Document DdM4VRqjGkYRk2LJ1EGDO8kwo

PLAINTIFF'S EXHIBIT GF-2232 The crt-Xttvy ::rr. logy an.' environ:.:-.'.tal control of asbestos report to the X::e-tituto oX Otc.i/.r.ricr.al and hnvirc".antrl health or. tivi engineer in - aspects of the Conference on Tv.z-.v oconicsis held in Johcnnes'r.vrg, April 23 - M?.y 2, 1969) G.W.Gibbs, B.S.C. Lecturer, Environmental Hygiene Departcent of Epidenddosy and Health McGill University *f *1t - GAF 16934 Ir. :? Ti.c Ccz.zrzrzz , ";.5c.'. '..`2= .'tu'-L-- in pv.c tv.i.V 2 ` p c/ v;.2 ,r3>.'\[. ._/i*icr.:. I.'.iv for Medical Fi-sc`vc/. ir. cJ'..:r.r.sV:.r, v:s divide ir/.o v.:;> t/.-.'-i*. V.;s :..r.ir. Con.'ercr.cc, ic`r. cmtcried ever th* zz:"Lc - April S3 to M?y 2, svpp 1 ; with s surra'. ; sessions or. er.gi.marrixg 3; :i: hair or. Moris;.- ii ?.: zri i/.o r.cruir.g of Turac'iy .-pii! 29. A visit '..vs paid during the Cor.'to crocidoliee stsstci r.ius at M.iriman. This report attempts to include ell information rslc.vr.nt tc the er.vircr.: :r\ rl control of asbestos. It ir.cludor date on the chemical, physical, and r.iv.or-1:~ical character of asbestos dust and scree details of ao.ph.ibole asbssoos arc included. Details of epidemiological studies, radiology ar.d enir.il experiments carried out to investigate pathological changes induced by asbestos ere not included. For convenience, the papers will be considered in order of prescr.ti.tion, ar.d corrcents are given a.t the end of each paper. One problem not discussed at this conference, but still a real one, is the question of standards. The dust encountered in certain textile industries will contain a higher percentage of fibre than is found at nost locations in a chrysotile mill. A high percentage of roci dust is really always associated with dust samples collected in the mill. Filters therefore will become overloaded with dust ir. order to obtain a sufficient number of fibres to count according to recommended procedures. Some recommendations are possibly required which apply to (a) the manufacturing industries (b) the mining industry (c) the milling industry. t During the Conference, the use of the term 'asbestos' was widespread and little reference was cade in some cases to the specific mineral type under discussion. Such a generalisation can often lead to confusion among observers as to the effects of different varieties of fibre. 'I AF 16935 uso oT cro::.:';lits i.\ Ores'. Britain at the tr.i oi this year, tccruso oi above vhieh it is not remissible to vcrl: vith crccidolitc. Thz rsxsri; sr.tcd c.t the Cc;`:r&'*cncc f.re to cs cor.ri } h-t.5 ic:_/. forr. shortly'. The inclusion of papers in this tool doss not include publication, and papers presented at this Conference will be published by the various e.uthcrs in due course. C GAP 16936 V. r.:, be o' gr'ft irmor-.?: ir. m umfer;"rr.;the ::r\;.-y \cr 1 act: t;. c` i: filrer. Z'r.t '.h; iv.flv .. re cf d It myth ; ::d ships o:' fibre; or. the relative r-.rriri lit;* of ( ' - r. re . .id ;.-.\.hlhule s.sc;r;os. Fibres of i.-.osite, vho:'..;-' litc-, erf crc ;icoI:';? in ir.dv.striai cust clov.ia s.r.i ir. lur.y; art straight, end there- is little difficulty in determining their dia^ters, Chr/dotile, or. the ether htr.d, often occurs as very fine curved fibres uhose length a::, diameter are difficult to determine. t O Rats exposed for ten weeks to dust clouds of UICC reference samples iu eov.el mass concentrations of resoiraole dust as measured vith the Casella type 113A horizontal gravimetric sampler vere killed 2k hours after the end of the exposure. Approximately equal -.-eights of dust were estimated in the lungs of the rats exposed to the cmphiboles. This was about six times the weight estimated to he present in the lungs of rats exposed to the tvo chrysotiles. To investigate this difference, physical experiments were carried out. The percentage respirable fraction determined using the Casselle type 113A sampler was slightly greater for the emphiboles than the chrysotiles, although a reverse result vas obtained using the Unico 18 cyclone- device. These measurements, which take little or no account of fibre shame, suggested that in the animal experiments with the DISC reference samples sore emosite than chrysotile would be deposited in the rats' lungs in the experiments, but the difference would only be a few percent. A difference in the solubility rates of chry3ctils and smphibcle ir. lung fluid* was considered as an explanation for " gap 16937 i o O r- r r. c-:-: Tc ir.*. enough strsiy'-.t fibre ~.o sir.uli..? f: : i: i'i'rr^s were such?:. thrcvyh r. bun.'3e o:' i GO tuc;; 1 cm ic..`.r. The tub=j -..er-? iOO -1 ir.1. _ nob iu.: tor r. the air velocities v-r e arrr-ngcd to simulate those in tie s.viler lur.c airt-ays. Distributin'.? of 3enrth err. t~r set ratio (definui as the iv.Li.o c:' the dirr-ter and length.) were constructc-l Gov the fibre pres;:...:::'. to the bundle and for that collected ceyond it. The result shoved a decrer.sed penetration of the fibres vitii an increase in length or an increase ir. the aspect ratio. Further experiments carried out using a hollow cast of a pig's lung gave more variable results, but even higher values vere obtained for the ratio of weights of eaphibole and chrysotile. Er. Tir'orell did not consider that the long chrysotile fibres which have been observed in lungs sonetimes in numbers exceeding those for asphibole vere in conflict with the possibility that chrysotile fibres are generally less respirable then ) amphibole asbestos fibres. Chrysotile fibres readily divide ir.ta numerous flexible fibrils small in diameter coapared with the emphiooles. The observation that a large number cf chrysotile fibres vere present in e lung was not considered a good indication of a large mass being present. Injection experiments do not simulate the particle deposition mechanisms operating on inhaled particles end should he considered as an examination of the biological activity of the fibre. This must be borne in mir.d when comparing the results of injection experiments vith inhalation studies which are more relevant to human exposure. o GAF 16938 Comments: It BUS' findI irm~ is an interesting one end *cossibly of great importance. .Tie in mini, however, from the milling standpoint, that fibre is f. f. 0 o?" m;-o Jj;;: c .w of ICOVIT-S,.: ... c.lu This shape factor is worthy of further examination in future field studies of dust conditions in the chrysotile asbestos industry and perhaps could even be included as a criteria for non-rescirability at sons ti.-.e in the future. o i *av: GAF 16939 L. C the Ur.i-.i I atsz. r,,; -.h.-;.:. sli li-.it. veV.i: ('..l.'.'.) csts-ilish;:*. - A.C.G.I.K. -or tsl-co'.c? i- tl.e U.-itci t:-.t-r :.* J.C mil Hu.-. cub i e feet r.ne this f.'.reshcid 1! ,.'.t r r - vx'.'I 1J:6 ids* : -- the t:.r j-'..'' lir.it valve ;c*'.r.ittse c:' the .-..C..C-. I.K. rsvisvee the beehrreur.I of the zzizl-zt thrsehold value clor-g v.-ioh coca that had emerged since the- se..-h c- Drc'or. il. on vhic"r. the star, lord vas steed. The revised T.L.V. tsr-rc-vcd uy the C-: :. i \ : _ under a notice of intended charges established a tir.s ..sighted averege fibre count limit of 12 fibres csr ml greeter then > microns in hcr.rth or a limit cf 2 million certifies -per cubic foot for total particulates. Five million particles per cubic foot vas recommended as a ceiling value. This standard is expected to take precedence and be uniformly applied in the United States. Dr. Cral'ey stated that the fibre is a better index of exposure to asbestos than total particulates and for this reason a threshold limit velue based on a fibre count is recontended when asbestos is a significant exposure. A value based on a limited portion of the spectrum of the respirable fibres present, such as fibres longer than five microns, serves as an index to control the overall exposure and is predicted on the basis that a reasonable ratio persists in the fibre . above and belov five microns in length and associated diameters. It vas recognized that some fibres could not be seen by optical nicroscony but for practical reasons optical nicroscony must be used, and a reasonable ratio must be assumed. Applying the threshold licit of 12 fibres per ml greater than 5 microns in length, the conference stipulated that the air sample be collected cn a membrane filter and that tha counting procedure employ phase contrast illumination at li30x magnification. The A.C.G.I.E. has recognized a transitional period end to keep exposures under the 5 nppsf limit it vas advisable to express the limit ir. GAF *16940 to;-..; : -I? \: r. i' tvs;:;,.. Z. f-. f:':-:-: ,r. it-:';- r.tVci'.vs teiiiii.