Document gD3ydZ5bK4V4ZeGGOXkDQxrrL

Keasiiky it. Mattison Comrov A?4UV.tR. I'CVKiTLVASlA arcs 1943. PLAINTIFF'S EXHIBIT MET-45 "o. 93-1 n. . F. Shepliord, Saq., Turner & Newell Ltd., Scotland, Hochdale. Tar r. Shecherd: Subject Sr. Le. >y U. Garde *3 Asbestos lust "Error acts. Further to this subject, I now havo pleasure in handing you herewith photostat copy of Dr, Gardner's letter of February 24, 1943 to Vr. Vandiver Brown, . and also copy of the "Outline of Proposed idonogratr. on Asbestosis." I have found this outline to be extremely interest ing. It brings out a number of Important new develop ments, but ro feel that reference to the question of cancer susceptibility should be emitted from the report sir.ee It is inconclusive.I I would appreciate receiving any comments which you my havo to mho concerning the enclosed cutline, and also mil fc~'ard you the final report es soon ca received.* "icm sincerely', .'u-w::: a kZ'::s::: c::. ol lew Follow The Saranac Laboratory FOR THE STUDY Of TUBERCULOSIS ' Of TNI tTWAAD L T1U0EAU KX'NDaHOH Sajlahac LaiI, N.Y. feiruary 24, 1343 Xr. Vandiver Broun Johns-Xanville Corporation 2 East 40th Street New Ycra, hew Yor* Dear Mr. Brown: . I have at last succeeded ir. a.naiyzi.nr reside:' cur v'y.l?'1 nra experimental data end assessing the results/! a respire tr.a't'this 6hould have been oor.pleted before this, but the emergency has left ne short-handed lr. the Laboratory and also r.eoessitsted my doing a good deal of extra traveling. I hope that the sponsors of our study of asbestosis will be charitable ar.d realise tr.at tr.e vor has far exceeded its original ecope. Ve have done over 40 different experiments, cany of them divided Into several parto, which involved exposure of animals for 1 to 3 years to various dusts. The buoir.ess cf preparing micro cccpic sections sr.fi chemically analyzing the tissues cr. more than 00 enicals has been a Job in Itself. My time for studying section end analyzing data has been eo limited that ve are behind our ache ule. a have still not had time to write a full report cf this vori which will of necessity be monographic. However, for the benefit c. the contributors, I an submitting a table cf contents ar.d an an notated outline to indicate conclusions ar.d the line of argument th will be developed. The latter Itself occupies Id pages, cut I hop they will find it sufficiently interesting to read. I shall worl c the final manuscript as I have opportunity. There sre a few experiments o should be completed by the time ve are ready methods.of duet determir.aticr., I consider im elude in the study. Tne cuestion of cancer ant t .an I had previously imagi 0A i, a 4- A. cr 1* wm..CA> < ^. Av repeating it from the can it will ta/.e two o three years to complete it would better be emitted from the present become possible to ma/.e tr.is 6tudy, I hope t cf your members to supply me with enough pur for the purpose. pecs which Ahe worh cr. .cugr. 1 11 V seem ' 1 vc I c dn ccjr.t cn ecze sre estestos i 1 Hr. Vandiver 5rovn c I I in Naturally, I shall velccne any criticise tr.nt ycu :r any of the ether contributors would care to offer, thee want to discuss details, 1-would to pleased to Hay I take this opportunity to thank, all the epor.scrs threurr. ycu for the support that v have had. Sincerely yours, LUG::5H Leroy l'. Gardner, H. U. -irectcr (2) ? AP.T II Exp gntffl AsSjfifjnl; 1 Methods (a) Inhalation exposure to cisn! dusts. (b) Injection Ir.to lungs through tracr.ea cf cure minerals (c) Injection of pore minerals Into ot.