Document 6B1LQDkn0GBJ0JgLm0k7d7ZkE

< l IMMUNWl Al Uli ll; J'l NWSVI VANIA Ofi'AnrMi'.Nr in- La turn and Industry \p!i , fcx.'UifJ I'. A 4' ASBESTOSIS--Part II. The Nature and Amount of Dust Encountered in Asbestos Fabricating Plants. Asbestosis Part 11. The Nature and Amount of Dust Encountered in Asbestos Fabricat ing Plants. Part III. The Effects of Exposure to Dust Encountered in Asbestos Fabricat ing Plants on the Health ofa Group ot Workers. ,. *r ii. " o ' ^0oFz5l5z3.O--S J"A-"M"*Af*MI*tt', i\v '""to.nCnhlcf,of^naltyIvg,f,,e :z^c ' "n-<*,,,'* cm,n ? ::|p!| 5?I- I* ?P| 2T -4 S' ns||> %' ??'/< ;v 'J VS t, l/ * * a . \ \ i ^`4..7: BB 0007154 8* ';x is ggo >, r"` n ii u; Introduction . In 1934 the Department of Labor ami Industry of the Common wealth of I'emisj Ivaitra received a request for information relative to the lieallli of workers employed in asbestos fabricating plants in Pennsylvania. The Department had no data available, anil a review of the literature at that time revealed a scarcity ol iiilorinalion~~on tlie uencral subject of asbestos pneiimokuniosisl Because, of this ~lack of information *! imlnctries in the State were consulted, and their cooperation was obtained to .conduct a survey, winch would s include an evaluation of the hazard from the standpoint ot the de x) gree ol dustiness and the physical condition ot the workers! Ait agreeinctit was made with the employers and employes that neither would be given specific information as to the physical find ings of any particular workman, and that the original identity of all employes in this study would be destroyed, case numbers only being recorded. All records obtained were to become the property of the Department of Labor and Industry. Asbestosis was first recognised clinically by Dr. H. M. Murray (16) at the Charing Cross Hospital, London, in I'XXI. Cooke (16) in 1924 reported a case of pulmonary asbestosis, Pnnconst and Pen dergrass (82) in 1926 examined a group of seventeen asbestos work ers. Since then, other investigators have reported individual cases of asbestosis, but it was not until 1930 that Mercwethcr and Price (74) published the results of a study on a group of asbestos work ers. together with some evaluation of the degree of exposure. Lanza, McConnell, and FrIntel (66) have recently published a preliminary report of a comprehensive survey on this subject. The industry in this State consists mainly of several fabricating plants engaged in the making of asbestos cloth, brake lining, in sulating tape, asbestos rope and wick, and other miscellaneous prod ucts. According to the 1931 Pennsylvania Industrial Directory (61) there are approximately two thousand persons engaged in the manu N facture of asbestos products in Pennsylvania. The nature of asbestos dust is such that many of the standard procedures used for other dusts could not l>e used. Changes in the accepted standard method were required in the collection, count ing. and particle size determination of the dust. In Part I of this report (41) the method of collection and counting of dust en Ul U countered in this study was described and summarized.* I Ls^' 4 Nntnplra of dual taken In planra fur fabricating aebeetoa product* wen coSected by * inrtrllAct! form ot the alandara mctlioil, ttcliif a fit per cent U. fl. P ethyl alcohol aa * rnnJIoiit In Ihln rinKiiui the parttctc* wrre well dletrltmtcd and rradfly counted. Wtw tlHIfM wafer aria utJIbrrt m the cotiertlng medium, agglomeration occurred Immediately, ami inaifr countJug frapo**lh|e. Plaperafon ol the duat in alcohol It food- A aettUag tlw* ij at least thirty mtntdea area required before counting. H*e particle count la any given IteM remained constant after tbit period. A modlltrd Kohler la described. It la eonetrorted of leather alra|M, In such a way Dial the fluid la the Imrfofcr flask la vtalbl* at alt time*. 3 t '1 I I '5 vi\ \ 'i i ' 1# : i X* "i r ">X1*'-.il*,-*n .1* .'if \ ;-C : .;i `,f;i tfj BB 0007155 I-- I i i i l l l i t G~) (J~5 c_n cn . ............... i,. 1 lie- culler-Ihui ol .iliiiusphcrir dust samples in each .1 Il,r ....... |,l.nils includeil in I In- snivel, general irifiirinatinii. wir .........................inning all pita-cs <d plant hygiene, with special referiw, to ilit pi in-ial plait nf Uic lat tury, number ami types (if opernIn.ti .. .................... t'f workrooms, iMuimnaliim, etc. 'nlr ......... ................. him <ii diM m a plant teas determined for each ..... in department. A eutnplr lc si inly of each operation was liia.li-. noting mi detail the nature i*f the work, approximate lime rc.piii eil I,.i i at It iiperatiim, ami changes in the process, so that .sam ples e.illeeteil wmilil he representative of the actual exposure to tllist. 1'norr.KTiKS or Ashes ros The Inin "Ashestfis" in its commercial sense is loosely applied to a gnmp of minerals with a ntimher nf suit-divisions having, in cotitiiioii, Muons structure, ami possessing more or less resistance to the artM>n of lire and acid. The three mineral groups are: 1. Anlhophyllilc--(Mg.Pc) SiO,. 2. Amphihole or Horiil>tcin1c--.Silicates of I`c, Ca, Mg .1. Serpen line--3Mgf >.2.5i( (,.211,0. The lliree types of asbestos ottlinarily used in manufacturing are elirysnlde, eioridolile, and aniosite. Crocidolite (blue asbestos) and ainosile, a yellow or brown variety of crocidolite, both belong to the amplnliole nr hornblende group. The principal source of the la.1 let loo varieties is, at present, Hltodesia, South Africa. Chrysotilc, a utmrial of the serpentine group, comprises the bulk (about 05':,) t,t the aslieslos of commerce.. Only relatively small amounts 111 crocidolite ami amosite arr used in comparison to the (ptantity of eln t sotile. The principal source of chrysolite is the Thetfnrd region of Can ada. about [iirly-live miles south id (Jiichec. The United Stales does not iank high as a producer of asbestos, the domestic output being lc-.s ill.hi three per cent of the auioimt used in its asbestos manu facturing industries (1(1). No asbestos is mined in Pennsylvania, although small amounts have been found in serpentine quarries from lime to tune. No attempt lias ever been made to separate the asbestos from the serpentine in lliesc ipiarries. Arizona and Ver mont supply the bulk of asbestos mined in this country. Saiupl)' St' t t 4 r. f. 7 H ,TAIUF i rvr*u W, 3,\ Xl.lStS OV CHItYfiOTltrP TrvU! | KeO | N|Mf Mfl -o, AMlj W Vi" I ! > ; . 2-41% :ai ! 4 42 j 4?.iri 4i as r.ai t Ml .... 42 i XI K | 40 X7 | 41 HO If 27 41 W 4IW f-SJ 2.61 . 1.64 0 CO 0 ft* | raso 1 40 42 42 r, | 296 10 62 1 t.92 1-92 Comb. Util 14.GO 14.37 14.3? J3.66 14.06 13.17 11.46 4 OP "H r-i cor> pL. t -i I ZJ2 M n i -t-- SO 3 In the Canadian deposits the rbrysolilc is found in veins trom om-eighlh inch to six inches in length, occurring as hands in the serpentine rock. The mineral is generally a dark to blackish-grecn lustrous color, although when the libers arc separated into fine filaments, they are white. The fibers arc very fine, silky, soft, greasy and slippery to the touch. They cannot be separated into a single liber like cotton or wool. Chemically, chrysolite is a hydrated silicate of magnesium with smalt aim units of oxides of iron and aluminum. There are many published analyses of chrysolite from the Thctford region, and they appear to vary but little. Table 1 gives eight typical analyses of rbrysolilc (95). The silica shown in the analyses in Table I docs not exist as free silica. It is chemically combined with the liases in a complex molecule. Samples of dust collected in the workers' breathing zone with the electric precipitator (30) were analyzed pc trograpItreally and were found to contain no free silica.* The chrysotilc of commerce is classified in two general grades, depending on the length of the fibers. Crude fiber consists of the hand-separated and -selected material essentially in its native or unfiberized form. Mill filter includes all grades that are obtained by mechanical crushing of the rock and subsequent mechanical sep aration of the fiber. Crude No. 1 consists of fiber whose length is J4 inch and longer; Crude No. 2 ranges in length from }$ inch up to ^ inch. Mill fiber includes all fibers less than inch in length. The spinning quality of asbestos fiber depends primarily on its length. Consequently, the best grades of asbestos textiles are made from the crude fiber. The shorter fibers arc used in cheaper grades of textiles and in the manufacture of asbestos shingles, paper, plas ter. and cement. Deschli'Tion of Process Preparation--Crude fiber as received front the mines has tindergone iiu treatment other than hand-hammering to remove the rock from the fiber, after which it is sorted and screened. It is received at the plant in burlap bags, each containing one hundred pounds. The fibers must first be separated and loosened to remove rock par ticles. This operation is done in what is known to the industry as a "preparing room." A miniher of bags, sufficient for one hatch, are opened and dumped on the floor of the preparing room. The filter is fed into rim-wheel crushers and crushed for about fifteen minutes. These crushers have two heavy rollers attached to a radial axle, ami revolve on a smooth surface on which the asbestos is placed. After the fibers have been crushed and loosened suffi ciently, they arc fed into the hopper of an opener or fiberizer, usually of the Saco-Lowell type. This operation serves to further ofien the fibers. From the opener, the asbestos is discharged onto a rectangular shaker screen where small pieces of stone, foreign, material, and some of the dust are removed. The asbestos is lifted from the screen by air suction and conveyed to storage bins. It is then ready for mixing with cotton. * Prlrnfrraphfe aotlyM* of ampin were eondurttri br Dr. A. f, QaUowar, of *be laduatrlM JImItm i-atHiralwj, Peanrl*anla Department of Labor and loduitr*. 