- ir.iv-tiy cf the Unit;:' str.i ss ;:rrit? tut vhs of Ccc-ov-. itr i.1 Sil'ity ir.i HiiltV. iliv-ii this vee squivr-.ls;.^ to ths_t 2 r.tt cpslvi.tr the 2 r.sptf ti.t.; vs: vhtsi ever: ~e lit.it, tits t.i i- sL iv;it rvr i used e: a stir,:': ri s-v-.plir* irstruv.snt and coustinv is dcr.e ty the li vit field tschr.irue at 1CZz r.srnificetio.n. C GAF 16941 >1 h.x. J -- ., L' in the P.cv.illic e" \1h Hrict sir.es ic'..j "ac ri vi^'c Tht c ry 11n' 1' i silict cor.tsr.t c:' the 2 types of roil handle:'., the ler.wth distribution fibre, er.d fibre to pr-rticle- ratios vere report-:e. The exact lever linit of the ierpth of fibre included in the concentration ^recorded for the earlier years vas not knovn. Prior to 1913 the longest fibre included in the count ves 18 nicrons, but from 1918 to 1966 the maximum length of fibre included increased to 2C0 nicrons. At the bottom of the scale it ves e practice until i960 to record particles as fibres if their aspect ratio vas 2 or more. After 1956 it became practice to linit fibres to a maximum length of 100 microns, to a maximum dieneter of 5 microns, and to a minima aspect ratio of 3. Konimeter samples of vere eraphibole asbestos/counted after heating to 580* c cum acid cun heat treatment whereas with thermalprecipitators the fibres longer than 5 cicror.3 vere counted after tee first heat treatment before the acid treatment. Fibres shorter than 5 microns and particles were counted after the acid treatment. Because of.these different methods of treatment, a number of correction factors had to be applied to the data presented by Dr. du Toit. Sixty-nine samples of banded ironstone rock bandied in amphibole asbestos mines vere analysed for crystalline silica content and gave a mean of 32?. There ves a difference in. fibre content es veil as average fibre length of the dust produced underground end the dust produced on the ii GAF 16942 fabc.v ' t icror. izzv.i cf the dvr - cr. the sr-rfer..- nr.c Z' ~ of tks c--.v. v.nCerfro'.r.i C"siaiiof fibre?. 0.* the rcroer.t:.;:es on the svrfece r-.f. 1/20th vr.f.zr;:o..:d Lrr.g:.- th.:.r. 5 :_io:v:-.i. The rlirvEotiic r.cbe?zos samples contained r.o cuer c -. Abe .si c.J" of fibres on the svr's.ce and about 0.2;' of fibres ur.dirrrsu.ri are Icr.rc v thcr. 5 r.i evens. Hcr.c = about cf the total count serve C.? nitrons o:: the- surface consisted of fibres longer than 5 microns -..-hereas cr.I,, C.C5;b of ti.z total count above 0.5 microns underground cor.3 isos of fibres lor.g.-r ther. 5 nicrons. Details of the absolute dust count means for the periods reporter are giver, overleaf. C \\ GAF 16943 Chr - ~ ~ i i_T r i3_. I.1-.:*.* c: r.:_i. `rr. i z,: z. 19^7-1952 196--19=6 19**7-1952 1964-1966 M; n 2o3 ppcc 125(? & f)p=c Surface kUO ppcc 100 ppcc Ran. 7*. 140-430 p pp.rlides f " fibres (p 6 f) = jarticles fi 17**-1100(p & f)pcc 180-2300(p U f)pcc Croc idol it e 19*40-19*42 I9I17-I9W 19*49-1952 196*4-1966 Underground (mean) 790 ppcc k60 ppcc 360 ppcc 210 ppcc Surface 890 ppcc 230 ppcc 3*40 (f fc p)pce 360 (f It p)pce GAF 16944 il i.-ie d:-vl'._. ..rft c; =7:..vi:.r r.ctkols -.ii reviev-.c., rhrly lv.st count: . r.'.th-. '1 th? io*- :.d ir.:iu."ci ihi u*e of the- Grser.bv.- S:.itr. dust ctui.'.rr, v*virus types cf r'inimeters ar.l t!.ei7^i:ircoi.yi.eters, hni involved the counting of vs.rticlia from J r'icrc.-; or fr: u 1 micro;-. in .'ire upvnrds.The ve:v large r.u-.her of sr.s.11 particlc-c often i-.s-de counting difficult and in the usv.il urban industrial atr.ospkeres it vas ret possible to distinguish bifvetn asbestos and ether dust ir. these small sizes. This meant the incineration of samples. There has been an increasing body of opinion that bundles cf fibres of 10 nicrons in length and upvards are the most dangerous constituents of the dust. Because of this the v Asbestosis Research Council decided to count fibres in the 5 to 100 micron range because this made counting easier and ricre reliable, since asbestos could be distinguished from other dusts of similar dimensions. The first collecting instrument used for this purpose vas the long-running themalprecipitator vhich proved not to be very efficient in this size range, and membrane filter methods vere therefore developed. The standard method has been described elsevhere and the sample nay be taken vith an electrical pump to take continuous samples, or a band pump for short term samples. The method may also be used vith slight modifications for personal monitors. A similar technique l- . . * has been used in the United States end has been described by lynch end Ayer, and is the test method at present available for estimating GAF 16945 ]'/ n.icrc.' '.hi:!-, is ci:-, c::i r.; . r.-jir.y lt.I co.v.. ir.^.vhic'j fcr e single record tr.'res about 3 cir.rtcrs of fr hover. Quick routine :..echc:'.s vr= described by Dr. Adcir.rdry, ..rick utilised a tyndsllor.etric instrur.-ent, the F.oycc particle ccurter. The earlier r.odel of this instrument gave an irr-.=iiate di rival indication of the particle concentration vith printed record if desired over a nutoer of possible preset periods betveer. 20 seconds end 10 ninutes, or if operated manually, over ar.y desired period. It could be set to eny one of 13 size ranges froze 0.3 to 0.U microns up to over 10 microns. It could count one renge at a tine but could be aet to count different ranges successively. It could also be set to count the total of all sizes above a set aize. In practice, it v&s used by Dr. Addingley to count everything above 4 nicrons. A sore recent model is transistorized, a little less bull?, and vill count a number of size ranges: 1 to 1 ., fc to 10, 10 to 20, and 20 to 100 microns. The size ranges may be altered by inserting different range cards. The operation of the instrument and its correlation vita the membrane filter method has been described elsevhere and for routine vork in large textile plants it represented an enormous advance. Its disadvantages are it-s bulk and cost, and the fact that it cannot discriminate betveen asbestos and other dusts; this does not matter in an asbestos textile factory vhere 952 or more of the dust above b-5 microns is asbestos. GAF16946 it fir* Uy with e.ilitci -..i.-i.-i the hi;-;; ccvr..- r urs cercrib as infispc.'^nble. Up ic .'C': cbserv?: icr.s p;r ci:_ cc r.aie, tr.r. u.:; alii'./c f'j:- :.j the- . rv.\ e-1 f : e .:r i vh_ : c. / i.r.C. r i.. i?.p uu rc'.sts col lectio:. i\'trill:'/. fv piss -a:*: -t:.htr. it the brciC!.:': g l i er.d in the working politic:: of the ope: -it or. and r.g'.`?yr etr. to prviit a general ai:-.o=ph-ir-2 "level". In braV.s lining factories O.e ms-.brent filter count it* thru is very satisfactory, out one operator can r.cke or.ly oil: to eight tests per icy. It is found by this method that as an overall average about 50 of the above 5 micron fraction is asbestos, but the percentage varies quite widely between about 30 and SO?. In order to carry out more testing the Royco counts were cade in the first place, and if these exceeded 3ptcc a membrane filter count was made at once. This method seemed to be working satisfactorily and should be applicable also in other operations such as asbestos cement and insulating material factories. Of particular interest in this paper were the costs. The membrane filter costs were estimated in the United Xingdom to be about $3.00 per count and the Royco counter if used to its maximum capacity will cost in the region of 50 per count. In addition, long-term sampling strategy in the United Kingdom in seme asbestos factories vas to combine dust surveys with medical examination of workers, especially with lung function tests at entry into.the industry and at intervals thereafter. II GAF 16947 Vi.is Tap-:-.u*t;:c cf the,f:eras the rhc".i;nl t:d physical proper",ice de;-_e'i of z: era obtainable f^c.