-.er crgmr.e. 2 Specie9 Susceptibility Han, guinea pigs, rafcmits, cata, vr.lte nice and rats dOZ3 . Pee-.iliar Cfcaraoteristlos of Ao tea toal3 (a) Up.ua ual locallcalor. of c PT yso tile fibre in lunrs. (b) Hare of resultant tissue r eac tion o;:"e rapid t.w.ar. to ouar * (c) He bo tie n to chrysotlle r. ot. or oore.es !> e after exposure c eae ee; again the revere * cr the situation in ecl loosi (d) As be 3 to ala Bodies 1 Composition and methods of formatter.. 11 Occurence Ir. different apeclea. Ill Formation does not parallel development cf fibres lv Gradual disappearance after expoeure ceases. 4 Comparative Effects of Different Aabestlfcrn minerals. (a) Canadian Chrysotlle. (b) Arlcor.a Chrysotlle, low Iron. (c) Crccidollte 1 Bolivian specimen, stiff and elastic. 11 South African, soft and fl-xlc'o. (d) Ar.thcpnylllte (e) Amoslte. y (f) Tremollte. t Effects cf Control Minerals ! ) Orar.r.ular Serpen.!Ir.e, same chemical czz .zs cnrysctlle. (b! Glees Vool, a synthetic silicate f1:re. (c) Bruclte, a fibrous magnesium hydroxide aim e111c a 5 Chemical Composition of As'ceetlfcrm mur.erals 1 (a) Nothing in composition correlated -lor. rel c s c a c 11 y . ( = ) ?re11m 1 nary acid treatment 11 Carccr.lc acid cvr-i::s c? pp.cpcsio m Sarnmc Laboratory Study under Grant A n b e e t c b A ? e c c 1 a 11 c ~ PAr.T I KUV.A.',' ASrISTOSIS 1 Kuaan Pathology - a study of 2 autopay oaeea^ Illustrated 2 X-ray Patterns in Aabestosis, Illuatrated 3 Ash and Mineral Values In Hunan Aabestosis 4 Complications of Asbestoeis (a) Susceptibility to infection 1 Tuberculous ii Hon-Tuberculoua iii Cancer of the lung 5 Disability, causes and comparison with ollicosls 5 Diagnosis (a) History of adequate exponure (b) X-ray film pattern (c) Physical examination. (c) Aabestosis bodies ir. Bputun, their eirr.lficar.oe :K a (3) (c) Effects of Alunlnua 7 Physical Properties in P.elatlon to Irritation (a) Length of fibre (b) Effect of Crushing (o) Haat treatment 6 Nature ar.d Significance of Asbestos!* Body (a) Porratlon b) Protective effeot preventing further irritation o) Ultlaate solubility in tissue 9 Theories of Aotion of Aabestlfcrn Minerals (a) Cheaical - reasons for considering invalid (b) Mechanical - experiaental deaonstratior. cf. 10 Ccrplicatlono (a) Infection, tuberculosis and other varieties (b) Cancer of lung - experiae.otal data suggestive but not proven 11 Disability 12 Essential Peatureo of Hazardous Exposure (a) Nature of duot - fibrous coccor.ent and site factors (b) Ataospherio Concentrations - probably lower than for quart! i Inadequacy of standard iopinger esnpiinr rethod which dees not collect the dangerous f!br;3 ii Electrostatic precipitataraanpling preferable but nethod Dust be nodi fled Duration cf Exposure 12 P.econnendctions for a New Standard of Safe Aluoapr.erlc Ccr cer.traficr.a of Asbestco Dust (a) The Teas 1 -official standard of 4 tc l nlllioa partiol; per cu. ft. (b) VorM upon better neihod of sarpilng (c) Necessity f:r conparieon of results with X-ray flr.dir.. in erplcyees !*i Prevention (a) Chenical rear.a not practical -- (4) 1 Acidosis r.eoessary to dissolve than Aetestosis 11 Aluainua "hcrapy inapplicable ill Chief reliance still upon, dust special ezphasis upon tre fibr lire in lures vers# never.tier, with s cczoonents j > - OJ T Human Pathclcrv and X-rnv Bait?: Based upon 23 human autopsies 2 Ash and Mineral Values in Human 3 Commutation of Asbestosle (a) Susceptibility to Infection 1 Tuberculous- Hlrh lr.clier.ce 1.-. Hr.rlish e.