Document Dvyb8zyN4YD1eGZyKRN3vXxBa

FILE NAME: Owens Illinois Library (OWL) DATE: 1955 DOC#: OWL044 DOCUMENT DESCRIPTION: Article from the Archives of Industrial Health - Effect of Inhaled Commercial Hydrous Calcium Silicate Dust on Animal Tissues sXHiarr Reprinted from the A. it. A. Arthives of Industrial Health September 1955, VoL 12, PP- 342-360 Copyright 1955, by American Medical Association , jtjh c t J ^ n k a le c t d o m m e r c i a t (jL i^ c tr o u (La.ld.LLm ^ilicaU 2 ) u t o n (LkL u e ha U panm oani Sradf S. W. H. SCMPCXS. M.0,, Die. T. M. OURKAN, M.L end A. 8. OEUHANT, Somimc lake, N, Y. Commercial hydrous caidum silicate is one of the products that have bees studied by long-term inhalation experiments at The Saranac Laboratory. These studies were commenced in 1943 under the direction ot Or. L. L*. Gardner and with the assistance ot two ox us (T . M. D. and A. B. D .) who car ried die work to its completion after D r. Gardner's death. Guinea pigs, rats, and ham sters were used, and the experiments were designed to reveal the nature of the pulmo nary tissue reaction to inhaled dust of the material in normal animals and in those har boring an experimentally induced tuberculous infection. From experience with other siliceous materials one would expect to nnd that a product composed only of calcium silicate would be relatively inert in its effect on tissue. Extensive clinical studies of industrial workers exposed to cement dust in high concentration have, tor instance, shown that the effect of the inhaled dust of that material on the lungs is insignificant. Portland cement is composed principally of two calcium sili cates. namely, dicalcium silicate and tricaldum silicate. Recognition must be given, however, to the possibility that any poten- Recorded for publication July 13, 1935. Director. (Dr. Schepers). Associate Director 'Me. Durban), and Research Associate (Mr. Deiaham). The Saranac Laboratory. dally hazardous raw materials used :o nuke a product might not be entirely converted to a nenhazardous form during the manu facturing process and, therefore, might appear to a greater or less extent in an unchanged condition in the final product. The d a y and shale used in making cemenr often have a quartz content of 20% to 30% or more, but chemical reactions, occurring when the raw m ixture is heated, convert practically all the hazardous free-silica min eral to a relatively harmless silicate. In most samples of cement the amount of quartz that has come through the manufacturing process unchanged is less chan 0,1%. The hydrous caidum silicate product used in The Saranac Laboratory studies was made from caidum hydroxides and silica plus a moderate amount of asbestos, which was incorporated in the mixture to impart cer tain desirable physical properties to the fin ished product. Analysis of one sample of this finished product disdosed that approximately 80% of the raw mixture had been convened to hydrous caidum silicate and that about 15% was magnesium silicate (Table 1). About '.% quartz persisted in the anal prod uct. Probably the greater part of the mag nesium silicate was present as the fibrous mineral cnrysotile. although a portion may have been in the form of serpentine, a min eral simiiar to chrysotile in chemical compo sition but one which is nonfibrous. EXPSJWMSHTAI. METHOD To determine the effect ot* inhaled dust of the product on pulmonary tissue, an inhalation experi ment was conducted. In that experiment groups of guinea pigs. rats, and hamsters were exposed in a cubical dust room. 3 it, in dimension, in which 1 iuhll-li 1*, No. 1. U,ii l<>. II. 12, II Hi. It. 211. 2| . ai. si to. it. ta, M Kx|mMIID lo Itimi, Mu. % i 41 H Uh Vi u 21 21 i't Mi xt M Itoti J.