- th a ?rc./r.r>:cr!ic:si3 ?.e???.; eh Unit in Ue`.sbv.v^ upon reeuese fer standard UICC reference sample?. or for data sheets. This in'orr." t icr. : ill subrecv.ar.tly be published by ir.vsr.iratc:-? './ho have carried out the verh on these samples. Characteristics of the International Union of Cancer Star-dsrd Reference g?mls? of Asbestos. V. Timbrell, United Kingdom C Physical properties of the fibre such as heat resistance, particle size, equivalent diameters, electron diffraction, patterns, analyses for trace cetals end conpositional analyses vere reported. The analyses for oil content of the UICC samples which had been kept in large paper bags since October 1966 vere included in this paper but appear to be in error, possibly due to a misprint of parts per million instead of percentage. Details of this information are also available from the Pneumoconiosis Research Unit in Johannesburg. O GAF 16948 b: 3 A. '.'.orrr. Kce.it:-."?;-., ir.vcstic2.ticr. of ccmpcsitisr. cf asbestos s:-.i the bvicv.r of fibres ir. biological systems. Irradiation of merry elements with neutrons ir. s reactor results ir. the production of radioisotopes ir. which the red ios.ctov-.- trotu-t i3 o:tcr i.-ft otic with the pe.rer.t element. Ail raj or elements of esbojios with the except ion of oxygen undergo thenceIr.eutrcn capture; however, the only relatively long-lived emitter produced is iron-59. All types of asbestos contain variable auantitie3 of trace elements, ar.d as some of these have high-capture cross-sections, the activity produced on irradiation mo/ be relatively high, despite the lov concentration of the stable parent. Sene of the elements which can be detected by activation ere antimony-122, antimony-12t, cisium-131*, chroaiun-51, cobalt-58, ccbalt-c, aangar.ese-5l, manganese-56, and scandium-U6. Immediately following irradiation, there will be many components contributing to the total radioactivity of the asbestos, but after several weeks' decay, only a few -emitting nuclei cen be detected. The authors shoved that each type of irradiated asbestos at this tine had a characteristic -ray spectrum. Iron-59 predominates ir. the spectra of amosite ar.d crocidolite but the former generally contains scandium-W also. Hie spectra of nthophyllite and chrysotile, both Canadian ar.d African, contain contributions of scandiun-U6, chroniam-51, iron-59 and ccbelt-63. The technique was said to he accurate, extremely sensitive, and suitable for snail amounts of naterisl. The sample is irradiated under the sene conditions as a standard containing known amounts of the element to be determined. A comparison of induced radioactivity in sample and standard enables the concentration to be determined GAF 16949 0 2 0 i(3 6 9 --i * a <? of V.:: ir.r.ivJ 1 of C:r.:.:ir.r. cl-.-.,, iC..iie ich :::rj ;-i- ..`jf ' o produce tho Cenu'liar, rsferer.oe i .'orgrn a;i Tir.cr=li h:v:- u:c.' f :.ff::-:..:: in the cc-.pc;:`tion of c:u-ysot ile ar.;' crociaolite Ere1. neutron aouivotior. Lualyt to e>'.?."i:;e the efficacy of .'cechcmicr.l bienf.ing ir. oroduoi:.;: t /.c. .cjc::en".; 'v..-_ Wr.^r.er, '..'ho studied tunour production in rati, follovLny adnir.istr:.. icr of different types of asbestos by su'oc 'Jtsr.cous injection, found that .tiryvutile nr,c crocidolite uere both more effective than er-osite in this respect. The ciervsotilc used ir. these sar.ple cxperir.er.ts, although not UICC reference raterial, contain:-' nuch more chromium, nichel, and. cobalt than either the tries ite or crocidolite. C As chrysotile is considerably core soluble then either of the anphioolss, the trece metals are released from the fibre into solution, and. it appears that the carcinogenicity of different types of asbestos is not related directly to trece metal content. It has been suggested by Roe and others that, folloving subcateneous injection, asbestos finds its vay to cesothelial surfaces such as the pleura and peritoneum, and remains selectively in association with thee. The-possibility of using radioactive asbestos to follov the translocation vns described by Holmes and Morgan, who administered 10 mg of either crocidolite or ; Rhodesian chrysotile to rats by subcutaneous injection. Animals vere killed after one,- tvo and three months, and the distribution of activation products measured by counting in various orgens. The crocidolite and chrysotile used by the authors contained 27$ and 2.6$ of iron respectively, and it is interesting to compare the distribution of iron-59 expressed as a percentage of the total injected C asbestos. After 3 months, 23? of the iron-59 had left the injection site in the case of chrysotile, and only 6? in the case of crocidolite. The iron-59 vhich hed GAF 16950 th'.t ir.-\-59 dicrolvsd frc:.-. t.-.. fir:-; r.t mfcc siv;. sicvly i~ th. ;;;j of crceoolite . i- r?pic.ly vi,v chryjroiile, ar.1 vhcrj"fl*?r foliovcl w'-'i- normal v.cit c lie cf italic :.rn. The relative p~ti:::e o. the tciivmticr. pr ducts is various cc-gcns or v:-. enicals injected vith chrysotils bore no relviionrr.ip tc these of the airmen itself, vhich indicated that most cf the translocmi id r&tior.'tivity v-j.z die to material vhicr. dissolved frea the tsss-stos, end not to cst-.tor.. 1'his did not preclude the migration of small amounts of asbestos. Ir. the c:~srL".3r.ts, 10 c.' asbestos vere administered, vhich represented approximately 10^ fibres. If one microgrsmi can be detected by radiometric methods, this still corresponds to 105 fibres, end optical examination of tissue affords a considerably more sensitive method for investigating fibre translocation. These experiments show that the metallic constituents of asbestos have a finite solubility in tissue, and that chrysotile appears to dissolve much more readily then either crocidolite or aaosite. Examination of the urine of the animals injected vith chrysotile shoved it to contain chromium-51 end cobalt-69, but no scendiua-l;6 or iron-59. Moreover, the results indicated that a rapid leaching of cobalt and chromium was occurring. All four activation products vere present in the faeces. Radiometric methods are not suitable for detecting the translocation of relatively small amounts of asbestos following subcataneous injection. After dusting or intratracheal administration, vhen comparatively large amounts of asbestos are removed relatively rapidly from the respiratory tract by cilliary action, radiometric methods may be used vith advantage. Holmes and Morgan have studied the clearance of crocidolite end amosite from rats following administration by intratracheal injection by V-counting iror.-59 in -aeces and in vivo. GAF 16951 Comment: ... The iron solubility i? not surprising as much of the iron associated vita it chrysotile i. probably magnetite end not present in the fibre molecule as vith cr?ci 11'~ J- - 7" (.13 2s -/.= t- = - - -y~ - - u.-ev vc clvv.-.- , _ v'ms? r Vj_ c of : : .*' prc;;-at In fcvvv b:;.iv.. C. e o': ' -... ;:.r the c.::.-. of fibres frcm ,V.::.g : irs; /11 i-vrrc/.vly r.vnr.2 vile e:.v: action fcchui to give cvn.titr.tivc rcsviist out c.ffcovsv vmvc=r types cf asbestos i.insn.ir different.1;.-- Chry.-cti'c, fo- c.tm.p.lc, -..-if.istocf. chr"ci :_2.:-.iy..l; tion least "di even distilled vater result Lag in sen? eliventnl let -.hi:.*, fire \.echni:_..s v.rsd for extraclioa '.:e.s to dry ash the tissue in vr-.cuo by electronical1;- * cuivr.':- i o:*'rcu. Electron nicroprcba analysis cf asbestos fibres were :..s.de in. ter_vi of the r<itior of the five raj or ele.ve.:ts found in ell commercial fibres: iron, calcium, silicon, magnesium end sodium, fee spectrometer was calibrate! vith the metals of iron, na-r.esiu.-i, aluminum, silicon, end o/.ides of calcium; end the nincral typos ItaCl and croc idolite vere used to align the probe spectrometer for iron, magnesium, silicon, aluminum, sodium, calcium X-ray emission. The iron-silicon-uagnosiv:~. l<--t omission for crocidolite fibres may approach emission ratios observed for some of the amositc- fibres; houever, careful measurement of the sodium and potassium emission in emosite has been carried out er.d amounts statistically greater than the bee'/.grounds hare not 0J-020M J72 been observed. Crocidolite fibres, however, did produce narked sodium emission. Tremolite may change emission characteristics if iron is substituted for magnesium in amounts which approach actinolite in composition. This can have the effect of shifting the compos itional point toward and even beyond the anthophyllite field. Treoolite may be easily differentiated from the other asbestos minerals on the basis of its atrong calcium emission, end anthophyllite may be differentiated from crocidolite and tremolite by its lack of sodium and calcium. Commercial fibres of anthophyllite possess at least 3f> ?e0 in their structural formula. Low iron anthophyllite, which possesses emission characteristics not unlike chiysotile, tended to have a higher Te Kg emission ratiothaa had been observed for any of the GAF 16952 i: Analyze:, r: c= Lij. o;.'