5 rTT^ TW,T ^rrr I (. . i* ii t `f > ' 1 i*.- --I - ' niis *.'i i. mj n,H nz ir-1 1'iu'ii *i ;ii 1 Ui niFiir. <|ik's m*l rnjmri' tlua |iirhminan |iniii's<m^ in iIm- urn n lirrl cnrsliris its ilms lln- vnuh1 lihrr* Tin* mill fihvr i1* lr] ibirrllv in 11 r l hr Sat Li*\\fN |11 ii'pkt, anil from then on is given Hu- s.imr Ircalmrnt as I In- runic fiber. .\sln"'his fibers when cxainineil microscopically do not possess llie* mii^h imbricated surfaces of oilier fibers such as wool. 'They icsrmbit* line polished metal rods, free from any serrated surfaces, 'i his elmaoleristic explain^ the extreme difficulty encountered in nllernptmg to spin a thread of pure asbestos. A certain amount 1 i o| toil must be added as a binder; for spinning. The amount added depends on the tvpe of fiber amt the use for which the finished pitiilurl s intended. Tahir II shows the average amount of ashes* hr* used in the mauufactine of products made in the four plants included in this survey. j AIII I n ei lU'LNTAIUH or AMIIKHTMN in VAHitUJH AHNKHTOH I'HOmiCTR ftf Mirrial nant A Mnnt ll Mjakr* lining lann-n) |hmIhI lug 1 it|m* ..................... Avlwnfo* cloUi 1 iHHirirulNl urmh` yarn ............ ................ ............ *0 7S ijnh'i hi'iiit yam anti ilntli IiId'hIim r<>|N' aittl alrfc . ... ........... Ml 1M V mtii ami rlolli, Ifinh-rarlM'r* ............ .. Alnlti> i-s'ini'ijlA .............. Minkr IJnlng (nmlitrfl) _ . .......... ------- __ ii*wr - - ................ -Vo niMgiK-ala Irmtlal kitt ............ A'Ih'I<><i *Mit*lrr himI liiMilwf r INpiupIN-a imtn InfiarmnlIon pm|>I0--1 tip tlu> ini rnt f.n tun1, w. flam ll "U 7D% flu - ['fruit ll Sj 1 no 7V I Ml nw w MV ir, Mixing--Weiglicd ijuanhiies of ast>es|os stud cotton, and usually x.mie on.ifj amounts of card waste, are rlninped in alternate layers m a pdr mi the llimr of the mixing room directly in front of the mixing picker. The haltli is shoveled into the picker, which is equipped with revolving healers. In order to secure thorough mix ing, the hatch is run through tin* same picker twice, or through 1 wo pickers arranged in series. The mixture is removed by suction to the storage bins to awail carding. Carding--Carding is necessary to remove the remaining small Inis of rock, and to comh I lie hirers into a more or less parallel con dition so that (hey may be spun. A card is a machine ivilli a series ol revolving cylinders covered with strips of leather, wound di agonally, and fitted with fine, close-M'l, sharp steel bristles- A card ing- unit, as used in asbestos plants, usually consists of two cards, I lie breaker and the finisher. The mixture of asbestos and cotton G I 1 f \ \ z oo Cl r' / ** . J J* 4 '1* ., !1T rr. .,1. ri-vt<> 1'iW -itvri^v H>i It v .Hf f pv*> X.inU mto llie feed hopper 11i the bn'ii k vr card. It is passed over the rc- vobing cylinders of the breaker card, emerging in tile form of a loosi' blanket or web. The direction of flow is then changed through ninety degrees. It next passes over a camel-hack into the finisher card. The fiber is stripped from the last cylinder of the finisher onto a moving leather apron where a set of reciprocating scrapers or rubbers condenses it into loose rovings or "slivers" of nnspi n yarn. These rovings are wound on long Jack spools to he taken to the spinning department. fhe rovings at the extreme ends of the cards cannot he used for spinning purposes because of their lack of uniform thickness. These are gathered up as card waste, and. together with waste from sub sequent operations, returned to the preparing room where the waste is shredded and added to later hatches. Some cards are designed so that a fine cotton thread mav be in corporated into the rovings as they arc doffed from the cartl. This practice yields a stronger roving. In the manufacture of asbestos rope and wick, only one card is used. The rope and wick rovings, which are not subsequently spun, arc thicker than yarn rovings. TIence, one carding operation is suf ficient. Generally a fiber of shorter staple than that used in textile manufacture, is used for making rope and wick. Spinning--The nnspiin rovings, as they arc doffed from the cards, nccrssarilv have no twist and therefore little tensile strength. It is necessary to twist or spin these rovings to impart the desired strength. This spinning may be done either on ring spinnimr frames or on a machine called a nude. In the plants included in this study all the spinning was done by the latter method. Several of the plants had spinning frames, hut thrv were not in operation. The mules had from two hundred and sixtv to possibly five hun dred and fiftv spindles mounted in a straight line on a carriage which is made to move forward and hack ward. The Jack spools from the cards are mounted on the mule and thr ends of the rovings fastened to the spindles. As the spindles recede from the Jack spools fa maximum distance of about fifty-four inches) the rovings arc unwound. The spindles turn slowly- as llu-v recede, to give a slight twist to the rovings. When the spindles have reached the point of greatest rcression they are turned very rapidlv, and the yarn spun. When sufficient twisting has been done, the spindle carriage moves hack a-ain in the direct ion of the Jack spools, caus ing the spun yarn fabout fiftv-four inches) to he wound on the spindles. The operation is thru repeated until the spindles are fullv wound with single-ply yarn. The duties of the mule sninner are to remove the spindles from the mule when tlicv are filled, and to tie the broken ends of the unspun rovings as the spindles recede. This last operation require* constant vigitenre, because the rovings arc continually breaking. Subsequent Operations--The spindlrs from the mules are next transferred to a spooling or winding machine to rewind the singleply yarn on other types of spools. This is simply a mechanical transfer of the yarn. 7 : : ln1; . j t' , t t i' 1I - y: *1. r . i' ' 9* . rv-j Ol o . ft-.' :* -*;1. - 7i* ' Y'1 . t\. ;i *" 1 `J .' 1 ilnM' "-ihhiU arc ticxl I: ki'li In a twisting machine where two nr iliii'i- nf the single |>lv threads art' twisted into one thread. For tin matin fa el me >( brake lining or packing the yarn may lie rrinlnnut with a fine tiK'lallie wire. Tills addition is performed dur ing 1 lie twisting operalmil. The twisted yarn is finally wound on ta|ir* spouts ahniil six inches long. The luislrd yarn mav he sold as such to other manufacturers, or 11 mav he woven into chilli, tape, nr brake lining, nr braided in the same plant. Weaving--Weaving is dune on looms in a similar manner to the nietlinil employed in wealing wool, rotton or silk. In thr weaving nl asbestos tape intended for electrical insulation, single-ply yarn with a eery low cot Inn euntenl is used. Most tape looms are con structed so that as many as twelve pieces may be woven at thr same lime. It is the usual practice in weaving asbestos lapr to ivet llie linhliins nr "cops" with water before weaving. The warp is kept drv. ( loth is wmeii in much the same way as iusnlalimr tape. Two ol- Ihtee ply yarn is used. Sometimes the varn is reinforced with metal lie wires, generally brass or copper. ICither or both the warp and fill are dry or moistened with water, depending on the use for wliieli the cloth is intended. Itiake lining is woven on looms in the same manner as tape. As many as eight pirres may be woven on one loom at the same time. It mav be woven dry or wet, nr with the warp impregnated with a 'dope" solution. This solution is generally a suspension of gilsnnitr in ea -oline to which other ingredients may be added. Final operations in I lie maun far! lire of woven textiles consist of i aleiuleriiig. inspecting ami winding of