--i'alNi>N<M'.v/.' . |t>I aitaieJ rtiMimniiiJ lly ilm a t i'a h ia u i Milifa le liu t i riKUMiit lathilt .. -- ** 1 1 1 1 1 II 1 il il littiw l`i|t* Were K*|H>sel liy IttitaIntimi CiuilMiiuMi.sly In lite Ihitl Uniti licitili - ----- ....... . ...........- ............. ..... . ... l.yiMiiti ilt| Unterl.leale li 1 1 n n 11 11, ti i + 11 i 11 i ++ llrttUrfcllilla lui llruurWal IMrrilimi 1 1 1 il 1 i H 1 1 i II ili 1 It 1 1 il II -- M-lni.N..i_ rii|ik.K..il_s.ttm*-*A*o..l...l.'.u.r.u.iMiM-uiiluNlii llrtotcitisi ItUlarII . .. .. h il+ + I 1 il II ili+++ Alleotaalolil lira*- II , e. . .. .. e. .. ++ ++ +++ +++ limaticyluala 1 ti H ++ + +i ii +++ iliili ili 11 + +++ I Miniar l'rnllf- AnImmI rail 'lliriiata lltullss 1 t , .. . i I i 1^ i il- i l +i 1 1 1 11 + +++ . .. .. .. 1 + II +1 + +++ , , , , , I I il il il ++i + ++ Ht|>ltir- lltural UNI llcacllon ,, .. .. ,, ,, + ,. ,, ,, ,, , , , + .. + 1 ,, + 1 1 +++ ,, +++ ++ Mcarilo In l'ultMiMtarjr UaMil. Knlar- l'inuma mi Ialina li + 1 ili li i + + + li 1 i l i ++ ili il II .. i l 1 .. ++ IttMtrail -f i il + -1 + + +1 HI 1 +++ +++ 1 I i.pmyk Mtoloa ik*rtS'UtntiSa alleatili 1- 1- + + + + , + ,, 1 + , ++ , + + li ++ i. all*Hi t>r liirtfiiut I I, twiibiiit nwllut; -- f-1-unksl reaction. T a w * 4.-- l'ulinoaary Itcaflion t inhaled C om m ercial H ydrous C akiuM S itu a it D ust liais and Hamster Were |{|wsal by Inhalation Conlititiously la lite Dust Until Dcallt U lritM u i K v lk u rtiil I'ltruuuiriwliitlii KniiiKiiiir Iti Ihll. Mo. Ullmux*l' .N-llnii in M*1* ^*1'Mt!* It* Uni iHial Al* i( 1 1 -a. ,,"li# SIC. * ' li i 1! i Sli .M. 2-1 . i --f, an. 2 . a*" IH .. .arti !- t.hjHkMt) || ut.. Ihl.l 3 Il li u , 4.6 n , . li, U in llitoti'lttit- lirttarliUI lilla atol IthliirlliMi lituoeltlal atti! l'itaI<li'i't.ilt.it IHaliatlloo lela I 1 + 1 1 I 1 1 11 " H i I 1 11 UHI i l i 1 1 i 1 + 1 + + 1- il i I- + + (felli llar l'fulljatalluu , % t + I 1 H+ . . + ++ +1 I'UminOh llskallnb i i 11 ,, .. .. i i 1 tl.!lltf. 1, nlitflil r Miikui icirlliin; *|*-| * kmIUin; | f f , mariniti fllldluil. KHunl|tH** lllrlttua-tlrltatlo I a. i 1 ++ l H 11 ++ i ++ ++ i IH ++ KhwUm la ItalaUMiarir l,yut|ili Hotlea i Manti ftltaita Katarmet lu lrallt.il KHtrtiela rrl tlrMll 1 1 1 1 .. .. 1 i l .. + i i 1 ii 11 1 i^ 1 .. .. 1 + a. ++ + + a. i- + 1 + + 4 ,* M * * $ Ji s :v '.fii: UrJ''t ( fl im>i*.sT aa Mi tM 4* marked tendency to peribronchiolar atelec tasis, with epitheliaiization of the wails of the shrieking alveoli and cellular infiltration among1-'these minette cystic spaces. This change produced a microscopic sectional effect resembling multiple adenomatosis, but as there is no lack of differentiation of the cellular components, no neoplastic change could be postulated. This adenomatoid pat tern was seen only in the guinea pigs, but as its evolution was in the nature of a de layed phenomenon, it is possible that it would also have appeared in the rats and hamsters had exposure been continued in their cases beyond the 18th month. Phagocytosis of the inhaled dust could be demonstrated in all animals from the com mencement of the experiment. It was most marked in the case of the guinea pigs and least prominent as a feature in the case of the hamsters. The phagocytes were domi nantly mononuclear macrophages until about the end of the first year of the exposure when muitinudeaced giant ceils commenced to be substituted in progressively greater numbers. At the same time these giant cells grew in size so that they often filled the alveoli completely, and toward die end of the third year of exposure the giant cells replaced the mononuclear cells almost completely, especially around the distorted bronchioles. As time passed, their cytoplasm became in creasingly more addophilic and their centers more charged with ingested particles. There was no evidence of necrosis of these cells, such as occurs in experiments with finely divided quartz dust and silica fume, which