-peri-r.ce r.et duplicated.in surveys cl American Plants. Available autopsy statistics deceiving because of sel ection of materiel. Nor-Tuberculous- The sane reason probably applies sb.ouli be cb.ecs.ei. by analysis cf ab senteeism among asbestco wonders. Cancer of Lung Ditto, but there are r.cv cr. record 10 cases of. lur.g cancer in asbestos verbena. Compared to tr.s total number of autopsies on aefceatoslc, thla Incidence Is e.tcesslv Jo such frequency has been discovered lr. slllccsls .or other forms cf pneumoconio sis er.oept^th.e Schr.eeberr mines cf radio active ores. The evidence la `surreetlve but r.ct conclusive that asbestcels msy creelpltste the development cf cancer in susceptible individuals. 4 Pis? Clin man! deyr e n 6 tUi. r--< y dteatllr.r aateetcsla la .-;eo 2 ccrrecpcr.ilr.r lr. astes:cGis I3 dje zzr.tzry r.esrt dleease. A3 ec.lcr. yr.creo.ees r e 0 j 1. a r. z n sjzz-z?.~ a c or c 1 -1 3 l s c Z v - r y 1 r. ^ c?rl t . e caseD vlzt r.z elrr.: rlean: (2) 3 c f r> d. e c '-i a t ? 5 sure to" 1 V d t t V f_- Q n - 2 A . e ctr.ce r. t r r. 111 r. a r. 1 Co) Ivlder.ce o.' disease `.In a characteristic I'-rcy pattern. V-V1-. (c) A physical uxor ir.st ton which reveals certain characteristic' sirr.s and nay reveal evidences cd disutility id present...- (d) Aa'cestasis bodies la the eoutur. are confirmatory vhen the" previous dactsrs are' all positive. However, the todies nay te absent,' particularly i:. the absence cd trcr.cnltis ir.decticr.. Ashestosvbodles unsupported by other evicence dc r.ct naitt ; .a diagnosis. Cccaslcr.al ones have beer, dcur.i ir. aocut 15 autopsy specimens od persons with no Strewn exposure and r.o fibrosis, probably of . r.on-occucational criri.n. PA.-.? ZZ Ix-cerln r.tsi Asbestosi T y , . V. . J , (a) Inhalation nxcoeures to Plant i>U3.C - Specific fibrosis . in lures, but r.o crar.rea elsewhere.1^. .. ` (b) Infections of- Suspensions of Pure " 1 r.era 1 a into Trachea :- b - Sinliar results. .' (c) Infection cd Suspensions c d P-ur e '.ir.?rsIsinto other orjar.s - Picres dieeclved; no asoestoeia bodies; tissue rescticr. con fined to phyrocytcaia nr.d encapsulation. Compare the asbestos cp rwj cf human. subjects ... ' .. `dV."' ;ec 1 es Susceptibility :.-vi _> ' ' Ur.lih.e dree oilicaacbestea does not produce its epecidic effect in any or-ran od-any species of animal.'. It causes fibrosis only: the lur.ro of mar. Jsr.d t.-.esa of-'a few- of-'the species testei. . 1 b r - s 1 a A cent -s Pod1 a - - - V.1. .' s ! .n ' S'.n-.* yc- 4I Cuir.ea Pir 2 + I*---1' ' r* CaV ' * 'V* ' Knit's hone a ' c 'i' Psbbit -e .-v-rvyd.: ''hita* Hot ' ' c ' o'-'.- (r- t ' -.'-..--n *rc.7 1 r.r Cm ar .ac t *r 1 a 11 ce, cd Aebosocal . ' 0 ' c ,'r.: I,a 0.a li oat ion of fibroua' miner .ais' in lunrs dldd era .... t.. r. cd rrar.ular dust par tides' ; 3- I Fibres like chrysotile having a certain degree of flexibility ar.d elasticity accumulate within tbs finest air tubes; granular dust Is carried further on and is vilely ocattere ' * hrcur.-, the terminal air spaces. (b) Pate of tissue reaction to asteetcs is much more rapid then, to an active dust like quarto. Evidences cf formation appes as soon ss sufficient concentration of fibres hao iooAiloed 'in speoifio areas; with cuartr, there is a later.* :eriod cf months. (c) Reaction to asbestos doea not progress or, cecsation cf expos ure. Young soar tissue that cay have forced, contracts r.d becccee core der.ee cut the area of Involvement decreases in. sloe. In sllicoals, the .young nodules become larger after exposure ceases. (d) , ^'fi T- Asbestosis oodles sre a specific concomitant cf this form of pneumoccr.iosia. They ars due to a deposit cf protein sr.d iron upon the surface of inhaled fibres. In guinea firs they form after about 0 days of contact vith the tissue. They ore sound ant in con and guinea pipe, (See paragraph 2 above) tut much larger lr. the former probably tecauso the larger sited air tube admit larger fibres. In cats,- rabbits and mice, there is an atypical coating of a few of the fibres after much longer resi dence in the lungs; ir. rats and dogs r.o bodies could be dis covered. - Fron paragraph 2 it is apparent that their occurence does not parallel development tf florceis. In lur.r injection experiment;, the bodies have nC developed until afts-r fibrosis Ve-uosJ-l scermced. The number of todies seems tu uccreaas several years after exposure ceases. 