the products. These operalions rue all mechanical ones, and require no description. I'artici.k Size Determination Cooke and Hill (22), in autopsies of asbestos workers, have found particles in the lungs measuring up to three hundred and sixty microns in length. Accordingly, in the determination of the average particle size of asbestos dust, all filters, irrespective of length, were measured. Methods of Particle Size Determination--Within recent years three general methods have heen used for measuring the size of particles. One method, a direct one, involves the use of the filar micrometer inserted in a microscope tube, measurements bring made by moving the micrometer adjustment and reading the vernier to determine the diameter of the particles. The second method, an indirect one, was introduced by Green (55) to determine the size of paint and rubber pigments. It lias since been applied to the measurement of the average size of in dustrial dusts. In this method, an indirret one, photomicrographs uf the sample are made on lantern slides, which arc then projected by a stercoptican on a screen at a known magnification. The images are measured and the average size calculated from these readings. With the third method, the dust is collected on a microscope slide, and the images projected on a ground-glass screen with a micro-projection apparatus, and measurements made. This latter method is the one used in the present study, and will be described more Tully in a later paragraph. Nature of Asbestos Dust--The dust encountered in asbestos fab ricating plants is non-uniform in nature. It is sren to consist of three types: particles more or less spherical in shape; elongated fibers; and cotton fibers. Figure I is a photomicrograph of dust pru- I:: if* * *, / cn C") Gasket Making--One nl the important uses of asbestos chilli is in the manufacture of ring gaskets. In this process, the asbestos i loth is spread on the floor and impregnated with a solution of rub ber m gasoline, In wliieli lias been added barvtes and other pig ments. The rubber-treated asbestos cloth is cut into strips of nrcdclrrmined sire, ami the gaskets formed by hand. They are then coaled with soapstone, calendered and packed for shipment. An iiirxponsiir gasket and packing is made by twisting thick rovings into asbestos wick and rope. Still other typos of packings are made by braiding asbestos yarn on specially designed machines. t. cn cn o- OmuR Pkocbsses Other products containing asbestos are made in some of the plants included in this suriey. These products include asbestos paper, in sulation for steam pipes, aslieslns cements, shingles, lumber, molded brake lining, and cold molded asbestos articles, generally electrical til lings and household appliances. The fiber used for these purposes is of short staple. Thr percentages of asln'stos used ill these ar ticles is indicated in Table II. fT 8 ii o ':? V I tr- ' (> vk r.-J.-'it,Ck -..yVi,-'. . .* -s. - v. ..'i; . > -. >'. L *;1 Tv *; ,J I.' Inn'll u In n pu.vis-mil; mill filter. The three types can be readily I'ntnl lln:ni.i' nf the unit iinifiii'inilv i>f Ibis type rtf diml, average pnrIn li' `i/c iv.i'- ifHi'i mint il in Inn di men suns, one at riglil angles In llic utlii i. Mr.-i-iitt imulx were mailt* of tin* bulges! diameters, "huh imi' termed l.utgil iiitiiial diameters, anti a sen mil set nf nir.'iMtirim'iili were made al .right ancles tn the first, which were ii rineil transverse diameters. M cl hod of Collection--Samples for the determination nf particle -i/e wi re cnlleeted b> the me nf the electrie preeipitalnr (.10). This niethii'l yielded samples that were satisfactory for direct microprnji'i limi and measurement. No intermediate steps fur preparing 1 In* sample were necessary. The pteeipitatnr employed was de.sicned on the (irineiple of the < 'nt Iri II precipilatnr. The air was drawn tlirnuch tlie precipitatinc iiihe hv a small rotary Ian driven by a motor, the rale of flmv brine measured by a flowmeter. The rate of sampling was one cubic foot f2.S .1 litns) per mimilr. The precipitatinc tube was made of Pyrex class with an inside diameter of 2.4 cm. A number I microscope cover slip, 22 by 70 mm. in sire was placed in the precipitatinc tube dircitlv hi'iieath lfie central efretrode. The dust in the air was deposited rlcrlrirallv on this cover slip. When a representative imple bad been precipitated, the cover glass was removed and finMinleil dry on a microscope slide. A total of sixteen samples was I'ollei ted at various operations, all brine taken in the breadline zone of the workers. Measurement--A miero projection apparatus with the microscope ai rump'll in a horizontal position was used. Apochromntic objrc- liirs, K nun. and 2 nun., and a 10 x compensntine eyepiece were einplilyrd. This sysiriu prnrtiralfy eliminated color frinecs, cave a that field, furnisbed maximum tight intensity, and permitted the iiieasineiiieiit of the lone fillers. The imnecs were prnjrrlcd on a ground-class screen at a pre determined distance from the mirrosenpe. This screen was ruled m centiim'ler sfptarrs to faeilitale measuring. A transparent rule :is used, and the sire of (be projected images recorded in millirneti'js Accurate focusing on each individual particle before meas uring was ai'i'omplisbnl In a reniofe roiitrol attached to the fine .idjtisiuirji! of tin" microscope bv a utrebanieaf sleeve. I'n di tenuim d magnifications of 2000 and 10,000 were used, deIii- idi ii; on tin objective Measurements were made according to ihr ...... suggested bv II. f,, tireen (5fi). Using the R mm. ob- (ei live I iiiaguihealiou 300(11 the longest diameters of two hundred liai Miles were measured, all lengths less than ten millimeters (five mieroust heiue ncctccled The number of fields examined was also teeorded An equal nunilicr of particles was measured using the 2 mm. objective (magnification 10,000), and all particles fifty milli meters ffive microns) and over were disregarded. Again the num ber of fields examined was recorded. These measurements were O-- used to eaten laic the average longitudinal diamefer of the sample. The method of calculation is shown in Table ITT. For tbr calcula tion of Mir average transverse diameter the same procedure was 10 r followed, with measurements being made at right angles to the longest diameters. iahi.k Ill tXAMri.i nr Million vser. is tiii: I'Ar.cci.ATiox or ------- --: AVt.NAOK I.OXt-l-l-T--lflllNAI,-I.-IA- MKTI-H--- - ------ -- . .-T=r- MttinlAmlton--Sflo (38 P1c*l 10,400 IIS rtctll -" f (1 It ft U mm. tt i IlM 2! Z po r" 19 i. it Oft ts IS n 7.0 is 1-5 ifl 0 0 IT 3 C 10 0.0 at 10.0 i\ 14.5 tt 11.4 ts 11.6 u rto is Tt.E n 11.5 n HO to 14 6 no 16 0 ii 16.0 36 17.S *0 13 4 37 13 6 3* 10.4 311 III 4ft SB 4 it 31.ft 41 tt.K 4fi tt.5 47 11.6 lift ff.ft Co tt 6 00 .10 ft ra 37.6 OR 1S.5 01 SIB TO J.4 73 M S T ST 6 W 4ft 0 3ff1i! 44;7 s5 ion 64.4 no 5Ti.4 iso fill ft nnoo 06,n 7ft.6 Iftft .o 170 tR 4 ("6 37.6 m flft .# ttn Iftft,n nn lOB.ft i IlS.ft ufaor. It*.# 11S.I 130.4 37ft 136 ft Titta) SI 0.00316 T .tXtOR a .00045 4 is JIM .39730 1 1 08316 .403 |B 1.43076 I.S&Ttt 4.34341 4.01310 1.0*360 0.10630 4.2*173 4S o.a i 4.4 37 IT 6 06 m 3 0 41 T 0.1 t 00 40 4.W 14 1 1M.1"l 6!.41 40..134* 4.90 tt 0 1 3 .106SO ,RIB ..0030001(66 t1..3mH3mSO OMm 1.00306 t 1 .OGGOft .00316 0O.7..4*1I72H460 13 .63040 0 BrflftO 1 .09016 0-44761 IO 1.0 to 1 90 ir l.t [ 4 J3 1.1 1 4l.J3*1 16 10 n 1! :to 1.5 11 1 n 1 11 MS 16 1.4 1 7 1 .*6 14.44 4tan 1I.0M t .41116 0.46410 n 1 ' 4 I4.*4 1 .fttlli 0 4Rf*17 3 1 .3(1610 .03116 1 3?M> 0 6-4040 .mss 5-S1II1 440ii 44.60 ____ _. 1 ll t 1 4.00 1 4.50 --------- ? 161.06 1 1 .03115 .08116 fot. mnmil?tu* _ -- f .wen l.ffiWT# llllll IjitRlh t*f litar Ni inl1llii^t#r4 l:ti ..4W30i0to6 fIt.I3mTJmC H - NrnirUi *>1 In mlrron*. 11 1 .4nis ..0o0n0s4t6f 0ft.7ft1ftnftitc t.tilra - i'rlupnfT 1 4 6 P1 5 .on* is .i.isno .10676 unto ..H00U3T1S6 0 T70K1 S4..6SAIAKI3ft 0 ffiflPW 1.0*423 6,3I*(13 HI I Ii ^ (11 i fil*Z {I* Hi Arrrftrr Pl*mr4cr Zilio > -- ------ Zf Sit 1 .03116 1.unci a .1WMJ 0.OCI6O *1 ; oeais .OfSThlO .onao 1t.ltOwftSTti 1 osw - 1..T1 mlrfftn*. 1t1 .OHIO .onto I.*1376 1.35764 4 .IKbO T.suno 1 .mus l.Wina 1 I n .OOlttft .0WMS 04 aiftnn 04104) l.ptrtio 1 t t .03316 .01316 UCUI6 1.61776 l.fHOfi! 