provoke similar giant cells. Interstitial cellular proiiferadon and infil tration are a late sign in all three species. It commences first toward the end of the ninth month of exposure, and for the suc ceeding six months it is almost entirely lim ited to macrophage accumulations around smaller blood vessels and bronchioles, at the angles between adjacent alveoli, and in the interlobular septa. Among these macrophages may be found isolated eosinophiks and plasmacytes. Fibrocytes first make an appearance between the l:th and the 18th month of dust inhaladon, and soon after this strands of collagen may be perceived among the cells. Fibrosis proceeds slowly, however;- before the end of the 30th month of dust exposure. Thereafter it is detectable in increasing amounts, particularly in relation to the ade nomatoid areas around the bronchioles. Fibrosis also appears prominently in local areas of consolidation, which become pro gressively commoner toward the end of the third year of exposure; In animals killed, respectively, at 33 and 36 months from the start of the dusting, extensive areas of lobu lar consolidation could be found, and similar consolidation associated with cystic disten tion of trapped bronchi could be seen in sev eral of the rats killed at the 15- and 18-month periods. No acute inflammatory process was demonstrable to account for these results. .Asbestos bodies of an elongated, slender. "If tapering, minute variety were demonstable by oil-immersion microscopy from about the 15th month onward in rats and hamsters and from the 18th month onward in the guinea pig. Cccasionaih aque rubbed * -r;v could be fOvina. in me.-, nsta.-; bodies were ifficv;t co sring i.uo iowui at, tended to be curved end spindle-shaped. Often they were intracellular, being partly engulfed by one or more macrophages. None were found lying free within alveoli. They were so constantly found in association with the areas of fibrosis that the conclusion of a causal relationship between these phenomena . is almost inescapable. Emphysema of the hypertrophic varen* appeared as an early sign in the hamsters, in which it was present to a quite marked and widely distributed degree at the end of the IS months of dust exposure. In the rats the lesions were also consistently present from an early stage but to a lower degree than in the hamsters. In the guinea pigs, on the contrary, hypertrophic emphysema was contrastingly absent during the first two years of the experiment. In the final 12 months, compensatory emphysema was man ifested as a prominent lesion silhouetted against the foci of cellular proliferation and peribronchiolar atelectasis. e 5mh.m7;;7 cr~ z gSLsr.T.Ti.v.Tf;; T a il ! 5.--Causes af Death in Guinea Pigs Exposed by Inhalation to Commercial Hydrous Calcium Silicate Dust and Also Injected with Tubercle Bacilli of the Ri Strain CniM O f Daactt a* ?aumonl> Ttp* o t xi>rimut &XPOM4 Aalmali. Deaths. Per >0. So. C u t SiauituM ous p b M .......... ... 30 1 09.4 SMcUTsUoa p b M ............ i.0 P tu iip o e itio a p b o u ........ ... 1 M.S Control: Group A ............... 34 4 U.7 Group 3 .......... .... !S i 12.0 Peitearditii ' Deotbi. No. 3 1 .. 4. 1 Per Cent 1C.0 Perttooitl* O tter C*u m . Total Dettiu. ? tr ' D ettai. Per ' bwaOu, Per Xo. C u t -No. Cent No. C u t 1 21 i.t ? i -C` i 14.0 . .. 344 .... <> 8. .... i U.7 * :u animal, which was killed at 15 months, the lesions were widespread throughout the lung but nbrosis had been produced. In an at* tempt to develop a strain of guinea pig re* sistant to the infection that had caused the pneumonia, some of the animals were used for breeding during this experiment. The two animals that died from progressive tu berculosis (at 14 months) and the single animal (killed at 15 months) that exhibited widespread lesions were all used as breede during the experiment, as were also fo other animals in the experiment, which h failed to show* extensive disease. Owing the element of uncertainty introduced by ti factor of breeding, and also because of t high mortality from pneumonia and to ver the suggestive evidence of stimulating acri of the inhaled dust upon tuberculosis, t experiment was repeated. Tails 6.