1 Cj2r recto of Different Asbeettp*.s Finery!s (a) Canadian '-hr'.'soti 1 - highly irritating. (b) Ariror.a ^hrvsotile (low in iron) equally irritstir.r and crt- duces Just as many asbestcsis bodies as ths Canadian product with over 11 times as much iron. (d) Ar.thoohvllltg - stiff, straight fibres - atypical asteBPcris belies ferns slowly bur r.o local! tailor. cr fibrcsic lr. lur.rs. (e) A-T03!.t - Ditto. (D Arohlbole - Ditto. ' (g) T rercollte Ditto but very few asbestools bodies - Observation being continued. V Control Xlr.gre.l (a) w 7* a. HU i1 o. '- Serpentine of acre cheolcal composition cs cbryootlle la Ir.er causing no fibrosis In lunss or ether errar.s. attraota Iron from the lunga but of ocuraa, r.o `bodies* develop <b) Plage "loo!(a synthetic silicate) fibres are net lnhalabie from alr-borna suspensions, apparently because of their stiffness (the dlaaeter Is not responsible as acne used vere less thas 1 nicrcr. thici) Cn injection Into the lungs, they do not locollos in the air .tubes but are vldely scattered. They cause r.o fibrocls. After 3 or 4 cor.ths ir. contact with lung fluid, a few glass fibres taie up Iron but rerain cnooth. They never show the swollen ends and lateral projections of the true asbestosis bodies. (c) 2: Interest because It la a fibrous rir.eral practically Tree of silica (o.9?). Crystallogrnphioally the arrangenent of Its Me and CH groups in oaoh unit oell 13 sinllar to that In chrysotlie. The Barpla uned also ocr.talr.ed about lev iron-, pro bably fror. contaminating nagr.etlto. The fibres are otiff end needle li'ae. Cbeervdicns not yet oenpieted but after 2 norths lr. the lungs, typi.cal aebestosis bodies develop but there Is se ye t r.o fibrosis . `he fibre are son C tfirci !"lt*.m lr.ste of being, localised inside the terminal air luces and tissue reaction occurs around, instead of within the tubea. flatlcr. to (e) in the following chenieoi c:ntcs 111 cr.s can be ::rvith variations lr. capacity to trcvcVie tlesue reaction. (eee Tnbia lent Page) -) Chrys- ty Op 37.435 P. 7 ; P* 0 2.355 0 AUC' 0.365 Co. 0 0.055 Mi0________ 3S.775 Km. 0 --0V t >.0---- KuC 0.03 Lcsrs 4105 A. 30 ' >105 14.92 Croold- 64.9=5 15.275 4 , 2=5 1.025 0.705 1O 6.92 0.57 0,02 2,55 Antho : 46^235 a / rr-uaito- ' . 53:c'a5' -'55,rc5 0. 0.515 ' " 4,065 * '3.035 `7.215' 6 , " z ^ ^ 07 33.635 0 o " a.` 0.255 1.0?5 lies* o. i 0.455 "'- 0.445 2,015 12.225 4,455 0.4C 5 ` 7 ' 29.645 0.52 6.295 0.33 23.205 0.40 20,525 53. = ?5 6. ?? *4 0.91 ' 0.15 0.10 0,12 0.9 = ' 0.15 0,52 2.42 0.56 -- 0.32 3.59 0.34 2.7S 0.53 on z s ` (b) Acid treat: ent .of ohryaotila flbrso 1 Cr.e hour In dilute or concentrated K3L dcsa not altar sppearance of fifcrs but after such treatment It rapidly dl aolvea and disappears on Injecting Into living tissues; 11 Treatment with COo bubbled through water cr lung Juice suspensions of chryaotile fibres causes partial solution with liberation cf silica and C3gneeia. (c) Colloidal allurlna does not neutralise the' effects of aebeat as it does cunrti. On injecting chrysotile suspended lr. aluminum: hydrate solution, fibrceie and aa'o estca bodies develop at the usual rate. It remains to dene r.strnte v*str.er t fibres become ooated