1.97064 1j .00316 .01315 51..1W.1 TMMO) 1 3l l .48115 ..0008014156 .08316 3.3123& 11.33400 4.3WJ7 6.14*75 i .08116 4.1312A rm ft WC6 174.11401 Results--Particle size determinations were made on samples of the dust collected at various stages in the process of manufacture fT"l but no appreciable variation was found. However, there was a marked difference in the average particle diameter of the dust frefm " tin two general grades of asbestos fiber. The calculated longi- 11 r"i tudinal diameter or (lie dust from crude fiber was found to be 2.12 microns, while that of mill fiber was 1.35 microns. Transverse diameters were 0.69 microns and 0.45 microns lor crude and mill Hirer respectively. The longest fiber observed measured four hun dred and two microns. The percentage frequencies of the various-sized particles were determined for longitudinal and transverse dimensions. Figure 2 shows these values (dotted on llazen's logarithmic probability paper. The difference in the two types of dust is further shown by ex amination of Table IV. Three per cent of the crude fiber dust was ten microns or more in length, while only 1.7% of the mill fiber dust occurred within these limits. Twenty per cent of the mill fiber dust was 0.5 microns or less in length, while only 16% of the crude fiber dust fell within this range. taiilk iv. Mize rargoRitt-v distribution or asbestos dost flip* Oro*ip In Mtrroni Onk Jlbn I^MirlimUnal Tranavrra* i'litVr *. ......................................... 0Gdj.ee ............................................... 1.0-1. ............................................... im. ............................................... t.DMB .. ........................................ I S ! W ............................................. ............................................... i.M.n .............................................. 4 0-4.40 ............................................... 15-1. ............................................... ft o and om ...................................... st m% tr.4 t.i a.f u t? u i t.r 1.3 t 4.9 J9.9 J.l .... " - .... Hill Hbtt 49.9% U.l 1.0 4.9 4.0 t.4 l-T 1.9 1.0 It 3.9 TraWTrm n.*% r 19.1 > .... -- --- --i.T Dust Concentrations in the Plants All samples were collected by the modified form of the GreenburgSmith impinger (58) using ninety-five per cent U. S. P. ethyl alco hol as the collecting medium. Dust counts were made according to the method described in Part I of this report (41). All particles were counted regardless of size. Particles less than ten microns in greatest diameter averaged approximately ninety-seven per cent of the total. The dust counts for the different operations are shown in Table V. 13 The retativr degree of dustiness in tlie various departments of the four asbestos fabricating plants surveyed is indicated in Table VI. Tliis summary of the average concentrations from the different plants has been prepared from the data contained in Table V. ' ' taiu.k vi iiKi.vnvr mist concentrations in to'Faiitmfnth or ARIOSTOS FI .A NTS iJtiMrriiwiit i Numltcr MampJra Crnicentradod-MDCrma of l'arttrk* frr C'tikle Foot of Air Minimum Matlmum Aterar* rrrpftrfltlfm *ml Van ling ............................................ rw Q4 ISM u.st Weaving nnl Uute Hptantng .................... ....... 41 19 , H.ai T*Mfng, Wlmllng, Rope a*nf Wick, Tiralillng. linakrl. He..................... ............................................. . W M NOTE: THIS DOCUMENT DID NOTCOME FROMPPGFILES It wilt be seen that the highest dust concentration occurs in the preparing room, where the asbestos receives its preliminary treat ment. The lowest concentration is associated with the making of ring gaskets. The figures given in Table VI, while showing the relative dustiness, do not explain fully the conditions in each de partment. The concentration of the dust in the successive phases of the process varies, depending on the type of fiber used and the method of manufacture. In order to explain these variations, it is ueecssary to discuss separately, conditions encountered in the sev eral operations. The figures given in the following paragraphs rep resent the concentration of dust in millions of particles per ctdtie foot of air. Preparation--The dust in the preparing rooms is practically all due to pure asbestos, no cotton having yet been added. The de gree of dustiness depends primarily on the type of fiber used. Thus, it was found in plant II that when milt filter was fed into the SacnI.owell opener, the average count was 119.4, as compared to a conrrnlration of 3,1.2 when the longer-staple crude fiber was treated in rxactlv the same way. In plant D one of the operations involved the screening of shortlength mill fiber without first passing it through a Saco-Lowell opener. The employe engaged in feeding the material onto the screen was found to he exposed to a concentration of 65.7. A sec ond workman, whose duty was to fill burlap hags witli the screened filler after it had been removed from the shaker by suction, was ex posed to a concentration of 96.1. In the mixing room, where the cotton and asbestos arc blended, the degree of dustiness was again found to depend primarily on the type of fiber used. For example, the concentration of dust was 10.6 when a mixture of cotton and mill fiber was being fed into the mixing picker. The concentration dropped to 3.t when the mixture 15 h.is iii.xtr from mult- Nn. t liber. In plant D, when I In* lowest grade mil was led mill the pitki-i, (In' concentration was 84.7. Carding--Tile maihcd dillrmrce in tin* total dust count in llic cm dun* operation as tin1 result of using ilitTercnt grades of asbestos icdl again lie seen. When llic crude fiber mixture is being carded lor I lie inaimlaetiirr of electrical insulating tape, a concentration of i I uas noted. The mixture lor cheaper grades of yarn, such as that used for weaving brake tilling, is generally made from mill lilier. The concentrations of the dust when mill fiber was being carded were 23.4, 24..1. 20K, and HO.O. The samples were collected in card rooms of various plants. (iccasionally the loose neb of asbestos and cotton, as it emerges iiom I be breaker card and passes over the camel-back, becomes broken. It is (hen the duty of the operator to go to the rear of the card and repair the broken web, the task requiring approxi mately one-half hour per day. It was found in one plant that the rniplnyrr was exposed to a concentration of 57,5 during this time, nlide during the remainder of the day lie was exposed to a con cent ration of 24..1. At intervals it is necessary to shut down the card and clean or "strip" the rolls. This is done by scraping them with a hand-card, nlucli is a brush covered with strips of card cloth. The cylinders are slouly turned by band at the same time. The dust concentra tion during this operation was 5.5. Sometimes the rolls arc cleaned while they arc bring turned at the customary carding speed. The eiiiployes staled that this was a very dusty operation, but it was impossible to obtain samples during this procedure. Weaving--The eoiicenlralion o( dust in weaving is dependent on many factors, but principally il]mn I lie following: (II quality of the arp and fill being used; (2) whether weaving is done dry or wet; f.l) conditions of ventilation; and (4) nature of the finished product. The inlliicnre of the first factor is shown in the weaving of in sulating tape and brake lining in plant C. A concentration of fi.ff uas associated with the weaving of tape (made from crude liber). In llie wraving of brake lining made from mill fiber, tile count was 27.1. In both of these operations the warp was dry and the fill wet. As pointed out in the description of the weaving process (page 8), weaving may be done either with the yarn dry or moistened with miter The presence of moisture materially decreases the enneeulralum of the dust, por example, in the wet weaving of brake lining (lie concentration is (i.|, but when it is woven dry the count increases to 27.0. The effect of ventilation is slimvn in the weaving of cloth in plant l>. In this plant, ordinary electric fans were located just back of the wearers, so that dust generated in the process would be blown away from the worker's breathing zone. When the fans were operating the coneeiilration of dust in dry weaving of cloth forlv niches wide was `>,0. When the fans were turned off, the figure rose to ,1.1.3. I he fourth factor, nature of the finished product, also influences the degree of dustiness. Thus, the average concentration en- IG s I I I " I V V t ;> m -- co O countered in weaving insulating tape was 10.5; that of cloth, 21.3; ami of brake lining, 23.0 The looms in time accumulate a great deal of lint. This is re moved periodically (generalli once a week) by beating the loom with a ilexihlr rubber paddle. Kadi weaver cleans his own loom, the time required being approximately one-hall hour per week. Muring this operation the dust concentration was 74.1. Spinning--The concentration of dust in the mule spinning room depends on the type ol asbestos fiber used in the making of the yarn. A count of 2.1 existed during the spinning of yarn made from crude filler for the weaving of insulating tape. A yarn made from a high grade of mill fiber produced a concentration of 5.5. Tbe dust associated with the spinning of commercial