-^Course of Tuberculosis Induced in Guinea Pigs by Infection with Tubercle Bacilli of the ?i Strain Control Study: Iaiacdon Only; N'o Dost Exposure PGiut.iaSmo . SUTTrrftl A tto r toteettoa. Day 4S............ 44 3* f ......... GO 1 40 l ........ 30 1 ........ t1m40 13........ u s ?T............ a o *1 Jv 1 ........ 38........ 293 *4{i ..... W Si........ 314 ) ........ JOS 47 * 1 ........ 49( 7 0 ) ........ WISA 7U 7 2 ) ....... JelulAv 73} ,JA 74 j ....... 771 Til 7* sol n ! ....... 730 95 ` 44 9 J r u 9M sqm sum su m SUM sum SQM CM DM SQM SUM DM snM SUM DM R IM SUM S11M SUM SUM SUM SUM SUM SUM SUM SUM SUM SUM SUM SUM SUM R IM R IM SUM ifflW t TUbeeoM. So. 3 4 IS 7 4 3 4 * 4 u * 0 4 l * 1 4 4 3 1 3 3 3j 3 4 2 4 4 Spm dlac Tubtreo lOMO ## ,, Cu m * ooa dm ofe ,, -w ti .. ,, ,, 4 0 ** Caidfl. uaaa .. .. ,, * .. ,, Istttlo a ia Pulreosirr irwoOSoam PtaurlU* ,, -- -- . . .. Soiar*toe MO ip M ---- -- -- _ -- -- _ ---- TTuotMrnRu-k , DlMUdBAtP clou L ite? Spk .. .. T- T -- T- T .. ---- T urn .. TA-- * T + dm .. e .. .. -- .. .. * .. ,, , , .. M .. HOP ,, .. .. .. ,, dwum ,, .... .. .. ,, , M* ommdm .. ,# ,, dmm ## VT " Symbol* --. sUrbc ru c tio n : * - r , mod.P it . ru c tio n ; *----r Pdraaeed rttc e o n ; T , mb.reJ* ia rm .tio n . iiri pig. Massive caseaung lesions were tound i; m the lungs, the liver, and the spleen. It ^ - was suspected chat this animal may have been accidentally infected with virulent human ,, tubercle bacilli. Xensequentlx, bacilli were recovered, cultured, and subinoculated into ] the groins of four healthy guinea pigs. These ; animals developed local abortive lesions char* > acteristic of the Rj bacillus, and no systemic tuberculosis ensued. By this study it was fairly satisfactorily demonstrated that Guinea Pig 73 was unduly susceptible to tuberculo sis. In the guinea pigs which were caused to breathe the hydrous calcium silicate dust after infection, localized spreads of the tu berculosis occurred in 13 out of the 30 cases. f In four of these the tuberculous process was V quite advanced, and in four others it was moderately marked at the time of autopsy. It should be noted too that five of these spreads occurred during the second year of the experiment, i. e., long after the tubercles should have been arrested and healed. At tention should also be drawn to the presence of cavitation within two tuberculous pneu monic areas in Guinea Pig 23. Pleural adhesions of a chronic tough va riety were also quite common in the animals receiving the dust exposure. The pulmonary lymph nodes showed a greater prevalence of late active tuberculous to d , such lesions in the control animals haring usually disap{ peared from the nodes before the end of the tirst year. From this simultaneous phase experiment it wouid seem, therefore, that the hydrous calcium silicate had a mild to moderately ad verse erfect on the course of the R t tubercle infection. REAcnvATtox Phase.: Covrsz or TcssjtcVwOsts tx Goixza Pigs W hich W exe Exposed to Hvsjiocs Calcxvm S iucate. Dvst Seyxxal Months A rrea Intscttox with R, TcXXXClt Bacjlu Infected guinea pigs were placed in the dust chambers at intervals of two months, i. e.. 10 at two months. 