Document jmGL9DoM565KJNXpqQoG1ynaO

The Response of Peritoneal Tissue to Industrial Dusts By ........... JOHN W. MILLER and R. R. SAYERS REPRINT No. 2234 IfiOM TDK PtnUC HEALTH REPORTS Vol. 56. No. 7 FBBBOiDT 14.1941 - Paces 364-272 WV-1087 FEDERAL SECURITY AGENCY UNITED STATES PUBLIC HEALTH SERVICE Tsowa* Stf'gn.Gennit i ... DIVISION OP SANITART REPOSTS AND STATISTICS fjnmV. Ans. iHiaM Sarfm Cmm)< <W OinM* + UNITED STATES GOVERNMENT PRINTING OFFICE. VASIDNCTON * IW Tor Mk h* ifee Sv*wrw*twdnt(DenacMh T.AiiniM, D. C Rid S m* 01 501 r,c 0011 ti; s THE RESPONSE OF PERITONEAL TISSUE TO INDUSTRIAL DUSTS * By John W. Mjusr. patlcUe&t, ud R. R. Sates,* Senior Surgeon, United Slate* Public fiadth Service The reaction of the peritoneal tissue to injected dusts has been described in previous reports3 and attention hea been called to the possibility of using the results of such a biological response to predict the pneumoconiosis-producing potentialities of industrial dusts- From time to Um*, minor meditations in the method of introducing the dusts Into the animals have been made to simplify the procedure without altering the results. As now practiced, the test is briefly as follows: Two cubic centi meters of & 5-percect suspension of air-elutriated (or 325-mesh screened), hcat^terilUed dust in sterile, physiological saline eolation is injected into the peritoneal cavities of a number of guinea pigs. Animals are killed and examined U, 45, and 90 days after injection (in earlier experiments at intervals up to ! year). The nodules produced by the dust on the anterior abdominal walls or in the omentum at the various intervals are compared. The gross appearance is usually sufficient for interpretation of results. Three general types of reaction are produced by the various dusts. These h*va been designated es absorptive, proliferative, and inert. Dusts of the absorptive group produce nodules which progressively decrease in size as the interval between injection and examination increases. Eventually the dost disappears from the peritoneal tissue. i Vreaa tit* IHvlfiea at lotfufUial Bnlrae. NMtoau lanttnuoT Scoka. jTMmaflr & xBar*aMe**. MlUtr.J. W, ud &?*.&. S.: Ttef*peBofpeaaakl*(4BMt6dtiAtst?<ia'edu]oRtca bedfe* Psb. JXttitb R*p,, *it SM#dwvTI*. ISO ttctnstNo. MB}. 1. Am. Mod, Aba. UB; ?-* <8p> to*r 88,). An. i. rub. nOc*. M: j4 (ApfU im. Pub. HW BJi*. H :l?7-l* ter4,1*36} {Reprtnt No. JW>. tiQltg. J. W-, usd Kofen. R. ft,: MlcnseoWe apsvw espetroesttity pradoi da* noiaiet Is tte patUtaam, rot. Et*J4 Rojk. M: 18J>-)08 <No**afc IS. U} (Retell No. J7>. aett&A--a i VOi 501 0012 2 BBACTXOtfS TO INDUSTRIAL DUSTS Microscopically, a typical early nodnle consists of & mass of the dust mixed with fine, granular, neooiic material. A zone of fibroblasts with an occasional macrophage Burreunds this more or less centrally placed mass. With time the necrotic material becomes less and finallydisappears. Brown pigment particles, apparentlyof endogenous origin, are usually found rather early, and in an experiment of a year's duration are the only evidence that the dust was introduced into the peritoneal cavity. Dusts causing a proliferative type of reaction produce nodules which progressively increase in size as the Interval between injection and examination increases. The maximum growth, using a O.l-gm. dose for each guinea pig, is reached in about 90 days. Microscopically the nodules 7 days after injection are similar to those produced by the dusts of the absorptive group. As the process continues, the fibro blasts in the cellular zone about the central mass of dust and necrotic material are largely replaced by macrophages which are usually filled with dust particles. This is most marked in the 30-day series. Later, the engulfed dust particles appear to decrease in numbers and fibroblasts and adult' connective tissue cells predominate. The area