with o layer of alu.plr urn mcrchydrate a: has been proved in ths case of c.uarlm. -f tr.sy have, the cc does .not affect their capacity to irritate tisaue. (a) L.nrth tf Fibre Short chrysotile fibrei-ur.der 3 cicrcn: are practically 00 to to micron fitree cauoc typical fibroale. Oh* effects of longer c.nes could not be tested for tec: reasons. - (b) Or-ip.nl nr completely destroys the fibrous structure cf erryootiie. Vlth loos of structure, all capacity to i: dioappears. cal tate fibre-istructure io prosor-red. Fibres beccua extremely brittle.: !"?he phyeioal change alters typical localise.tior.'within the lungs, r.o fibros'e dsvelopo reaction-United topnyagccytceio: Ko asbestcais bodies forced. ;VJ" VIII ?' n turr and Sjrr.lfioanca' of AabcatcetB Bodice ' (a) Sodlee probably result fron dopceitlon-'of Ircn;ar.d organic natter on a slowly dissolving-fibre .of iaotea too . :-The source . of bha iron ia core llhaly to/fca tha lung tissue than the cir.eral lbaelf oa tho coating'is'-Juot-as-heavy'on-fibrous cir.srala cf lcsf iron content.ca upon.thooo high.in iron. ` : ,i --- : ' . - vh..* (b) -t he effect of asbeatoals'body^fomatlon'is assured to be pro-: tectire although it has not'bear, .poeslbls :to isolate a lerge enough quantity of. these otruotureain.unaltered fern for purpeoes of test. The ncooth'rounded-ends'presented-by tha bcdis8 would not be ceohondcaily,irritating. (o) If they vers oapabla of csueing'lrritation,.the-fibrosis in ths lur.g3 ar.ould progreea after oxposuro ceases which it doe: not. (c) The gradual disappearance of bodice {and'fibres) long efttr excosuf'f'Jccinta to ultinate solubility in'tissue fluids. { s) * he bodiea are probably a fortuitous cor.ocnnitar.t rather than a cause of fibrosis. IX Thee ri a 3 o f Irri t -.r.t Act *.pn c f Aobp t1 fora !! in pro'- a (a) Cher.Ionl -heee e.tperiner.ta do not cor.firn the to.scry that esoostofis ia merely a fern cf silicosis result!r.r iron free silica liberated in the eolutior. cf a silicate cclecule. If this vjr? true asbestos li/.e cuarti phculd cause ficrcais in sr;.' organ of any ot-ecieo for the experiments have rave that ir.w'eotel osoestoo disoolvea in these locatlc.ro. However, it ices r.ot o-use such reaction in any location but the lungs cf (h) a o o 10 n <n f k The fibres must be lor.m enough bo that they ccr.r.:: be completely : surrounded by pharooytic cells vruch would proven: contact cf thes: round, crc'/.en ends with the delicate cello supporting the air Observation has demonstrated that t.-.eae conditions arc reaiito tdr.es cire treated with icnr f*bre c.nryoctile one fiirocis re Vith the other asbestiforn r.ir.eralG that havo teen teoted, ecm all of the prerequisite veto lachinr and :.o fibrosis developed (c) If the irritation were chemical, fine serpentine which ha sorts chemical ccmpceltlcn ss cr.rycctllq sneu-d havs suso fibrosis. The crushed chryootile fhcudl have been r.ore a than intact fibres, because of the greater curfaco nrcao posed to body fluids. On the aeaumptic.n that chrysotile, cuart i, becomes coated with a very thin layer of alumi.oc: treatment with colloidal aluminum hydroxide, capacity to fibrosis Bhould be destroyed if the eotlon were chemical such ij not ths case. ._ tf n (d) *he heavy cca tir.g resulting from aacestosio ccdy .creation a: psrertly do'es stoo tissue reaction cut here-the effects-are probably mechanical fer reasons cited. (e) Heat sufficient to alter chemical structure c estroys power to Irritate but it also alters essential physical characterise; that affect localltatlcn of the fibres in t.ne lur.rs. X Complications (a) ^uscer.tibllltv to Infection ZJi rz 1 tuberculous - Asbestos