. cr. the- folic-;!-./ r.?.ferlt.ls; 2) eebzetos to!!:- in e. '.jor'i-zzs: t-xpoie:. to amorite 3) P-?h~stc. . bo; 2 ir a vcv`:.-.n cv'-orsf. tc c hv;-o: 1 e: Electron pro:; s..* * lyses vere obtained cn five asbestos bodies e::t: act if. f;-::; echcf. .vr - tissue of ' Eibsstos vorbev -..-ho v: s employes in the C?;.rr'itch.-y.-Ti-.'.a field, Aj-.alyso s vert i.s.se on single large asbestos bodies, end 137 on: lyses frer the bodies were carried out. A comparison with Jeffrey chrysotile was made. 1*) asbestos bodies: hamster in vivo chrysotile studies: Electron probe analyses were made on 20 asbestos bodies entractedfrov ached lung tissue of golden Syrian hamsters. Arizona soft chrysotile was introduced intrc.trachcclly into the hensters &>9 days prior to sacrifice. Multiple analyses were made on the 20 bodies and 815 analyses were presented. 5) asbestos bodies in individuals in the general population not known to be exposed to asbestos: Seven, cases were selected from the current study of asbestos bodies in the general population of lev York City and sixteen asbestos bodies were analysed. Results; The asbestos bodies frost the lung of the workman exposed to enosite analysed as tmositc when a portion of fibre which protruded frost the bodies was examined. The emission ratio of iron, silicon, and magnesium was not consistent in the seme body when point traverses were nade within several tenths of a micron of each other. This va3 interpreted as indicating that the fibre did not necessarily occupy the geometric centre of ar. asbestos body, nor did it have to remain in a fixed position GAF 16953 c:' tv. v.-C rtin.VwI, vryz *: ;.*L'h hi^v lcrvi*!., Ths cc.' iJicr.s.1 `.0 i..v k ,'bCt.b. 1. 1 - U - J si .. 1!. V i J. . wl* G1 ` d. j I * , r_ ; ^ ^*w ; f " *f ::v o; ::cr._*.,.-n c:::m: to V . i _ i ir.i:.2?Ui. t/r.t th;** "crt cf ci*::-J r J.e-vy to rtrj::\s.vG cr.r;--otil* frc:.. Jeffrey "in- C:". Iren v'r.s t.:- t'.vi cr.c--.if.tr.-, tut nhe !!" :2 rt.tic, remainid for -act bciics x:c'.'.r.tr-i Thi'-n- -.:::, ho:: c.-, t number c.' Cc.se.: cT vvrhri -r.: u : leer, -.rich "r.s cr-tsctct in st> tidies (less than 0.6 microns ir. thickness ) -..-inh little or rso cc-..-ir.; c:i-.."/or.'' . Ferrous neoalite (fibrous brucite) vas observed to be present i:i the stani-d Jeffrey sample. "er.alite tends to occur in thick straight lathr-rith r.o observable curvature a lor- its fibre length. Although no bodies vere analysed vith ncr-c iliec.-. high magnesium cores, the possibility exists that ne.te.lite may form "asbestos bodi;_. The asbestos bodies observed by the authors vere nucleated on chrysotile. Lb:rtr.ir.aticn of the asbestos bodies fron the aniral studies revealed that, whereas neralite from the Jeffrey sample vas observable under the electron microscope, the Arizona ner.i2.lite vas not. Admixed with chrysotile as fine inclusions, the large chrysotile bundles vere analysed as containing about 15% excess magnesium. About half of the analysed bodies possess e Mg:Si ratio characteristic of chrysotile, but some of the fibres protruding from the bodies vere substantially depleted in magnesium, as vas observed in a chrysotile workman. Within the suite of the analysed asbestos bodies were unusually thick bodies with very great calcium emission. Polarized light microscope examination of lung residues from the hamster indicated the presence of Schaur.ann bodies, which vere nucleated on asbestos bodies. Seven eases from the general population which vers selected for asbestos body analysis were chosen on the basis of perticle abundance observed during the course cf routine section scanning. Cf these, one clearly possessed the characteristics of en amosite fibre core.and fifteen or sixteen of the bodies analysed vere GAF 16954 iRdii-:ir.i ? -*- acii*-., a shew;--: tracts si* sciii. .. C..c r: v-;i cf scl>;: vrs high in ire.;. '."hie r.- hr a e: croc*i l '.ici's 11 ir;sr 2.ii>.'-"Srs \.*; ^"cr. or.ur^crc>'s c.r. i thz w?.i\vr c * obi'srv:.;ior. of calci;.-. zr-l r-eiiu:.. briiss -. y indie:-.J.r the are;:;.:: of pvc ;1. i .... irr. or e;n'e-5rx v=i salts., a. colciur. phosphate. Three of the sixtsa-; conii; -.rir; observe 1 to ev.tr m ;ly rich ir. siliccr.; coreei\ably , these re;- indie;e t':.e rn of fib-oua glass bodies, T'-ey n?y also `os ir.terp~eted as a siliceous chryscuilo residue, opal phytolith bodies, or diatom spiculss. Those analyses ;:erc not ra::d;,,: in nature. They vert obtained on portions of the body where it vas considered thru the coating vp.s least dense, where fibres were exposed, ar.i where p invent at ion. permitted a look at the core. Sur.sr.ry: Kicroprobe analysis can prove unique identification of single asbestos fibres of all fibre types. '.Then fibres are coated in vivo, the resulting coating of the asbestos body introduces analytical difficulties. These cay be decreased by reroving the coating or by analysing the fibre core at points of minimal coating such as projecting fibre tips or intervals between asbestos body segments. A major difficulty is the chemical degradation of chrysotile in vivo and its tendency to stretch into very fins fibres not visible by optical microscopy. Specimen selection may introduce a bias. The larger bodies in a population of asbestos bodies would be analysed. These difficulties suggest that, while aicroprobe analysis is very valuable, complement ary techniques such as electron microscopy and electron.diffraction increase the reliability of particle analysis. The analyses indicated that emosite remains intact ir. lung? for at least ten years and large hurdles of chrysotile may also stay intact for a long period. Analyses of sixteen asbestos bodies obtained " GAF 16955 ceres. C i ? ? fv. 1 e:cs_*:.ir." -.ion is requires to avoid cor.i'usicri Y'ith er.ic^c-sur ?;lts. Tiv: o c :r_- 'ire: c" pst ,:i:>-r.s esstos cciies in hur.nn lur.ps should t? r;o::s.-.ir.si:. torus of schistos tody coJoinations. ( O II > - %V GAF 16956 c::, Ir. 5U1...A17, the jj-'-br reported th:t respiracle fibres '..-era ubiquitous. ?hey arise frc.r. industrial processing, community er.d personal acti/iiias, ?r.d the action of natural forces. Before prospective assessment car. be made of the moaning of fibres in the lungs, definitive evidence must ce obtained on the identification ar.d source of the fibres. c In discussion, the Question vas raised vhether any of the fibres are in fact edge-vievs of piety minerals, and Dr. Cralley replied that this vas highly unlikely Details of some of the content of this paper have beer, published in the A.I.H.A. Journal (1968), 2, pp 129-135- O GAF 16957 :'-y c- b i' lhc r.r: as: ivy c: a. thor v ..yk 1:'':t it.-. of the ~ .":r.' r c d: types of curt sr.t.p: ers .fhc-r. s:.vplir.g txbrstci d.\r. ss tv. frc.. th: dv V - that hr.'. tv:'. cv.-'::r - b fr::. t i::: is ti-' = by t. v b : . c; r _iho'' whether ir.bt:-u.:sr.ts originally c'.i:'.c.'.:b to coll art i to cl'.ssii'y :,s 2 02 equidi.-.rrsional pertibles of 10 micro..- .'.iace.;-.- or less -.-e-yld 22 suitable for the collection of fibres to 2C0 micron:: in length. The instru.-e.tts select:! vert: 1) Casella thermal precipitator (standard model) 2) Casella Hexblet 3) midget impinger 1*) M.S.A. Cyclone 5) Konimeter (Ur.ico Model 18) 6) iarge pore membrane filter (Uitvatersrand end Sartorius 500). Because of the very different morphology of the fibres of erphibole and chrysotile asbestos, each instrument was used to sample the dust clouds of both materials. 1) The thermal urecimitator. Air was passed through the thermal precipitator followed by & membrane filter (Grade GS with nominal pore site of 0.22 microns). Before the sample was taken, the system was run with the thermal precipitator col to obtain a deposit on the membrane filter with which the later deposits, if any, could be compared. To make the dust risible, the filter paper was cleared, using either the methods recommended by the Asbestos Research Council of Great Britain or the U.S. Public Health Service. From the photographs shown by Dr. Rendr.ll, it appeared that the only particles likely to penetrate through the precipitator ver aggregates and these arc presumably non-rsspirable. GAF 16958 .c CD: . . . ' ' . / ."t thi** r c)'X.