grade yarn, the cheapest grade made, was found to be 13.2. These figures are for the mule spinning in plant II. In plant A the average concentration to which the mute spinners were exposed was 23.0. In this plant all operations from preparing to weaving were carried on in the same room. Consequently, it is impossible to state that this con centration is due to mule spinning alone. Other Operations--The minor mechanical operations necessary in the production of asbestos textiles have relatively smalt concentra tions of dust associated with them. In thd winding operation in plant A this was found to be 80. Again, this number cannot all be ascribed to winding because of the fact that all operations were performed in the same room. In plant B. in the twisting room, a figure of 2.4 was found associated with twisting two-ply yarn. This figure increased to 4.0 when yarn was twisted three-ply. Warping is a mechanical transfer of the twisted yarn to large spools or warp beams for the looms. It gives rise to very little dust, the concentration being 1.0. Host Concentrations in Other Processes In addition to the fabrication of asbestos textiles, one of the plants manufactured other products in which tbe amount of asbestos was considerably less than the amount used in textiles. These products included 85% magnesia insulation, molded brake lining, asbestos cements, shingles, lumber, and tile. One plant made as bestos paper which contains ninety-five per cent of short-staple mill fiber. Determinations of tbe dust concentrations were made at some of these operations. The results are shown in Table VII. Other Potentiai. Hazards This survey was concerned only with the hazard caused by asbes tos dust, but other materials that must be considered as potential hazards were found. These materials arc gasoline and benzol in the gasket and nioldrd brake lining departments, talc dust in the gasket room, and lead compounds in tbe rubber mixing department. In the finishing asbestos lumher and tile, additional potential hazards arc lacquer solvents and sand Irom the grinding and polishing op erations. `f.. if, i \* ' Ji Iv C *< -V  :'4 A m A-s?; ins ( - M.J! * . U\ 3 - 'V ' 'A o vxj''..'{a *v% # > -r .`'Tl' ;lv -mm fV.-V sS ,' - N..1, ,;:, \;V , V<- /'M- M&;1- '.'"1'- .; !: ffj ft:I cr~> ci #11-fe, O' fflst .1 l ttil I All hfrsr t MM f M IM TI*NS <* MINI'KM AXH HW orHtA'J H INH JN AN A^HI.K'I US 1*1.A NT Ctioeen- 1 tnllfiii In II Num- ber; Minimi* of linn Felra J Hample* 1 ir euWe 1 frMlt of Air r MkJl iir.-.. IIh -.to llltikrit f'ru*lihi* nPbr'tiH linlll ntnr) ___ t'AKTKlnK Nhriln finHI flint! -............ Nun hi* "nlr 4fl!' jiiji* tnvrrlnff ............ ........ ...... ........ hit nine nHtrntii* Emitter ............ ShillIlfiR bmilvr anti IHr...... . fiiiiiiriiit linMirtniirt fIM _______ ........ iJiralliitf IHi> f.|tlof pcr loDlbt.............. Millnr bnrrrla wlfli niaRin-fflfi ............ hhovrfliif Hnuriir<<1ti rm |ilM ............... tnitiiiiliiR liRffi'M littu tnl*.t*r ......... * NnliiK f>I|H" fimlili ................... !<i'iIIiir lo.aiilnllr>n Im 1 o trjnmifr__ . . -. Ihiiinviiif In* nl utilnr from irlintnrr ............... .... Oushhifl nmt bng*ln* .......... ''Skinnine'' fuflitirh ......... ...................... firliMHin; iM=!iriii`t inpor rtiifcb lirlntt* I'Tfllliiit iMiiitt rbKtli fatlttRi ....................... ... ...... f rc i mi l ( I l:JMEMMl ;l l.ai t ie.n-"j.n t 1.1 ;i2-! \ i at 7 11 i n jmim i; ii i HR.7 IRR a 1 s **i.1f.t: 1 2 via ft s1 an m.i -is.t 1 12 i O <=> tn O o rsi :.o X O -::> -o 1 ~2, rn --$ r-- O 18 rn pi c/5 c-' ASBESTOSIS--PART III.--The Effects ol Exposure to Dust j ,'r'. Encountered in Asbestos Fabricating Plants on the Health oi a Group ol Workers. 1:- J i Complete physical examinations were made of sixty-four persons (48 men, 16 women) employed at the time in the plants listed in f 1'art II of this report. Of this number seven men without previous exposure were used as controls. Selection of the workers was re stricted to those employed in textile manufacture. Those workers longest employed were chosen because the necessity of including n sufficient number from this group is evident. Attention was also paid to the group with exposures of shorter duration and to the particular operation at which the worker was employed. Table VIII shows their age distribution. tadi.k viii. iHSTHtmrrioN nr aok or m l pf.wions rxaHinr.n Oroup Number of rvranna Kiaralnetl Uniter 30 Number Id Ate Qroap SMS Ift-W v todm ' " 'roiitffibi .................... 7 I l Afftatoffln ................. it ....... "Nt'jtallre a IS .- 1'olaJii ........................... n IT 4 H t S-: 1 `V. 7 t) Asbcslosis was found in fourteen persons (12 men, 2 women), t or 25 per cent of tlie exposed group. Forty persons were diagnosed as negative and the remaining three doubtful. Of the latter group, I one individual had previous exposure to silica dust which may have I., been the primary or contributing cause and, as a result, has been eliminated from any further consideration. The cases having as- bestosis were divided into those having slight and moderate pul monary fibrosis, no advanced cases having been found. The esti mation of the degree of involvment depended on the amount and extent of fibrosis seen roentgenologic ally and in the clinical find- ings. The present, past, and family medical, and previous occupational histories were secured from each worker. Direct questions, which might influence the individual's replies in regard to his subjective symptoms, were avoided in obtaining chief complaints. The pre dominating subjective symptoms in the positive group were cough and dyspnea. Other major subjective symptoms were dry throat and frequent colds. One individual in this group had no subjective symptoms. 19 LUj i . < >liii-r!i\r)v, the major w niplmiis were again cough anil dyspnea. Iliitlivij prisons nt I lit <-'i" diagnosed positive fur axhostnsix com- pi.imeil u[ rini^'h, ami eight nf dyspnea. Ollier Irnpienlly elieileil ulijerliw symptom- wco- frequent colds. pnlpnlaliun, weakness, pi ei ui 11 n I pain, ami pliai lineal ill mess. Nn nlijeelive symptoms iiiiil<l lie nlilaineil Iinni mie iml!viilii.il in 1 lie positive group. i leenra vine of acute respiratory infections was partieiilarlv ol>- svi i i'i| in live pasl itieilirnl history Frequent riirvy.il ur other upper or passage iiilritioiis tvliii h ili'l mil result in a loss oT time of three 'r nioir winking days, were listed as objective symptoms. I'neniiiooi.i during the eotirse of employment occurred in three of the positive and seven of the negative group. The past inediea! his tories were otherwise negative escept for ati attack of pleurisy in one imliv idlial of the exposed group diagnosed as negative. ('aunty histories and, in partieular, tnlieretlhnis contacts were imled Two workers with ashestosis had roentgenological evidence of healed tiiherenlosis and negative family histories. Two others who showed evidence of healed tuberculosis, and who did not have ashestosis, also had negative family histories. I'hysirai rxu Inina lions were made with the workers stripped to the waist Mean variations in the present and greatest weight were h ss m the ashestosis group than in the group diagnosed as nega tive and in the controls, hive minute oral temperatures showed a mas.....mi elevation of 0 Vf. Four persons having ashestosis had an etwation of temperature and eleven in the negative group showed it I- Ivvalion of body trinpcratnre in tile control group was absent. I lie miivons membranes o| the nose ami throat of the entire group were essentially negative. The conjunctivac did not appear to he nutated. Tenderness over the antra and frontal sinuses was not loiMiil I lefleetcd nasal septa were common, and diseased tonsils wen- noted in a few eases. The external auditory canals did not -limv evidence of plugging or irritation, I finiral examination of the thorax included inspection, palpation, percussion, and auscultation of (he heart and lungs. A tendency to increased anterior-pnslciioi diameters of the chest in the positive exposed group was noteil. In the (uisitive group the respiratory nmrnmi and vocal resonance were impaired in live cases. Crepitant, wihei rpitaiit. sibilant, and sonorous rales occurred in nine of the ashestosis cases, the two latter types heiug predominant. t'lie recognition of cyanosis presented a difficult problem. When it oveni red the skin had an unhealthy leaden hue, with variations in the degree of intensity in the three individuals in the positive gnmp showing this physical sign. Ixoenigenrilogical examinations, made of all workers, included llooios,npic examination, stereoscopic anterior-posterior and oblique skiagrams of the chest. In addition to noting gross chest pathology, the movement of the