behaves lihe most other rdnsrs:/,is this respect and no: lihe cuart: which specifically increas-. .native susceptibility to tr.e tubercle bacillus. Tr.ls 1 nfecticn may spread far a time but then heals. The resuutant fibreois accentuates t.nat caused by t.ne mineral fibre. ion--uberculau8 - of no rreater frequency tr.a.n in animals 1 nhn 11 r.r dusts of other binds. Occasional epidemics of pneumonia occur In cur dust rooms -'s a a ire cue to methods cf housinr rao.ner ar. _c iney also occur in ur.exposed animals. -unr .'0 experiments vere^desirr.ed to elucidate tr.ls coin tut certain ovlienee surresto tr_at asde913c 12 ray actually favor development cf.turcro in susceptible species. 1 Ir. ruinea p 1 r 0, raboits, rate, cate and dc3 lur.r tuners are rare. When these species vere subjected tc 2 to 2 V A LT 9 _ T. ~ halation of asbestos dust, tr.e incidence cf vas r.ot increased. y 2 Sore strains of white rice do develop tutors without apparent cause. u Such a strain o' white rice vso unlr.ter.1lcr.all7 uaed lr. three Inhalation experirents with asbestos. 5 Cf 11 rice inhaling 1 ?nr file* aebeatca Ter 15 to 24 rcr.t.n. 6 developed caiigr.ar.t tuners lr. their iur.es end 6 cf then h&z. turooro in 0 *361v? , c Cf 22 riIccee lirn.hhnaling short fibre aobestos for r.ot lender th; 1 0 rc.ntha only 7 As controls, w* dust er.peri.r.e.nta. short 1 e r 1 c d . there were 51 rice exposed to 4 ether kinds od dust for 10 to 12 ror.tho. lr.clder.es of lu.tr tutor i.s*. ror 1-cr..~ por 1 ods . there were 142 rice exposed to 4 dlfferer klr.de of duot, including pure cuarte, 23 to 21 ror.ths. fen all this group of rice the sverare incidence cf lu.tr tutor was 13.<jiT the highest rate (2c>5 was In a sue.roup exposed to fldr.t dust. sn -tr Crus the incidence of lur.g cancer in the lore fibre as '.os over 15 tires the average for rice inhaling ether ccrparabie periods ar.d over 3 tinea the raxirut for ar. Mice exposed to the practically Inert abort fibre asbestos shoved fever lung tutors although 7 tires core than those !r. short expoaur to other ducts. -hese observations are suggestive tut not conclusive evidence of a cancer stiruinline action nsceetos oust. r.ey are open, to several cr: :1srs . .he strain of rice was r.ct the eate in the asbestos experlnent as in ran;-' cf the others cited; apparently the forcer were unusually susceptible. Not er.curh er.icals survived in the d..u.s.. longer thp.n the 15 rontho apparently necessary to -here were no u.oexposed controls cf the sate strsi.n a-r..dj age nr.d r.c dirllnr cor.troia expo ether dusts. It is hoped t.ont this expenror.t rcan-r.. hoae -r<e= peated under proper." to ietereins whether ascestcs actus11y favcr1 -e.emined :r. andnais. -r.e e: s:.i causes ret with in all cur ? r. t a 1 d e a t h a vspent ini "rotors cf Har.nrdo'.m ? x-o -r** (a) Safjr; of guii '' if: out: 1 V" ~ * ?-'Uv i "h* hairda increases vith the proportion cf intact fibres rv^. in the dust. Oranular material and crushed fibre are inert diluents. *" -." - -i 11 `he lcnr fibres must te thin enough (1-3 -icror.s) ar.d sr.srt ' enough (under 50 klcrcna?) to be inhaled. Hi Very 6hort fibres (under 0 Hicror.s) ore practically inert. (b) Atmospheric Concentration Still under study. Apparently this factor la lover than in the case cf dueta composed of granular minerals but methods of estimation are misleading. , I The average standard Publio ^ealth Service implr.ger count in the long fibre asb;stos dust room-was 43 million particles per cu. ft. of air. ^als'concentration-caused fibrosis visible to tho naked eye in 0 to 24 months. -ror comparison the average impinger counts in an experiment with purs