*i<v. :: to i " e c to c:-\ ': t .. _ r In: i. only ir. i mo s? pressed out to relics? the rlf tes for -.-ire protectcr .as re.r.cved Iron the instru.--.ent as this v:as found to collect t. henry deposit of fibre durir.p sampling. It wes observed by Dr. F.er.dall that ;?s this should have beer, left in place in vie:; of the interception effects de.~crifc?d Vy Dr. Tir.trsit earlier in the conference. To check whether the instrument -.:as functioning correctly, a snail quantity of glass heads of size less the-. !0 mi evens was injected into the dust clouds end passed through the elutriator. The respirable- fraction :;as collected on the neabrane filter held in the holder designed for the purpose vhich is being used generally with the fcexhlet. Froa the evidence, it appeared that the horizontal elutriator is suitable for elutriating asbestos dust, providing the entrance to the elutriator is unimpeded by protective or flow straightening grills. 01 "0204379 3) Iaoinrcr. The MSA midget inpinger was chosen to represent this class of instrument end the filter was inserted into the return air stream. The instrument was operated in accordance vith the instructions obtained in the American Conference of Hygienists publicttion,"Air Sampling Instruments? except that a nechanical pump was substituted for a hand pump er.d the air flow neasured with a suitable rotameter. Sthyl alcohol was usei in the ir.pinger and this was found to be cor?let*]-/ unsatisfactory as heavy deposits of particles end fibres were found on the filter. Further trials were made using dust-free distilled water er.d detergent, GAF 16959 dust. Tie lev resistance five micrcr. pore si:o rmn'orane filvt? ippci.-,,c be suitable for sampling asbestos dust clouds. Based on this experimental verk, the standard thermal precipitator vr.s rrcc_:cni for fibre counting. For total gravimetric measurement the five micron port size membrane, and for the respirable gravimetric measurement, the horizontal eiutriztor were suitable. Comment: A point ves raised during discussion vhethcr it vas necessary to justify the use of the thermal precipitator vhen the membrane filter vas obviously more efficient. In. relation to this, one might connent that vhen collecting dust on the thermal precipitator it is often much easier to regulate the flov through the instrument than it is vith the membrane filter end at low flows this is important. In addition, no clearing technique is necessary as vith the membrane filte One criticism of this work night be that the testing of these instruments, appeared to have been carried out under extreme conditions. All the filters appeared to be too heavily laden vith dust to carry out dust counts and the efficiency of these instruments may have beer, increased if they had been tested under conditions in which they vould normally be used. The efficiency of the nidget impinger may have been increased, end also a 100J5 efficiency nay have been achieved 9 for the thermal precipitator. /I - \\ GAF 16960 c: o. Electr i-vicr ?tV.j c1 lur.r s a j. i c... ri:c ey.nfici to toe UICC crocicol'Te and a.r.vr.o_.'.yl' i oe shc*et tt c dusms to be styii~ht t-i the cb = i.-v;.' dif-.c.te:- uniform ovor toe vhcle fibre lsr.gih. The FJ-.oiii.e- fibres e:iubited j. rfcct-.n-.ylvr Feet ice, the croeidolite fibres p-n ell::t:cal or c: rcr.lgr cross metier, vhile the er.thcrhv 11it = fibres vere thin flails3 , often thir. enough tc r_-eo- - tror.sps.rent. The chrysotilc fibres vere marhedly different, the fibres being curved in a variety of shapes. These fibres consisted of bundles of very fine fibres, usually partially opened. In the rat and human lung sections each type of fibre c tended to occur in bundles, the longest fibres being observed in the non-cilli?.tsd regions of the smaller air duct s. Fibre length: Asbestos fibres in lung section have considerable length, which can greatly 01-020M 301 exceed the dimensions of the particles of compact shape such as those of coal or silica in similar circumstances. Since some of the fibres can be longer than the' field of the electron microscope, the cxeninations on length vere performed mainly with the optical microscope. The longest fibres usually appeared to be in the respiratory bronchioles and alveoli ducts, and the fibres in the tissue were shorter. This observation was confirmed by measurement of the fibres in these regions. The fibre dieneter distributions reported, shoved fibre in the alveolar tissue to be o shorter than fibre in the air ducts, which in turn was shorter than that in the dust cloud. The feasibility' of long fibres penetrating the lungs and reaching the pulmonary air spaces vas expimir.c-i by the fact that the falling speed of the fibre depends on its diameter and is not vary sensitive to length. A long fibre, if it is short and it II GAF 16961 th::: e-.c.-;v,. c;:: t-vsi; bzi::; Ik iv.iy gr- it-z:r..:; :.v. zv i.:_.-Li'_l ob: er:zi ;i::. cl lo:-.- fil.-i i.: thr- ir:: Ir..".:z'-.ioXij ii i : r..-_ probability or & fib re inters*: ti:.-.; t-.s v..Il cf-rr. ra.-.?. lcs:.:;s vith ir.srzrsj ir. fibre ler-gth :-r.l C:.:..c- ir. ci;dir.v'. zz. Cr. v, vhcrezz ir.. :r I z z iz no., i:.rsri:..:v in tit- orzcr.c-s. r.vr Iz-'j-r zirz.yz, ir :.s very efficient deposition meckr-mirm zor Ion; rir.rez in the sz.zllzr eir i/i. Fibre di~-.g\ar: Electron micrographs or Ez.izzrz suygsztzr that crzoido." : us iz : ?:; than f.-zcaite, which is r'.ore slar.z'er thin anthegky 11 i t e. Fui-ti.:.-, the rizci- ri.v-. of the anthophyllite is thicker than that of the anosits, and the a.'tz:`te is thicks.. than that of the crocidolits. The same impressions were obtaired from nicrzg-wri.s of the UICC dusts, industrial dusts, and human lung sections. There observetiers vc -e confirmed by measurement of the diareter distribution of the fibres. Chrysotile appeers to follow a. different pattern, as the fibre occurs in bundles and the diameter cannot be accurately defined. Fibres appeared to have a definite nir.iiir-um diameter as follows: crocidolite O.Oo microns; aaosite 0.1$ microns; and anthophyllite 0.2$ microns. The diameter distribution for crocidolite and emosite showed peaks et 0.2$ microns and 0.$$ microns respectively. The points in the distribution diagrams for anthophyllite show considerable scatter, which suggested a multimodal distribution The agreement which ves obtained between the resultB for the UICC dust and those for the rat lung sections was not surprising, since the UICC samples were prepared to contain in the main fine fibres of which a high proportion would be respirable. The reason for the similarity shown by human lung sections and other samples ves not so obvious. To examine the possibility that this was due to the fibres of each type of asbestos possessing a characteristic diameter distribution, a comparison was cade of the UICC dusts subjected to different mechanical actions. These included the actual UICC samples, the raw materials from vhich the UICC camples had been derived by grinding, and the UICC dusts which had been irradiated in an ultrasonic bath. Larger GAF 16962 2`- tv.'. -C e; "'.pmc-d. 7c.* c-r 'yc; of i o z. ~.iz~ -t____ _ ^ tr.i tii . .17., it- . Eir.eo bfccc c'.ir'.ricv.; 1,'...; ry r.'.v.'.f _, rc: ;vi.i ;* v,.- - ,, tirtrrlif fmm the re/ r.L:eriel hai its grtr.te..* fecc on the cce./;.c tr.:. of vhi distno-:.cr., c.. . evo.. here :e s:.a31. -hr h\v-.:.n Jury sestrc-.r vtro z'l. the Et .: 5eocra:-:-.i:s.i distributee,:-..- ao the 'JICC i/sts, the croeicclitr j Province), r.-.OEies (Trp-nsvrnl), Enohcyhyllite (?:chilla, 7i.-;2. The result.-; i'.iicftel thoi. fibres fro:, a ~ivcr geogr'.phic'l locc.tior. comminute ir. a d=fir.'