3 at tour months, and 8 more at six months after infection. In order to follow the course of the tissue reac tion, a pair of animals of the first subgroup (two months in normal air) was killed aiter only 2 months of dust exposure, and, in ad dition, animals from all groups were killed in pairs after 4, 3, and 12 months of exposure to the dust. Examination of the tissue oi the dusted animals failed to reveal a significant reactivation of the tuberculous disease by the inhaled dust (Table 8 ). Only dve animals showed evidence of spreading pulmonary tu berculosis. In three the disease was minimal in extent, and in two others there was moderately extensive local spread. Casea tion persisted in one animal to the end oi a year, and slight to moderate foci of f.brosts could be discerned in a few animals, suggest ing that not all the tubercles healed by resolu tion. Chronic pleurins and pleural adhesions were present in 10 of the guinea pigs, which was considerably in excess of what is cus tomarily found in a typical reaction to the introduction of R t tubercle bacilli. Dissemin ation of che tuberculous process to abdominal organs and to the pulmonary' lymph nodes did not occur in any but exceptional cases. Guinea Pig 52 was probably one of these "sports." The term "sport" is given to a guinea pig in which the inhalation infection with the attenuated bacilli is not cottoned principally to the lungs and pulmonary lymph nodes but extends also to other organs and produces in them tuberculous changes of sufficient extent to be recognized macro3copically. Since "sports" represent a de parture from the normal pattern of tissue reaction to attenuated tubercle bacilli, whether the infection is combined with dust exposure or not, such animais must be ex cluded in assaying the effect of an inhaled dust upon a tuberculous infection. It is be lieved that ``sports" are animals whose na tive resistance to che attenuated Ri organ ism is unusually low. Support for this belies is given by experience with quartz dust, a definitely hazardous material which reacti vates an inhalation infection produced by attenuated R i bacilli but ordinarily is not as sociated rich tuberculous extension to organs other than the lungs and pulmonary lymph nodes. 11 Ta ils 9.--Influence of Inhaled Commercial Hydrous Calcium Silicate Dust on the Course of Experimentally Induced Tuberculosis in Guinea Pigs Predupoutioa Phas: Animals, Alter Being Exposed to the Dost for Three Months, Were Inserted with Tubercle Bacilli of the R* Strain and Then Were Immediately Returned to " ~ the Duet Room Where Their Oust Exposure Was Continued Until Death ' rurtfecr ipp<ttll jUiBM Plf, No. ur i * i u vs :h H m i Hi m !*> :is >,* us UT V<t I'M in 1 H'l l'K u* (atwdoo. Days 0 0 0 0 0 39 0 139 139 1 uo no 99 :to IW 300 0 S ti Hi m Ml OS uo M9 400 49930 90 30 7o SOM sum sum snM SOM DM sum SQM sum EDM SOM DM DM SUM SOM SUM SQM DM SQM SQM DM DM DM DM SQM SQM SQM SUM SQM Putonooory XMeao SofoodlM TuttticM, TOM* COTttO- So. M doe .. .. .. IT f 2t 1 4- 14 ? 11 It H 1'! i"l i 3 0 .. 39 2 s ^ in * 4 .. ... HHH -Hr -H P .. --- r .. +-W- .. i" t V .. 4 s 3 PM rita .. .. .. ,0 .. .. .. -H -K .. M +-P TT .. .. -P .0 + 0 -H* .. .. OiMcaiaadea Putioeoarr ,vw EaUrto- TutMrmoot cvJoou Liter .. .. ,, .. .. .. .. -i--i. P .. .. H--H p -r .. T* .. .. + .. .. mu .. -* p* r p ri--p -- -- ~r - p> p* -- .. .. -- *T * p .. -- p SolMO ,, .. .. .. .. .. T+ .. .. .. .. Smhois: iilfftt or Im p M c rwottoa; 4-r. aoSomr rtootloa; aarsad rooedoa; T. mbweaioeU. It is of interest to note that the extension of the disease was almost entirely confined to the pulmonary tissues, tuberculous to d being detected in the spleen of one animal only. The reaction in the pulmonary lymph nodes was not of a significant nature or de gree. These itndings indicate that a tuberculous infection which originates in guinea pigs several months after a prolonged exposure of the animals to dust of the hydrous calcium silicate product was initiated may be unfa vorably influenced by the inhaled dust. A separate control experiment was set up, us ing 23 guinea pigs, as the