of necrotic material persists throughout the duration of the teat. After 90 days fat cell fonnation in the cellular zone and calcification of the necrotic material is noted. All of the dusts classified in this group studied thus far are various forms of naturally occurring silica. The nodules produced by the inert group of dusts are, in the early stages, grossly similar to those of the other two groups. As the interval between injection and examination increases the nodules become fattened with irregular edges, and numerous dispersed par ticles are present in the adjacent peritoneum. These are often found a considerable distance from the original nodules. The amount of dust found in the peritoneal cavity 1 year after injection is essentially the same as noted in 7 days. Histologically, the fibroblast is the early predominating cell. An increasein macrophages is noted at the 30-day interval and eventually fibrous tissue and accompanying fat cells predominate. No necrosis is noted at any interval in the entire process. The response is characteristic of that caused by a nonirritating foreign body. It has been possible to correlate the response of peritoneal tissue to certain dusts with the results of X-ray examination or of post-mortem study of workers exposed by inhalation to high concentrations of the same dusts for protracted periods of time. These records are far from complete, because medical and roentgenograph*} surveys are available for only a limited number of the dusty trades. Neverthe less, the preliminary result* of such comparisons can be summarized: (<s) No cases of pneumoconiosis have been reported and confirmed among workers exposed solely to dusts of the absorptive group; (b) oil REACTIONS TO INDUSTRIAL DUSTS 3 of the dusta so far ex&minftd that fall into the proliferative group are knows to produce & nodular, pulmonary fibrosis (sUfcoeis); (c) pneumoconioees caused by dusts of the inert group (asbestos/ anthracite mine dusts,* bisque ware* mica,' pyropbylliie,* and talc*) have been reported as a result of S-ray exanunation of industrial worker*. Where autopsy material is available, certain of the dusts of this group are known to produce a diffuse, interstitial, pulmonary fibrosis, or a mixed nodular and diffuse fibrosis, such as is produced by anthracite coal containing free silica. Interpretation of the response produced by a dust is the peritoneal tissue in animals cen be used as an index to determine the potential barmfulneas of an industrial dust to which workers arc exposed. Thus, an absorptive reaction can indicate that the dust is relatively harmless, while a proliferative response would indicate the du&t to he definitely harmful. The dusts producing an inert reaction have bees considered as less hazardous than those producing a proliferative reaction, and more dangerous than those of the absorptive group. The intraperitoneal method of studying the physiological action caused by dust* not applicable to highly toxic material, a aubUtb&l dose of which is too small to be grossly visible in the peritoneal tissue, or to dusts that are readily soluble. The following dusts have been examined by this method and the results, with pertinent identifying data, are given below. DUSTS CAUSING AN ABSORPTIVE REACTION CaieHe.--A pure mineral dust. Chemical analysis; Acid insoluble matter, 0,0 percent; silica, 0.0 percent. Petrographic examination: A calcite of high purity. Cakiu.--A pure mineral dust. Chemical analysis: Acid insoluble matter. 0,1 percent, all of which was silica. Petrographic examination: A calcite of high purity. preapiUUtd caUiun ctutertoU.--A chemical byproduct, Ao industrial dust. Chemical analysis: Silica, 0.4 percent; calcium carbonate, 87.9percent; magnesium carbonate, 10.2 petteat; magnesium oxide, 6.2 percent; iron and aluminum oxides, 0,6 percent. Petrographic examination: Precipitated calcium carbonate, about 98 percent; crystals, probably sodium carbonate, about 2 percent. <7ypsum.