced by injection of asbestos fibers Into the peritonea, where there is also a degree of nobility, but not in other extr&pulaonaxy organs. 0 /* 'i' t LPIVIIL Cp^lICA3|XQffS" Tbe experimental ioreatlgwtion with ashastog minerals was concerned primarily with the effect of the dust on normal tissue but some attention was given to other phases, suoh os susceptibility to infection sni occurrence of nailenemy. 89. Infection. The only experiment in which the effect of i nKal <y. asbestos dust on a pul monary infection was studied was the. first inhalation experiment, carried on with "King's floats* dust. Zt is, perhaps, unfortunate that infection studies were not made in the other inhalation experiments also. i..* 90. 5u3cerrt.ibili.ty to Tuberculous Infection. The dev-alopmeut of tuber culous process'initiated at the beginning of exposure to asbestos dust, end also of an infection superimposed upon an established asbestcsls, -eas described in Sections 19 and 20 of this re port. It -rill be noted that asbestos, wheo classified according to the effect % of a dust on tuberculous infection, would be placed below an active dust quartz but above inert dusts, such aa calcite and gypsum. In aninalg infected with attenuated tubercle bacilli, quartz will cause the infectious process to progress until the animal dies of tuberculosis. Inert dusts will have do effect on tha infection and the lesions will usually heal and the disease disappear. Asbestos dust is in a different category, then tbs fibrous duet was being in haled daring the evolution of the infection, there was a spreading of the tuber culous process for a time but usually the atimins far continued proliferation of the tubercle bacilli was not sustained, tha progression was arrested and folloved. In guinea pigs infected with attenuated tubercle bacilli following the completion of nearly three years of exposure to asbestos dust, progressive disease did not develop. The only nwdi.ficacti nw of the infection was ana of localisation, a few badlli being retained in the fibrous terminal bronchioles and farming tubercles there in addition to the usual fod beneath the pleura. Such tubercles healed in a few months and there was nothing to suggest any influence on the course of the disease. 91_ Susceptibility .to Moo-Tuberculous Infection. Thera was no pointed ex periment concerning tha effect of -t-nhaind asbestos dust an con-tuberculous Infection. Intercurrent pneu monia aranng animals exposed to asbestos dust was rather coanan, the frequency in guinea pigs exposed in the four inhalation experiments ranging from IS to 39 per I cent. This incidental evjdancf siesta the possibility of an effect of aabestes dust on noa-tuberculcus irfeertion. rigrartheless, sines such epidexd.es are not uncommon in inhalation eseparitsants viith other dusts and even in the colony of noraal cnimals, it is felt- that the inhalation of asbestos dust docs not ssert a significant effect on the susceptibility to vncn-tuberculous yuluDnary infection. \ 92. Becplkam. Ho specific escpericent *ras ctfeducted to cotemLne whether the inhalation of C-fi i -./fc,a ' ocl t*y**~ f. --* - * ^ y.C^- o ---i ^ (> .. . asbestos fairora the development/of neoplaptic .diBqgfla but certain observations on this arabjsctytiwm recorded in/be ontUaeof the proposed moit'sraph. on aebeatosls submitted by the late Dr. L./o. Gardner la February 19U3. In it he called atten tion to the hlg)^ Incidence kt lung curaramong mice -inhaling Iccg-fiber asbestos. In his aoqpartmental notes/hoirtfu, ha^r^ferred tb these lesions as adenomas. There is on dist ;lon between ac and cancer rbich should be \/ / made clear. A cancer is a tuner, or neoplasm, capable cf local in*asicm and de- t/ /\ struction of tissue, Vd/icfa can distribute cells through \he lymphatics or blood jf ^ / stream to produce isolated foci, l^bm which new tumors flop. This phenomenon of 4<--idwMnw Is Jtmdpa as mej^stasis and stay tumor which its it Is a malignant growth, oi afticb cancer is one type, in adenoma, oi^ the o .bar hand, is \ a, so-called benignfar ncuv-n^-ignant tumor (neoplasm) which may azr not be capable of local invasion but^ which does not netastasiae. In order to clarify the edact nature of these lesions the pat logical nater1*1 is being carefully axanl ned A^Slncc it is felt desirable to bar the benefit of Doctor Vanxald's judgment, a review of the data on this subject is b^ing post poned until after his return from EtnSopa. Rather than delz^y the ent're xn^art, I further discussion will ba reserved faX a supplement to bo issued lat v. 4 aogs. Both inhalation aenodn injcection experiments provide axpls support for this ionclr.sian/'iiLgures 5 and 6 ehov the reaction jJ ,ito two different Tc of asbestos mineral. U% 1 a gr> -- m * B. The node of .iction^ap L^-y,rather than > chemical in nature. *rf ftf+y'*' The evidence is gii in section LXXXVTT. Figures 1, 2, 3, U and ? illustrate the structure of as tani paints. The fibrous fUaaent*-! js^^eerx^ pla/" an essential part in the Irritating action, :e the solid fibers of glass wool da not produce fibrosis see Figure 8). ir C. Stiort asbestos fibers|do not producetfibrosis. The omstaRtea is implied in ths evidence cautioned in para graph B above. Experiments which further support this find!n[ are Tvpee^e^ir. Tables 21 and 23. Typical fibrosis can I be produced by an atmospheric suspension of cV. tinned Ti&ls Id;, aiii'.c/u,;-...;i Icsii than 1 per cant of t're hhua-s; h'lTic cust co.osisted rf fibersi loader thar. 10 riemnsj is ahenrn in. Tabic 11- In contrast, the intra tracheal in^s-ctioa experiment Tsith fins asbastes dust cor?-- triaLsz nz lung fiiars failed te produce fibrosis,. (see Taijlr 21;. Inhalation oi f-sfcastos duot eppar-or.'blT' * ss not altei* slgni flcantly the ... eoi'gse of erpericsntsi .tufcraKinlosis iar*guinea pigSAb*-*^ This figaeTOttslen 3 tentative since tije evidence on vfcich it is based does set conform nith cur Mpaal experience. Rafer1- ence to Table 3 rill she* that mhen /infection -was coincident Tith onss*-' of dost exposure there v^s taspozary projpressior of the disease vith xobsequent healing) -cben infection ras initiated after 25 3/L months of djtat sxpesure the course c-f the tuberculous disease css sot apprecfLably altered. In contrast}it has bean observed in experiment? ditb mixed dusts containing quartz that if there is a alight irogression of the tubercu losis Pfceu infection and dust exp JStrre are coincident., this effect is nore earned (instead oi lass, as vith asbestos) then infection, is initiated after a pe riod of dust exposure. This conclusion concerning the e `feet of inhaled asbestos dust on tuberculosis seeas Justi. led because in the more sensi tive test (infection initiated a ter & period of dust exposure) there twas no appreciable increase in susceptibility to the tuberculous infection. liorrsTsr, since the findings in ths ^'.'C /j.'-ti* tccparionci;, l *-