.;t fashion, and, ev:a after differe;.t treatments, emr. it it characteristic fibre cistrih..' The diameter distributions v:ere almost stable at the iorer end. Tr.is vas ierjlained by the fact that agents that operate to ramove particles from the dust, for insutr.ee, the deposition, mechanisms in the lung, shev at least size differentiation in the snail diameter region. Examination of other fibres including trenolite end actir.tlite indicated that each type of fibre has a characteristic diameter distribution, vhich depends to a limited extent on the source. Australian crocidolite fibre contained a higher proportion of fine fibres and the finest fibres vere of smaller diameter, 0.025 microns, then the crocidolite from Cape Province. The diemeter distribution, hovever, vas similar. Examination of the frayed ends of the chrysotile fibres has shovn that these consisted of very fine fibrils. This structure has also been seen in the nein body of tbe fibre, lleasurenent of fibres vhich appear single gave for the elliptical cross section a range of ratios major to minor axes froa 1 to 1*, minimum value of minor axes 0.010 microns, and maximum value of major axes O.OhO microns The mean value of the observed diameter vas 0.025 microns. Identification of types of asbestos fibre in the lung. GAF 16963 The identification of fibre types requires the use of evidence acquired fron different methods. The authors obtained e high success rate using diameter distribution as en aid to identification. The location of the sections in the lungs for this type of examination vas found to be unimportant. In examining a lung section for identification il rvir*jo-- th cr-since of long, curved asbestos fibres is a positive indication that the iu-f-5 CCtdainf cnrysotiie, as is the presence of flores of 0.&25 nicron diameter. * v -- r ic r c- . c:' hfr/l.-'LVj this s .. but irp::-t*-:t to c..viv. : - r ' i . :-r-; ' v.-.-s co:.d':r*.i-- '-'cl:;:::-' ' ; Stroles of rii; = d fibre verc- collected personally fre.u c :'. cthe f esbestos r.ilis. They vere collected ir. the last stage of rroces-'ing :afore bsggir.g and pl=ced directly into polyethylene tags. This avoided possible contar.ir.aticn by jut-: oils as described by Harirgtor (Ar.r.. !!.T. Acad. Sci. IS Id g Twenty and fifty greco quantities of fibre were extracted vith benzene fer six or eight hours, cvatcrated to dryness and redissclved in cyclohexane. The solutions vere in scr:e cases distinctly yellow. Ultra-violet visible spectra vere obtained for each e:-rtract on a 3ec!t=cn D.K. 2 spcctrophotcreter. An absorption pet!-: at 421 rji vas found for extracts of ail sar.ples collected in certain polyethylene bag3 (to: be referred to as Type A). Extracts frer. the other sarnies collected in bags oct ained frer a different source did net show ar.y absorption peak at this vaveleng GAF 16964 In an atter.pt tc; isolate the conterinating yellow substance, a nutter of polyethylene begs (ty pe A) vere extracted with cyclohexane, but the extract obtai did not absorb at l2i r.u. This suggested that sene reaction vas taking place in t bag, possibly catalys ed by the presence of chrysctile fibre. This vas confirmed : extracting sar.ples c 1" fibre until no further yield of r.atirial could be obtained and-replacing this ft,bre in a bag (type A) for two days. This fibre vas re-c::t:v.c I- U;~ : A). The e;:t,from the 1G1 ' 3s jrr se.rplf-r' -'er; ocni: = -;.:tiy -.:cr p'.-.r..-. these from samples in polyethylene f.r.5 solutions of the ei.tre.cts shoved ::c absorption yeek at 21 r^:. Three analyses of UICC (Internationaticnal Union Against Cancer) standard camples vhich had bier, stored for at least one year vere analysed and chrysotile A end B gave yields cf 'oil' as high as 0.tl;5, both with the strong absorption peak i;21 np. A sample of ar.thophyllite (UICC) also gave a high yield of 'oil' (0.2L5), but only a very slight absorption at 1*21 bji. O1--02043B5 About this tine 3.T. Commins (M.R.C. Air Pollution Research Unit, London, England, personal communication) observed the same phenomenon with other UICC samples, and isolated a quantity of the yellow substance vhich vas identified as 33* 55', tetratertiery butyl dipher.oquinone, probably formed by the oxidation of sone antioxidant present in the polyethylene. It is important to note that this compound vas identified because of its colour er.d striking absorption spectrum and other compounds may be present vhich have so far escaped recognition. cd ir. lyffthylcr.fi r.2.y therefore bccor.c cont?---.f.r.!,-tcd vfth 'oils' vhich are nearly alvays present in polyethylene, additives from the GAF 16965 ;-- ;' w.-. . .`..`-c: r.ol;'-. .; .: e.. ' ;r */ j ri'-c *` r , 7 i ' * - tr-'j-'i c hr Id :'-i- ; V - , . rxt:. -:y .'-yc.- -ent ^ , s. . t.cc :........... :: - - r." e;.'--'- . `b ' * *' ` * - . - C ' t, : or sr.t: t. i::-ir;: - .. .car.. At ..v t: -c-tb:':-- :>c : . be versi'.he :c the pclyethyjen ciy (a) t herns el* :s act as carcinogens (b) enhance care in*, gen ic r.ctrvi;; c subs te.r.ces sueh es trece -T.ets.ls, asbestos, or associated oils !c) inhibit c: of carcinogens cresent in the fibre (f.) have no influents or. biological cct whatsoever. A f ifth possibility perhaps worthy of co:.sicv_-*>tic:. is that s.hs of oils of a"y type ray affect biological action. It is veil known that the properties of certain ores are affected markedly by traces of oil. This is presumably due `to the hydrophobic nature of the absorbed oil and it is toss: the presence of natural oils, oils absorbed during processing cr oils ebsori storage in polyiethylene bags r.ay interfere with solubility or other physicochemical properties of the fibre. This would also influence studies of asbe: in anir.als as veil as studies of carcinogenesis. Samples of fibres used for animal studies should be examined in the li these findings, and polyethylene should not be used for the collection or s of asbestos fibre which is to be used in biological tests. GAF I6966 Graham V. Gibbs, 3. Sc. McGill University Peoartr.er'1. of rpidericl 3775 University* Street Montreal 110, Quebec, C cv ' .. c C".: t>... a.-r-:z?u rc-.-wi. T.-j fil-rj vw riJc^al rA-.; :'v. C.r: lev tn lev :v!:. !.* r bn-vr. ;;:.rti-iir;- ' V-uv iv- r' i'A brnirv.l.'-;- = r..-'. cpiru bios tr.' o cuvty ore or* it r.c-t .-nshe.l. A hi;;b proportir... of fir.r.r. pro .'.'ice-A dv.rirj '.If s'ci:. - vnder.prcv.r.e topether vith fluff rirr-.- v. vlifr. c.1 wive >v_r. tivc*. tV.is is off e.ncl dries. vdov2 v cw be _y^r\ ;. -tp; other era. frynrs tan solver- provido 5. typical Cunt pr-obleCrvnr. nre are r. rutnrv cor.n-r. rzi notoriously difficult to dciurt. th.2 ere is crushed to -3/i incl ir. hau.-vsivsills to release o.r<i fluff the fibre, "ibr* is tirurshei iurir.-. E.Toirr.tieu eni co.Msntei in the nyeioo :s. Ihist collsetiou is curried out usir.p fe.brio tub vs sr. filtering s-enia. Ttilirp di.v;"ii fives rise to lust; especially under sc-.r of thu dry condition*. which srs experiatcol it r.c.ve parts fouih Africa; hcvev-r, nth2 revs ere biir.n to .pre-ss certain err* t. ?ach.rpir.y has creat-cl *. lorpe pro':*; n-v. bccs.v?c the lcnpsr fibres have resisted all cttor.pts at r.achnnicel br.-^ir.- re this is still a hand ou-mtic.n vhich rr.-.?ins duttv it spite of ventil*.tie's heal?, enclosures, end berfirr eewJepM. il e V-tr.tit" cf jcr-r.ibrio fibres hoir.y rrcr.esive rasl.ri is incrcvvi Kv'iti-.v.ll pe.yar soc'-s five the cjnar.ont pact: pr.l sre the lerst dusty cf nil, aerovdirp c to the eutr.cr. tut thuir strenyth fc.-n bier found to be r.v.r;ii.nl end thereTcre prune to ox::,: tr e.-.hnlurirp thipr.euh. Hessian vit'i 3e?.J.j:\ polyythylens filu lir.ers van next hoot ml in r.vc'i stvo.-.pnr; this n,-t--inl in the r.ont favoured e.t prem-.t. GAF 16967 f *6968 Ql. follows: F Kg x Ka 100 Kg is the total particle concentration in T/cc end Ka the asbestos fibres concentration per 1 cc. The HS konixeter {sample volume 2.Sec) is used as the sampling device. The evaluation of stmoles and also the determination of KE_ and Ka are carried out usins projection microscopy (lens 25x; HA 0.50; ocular lOx) vith a magnification of 370x. All particles for which the ratio of length to diameter is greater than 3:1 are described as "fibres". For assessing conditions in a working place, the characteristic value for T for asbestos is divided into three classes: Class 1: F< 20, safe , Class 2: 20<7<60, relatively dangerous , Class 3: F > *0, dangerous. 01-020M389 A konineter sample will only give evidence about an instant dust concentration. Since the occurrence of concentration distributions, which in r.ost cases are log-r.crm Liust be tekeri into consideration, 20 to 30 individual samples are required for assessment of a working place or operation. The cost evaluation is thus considerable 1 ;o 3 c..' cf (Gravihc:., Porti/.er) for the deterr.ir.'