---The unealeined, natural mineral. An industrial dust. Chemical analysis: Silica, 2,3 percent; c&lrJuro sulfate. 971 percent. Petrographic exam* inatioo: Gypsum, about 76 percent; calcite, about SO percent. XHeewn, W. C,, D*BT*nth}. Met bJ.; A sEodyW febesfess Is the*sbe*U* *tO* ttfloazrr, pnh Beatsfi Bufl. No. j*!. p. & Oomeoeu Traitor Offlsa. was. ssyns. ft. ft, BtawftfleM, J, ec aJ.: AathmeeUlcoes sses hwd><s*l olac**. Fob. RflOlb BtfU. No. St, U. S. Oovmuom Prams* Offlrfw, IMA i FUss,ft. B. DrosMS, W.,, rtat,: 3tBs*sod teed pjisohfataaro; pxury*lcer*. Pub, BeeJih BoR. No.*t P. 8. GflTPnaxm FHstia* Office. ISO. > praosse, W. C., DeliaVBti. M,,rtat.: Faecfnecttdeei**aaoi oteand gegtaeUie pub, BaPtfi Bun. No. 2iX O. S. Gewnuaeot prtsiUrf Office, 19*9. gaaea, 5. P,,Trfee,W. F,,and Cwjxaur, C. C.: AcudjoftherSeeUofeiia*urtsu.stisthestoic* acd mllHng c( pyroptiyfllse. Repcet, Konh CaroJla* Stole Bcert of SceKb, KtbnW iss. DweiMu.'Vf.C,,ujfi DaJkV*?*, J. Si.: Zltecuof trrosotto6an toxwe Qeonpi tale mtitt aad ofcttte. Peb, Be*)ib Rep, M: l*M<3 (Febroary i, tra (Repent No, iK. 01'. 561-0614 4 REACTIONS TO INDUSTRIAL DUSTS Ljrawtoot--An industrial dust. Chemical analysis: Silica, 1.5 percent; calcium oxide, 54.4 percent; magnesium oxide, 0.4 percent; iron and aluminum oxides, 0.4 percent. Petrographic examination: Irregularly rounded calcite. No impurities noted. Limestone.--An industrial dust. Chemical analysis: Silica, 2.73 percent; calcium carbonate, 95.21 percent; magnesium carbonate, 1.17 percent. Petro graphic examination: A dolomltie limestone. No impurities observed. Liras*lone.--An industrial dust. Chemical analysis: Acid insoluble matter, 7.2 percent; silka, 5 percent Petrographic examination: Only au infrequent quarts crystal was Doled. A high calcium carbonate content. limetione.--An industrial dust. Chemical analysis: Silica, 11.7 percent; calcium carbonate, 81.7 percent; magnesium oxide, 3.4 percent; ferric oxide, 1,4 percent; aluminum oxide, 1.5 percent. Petrographic examination: About 10 percent quart* and about 90 percent calcite. Portland cement.---An industrial duet. Chemical analysis: Silica, 21.1 percent; calcium oxide, 74.4 percent; magnesium oxide, 2.8 perceae. Petrographic exami nation: Normal Portland cement. Pyrol\mlt,--Kn Industrial dust. Chemical analysis: Manganese, 54.9 percent. Petrographic examination: No quarts observed. This material was much more slowly absorbed than the others given here. DUSTS CAUSING A PROLIFERATIVE REACTION 25ii$us iMre.-"An industrial duet. Ground setaivitreous pottery bisque ware, fired at a relatively low temperature. Chemical analysis: Silica, 72.0 percent Petrographic examination: Quartz, about 40 to 50 percent. The remainder is eemifused clay and feldspar. Chert.--Ao industrial dust. Chemical analysis: Total silica, 75.1 percent. Petrographic examination: Quart* and chert, about 00 percent (about 25 percent of the silica U normal quart*). Calcite, about 40 percent Zfcotojntto.--An industrial dust. Chemical analysis: Silica, 92.5 percent; aluminum oxide, 3.5 percent; ferric oxide, 1.5 percent; calcium oxide, 0.4 percent; magnesium oxide, 0.7 percent. Petrographic examination: Pure diatomito. No quartz or calcite present. Greenware.--An industrial dust. Ground semivitreous, unfired pottery ware. Chemical analysis: Silica, 09.0 percent. Petrographic examination: Quartz, shout 50 percent; feldspar, about 15 percent; clay, about 25 percent. (heemoare.--An industrial dust. Ground vitreous, uofired pottery ware. Petrographic examination: Higher quarts and leas feldspar than the above. Clay, about the same amount. Porcelain enamel frit.