diaphragm was measured in centimeters dur ing the lluoroseopiic examination. Fight ami left oblique exposures of the chest aided in the interpretation of the films and particularly in the deirction of thickened pleura. The hila, trunk, and lung niaikings of the tihrolic lungs were increased in prominence. In some Mins the lung fields showed a slight tendency toward beading ami Modulation. A small area in the distal third of the lung in one 20 film suggested atelectasis. Increased aeration, such as one sees in emphy sema, occurred in a few cases. Thirkcned pleura amt ad hesions were noted in a few eases. The average movement of the domes of the diaphragm of the positive group was less Ilian that of the negative exposed or control groups. Three of the positive ami two of the negative group were found with roentgenological evidence of healed tiiherenlosis. Further evidence of pulmonary disease in four of the positive group was clubbing of the fingers. The occurrence of asbestos bodies and the presence of B. tubercu losis were determined in a single specimen of sputum obtained from each person. Each employe was instructed in the proper method of obtaining the sputum specimen, and was requested to collect a morning sample. An equal volume of antiformin was added to each sample. After complete digestion of the mucus, the mixture was centrifuged for three minutes at approximately 2000 r.> p. m. and the supernatant liquid decanted. Distilled water was added to the solid centrifuged portion, and the mixture rcccntrifugcrt for three minutes. A drop of the deposit was transferred to a micro scope slide and examined for the presence of asbestos bodies under both 8 mm. and 4 mm. objectives. S^? 2Zb o rri O* m O OO ASBESTOS BODY. MAGNIFICATION SOO DIAMETERS s o The greater percentage of sputum specimens were of a whitish color, but a few were niuco-punilent. The asbestos bodies were a pale yellowish brown color and varied in size, shape, and number. The largest asbestos body found measured 117 microns in length. The bodies occurred singly, clumped, and as fragments. When present singly or in clumps, they presented a bead-like appearance ZD Zb or a dumb-bell shape, with bulbous ends tapering into a narrow strand at a position midway between the ends. Figure 3 is a photo ; s micrograph of a single asbestos body. In one specimen an average of two or three asbestos bodies or fragments of bodies were seen in Co o 21 r irii biw jii tvn field. tt littr in ollicis. only one or two bodies were i * ii k n * I in i In- i`ii 1111" '>1 mu nut'll Table IX gives the occurrence of 4i"Im'"-ins lmilit -> m a ^im^Ii' <|icnmeu from cach person. Merewethrr l/H reports 11r;iI ibe piesrurc of asbestos bodies caniiol be taken .il ioi m iiI as mdualing anything more than previous exposure lo ;rJ*c1n; dus|. This is in accord with our findings for it will be nolcil ibat llirv wm fouml in a specimen obtained from one of the nmlrnls who at the lime tv a* suffering from an acute bronchitis, proilnel o c of a unieo purulent sputum. I bis worker had been nuplovi il as a packer foreman in the magnesia department for fifty xe.irs His only exposure lo asbestos dust was a rare visit to oilier paris of the plant. nnu iv. in i turn: ok ok ashkkrox norms in HrirvuM NmimIht IVrrniliiif HrmnI i*ii TmIdI 1 tins'll n Nimibrr if I'mxiiii ; Sprrlmiii* I- k.imiI j \,>hi "in* liiulli"* ^rnxiit i Wii^lnk |lwlh* nI^cmI \m sjM , a,join .... . l 11 * r* ' * mu- AkIwa | t'nil- Aft***- ' Mfitn Hu- 1 lri>l Iihji ! Uvp | ln>l | tuMlit | tlei* I'nnlml II \ f t JKin | si n ii.i ,>i.i | o n i " r 'j 1 "i :tr*,7 j ?ir r 1 it n u.i: j vj :i | 711* n i an n j ii* A single spnliim sprrnuen obtained from cadi individual was sfaim d and examined for ibe presence of It. tuberculosis, llotb direct smears ami cenli ifnted anliforminized specimens were found lo be nrgalive. t lanieal examination of the heart showed the apical impulse to be displaced in a few c.vrs. Apical systolic murmurs were beard in lu r id the positive and two of Ibe negative groups. The Idoml pressure was determined with a standard mercury sphygmonnitouielcr. II v pcriciision. although present in a few cases in each {roup, occurred only in ilir older workers. Itocntpenological evi dence of enlargement of the heart was not found. However, the cardiac silhouette in two indivirlunls having asbestosis was found to (ic top normal in size i'.h rtrocardiograms of fifty-six of the workers were made followinir a Hirrtv-mimite rest period during which the subiect was in a miming position, while ei'dil were taken with the subject in a sitIini' position following a short rest period The most consistently iHiMtoc electro cardiot;ra]dire finding in the entire group was tow voltage. It was found to he present in seven of the positive and 22 oo "H --| om ^ r--ci **t*U ~r; 00 O O `O is! ~3 T/ o an cj eighteen tif the negative groups, compared with four of the con trols. Right predominance was not present in the tracings of the control group, but did occur in two tracings of individuals with asbestosis and three of the negative group. Left predominance was most frequently found in the tracings of individuals in the ad vanced age groups. Kata and Slater (62) found eighty-six per cent of individuals with a second positive wave of the Q-R-S complex to have changes in the heart muscle. Our findings show that six of the exposed group had a second positive wave of the Q-R-S com plex; two of these had asbestosis, and four were negative, as com pared with an absence of this finding in the control group. The I'-R interval was increased in the tracings of two exposed per sons found to be negative. A functional test of the individual's response to effort was per formed by having him place one foot on a chair and then raise his body twenty-five times in thirty seconds. The pulse rate was de termined immediately before and after exercise, and again at the end of a two-minute rest period. The respiratory rate was deter mined immediately before and two minutes after the exercise test. Table X gives the results of the functional test. Greater variations were seen in the rate of respiration following exercise in the ex posed group as compared with the controls than were seen in the pulse rate. Individuals with a pulse rate of 10 above the normal resting rate, two minutes after exercise, were considered abnormal. * V. fk TA11I.K X. rUNCTIMNAI. TKKT Of HKNPONAR TO JCPPORT Group Pub*1 BeipFrattoa * Number Peremlate Number Ferreal if CONTROLS Male ............................................................. - t .# XKGAT1VS 1 ta 11 *4.3 Female .................. ................................. . 1 14.) 4 in a ahbkstosih 1 i-l a N* i pulw rat* 19 tboti normal mttnj rat* two minute* after ;****_. 1 Hrnplratorr rat* t aboie norm*! rotln* rate two minute* after caeretM. Asbestos warts are thought to be produced by a fiber of asbestos which has become lodged in the skin, largely through the irritation and overgrowth of the horny and ntalphtghian strata (27). These! growths arc usually found on the hands but may also develop on the feet. Forty per cent of the exposed group had one or more of J these papillomas on their hands* rpr-e jnrT-'V' r,,j yn wyf 23 r'i :i4 Jl< , f T - n'-' , v. '= :% l ^ .,;V. ,[h'iW- iV vr Vi !Ki` -,,~sr\ , /;<ii ;ai^:. \&!.y ;?a * * *t 'VJK,A -,!H T \,. j r'.:, 'H,< V.' r- f`l1t-1;; &|SfcVJ 1- vSvj.:;`,; i i } rf x`J ??;' r sir Y'> -jj .JV': 'f ' ' 4r .V `'" r ',\f 1 .- ' i jriV- ';j.n;,"'V":.` /t . ,- v;:;;,'ri. {-^ii; -;' "> w- St mii *. , - r \ .-i',^ 1 j yfc .i . Li -* V ' '.'' : '/?- t -- i ,~,;V'i ..k, i t ,;.v.>t Yl- * to * ,i : .' ^ I to {&*.- : it; I I YiY - is *M CD CD Lr ; - '"'^vkA ('-iHiiii- irj-ia i ami uiHiiih m*< writ- iiiinlr mi rail) mchvul- u il . ............. . il;imii>glitlim :r- dclcnnmcd by 1 hr liailrn ami ll.ni'M i <Imiiiih Ii ic rucltiml am) c\pnkssi'd as grains of hnernu- gbiliin |m i HMJ ir t.f MihhI Smears fur ililfcrLMlbl cminls were ^i.iMinl iviili \\ iiKIi|\ slain amt cells slurlied niiiTisti>picall)' .i 2 min mil imm^rsi..n oh|rcltve. I 'radically Jim change was hi llie IiIihmI j>icinve ( the three groups. Comparable .um^' i.inatnms etui not uour ill either the erythrocyte tir lencti- \i v K'linl In I wo imli\iiluals with iiKKlerately ailvancnl pul- imniarv hlmisis, the total leucocytr counts were 10,800 and 11,400 with n<i irx|miidiii^ increases in the percentages of polymorpho nuclear li ima`)*les. Changes in the percentages of other types of while cells were not observed. linin' specimens were collected from each worker at the lime of physical examination. Specific gravity, albumin content, and the prcM'riee of sugar were determined and a microscopic examination nude nf a centrifuged portion. Urinalyses were essentially negative esccpl fur a trace of albumin in four of the positive and thirteen of I lie negative exposed groups, as compared with two of the controls. A brief summary of the clinical findings of Hflp asbestos mill workers and the accompany jug illustrations (KiguVes 4 to 7 iuc.) ,ue presenled to show llie two stages of ashestosis ^encountered in I Ins study. ^ l ast' imiulirr A-H7.HI While malt; agnl .U) years. t'liid Mwii|iliiiitt<i Giugli. OttiM*vc symplnms- l )\ v *mfomtnl htadathc (2) F.pialasia Tare |5) t)ry inluroctuilive eolith {A) t'iniRliin|f aiUeks jHeci|jiUttd by strenuous exeri ise. Pa*,* Medical fthlury- Usual iliilfllnHid diseases. Traumatic orchitis. I9.M. (hciiprthniial History--Ihgau working at 16 years of age. Milkman, 2 years. Mole spiiimr, word'll mill, 2 years. Jcc man, I year. Mule spinner, asIm >ims fahricaiiug pl.mf, V years. Physfoil r.xanmiatiii~ Antcimitly healthy adult male. Height 62 inches. Weight 122 ihiuixH IgrrahAl weighl 122 pounds). Skin clear. No cyanosis. Ad* Uus warls on ImiIH Ivands. Pulse rale before, iiunicdialcly after, and I''........ after exercise, K4, IlHJ, 72. Kcspiralimt rate immediately be- hrc ami two inimlies aflcr exercise, 20, 22 Chest, normal slta|ie; per msMon normal; brealh a*>d voice snuuds ixirnial; sibilant and sonorous rales Imlh liases. Head, apical impulse, $lh inlerspare mid-clavicular line; no murmurs. HUnkI pressure 154/9(1. Huniirsiojiy--Diapliragmatic movement, right dome, 2.5 cm.; left dome, 1,5 cm. X-Kay 'I hnradc cage is negative. The trachea is in the midline. The cardiac sillHiuelle is within normal limits of sice. The arch of the aorta ia not WHjrned. The domes of tin* diaphragm are somewhat irregular on the left Mile lint fairly irregular on Hie right. The pleura appears to be slightly ihkkeocd on the left side, and is more dearly shown in the oblique view. In the right apex there is imssihly an old heak-d tuberculous process giving llie a|pearaiirr of an a|ijra1 cap. The liita are increased in prominence. The trunk markings amt linear markings are increased in prominence. 24 T r-*"' +r Mwx^y 7B-W X1 n*1 4 1 i: - i # v:;v';v v. iI v., i-i .1 * W1 Cf; y:;i *\` i yi ^ . W\- ^V\ f 'J ;..1 \ v- .'v*/r" tr,';V 1 r':' r - Vi V J IV If;Vj Vi-' Iv&; Isifej .iisl-4$ i o i VA-jM 5s -; cn t !'l pMi on Hi' twi anlii.giaui * .itill h m!v 72 I' l< niuri:il 0 Ifi sixowl Voltage 4 mm. I *l,i)Mi'sl` '\vln siri--isi i .tn fs) imilH-f 447 W hili rn.di ; agi<l 47 vcar>. 1 hi* I 1 isttipl.ilnl s. { .mu11; 4*| SlKirliicss of hnulh I'.i'-J MnluaJ History Umi.iI ththlhood ilisc-asi*.. (iitiurrluM, 1922 (KMt|ta|it>tal JIntiiiy Tartm r tinlil 2** years <if ;ige, balmier sled woiks, * wars. balmier gram mill, I war Pr |inr;ition room a*4H"dns mill, 15 war*. ___ rv'_'"-'w"i FIGURE 7. ELECTROCARDIOGRAPHIC TRACING OF CASE NUMBER 447 Hus*,.!* rx.miinalii.ii (.eurral Hindrance (air. Ski dear Height 59 inches* Wch-li! 120 .......... t greatest weight 125 prmuU). No dnhhing of fingers. No aslirstos warts. Nail I wife not cyanotic. Chest,. normat shajtc; per- unsiiin iioriii.il: respirator* murmur within nortrial limits; vocal resonance unaltered; sibilant ami ..... . rales. Heart, no apparent enlargement; *k murmurs. I*u1*e rale 1nforet immediately after, ami two minutes after 26 fumtional exercise lest, 76, IIH, 76. Inspiration rate before and two min utes after functional exercise test, 14, 18. Ilkmd pressure 134/90. KUmroseopy--Diaphragmatic excursion; right dome, 1.7 cm.; left dome, 2.5 cm. X-Hay --The thoracic cage is negative. The trachea is in the mid-tine. The carrliac silhouette is within normal limits. The chimes of the diaphragm arc regular. Tin* laifa and trunk markings arc increased m prominence. The lung markings are also increased in |mnti nence. Electrocardiogram--Carrliac rate 00. P-R interval 0.16 second, Voltage 3,5 mm. l.ow voltage of all O'K-S cuRiplcxes. Diagnosis--Asbeslosis, moderate. TAHLK XJ. IfKTIMvNrj? XNir r>KrtRKK or ASRJvHTOHIH WITH BKl.ATfOK TO OVbTJPATIQN, MIST rONCRNTHATION, AN|> rgARfl Or KIPOSURK OmijiaHixi Aonxr Owmtiv (ration Million* o( ptrlle'c* Tran pet ruble of Tid at Number fool Kxporurr ExnmliKd atlfht KoiWMf Advanm! fumtrtful ii r . t. -> ! *1 v-r - -1 Tlie r>rincii.iiF factors no'v tlnm^Mt In ilclfnninf incidence amL ii) Hi f nnFiiiimnoffiniosfs nrc nalnrc and ctm centra I ion of *^he<liisl. Irngth of rxpnsnrf. find imlivi.l.ial suscepliltility. Tlic in-" 27 "`,!1 \ AW' .i: q W71 :i V`:  nirurr iff asbestos^ ilh rein (inn to occupation, cmu'cntralion of ilit* -Iti-l. ,ind Irngih of cvpnmirr in the fifty-six persons examined in I lib. slmlv is imlit.i led im Table XI. Obviously the exammntirm of vim !+ .1 relatively small gniug prevents the formation of drl'mitc convluvions as to the mllm'in r of these {actors. Nor is it possible from oin Junlmgs to establish tiro iiiaximuin safe concentration of asbes tos il'isj in the air. Mon ever, the results of this investigation show (lie mressitv of a mine*ion of the dust concentrations in (hose opera I ions, show n in Part fl of this study, where there is continuous exposure In high mm enl rations. Summary fl) 'the concentration of dust in asbestos fabricating plants de pends primarily on the grade of asbestos; mil] fiber gives rise to a big hri concentration I ban crude filler. Operations arranged in dccif`nsmg eoncentmliiin of dust aie preparing, carding, weaving, spin ning, hvisling, winding, and warping. Tbc average pailiefe size of asbestos dust is stated in two diami lers, longitudinal ami transverse. f.U Petrographic analyses of dust encountered in asbestos fabri cating plants collected in the, workers* breathing zone shows it to i onlaiu im free silica. { l >. Fourteen, or 25% of fiflv-six workers employed in the tex tile depai tnients of asbestos fabricating plants in Pennsylvania had bolli tlinkal and roentgenological evidence of nsbestosis. Af'K NOWI.RDGMF.NTS The Department of T.abor and Industry of the Commonwealth of (Vmisvlvania wishes to thank the management am! employes of the plants studied for their cooperation and interest which made lbe success of this siudv possible; Dr. H, K, Faiieoast and Dr. 1C. P. i Viulci grass id the University of Pennsylvania, whose interpreta tions of the films have been used; Dr, G. W. Crier of the University of PiMsbnrgb, for bis interpretation, assistance, and advice in the roenlgeiMitngical study; Dr. J. Evans .Scheeble, Secretary of the I'enitM Kanin Department of Welfare, in extending to the Departmenl of Labor and Industry the facilities of his department; Dr. (* A Lauhach, ronitgenobigisi amt cardiologist of the Norristown Male Hospital, for doing a large majority of tbc X-ray work, and h*s icMiimians for the routine laboratory examinations; Dr. J. 1). t leant and Dr. A. It. Fuller of the University of Pittsburgh, and Dr t . i . Wolferth of the University of Pennsylvania, for their as sistance and interpretation of the cardiograms. flrm.iooRAntY I- Amianlr. Ilyg. du trav., 1:101-192, 1930. 2. Anderson. If. V.. and Clark, G. I,.: Application of X-rays in the Classification of Fibrous Silicate Minerals Commonlv Termed Asbestos. Tmb and Eng. Chem., 211924-933, 1929. 28 `TvW [ ^t** 7r5rjTe/< NOTCOME FROM PPGFILES I O -H m -H : 1 -H o 3. Auribault: Motes sur 1'hypiene et ta sfeurite dcs ouvriers dans les filatures ct tissages d'amiante. Dull, de I'lnsp. dti trav., p. 120-132,. 1906. 4. Itaadcr, E. \V.: Asbcslosc mil WarzenbiIdling. Miinchcn nied. Wclmschr., 79:83, 1932. 5. Hepcr, P. t. r Ucbrr die Asliest os is Korpcrcticu. Vircli. Arch., 290:280-353, 1933. 6. Iti'Ker, P. I.: More on Asbeslosis Bodies. Vircli. Arch., 293: 530-539,1934. Abstr., J. Jnd. Hyp., 17:32, 1935. 7. liefer, P. I.: Injurious Factors in Asbeslosis and Silicosis. Med. Klin., Sept. 14, 1934, p. 1258-1261; 1922-1927. Abstr.. J. Ind. ll>fr, 17:32, 1935. 8. Beintker, E.: Asbestosis. Arcli, f. G civerbepath. u. Gewcrbeliyfr., 2:345-358, 1931. 9. Beintker, E.: Asbestosis Bodies. Vircli. Arch., 293 : 527-529. 1934. Abstr., J. Ind. Hyp., 17:33, 1935. 10. Bowles, Oliver: Asbestos--Domestic and Foreign Deposits. U. S. Bur. Mines Inf. Circ. No. 6790, June, 1934. 11. Bridge, J. C.: Asbestosis. In: Ann. Rep. of the Chief Insp. of Fact, for the Year 1928, p. 95. H. M. Slat. Off., Lon don, 1929. 12. Bromley, J. F., Wood, W. B., Ellman, P.: Pneumonoconiosis --A Discussion- Part I--Silicosis; Part 11--:Pulmonary Asbestosis. Part III--Pulmonary Asbestosis. Brit. f. Radiol., p. 262-295, 1934. Abstr., J. Ind. HyB,, 16:1023. 1934. 13. Buttncr-Wobst, W. and Trillitzsch, C.: Die BerBffachslnBe (asbestosis) und was der dentsebr Arts von ibr wissrn muss. Tuherkulosc, 11:11-14, 1931. 14. Cirkel, Fritz : Chrysotilc Asbestos. Its Occurrence. Exploita tion, Milling and Uses. Mines Branch Bull. 69. Canada Dcp't of Mines, 1910. 15. Clynes: Asbestosis and Silicosis. Brit. Med. J., 1:379, 1931. 