/cion of r.r.ss eor.rer.tr;irr. ir A aspiration rate of the sampling instruments used is ehout I. 3 meter per seccm. gives approximately the sane velocity as encountered at the hu-'.n nose. The au'.r.c consider the advantage of the gravimetric r.ethod to lie in the fact that it is possible to evaluate correctly the average dust concentration over a long period c. tine, as a rule, several hours, and that large quantities of dust arc obtained for analytical purposes. To associate the gravimetric method with the asbestos characteristic value F, vhich is based on a particle numerical determination, extensive comparative investigations were carried out in the asbestos textile industry. The relationships found between the mass concentration of the total due in mg/n3 and the asbestos characteristic velue ? have been correlated in Table I. These relationships are valid only for asbestos textile industries in which the asbestos content of the mass concentration of total dust has been found to be between TO;* and 853. The evaluation of the asbestos content is effected by the authors by heating dust samples at 700? C. The residue is considered as asbestos for the range of the asbestos textile industry. The orinciole of assessment accepted ; the present tire in Germany is as follows: If the asbestos content of the processi raw material is below 1C3, the total dust concentration should not exceed the veT of 2 mg/rA i* the asbestos content is between 1C;1 and 50', this value should r.ot GAF 16969 > 1.0 - v. 1 i : Cc _ Dr. !>i: .;s ci fei"-'" :'cv t: * r: he cm ; . V zZzzr. z: Z: i. . z~ v--i vcrv :1c*. * -<n -f:.t:; v.vd Iriu:.-.:.. The :t-; cpprc: iV- 30 her:. .iter sr.r.plss per 2 : cr'i leer;ii. iyr. ~ following r.;.-ht le r.-.nf.e ths rethed of cvrlrvtir.p : -tea cos. I'- cl were heated to TuOr C for sens tir;e, quite ser iev.s docc-.cjcsitior. of the fieri CCV. i:. occur. Loss of water in the .noleeule could result in a decrease in the eseeetr content. In addition to this, there could 'oe minerals present ir: norms.! assert textile industries, which would also remain even after this heat trentrant, an perhaps is not the best method to determine the asbestos content of the dust. Evaluation Class Table I Dust Index F KgKa/100 Total Dust Concentra tion (ng/n3) 1. Safe II. Relatively dangerous XXI. Dangerous c <20 20 - 60 <^0 o.l 0.1 - 1.0 1.10 GAF 16970 The e?ti:~;~ior. cf chrysotile. It was rec::;v.er. r.=a by the author5 that sentrane filters ere better b:-e: . they attach nore ir.ecriar.ee to long fibres. The ther.eal precipitator, of which the lor.--rur.r.ir.p one has been generally used, has been shown net to be very suitable for asbestos. C-ravi.netric and dust counts should perhaps both ce carr out end the relationships between the size and shape of the particles be tsher. into eccount. GAF 16971 ( GAF 16972 Ic: t.J. r ............ 1.` . 7. : r . c; vit; , 1-T 1, V T-- ~ . .. _ _ .**._. ' * . daLerci.-.?.. ;on, r:::. r:: in th-- pr.-t st ie^.-l 7 :.g ef ash. (.'ofc.y > : co.:3i- :r; i i y:. .:.) 7..ir led to the dev; lop___ ; of 1 Vi 1 at `-he h/ r.:. ... .... - , r.. t>. Vi ,,,, ... , .... .. . .... elutri-vtor '. a.5 tahe.-: as : pre3=lsctor for tl.; F71-D:-''.r:y :;v: vhi.v- -..V.' c quantity of 3 n-/hr. of air folic-.-; the Johannesburg re ec-v .or.: -or..*:. r-vl..;- principle of coarse C\-.st separation vas foxlo-'ev during the design of the 7.-.7 7. The coarse dust separ;i.tor vas a cyclone of an artificial, resin casting vith alur.inu-. povder. The :quantity of air suched vas 12 n^/hr. and it *.:as also produced by a cor.pres =:ed air ejector. This instrument, contrary to the Johannes:-.- recomencations, scrrplltd fever particles in the entire respirable size range and also relatively fever perticles in the coarser range of the respirable dost. The KHE gravir.et:ic sacnler gave on average a 5-lx higher concentration =f fine dust than did th*: EAT 1. The last ir.strusent v3 the SAT III, vhich differs the previously descril:*d instruaer.ts in essential respects. A second cyclone coll the respirable fine dost instead of the filter. The fine dust passed by the first cyclone goes into a second cyclone vhere it is separated in a dust container. Or.l the ultrafine dust, costly particles less than 1 nicron, pass the second cyclone into the opes air. Th-s sizing processes in both cyclones remit the collection of the respirable dust a:icordir.p to the selection curve far the prototype with an ai throughput of 5 sVhr,. With the EAT III, a concentration of 5-lx higher than vit the EAT I vas found. ;-.rair.st the filter devices, the EAT III has the advantage th the high tr.i unsteady pressure loss by clogging of the filter is elininited; a constant pressure ire-- of ICO am vater guage suffices to operate the ir.sLrur.int. GAF 16973 C-. c?; r.:*: C 16974 - : ^ - :: pm ;r; ; ; r eif-c. o:.w :: o'- v:.sr:.i.l : roc ip itt.tr.: "it!. or.'.r; c:. cu-c. tir.g re-:i:'o2 p.r..i.= :v: fill:-:.: s-.-nlc-- zo 1: me':: : v:ivzly on i'.: e?-..- . I.'de. ~ r-i.".:.. L\ i . c" grt-vlmstric smuulin: es opposed to thorn: .a*. pro-ipizazinn ire it vas concluded that the asseeer-.ent of thermal precipitator s:-".pier Mr.'. provided the most rapid and convenient, while least expensive. : del or. .'fr. ^ the significant parameters of dust produced in gold mining ope:r-.uior.s. The recommendation uas made at the 1959 Pneumoconiosis Con.rerenci th-t - surface area (FSA) vas the most appropriate measure of the her:..fullness of a czirce dust. In order to fulfil this recommendation, an improved tech::ique vas required for application in gold mines. DI5A was developed. In addition, e ::e*.: sampling ir.ctrun-z-r.P vas required, as the .characteristics of the konimeter made the instrument unsuitable for RSA determinations. A codified thermal precipitator vas deceloped, and this is still undergoing tests. The diffraction site frecuency analyser (DI3A). When light is diffracted 'ey a hole in a screen, the scale o' the far field pattc: of diffraction is reciprocally related to the sice of the hole., This is know, as a reciprocal property of diffraction and forms the basis of the ;rarticle size measurene: in this instrument. Vaer. many holes are present or. the screen. their diffraction patterns are superimposed on one another. Provided certain assumptions are made concerning the shapes of the holes, the composite diffraction pattern nap be re, as a representation of their size distribution. From this information, the site tion can be computed in more familiar form. GAF 16975 !' C - -- * - - -- > c- : -:r - * thei. " :Tec.A *r._ c. cl in t--.rn is positicr.id e.v _ ; ic?.j1.y in -.V. DIS.* rossurts the projected rvea of the si.'.ple, so it is alro neses: ;.;-y -o l..:.: hov this crer is related to ISA. DIS.-. *= 3 crlior?.teI r.orr.ally or. the ;; sv.r.tktV. the TSA vas ix the projected area. The se-TO.irir instrurent. Operation vas naie as sinple as possible and only one control vas fitted. This advances the slide, closes the hot vire circuit, and starts the purp. A volune of air of 50 cn^ is sampled over 5 minutes. The hot wire current is controlled electronically at 2.h aiips and up to fifteen sanples ney be taken on each slide. For sampling only the respirable fraction of the dust a particle size filter of the impingement type (Jacobs 19=3) could be used. This filter vas not necessary, as it was often preferable to do the size selection optically by rear.s of DISA. Determination of resr-irahle mass. GAF 16976 There is sous evidence that hamfullness of quartz dust ray correlate r.cre close!; with respirable aass than with ESA (Goldstein and Webster, 1966). The respirable mass cannot be obtained in or.e direct reasurerent with DISA the sane way as the HSA. The be that can be done is to record the TSA and ESA'and obtain the respirable rass fror. the tables. When particle size selection is used to sample the respirable fraction only, t`. total respirable rass cannot be rezsured. A further disadvantage of this rethei is tha the coarse particles which settle on the slide during handling end storers contribute to the Bcasu.rcr.ent, thereby giving en artificially high result. With DISA, these ccars c c-- to -::C r t;- hr-lo:- >:c : : crie..'. ?.tir *0 : so c r.-;.;;.* c: 'jrc. _cZe: , \\wt. ; :-v gi v-j "?scs to svr: GAF 16977 r;' - : c c 'i , c`.r? c:. \ . i _ rc.-m.'i.-.: h ? __c r . * - ...i j 3 .* .* *i -- Z'/. u vcj"1. *. c r 'C 7 \* i _ * rnr . .zz to..:-.fII pv.p is carrief or the Inch c-i tl- zl with the sr.