--An industrial dust. Chemical analysis: Silica, 35 to 50 percent; the remainder is oxides of antimony, sine, and aluminum, and fluorides ofsodium, aluminum, and calcium. Analysis varies withta (he above silica limits. Quarts,--A pure mineral dust. Chemical analysis: Silica, 99,4 percent. Petro graphic analysis: Normal crystalline quarts of tdgb purity. Quart?.--A pure mineral dust. Chemical analysis: Silica, 99,3 percent. Petrographic examination: Normal crystalline quartz of high purity. Quartz.--An industrial dust. Chemical analysis: Silica, 99.1 percent. Petro graphic examination: Normal quarts. Quartz,--An Industrial dust. Petrographic examination: Normal crystalline quarts of high purity. Quartz.--An industrial dust. Identical with the above sample but treated with 0.6 percent crude pine fatty acids. (ft?- Aftf REACTIONS TO INDUSTRIAL DUSTS' Qaartt-serieite,--The source 0/ tWa dust la not known. Chemical analysis: Total silica, 81.04 peroeat; calcium oxide, 0.80 percent; mftgrahim oxide, 0.48 percent; sodium oxide, 0.10 percent; potassium oxide, 0.98 percent; iron oxide, 0.2$ percent; aluminum oxide, 14.26 percent; total water, 2.61 percent. Petro graphic examinatioa: Quarts, about 60 percent; muscovite (variety, sericite), about 46 ptfoeov, fcbrooa Msfefee, leu than 6 parent. Tripoli.--An industrial dust. Qwmeai analysis: Total >*, 98.9 percent; caiotero oxide, 0,2 percent; magnesium oxide, 0.1 percent; iron and aluminum oxides, 0-3 percent Petrographic examination: Chalcedoote silk* (crystalline aggregates) with an occasional crystal ol rrfrm&l quarts. &U8TB CAUSING AN INMT &BACTXON Aiuminurf.'^-Pure aluminum bronzing powder of the finest grade. Chemical analysis: Aluminumoxkle, U.Operant. Alurutum.~~An industrial dust. Chemical analysis: SlUca, 4.6 percent; aluminum oxide, 88.4 percent; ferric'oxide, 6.9 percent. Petrographic examina tion: Weil crystallized, artificial alumina. Asb&stoa (amoette),--An industrial dust. Chemical analysis: Total silica, 48,81 percent; calcium oxide. 0.48 percent; magnesium oxide. 0.66 percent; sodium oxide, 0,72 percent; potassium oxide. 0.02 percent; iron oxide, 44,2? per cent; combined oxides, 46.37 peraot; total water, 3.62 percent. Petrographic examination shewed predominating individual fibers and about 1 or 2 percent of dolomite. ' Aihutot (chrysolite).--As industrial dust. Chemical analysis: Total silica, 37.52 percent; calcium oxide, 2.00 percent; magnesium ride. 36.85 percent; sodium oxide, 6,54 percent; potassium oxide, 0.08 percent; Iron oxide, 7,70 porcent; combined oxides, 10.30 percent; total water, 1236 percent. Petrographic ex amination: Serpentine, in part chrysolite, about 85 percent; dolomite, about 5 percent; magnetite and (or) chromite, about 5 percent; talc, leas than 5 percent, Ariestes (crocidoUle).--As Industrial dust. Chemical analysis'. Total siUca, 50.86 percent; calcium oxide, 0.68 percent; potassium oxide, 0.68 percent; iron oxide. 38,33 percent; combined oxides, S9.03 peroeot; total water, 5,02 percent. Petrographic examination showed fibrous material only. AniAratile cool,--'An industrial dust. Chemical analysis: Ash, 12,6 percent; silica, 6,6 percent. Petrographic examination: Coal about 95 percent; inorganic material, about 8 percent. About 60 percent of the Inorganic material is quartz; about 40 percent is catelte. with an occasional crystal of rutile, AnlbroeiU coal.--An Industrial dust. Chemical analysis: Ash, 16.0 percent; silica, 8,6 percent. Petrographic examination: Coal, about 95 percent; inorganic material, about 5 percent. About 95 percent of the Inorganic material is quartz; about S percent is cakite, sideriie, limonite, and rutile. BeiUonile.'--Aii industrial dust. Petrographic examination: Clay, variety montmoriQonite, about 97 perceot; feldspar, about 2 percent; quarts, oooe observed. Bitqat tnrvs.