predispositionphase experiment was started at a later stage chan the preceding studies so chat a fresh Ri cuimre had to be employed. The results ob tained were so similar to chose given in Table 6 that the latter may suffice for the purpose of this paper. ANALYSIS OF TISSVE OF EXPOSED ANIMALS Chemical analysis of lung tissue of unin fected guinea pigs that had inhaled the hy drous caldum silicate dust for periods up co 36 months yielded the data reported in Table 10. It will be noted that as the period of ex posure became longer the values for the tis sue ash gradually increased, thus showing that mineral matter was accumulating in the lungs. T here was a pronounced increase in the silica component up co about 30 months and then a slight decrease. This phenomenon is illusory, as ic is due to the relatively rapid rate at which inorganic .-n.rr.Ter `as deposited 555555 13 W hy the alveolar ducts and bronchioles, should have dilated at an early phase in die rats was not clearly revealed. No proximal obstruction qpuld be displayed which could account for the distention on mechanical principles. Possibly the cause may be re lated to the tendency to peribronchiolar atelectasis. Perhaps a neurogenic mechanism was at the root oi it all. To be true, the larger cystic distentions were usually found within areas oi chronic diffuse consolida tion, and it is possible that in such instances the distention of the trapped air passages resulted mechanically from cicatricial con traction. The origin oi two types ot emphysema which were discovered may have similar ex planations. While that which developed in the guinea pigs was definitely compensatory to the tod of atelectasis and fibrosis which it surrounded and the emphysema found in the rats and hamsters was of the hyper trophic variety, both may have had a com mon origin in the damage to the bronchioles. The mild to moderate tuberculogenic ef fect of the hydrous caldum silicate dust mani fested itself in local or even diffuse spreads, delayed healing, and dissemination to other organs. It is not yet possible at this stage to attribute this phenomenon definitely to either the chrysotile or hydrous caldum silicate components. The tact that the tuberculous process did not persist m the pulmonary lymph nodes, whereas it was activated in the lungs, parallels the observation that only in the lungs \vere asbestos bodies found. It must be presumed that the hydrous caldum silicate dust was transported from the lungs to the lymph nodes, to judge by macrophage accumulation at the latter sites, and it is probable thac the dust was more densely con centrated in the lymph nodes than in the pul monary tissues. This suggests that the stimulation to perpetuation and spread of the tuberculous process may have derived from the chrysotile fibers rather than from the hydrous caldum silicate. Such a con clusion naturally requires further confirma tion through experimental investigation. SUMMARY Inhalation studies have been conducted using a commerdal product composed of hydrous caldum silicate and chrysotile on normal guinea pigs, rats, and hamsters and on guinea pigs infected with tubercle badlli of the Rt strain. The dust caused marked chronic bronchio litis, with terminal peribronchiolar focal fibrosis, bronchiectasia, and epithelialization of atelectatic alveoli. The final lesions doseiv resembled those found in eyppf^gnta) as.-- bestosis and induded asbestos bodies. The course of experimentally induced tu berculosis was mildly to moderately ad versely affected by the prolonged inhalation oi the dust. It seems ;ike:v that :iie chrysotile compo nent oi w s cotrmerca: proii-c.. Mh; . than the hydrous caidum silicate, v ts tii cause of the deleterious effects on the tissues of the experimental animals. Printed end P n M th ed in the L'nitcd States of A m enta