c.uartt vas 120 million particles per cu. ft." end ficrcsds developed at about the aame rate, e , II Hovever, implr.ger cour.te are deceptive because by this method of sampling very fev fibreB, which ere the significant elements lr. the dust are collooted.. IJ M ill Sampling with an electrostatic precipitator is a much mere efficient means of collecting fibres fro pensions. Samples from our long fibre as shoved that the dust in the air contained 22.S.S cf fibres few of vhich had been collected or counted in the Impir.ger esmple. `he latter sampled largely the inert granular parti- y cles. ' lv Aa ordinarily employed precipitator samples are weighed and the reeuits expressed lr. mg. per cubic feet cf air. There ia r.a mesas of converting such values into numbers of particles particularly vr.en thess vary in sice, chape and ''specific gravity. v Simultaneous aamplir.g with precipitator ar.d standard Im pir.ger yielded the respective values of C.oo mg ar.d c3 mil lion particles per cubio foot cf air. vi `heoretlcally the best index of ha card would be eitr.er the number or veigr.t of fibrous elements lr. tr.e dust. c -10- (=) -urntlor .r.uorur Tidrcsla vitlblc to the noised eye after 11 r.cr.tr.s e.' increases lr. extent in oubsepuer.t 13 zor.tr.s. 11 The anon of life of our cost susceptible 1 . t. . t . i"-- -isease ----- r-------------- ---------- - ----- thrysotiie. The long lived opecles, llhe cats, cc.js are ur fortunately r.ot susceptible fM'' -*T'.-1 igt-h 111 ;or these reasor.a X-ray changes have beerr,. z!lnizal sr.d ve were not able to fulfill one of the objeotivves cf ir.is prograz. ---cor i -o-r. for a New Standard of Safe -Attcsrherlc Concent: o f Ascestep wjg t. 3 `(a) i' t: (b) vr.iie there If no official standard, the'tentative cr.e cf 4 or 5 zillion par_ti.cles per cubic f.oot of a,ir ii s. ^fr_e___c___u___e___r-.all,y ousted. TThis is probably -unreliable because It Is based upon sar.plir. vith. a standard lzplnrer which we havershc-'r. does not coilec "osfof the fibres that ere the source orf uha_ _ ___: <IM (c) e ncvr third-: that a standard should be baeed upon settles collected with an electrcatatic crpcluitatcr if it is'feasl to determine readily the relative proportic r. cf fibres in such nr terial. ?- (J) Vorh is still in progress upon the lat ter pc ir.t. (e) To be of -value the'new standard vould.'-have''.to-be correlated with the"X-ray findings upon'-ezployeea 'exposed .to .different concentrations cf dust. . ... . .. . - - * . w , -r.e enperi-ent s have failed to develop t.ny -'oractloal chezi cal e as cf neutral! cir.g the botiou'of fibrous;rsbes:cs.. '.a) To niter the huza.n'lur.g co that it would-di c solve '. as ce c t o a f lores rpplclv ii>e a rat would necessitate j- _ r r' creating j.i acidosis wnich. would be .worse than the effects cf . * r~s f'T r;Z`>7 'cyr.'v ;y/;M::*v . 'a 1 V.i *.` L't** t -s'-' (fc)`.` Apparently alualnun'/.shlch lo. co affiOtl7o E^alr.rrSV.ff * s iil.cs :: has.little InfItienco "upon fitroua chrysotils sj&ix .tiyjW j. '. " ,'. *- ^-"^ ~ L ^ ' ' - * '-1-''- ".'''* V^-? ' * ~V *-r^y^ . (cc)) ; HcveTer, it wpvld* ba.^of gr?it.'tfceoreticfll'ir.tcrost-to troac*c:' -1r:` few caaca with rsQlrdjspnoea'Jrrca aoheatcsla hy alualr.u:'ln-^:;- ,-.>. halation. K are-.by'-no ceana'pertaln, yhpthe^-tha.' favcraoie.>_; 1 J < a." ** ***'- " 1 * w-.. - --^ -,.w. tev//-?'!'.' fibrous oospononto* of ouch `dust. :;.* .T-y- :"*.* W- - Vivr-.'t'.'A"' "' .. ...-:.;, ':<n- P'Vy'.K'vi >' ' ' ' \ ' "t'i'.l-Vt.'V:'' --J y::y ~.":rc*.r-c^; '-'A.-T'- .t - ,\ms rVV_ l. -^y_" ... A "I '. Yv *v,tr r' v?..' If. vi.' < iT.** * *V. J.. , . ... * `-is -y[ : rj\ . - ' -V *\ 7: t 3