--An industrial dust, Ground vitreous pottery bisque ware, fired at a relatively high temperature. Petrographic examination: Quartz, about 30 to 40 percent. The particles are wholly or partially covered by the glass phase. TkU is absent in the semivitreous bisque ware. Bituminev* mat--An industrial dual. Chemical analysis: Ash, 8.5 percent; silica, 0,8 percent. Petrographic examination: Mineral content (cslcitel, about 1 to 2 percent. ~ 01 mi ooi REACTIONS TO INDUSTRIAL DUSTS BQuvtiiuiu* ead.--An industrial duit. Chemical analysis.' A*b, 8.0 percent; silica, 5L5 percent- Petrographic examination: Mineral content (quant, cxleite, da;), between 1 and 3 percent Cbtottm ptospAele.--An Industrial dust. Chemical analysis: Calcium phos phate, 75.38 percent; calcium carbonate, 3.98 percent; cdcfom fiuorfde, 630 percent; magnesium rarbonate, 031 percent; iron oxide, 3.08 percent; aluminum oxide, 3.12 percent; free aOica, 2-70 percent; combined aSics. 137 percent. Petro graphic examination: Earthy phosphates (not apatite}, about 97 percent; normal and ehalcedoale quarts, about 2 percent. Chram&e.---An industrial dust. Chemical analysis: Sihea, 7.8 percent; chromic oxide, 25-0 percent. Petrographic examination: Quarts, less than 3 percent. Dtemond dusf.*--An industrial dust- Pure borta diamond duet used as abrasive. Petrographic examination confirms identity. Feldspar,--Chemical analysis: Total alljca, 63,6 percent; calcium oxide, 0.21 percent; magnesium oxide, O.iO percent; aluminum oxide, 19.55 percent; iron oxide, 0.28 percent', potassium oxide, 3 98 percent; sodium oxide, 3-18 percent- Petrographic examination: FeMsp&r (plagioekse-mieroeltoc). about 95 percent; normal quarts, about 6 percent. Fuller** *atfh.--~An industrial dust. Filtr&l clay. Chemical analysis: Silica. 55.7 percent; free silica (estimated), 1.0 percent; water, 15.9 percent. Petro graphic examination: Clay and residual decomposing feldspar, about 95 percent; quartz, leas than I percent; gypsum, less than 5 percent. PvUcr'i e&lh.--An industrial dust. Chemical analysis: Silica, 56,4 percent; freesilica (catimatnd),7<Q percent*,water, $ percent. Petrographic examination: CUy and decomposing feldspar, about 90 to 95 percent; quartz, about 5 to 10 percent. Fuller'* earth.--An industrial dust. Chemical analysis: Silica, 67-9 percent; ferric oxide, 2.5 percent; aluminum oxide, 13,1 percent; calcium oxide, 2.9 percent; magnesium oxide. 8.3 percent; water, 6.7 percent. Petrographic examination: Clay-like masate, rounded and irregular, about 70 percent; quartz, about 15 percent: dolomite, about 15 percent. Fuller11 ecrtA.---An industrial dust. Filtrai clay. Chemical analysis: Silica. 62,1 percent; ree silica (estimated), 3.0 percent; water, 14.9 percent. Petro graphic examination: Clay and residual decomposing feldspar, about 93 percent; quarts, 1 to 2 percent; feldspar, an occasional fragment. Clew wool.--Ao industrial dux*. Finely ground sample of commercial hard glass wool was used. No chemical or petrographic csaminatloss were thought necessary. / Hmahte (Jewelers' rouge).--Ad industrial dust. Chemical analysis: Total "silica, 1.5 percent; iron oxide, 98.3 percent. Petrographic examination showed no fenparitica. EoeKtt.--An industrial dust- Petrographic examination: China clay and hydremic* predominant; quarts and feldspar, a trace. Lanthanum u*Wiwle.--An industrial dust. From tho burning of white flame electrodes. Chemical analysis: Lanthanum, 40.0 percent. Petrographic examina tion: Particles too small to Identify. A/Yca.---An industrial dust- Chemical analysis: Silica, 46.92 percent; magne sium oxide, 0.8G percent; aluminum oxide, 34.95 percent; ferric oxide, 2.65 per cent; potassium oxide, 9.54 percent; sodium oudo, 1.02 pwcenv, manganese dioxide, trace. Petrographic examination: Mica, both as plates and fiber*, pUtee predominating, about 98 percent. A very small amount of quartz and feldspar. ^ Precipitator ojA,--An industrial dust. Chemical analysis: Total silica, 49.86 percent; eaicium oxide, 6.03 percent; magnesium oxide, 3.01 percent; Iron and 01 Sftl 0017 KBJjmom nmcBrni mjBte 7 aluminum oxides, 40.4$ percent. Petrographic examination: Loosely consoli dated, white, soft, grit-fee aah, about 40 percent; pertly rounded aggregates of semifused ash, about 45 percent; smooth fused glue globules, about 20 percent; normal quarts fragments, about S percent; untamed coal, loss time \ percent. PredpUeier A.