16. Cooke. W. E.: Fibrosis of the Lungs due lo Inhalation of Asbestos Dust. Brit. Med. J.. 2:147, 1924. 17. Cooke. W. E.: Asbestosis. Brit. Med. J., 2:1024-1025. 1927. 18. Cooke, W. E.: Pulmonary Asbestosis. Brit. Med. J., 2:585. 1928. 19. Cooke, W. E,: Asbestos Dust and Curious Bodies Found in Pulmonary Asbestosis. Brit. Med. J., 2:578-580. 1929 Abstr., |. Am, Med. Assn., 95:1431, 1930. Abstr., J. Ind. llyjf., 12:34, 1930. 20. Cooke, W. E.: Asbestos Dust and Asbestosis Bodies from Lungs of Asbestos Workers. J. State Med., 39:544-548. 1931. 29 ; ,3 X . p i ,* |!J?* '- ' ; * * J *' ., Vf'i ' M'T I' - .1 H f i '-j IVi '.Stl '>' ! -,4-, V*'^>P-!.'&1. *.1rii'a fIit tI if^'vi*-g.a j iV?. v**5 I CO I ci Li ' ' 121^1loft * 'J! siSK.iS .'l ( in,c. U ). ; Siln.i Anllsrnrn^ts Presenting Curious Undies Similar (< Thnsr in Asbestosis. Itrit. Med. J., 1:656-657. i'Ui. 22. (miUr, \V. I'., and Hill, C. F.: Pm'iimnkoniiisis line In As bestos Dll'.! .1 Roy. Micr. Soc., 47:2,12, 1927. 2,1 l iinkc. \V. F , anil Mill, C F.: Pncliniokimiusis C aused bv Asbestos Itost. I!iit. JVIrd. J., f.fi'tO, 1927, 2-). (nuke, \V. F., Marl lojiald, S,, Oliver T.: .Strange Itoifies Found in Asbestos Workers. Lancet, 2:136-137, 1926. 25. ( nuke. W. F,, amt Mill, C. F.: Further Observations on Pul monary Asbestosis, nidi Special Reference tn Asbestos Mu'-! ami ( niions Bodies found in die lamps. J. liny. Mier. Sue.. 50:15 19, 19,10. 26. Mavis, G. (7, Salmonsrn, F. M,, Earlyxvine, J. I..: Tlie Fncuimninkoninses (Silicosis). Bibliography ami Laws. Irnl. Meilieine Ine., Chicago, 1934. 27. Denirlz, A. I'.: Warts from Mineral Substances. Roussky Vestniek Derm. 1 :243-2-l7, March, 1930. Abstr., J. ind. Hyp.. 13:125, 1931 28. IHicrs, V.: Auiismt' el asticstosc pxdmonnirc. La tiled, tin teav,, 2:147-172; 187-209. 19,10. Abstr., J. Ind. Hyp., 13:49, 1931 20 Mnnurllv, L: Pulmonary Asbcstosis. Am. J. Pub Health 23:1275-1281. 19.1(1. At). Drinker, I'.: Altrrnatinp Current Precipitators fur Sanitary Air Analysis. Ind. Ilyp., 14 :.364-.170, 1932. 31. Drinker. P.: The Size Frcrjncncy ami rdcnti'ficafinn nf Cer tain Pbapney Inscil Dusts. J. hid. Hyp.. 7:305-316, 1925. 32 Ftfeet nf Asbestos Dust nn Wurkcrs' Health in Asbestos Mines and FneOnics, l.abmir Gan., 12:761-762, |9| 1-1912, Ottawa. .1.1 k.lluinu, P.: Report nn Cases of Pufmrmarr Asbcstosis. Proc. Rov. SiK'. Med,, 21:526. 541. 690. 19.10-1931. .14. k.llinan, P : l lies] Diseases in General Practice. London, II. K. f.eivis, 19.12. p. 116. 35. k.llinan, P,: Pnlminiarv Asbestnsis. Lancet, Feb. 4. 19.13 p 252 253. \t 11 . |. Ind. Ilyp.. 15:43, 1933. .ki I'.llniaii, P : ..........nary Asbcstosis: Clinical, Kadiotopical ami Pathological I1'rat tires and Associated Risk of Tultcreulosis Infvvtiitn. (. Ind. Hyp., 15:165-183, 1933. 37. Fabr, T.: Ashes! | mrninokoniosr. Aerial. Vercin. March 3. 1914. Haiuliurp. .18. I'iibr, T.: Aslicstnsis. Klin. Wcbnscltr., 11:1(14, 1932. 39. hril, A.: Asbestnsis in Asbestos Workers: Professional Asfieslnsis. I'resse Med., 39:1931, 1872-1874. 110 .V yi i. : t < *n. t ye >. - ... r ~-.y ---. --- 40. Feuerslaek: Ueber <las Vcrbalten des Fpithels der Lungenalveoleit bei der fibriniisen Pnenmonia. Gottingen, Preisssdirill, 1882. 41. Fulton, W. B., Houtr., R. L.p Dooley, A., Matthews, J. L.: Asbcstosis. Part I--The Collection and Counting of As bestos Dust. Spec. Bull. 37, Pa. Dept. Labor and Indus try, 1934. 42. Gardner, L. U., and Cum tumps, D. E.: Studies on Experi mental Pneumokoniosis: VI. Inhalation of Asbestos Dust; Its IClIect upon Primary Tuberculosis Infection. J. Ind. Jlyg., 13:65-81, 97-114, 1931. 43. Gerbis, H., and Ucko: Ueber Asbcstosis der Lungen. Ver. f. inn. Med. z. Berlin, SiU. v. Dec. 7, 1931. Gerbis, H., and Ucko: Asbestosis of the Lung. Deutsche mcd. Wcbnschr., 58^85, 1932. 45. German Work on Pulmonary Asbestosis. Lancet, 3:92-93, 1932. 46. Gloyne, S. R.: Presence of Asbcstosis Fiber in Lesions 1 Asbestos Workers. Tubercle, 10:404-407, 1929. 47. Gloyne, S. R.: Reaction of Tissues to Asbestos Fiber, with Reference to Pulmonary Asbestosis. Tubercle, 11:151-153, 1930. i: 2! O - -V O --1 rn 48. Gloyne, S. R.: Method of Staining Asbestosis Bodies Found in Sputum of Asbestos Workers, J. Ind. Hyg., 13:85-86, 1931. 49. Gloyne, S. R.: Formation of Asbestosis Bodies. Tubercle, 12:399-401, 1931. T 50. Gloyne, S. R.: Presence of Asbcstosis Bodies in Faeces of Case of Pulmonary Asbcstosis. Tubercle, 12:158-161, 1931. 51. Gloyne, S. R.: Asbestosis Body. Lancet, 1:1351-1355, 1932. ; ; CO 52. Gloyne, S. R.: Infra-red Photomicrographs of Asbestosis Lung. Tubercle, 14:208-209, 1933. ' O 53. Gloyne, S. R.: Morbid Anatomy and Histology of Asbestosis. i^A Tubercle, 14:455-461, 493-497, 550-558, 1933. Abstr., J. Ind. ' " .1 Hyg., 15:127-128, 1933. 54. Gordon, B., Jr.: Asbcstosis. Pennsylvania Med. J., 35:637- 639, 1932. J-tC* *. . . I.TiiiJ 55. Green, Henry: A Photographic Method for the Determina tion of Particle Size of Paint and Rubber Pigments. J. =:> V4* Franklin Inst., 192:637-666, 1921. 56. Green, H. L.: Some Accurate Methods of Determining the t" o Number and Size Frequency of Particles in Dusts. J. Ind. Hyg., 16:29-39, 1934. m -- 57. Iladdow, A. C.: Clinical Aspects of Pulmonary Asbestosis. TSJ O Brit. Med. }., 2:580-581, 1929. 31 t . I i; C7~.) o~i ---j CO ."iH I Inti'll, T.. Warn n. H., Drinker, I'.: Modified Form of the l irccnhnrg 'iiiiiih Impingcr for Field Use, with a Study of its tipetalmg t haracleristics. J. lud. IiyK-, 14:301-311, 10.12. 5'f If.itch, T. .iii.I t'ool, L. I,.: Quantitation of Impingcr Dust Samples I.) fl.uk Field Microscopy, J. I ml. 1 ivjj., 16:177101, 1934. to Ilolt/uiaim. I'.: Du' Kiinvirkung ties Asheslstanbcs. Zculralbl. /. Gcwcrhehyg., 8:225-226. 1031. til. Industrial I tircrloir -- I'M) 1`diliuu. 1'a. Dcp'l of Infernal Affairs, I lurri-dmrg. ti2. Kalz ami Slater: The Second Positive Wave of the O K-S Complex. Areli. lut. Med., 55: No. I, Jan. 1935. 63. Kettle, K. II.: Interstitial Keactiuns Caused by Various Dusts and their Influence on Tuberculous Infections, J. Path, and Pact., 35:395-405, 1932. 64. Knopf, A.: The Quantitative Determination of Quartz ("Free Silica") in Dusts. U. S. Pub. Health Reports, 48:183-190, 1933. o5. Krugrr, I*'., host..ski, O., Saupe, K.: Asbcstosis. Arch. f. (Icwrrbepalli. ti. Gcwerbehyg., 2:558-590, 1931. Abstr., J. I ml. Hyg., 14:144, 1932. tv., Lanza, A. J . McConnell, W. J., Fcbnel, S. \V.: Effects ot tlie 1 uliahilic.il of Asbestos Dust on the I,tings of Asbestos Workers. A Preliminary Study. U. S. Pub. Health Re ports, 50:1-12, 1935. t.7. London Letter: Pneunionocontosis Caused by Asbestos Dust. J. Am. Med. Assn., 89:304, 1927. tvS. I ,o\ isetto, I).: Asbeslusi, In: Studi sulta pncumaconiosi in Italia, 1930, p. 115-132. lstit. Poligr. dello Stato, Rome. (.9. Lynch, K. M. and Smith, W. A.: Ashestosis Undies in Sputum and J.utig. J. Am. Med. Assn., 95:659-661, 1930. 70. Lynch, K. M. and Smith, W. A.: Pulmonary Ashestosis, II. Including a Report of a Pure Case. Am. Rev. Tuberc., 2J:<>43 riDl, 1931. Abstr., J. Ind. Ilyg., 13:241, 1931. 71. AlarDunald, S.: Histology of Pulmonary Ashestosis. Hrit. Med. j., 2:1025-1020, 1927. 72. Merewetber. E. It A.: Occurrence of Pulmonary Fibrosis ami Other Puimonmv Affections in Asbestos Workers. J. Ind. I lyg , 12:198-222, 239-257, 1930. 73. Merewetber, E. R. A.: A Memorandum on Ashestosis. Tubercle 15.69 81, 109-118, 152-159, 1933. 32 V ' ,1 oO d--1 m --j r-T TI *; * :/> ''*5 1 O c. , O "T "P m L. *" r" O m-- lo O 74. Merewetber, E. R. A. and Price, C W.: Report on Effects of Asbestos Dust on the Lungs and Dust Suppression in the Asbestos fmhislrv. Home Off. II. M. Slat. Off. London, 1930. Abstr., J. iml. Ilyg., 12:117, 1930. 75. Mills, R. G.: Ashestosis: Case, Minnesota Med. 13:495-499. 1930. 76. Mussa, G. Note cliniclic c rndiolngichc sulla pneumoenniosi da amianto. In: Studi sulla pneiunonoconiosi in Italia, 1930, p. 133-139. Islit. I'oligr. dello Stato, Rome. 77. Oliver, T.: Pulmonary Asbcstosis in its Clinical Aspects. J. Ind. Hyg., 9:483-485, 1927. 78. Oliver, T.: Asbcstosis in its Clinical Aspects. Brit. Med. J., 2:1026, 1927. Abstr., J. Ind. Hyg., 10:97, 1928. 79. Oliver, T.: Asbcstosis. Brit. Med. J., 2:204, 1929. 80. Oliver, T.: Pulmonary Ashestosis, Abstract. Monthly Lab. Rev. 31:74-76, 1930. 81. Oliver, T.: Putmonary Ashestosis: Socio-Medical Study. Arch. f. Gewerbepatli, u. Gewerbebyg., 1 -.67-76, 1930. 82. Palmieri, V'. M.: Asbcstosis. Riforma med., 46:1207, 1930. 83. Paucoast, H. K. and Pendergrass, E. P.: Pneumoconiosis, A Roentgenological Study. New York, Paul B. Hoebcr, Inc., 1926, p. 155. 84. l'ancoast, 11. K. and Pendergrass, E. P.: Review of Pneumo coniosis--Further Roentgenological and Pathological Stud ies. Am. J. Roentgen, 26:556, 1931. 85. Pancoast, H. 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