--An industrial dust. Prom the boiler plant of a coal com pany, Chemical analysis: Silica, 48.2 percent; aluminum oxide, 29.3 percent; ferric oxide, 8Ji percent; calcium oxide. 2.2 percent; magnesium oxide, 0.2 per cent; organic matter. 8.6 percent. Petrographic examination: Predominantly spheruliaed glass, some eoal fragments, and a trace of quartz;, Precipitator aeh.--As Industrial dust. Chemical analysis: Silica, 48.3 percent; aluminum oxide, 29.4 percent; ferric oxide, 8.6 percent; calcium oxide, 1.8 per cent; magnesium ride, 0.4 percent; organic matter, 8.7 percent. Petrographic examination: Predominantly semlvitrified ash particles, come spheres, eoal. aod a trace of quartz. Precipitator <wh,--An Industrial dust. Chemical analysis: Total silica, 44.7 percent; moisture, 0.1 percent. Petrographic examination: Mostly spherical fused-giaee particles, with some aemifused masses of crystallites, quarts, possibly calotte and coal fragments. Predpitoior o*A,--An industrial dust. Lampbouse deposit from the burning of carbon arcs. Chemtea) analysis: Hare earth oxidee {cerium group), 70.7 per cent; ferric oxide, 0.3 percent; magnesium oxide, 0.5 percent; moisture, 9,8 per cent; dlka. none. Petrographic examination: Inorganic material, rudely rounded, about 5 percent of opaque carbonaceous material and so quarts. Precipitator crA.--An industrial duet. Condensate from the Sue system from taming of carbon ares. Chemical analysis; Hare earth oxides (cerium group), 59.5 percent; silica, 1.0 percent; ferric oxide, 4.1 percent; magnesium oxide, 0.9 percent; calcium oxide. 0.5 percent: ignition loss, 18,4 percent, Petrographic examinatfcua; No quarts or caleite. otherwise similar to preceding sample. Pyrophylliu.--An industrial duet. No chemical analysis obtained. Petto- graphic examination: Predominantly pyrophyllite, with a small amount of rutile and some quartz. The quantity of quartz was hard to estimate. Rock woof.--An industrial dust. A finely ground sample of commercial, insu lating rook wool. , Selenium.--Ad industrial dust. Chemical analysis: Selenium. 98.8 percent: tellurium, 0.01 percent; ash. 1.16 percent. SeUnivm.--A chemically preoared sample of highest purity. Seriate.--'A pure mineral dust. Chemical analysts: Total silica, 51.74 percent; calcium oxide, 0.61 percent; magnesium oxide. 2.74 percent; sodium oxide, 3.40 percent; potassium oxide, 4,48 percent; iron oxide, 5.83 percent; combined oxides. 31.82 percent; total water, 6.26 percent. Petrographic examination; Sertelte and feldspar residues (fibrous serfcite predominates), about 95 perecat; quarts, leas than 5 percent. Shole.--An industrial duet Cbetniral analysis: SQlca, 61.0 percent; aluminum oxide, 12.4 percent; calcium oxide, 4.5 percent; ferric oxide, 5.0 percent; magne sium oxide, 1.3 percent; sodium oxide. 2.3 percent; potassium oxide. 1.5 percent; moisture, 10.3 percent, Petrographic examination: About 35 percent quartz. The majority of the particles appear to be coaled with clay. SSieori carbide.--Pan manufactured afikoo carbide. Chemical analysis: Silicon, 67.5 percent. Petrographic examination showed no impurities. Soapstone.--An industrial du6t. Chemical analysis; Total silica, 49,9 percent; calcium oxide, 1.7 percent; magnesium oxjde, 28.2 percent. Petrographic exam ination: Talc, as plate* or fibrous splinter*, about 65 percent; tymolite, as long fibrous crystals, about 36 percent; dolomite, about 5 percent. 01 501 001S REACTIONS TO INDUSTRIAL DUSTS 8oopstcn.---Axt industrial du#i. Chemical analysis: Total silica, 38.5 percent; eaWeia oxide, 5.t> percent; aagjieshjiQ oxide, 22.7 perceoc. Petrographic examination: Talc* about 85 percent; dolomite, about 30 percent; tremoltte, about i& percent. No quarts observed. Talc.--An industrial duat. Chemical aaaiysii: Total eiliaa, *.4 pereas*; calcium oxide, 8.6 percent; magnesium oxide, 22.6 percent. Petrographic examination: TremoJite, about 60 percent; tek, afeouv 40 percent. Talc.--An industrial duat Chemical anjdygi^ Total aiiica, 58.64 portent; cakivon code, 6.25 percent; magnesium oxide, 30.74 percent; calcium silicate, il.00 percent; calcium carbonate, 2.88 percent: iron and aluminum oxides, i-04 pereanj; ignition Jose, 4.8(3 percent. Petrographic examination: Talc, mostly fibrous, about 75 percent; treateUte, partly altered to talc, about 26 percent; calcite and (or) dolomite, about 2 percent. 7%antuw oxide,--An industrial duat. A finely divided bjgb purity sample. Sodium nlieBt*.--A laboratory prepared sample containing 2 pan sodium oxide to 3.1 parte a&k*. Esther rake of sodium oxide bill the animala. Trap roek.-~A.ti industrial dust. Chemical analysis: Silica, 61.7 percent; afatrri&um oxide, i&.O percent; ierric oxide, 2.0 percent; ferrous oxide, 8.9 percent; calcium oxide, 10.0 percent; magnesium oxide. & petoent. Petrographic examination.' Feldspar, some slightly decomposed, about 46 percent; pyroxene, about 46 percent; rpognetito, about. 10 peeeeav; Wo`d\r abouvl percent. Volcanic euA.--An industrial duet- Chemical analysis: Silica, 54.4 percent; dumteuta oxide, 24.5 percent; ferric code, 33 percent; magnesium oxide, 2.6 percent; calcium ajide. 0.7 percent; ash, 78.2 percent. Petrographic examination: Vina vnietcotc ash partial)y altered to montmorillotnte. No quarts observed. Volcanic aA.--A specially treated sample. Chemical analysis Sliioa, ?4.2 percent; mined oxides, 26.6 percent; ferric oxide, 2,2 percent; calcium oxide, 0.5 percent; magnesium oxide, 2.2 percent. Peuograpfcic xamfeAtioti: Ctase ouiy. No quarts or calcite observed. SUifMABT AND CONlLDglOKff A definite quantity of dust injected into the peritoneal cavity of a guinea pig produces one of three types of reaction. It disappears, cause* proHfecorioa of the peritoneal tisane, or remains as an inert foreign body. These reactions may be used as & basis for the biologies! classification of industrial dusts, and seem to indicate that some rela tionship arista btiweea tht: type ol reaction produced in the peritoneal tissue by a dust aud the ability of this dust to produce a characteristic type of pneumoconiosis. An absorptive reaction may indicate tbai a duet b relatively harmieas, 'while a proliferative reaction, characteristic of quartz, may be associated with the ability to produce pulmonary fibrosis. Dust* of the inert group, that is, those that show a tendency to remain in the tissues, should be considered as potentially harmful, but not ao dangerous as those causing a proliferative response. With this biological method of classification, which in a number of instances bos been correlated with clinical observations and industrial surveys, it is quite possible to determine the pueumoeonioric potentialitlesof a dust in & relatively short time, usually 60 days. 01 501 0019 HEttmOKS TO mrrUBTKUL 5TJSTB 4CSK0WXEDQUBKT8 Acknowledgment is made of the kindness of Mr. W. A. Seivig of the United States Bureau of Mines and of Associate Chemist F. H. Goldman of the United States Public Health Serrico for the chemical analyses of the dusts used in these experiments. The petrographic examinations were made by Dr. Alton Gabriel of tbs United States Bursae of Mines and Dr. F. H. Goldman. Acknowledgment is also made to Technical Editor T. 1. Edwards for assistance in preparing this report and to Medical Technician E. C. Thompson for technical aid. O 01 501 0020