-.plir-g dev:Ire over the shoulder. It appeared to he srrv.h-.t r.zr-. than the C?sella or Vr-ico instrument? , tut h?d sene advantage, according to Dr. Hi~~er.s, ir. that the zisrts were not accessible to the operator. Comment: The use of perse:zal air monitors should be increased. The level of dust exuorur of the individual may often differ markedly from the general etmosphere dust concentration, and this has been our experience in the Quebec Asbestos Mining Incur zr;, as well. It is possible that often 'individual susceptibility' nay to sens extent be due to the large variations ir. dust exposure of the individual. This'nakea it difficult for any ;Lust exposure indices to be particularly relevant to individuals, and cer. only be succe:sfully applied to a large peculation. Dr. M. Jacobson ::f the United States, vho presented a paper on bituminous coal :.i sampling, took sables with midget inpir.gers, the 132 ser.pler, end personal air monitors which utilisesd cyclones. Men were trained to take gravimetric samplers, parse air monitors, and aic;jet dapinrers ur.dergroumd with then. A stationery sample was talcs using a personal monJtor in addition to semclss taken by supplying personnel with the monitor. This paper did not present much data, tut the principle of multi-type sampling ray be a useful one for further research. work in ell dusty areas. GAF 16978 2c: all respirators protecting against radioactive dust, bacteria, viruses, snd also dusts of the sen: or s. higher tcxicity then berillium. Stage 3 respirators are used for suspended ratter, vat cur and gas mixtures. They have a suspended ratter filter and a gas filter, and rust be used for all dr.sv.-. or mists vhich have a high vapour pressure. Respirators of Protection Stage 2a are subjected to respiration at the rate of 20 strobes per minute of 1.5 litres in an atmosphere of quartz dust and air vita a concentration betveen 3 and 12 thousand particles per cc. The test tine is one hou The efficiency during the first 20 minute3 of this testing period is measured every minute by means of a tyndalloiscope. The filtering performance of a respirator is considered to be sufficient if the initial separation efficiency of a nev clean filt neesured by a tyriailcr.et ricsestt^nLight measurement is higher than S55 and if the average separation efficiency obtained from the values measured the first 20 minutes of testing time is higher than 9&>. Fine dust necks of Protection Stcge 2b mart satisfy the requirements for fine dust casks of Stage 2a, plus an additional testing vith a brand nev filter in a paraffin cil cist at a concentration of 10 r.g/n^. More than 90> c? the suspended psl*wiCi4 3 fG._ir. w.jC t uaVS & il 5-Mi til* --iller txicbll 21C2T5I1* T*tC frequent particle diameter should lie letv;-cn 0.3 0.5 nicron. The tect tir.e is GAF 16979 I.--, Co.-.- :-.t : Dr. Holr.es of tr.e Asbestosis Research Co'.u:cil raised the question of fitting of casks. He pointed out that the standards of S6,> efficiency neant absolutejv nothing vhen one could do tests on face casks and find that r.ost of the particles vere in fact going around the sides of the face cask during breathing. Dr. Kascr.cl or said that they vere fully avere of this problea, but the casks vere not tested vhen fitted. Ee remarked that three sizes vere available and that this vas net appreciated by many, so a suitable cask should be available for cost vorkers. GAF 16980 vcxe live'. t: . . use c..it f;/ -.i..: .-. : l:--' is extra: i.i in : \s cf tns product of f.L ru ...d.: c; vcrbed. Ine imde:: curdo give r.o'cr:.. tier. on the ir.viov m:.:...: 1 freter; .... von.', in. ~ yl?'., v. iecu 1'ibv..- x.o Vr.-i- dove-Ic .:.e..v c.' p cc..io - i.- , induce the durauior of work underground, as veil as d'-.-r- g: ;j ogre:.'. r . ~r; b i:.-: ' conditions. The ino'er.-.at: on giver, on the cards, especially the resents cf routine dust sampling, and the medical examination are important for correct deployment of lac our underground. The data on the index card is entered ared choo`:.'_ each couth. The keeping of records required one can for a labour force of 1,00" to 1,500 miners; whereas the keeping of cards by data processing enables cue ran to look after records for 2,000 to 20.CC0 ten. The dust is divided into three- categories end the tens' occupations into three groups. Age is teker. into account to some extent, and the pulmonary changes in vorkers deterrin; the group into vhich workers fall. The determination of the quartz content of the dust will be required only in the range of cediun dust concentrations characterized by the light intensity values of the tyndalloscope between 35 end TO and ssrples will additionally be taken with the BAT I. The papers dealing with this type of index system were es follows: 1) Hazard indices in 'Jest German Mines. Xerl Schulte, Federal Republic of Germany; 2) The labour involved in computing cumulative dust exposure for individual miners and the reaction of miners to being removed from one working area to another to limit their cumulative exposures. "arl Schulte, Federal.Republic of Germany; 3) Cumulative dust exposure and yr.iux.ee:miosis responses in German coal mines. M.T.R. Fcisner, Germany GAF 16981 to sig-ifderm; d.;;t '.;are filUr; 'cogs -Mth long fibre a: 'tcp.-.'. .. 17 ' b ; have t s ..bit art ini exposure. Most cf the begging carried cut in the mill is cf t;.:- : packed variety because there is a problem vith pres sr.re-p'. ;L;ic~ fibre, ar.d >!; carry of the buyers stipulate lcosc-puch.cd fibres. The hammer milling operrlicr v:-r fr:r fron dust although there might be a certain amount of expc-ure for mint?ir rrce perse.::-.-' vho have to replace the hatters regularly because cf the abrasion by the very hard erocidolite cap roc>. The conditions for contamination of fibre by trace medals when milling erocidolite vould appear to be ideal because banners are replaced so frequently. The screening and grading vas slightly different from the Canadian system. The mill was only two or three floors. Screens were completely enclosed and corrugated rubber joints were fitted vhere roving parts were involved. The system appeared to be extremely efficient ar.d no dust could be seen. It was understood from Mr. C.G. Hardy (Deputy Government Mining Engineer) who has been responsible for the dust control in these mills, that e new mill is to be built shortly, using a similar system to the Quebec mills. The present problems which are encountered controlling the dust at this erocidolite nill are slightly different from those encountered in the chrysotile mills in Quebec. The specific gravity of erocidolite ore is slightly greater than that cf chrysotile ore, ar.d the stages of fiber izi.ng appeared to be mainly carried out with hammers followed by screening, and involved in no way the complicated system for the GAF 16982 Table 17.3. Asbestos Fiber Concentrations During Use of Patching, Joint, and Tape Compounds (Rohl et al., 1975) Operations Number of samples Pole-sanding (1 to 1.5 a) Background (2.5 ra), same room Background (7.5 m), adjacent room 10 3 2 Hand-sanding (1 to 1.5 m) Background (2.5 m), same room Background (4.5 a), adjacent room 11 2 2 Dry mixing (1 to 1.5 m) 2 Background (3 to 6m), same room 3 Background (5 to 10 m), adjacent room 2 Sweeping floor (3 to 15 m) 15 Minutes after sweeping 35 Minutes after sweeping 1 1 Peak fiber concentration (fibers per milliliter) Mean 10.0 8.6 4.8 Range 1.2 to 19.3 3.5 to 19.8 0.7 to 8.8 5.3 1.3 to 16.9 2.3 2.1 to 2.5 4.3 1.5 to 7.1 47.2 5.8 2.6 35.4 to 59.0 0.5 to 13.1 2.1 to 3.1 41.4 26.4 269 GAF 16983 As is Che case for nose asbestos end-uses, the largest environ mental disposal of patching compounds occurs when products are replaced or demolished. Service life-time may be for many years. In most of these replace ment scraps, the fibers should be bound in the binder; however, removal may cause an undetermined percentage of the fibers to become airborne. Wetting according to EPA demolition procedures should reduce airborne dust concentration. Re placement scraps are normally hauled to landfill sites for disposal. 17.1.4 Alternatives Approximately one-half of all patching compound produced in 1976 did not contain asbestos. The percentage of non-asbestos patching compounds will grow due to the CPSC ban. Therefore, asbestos replacement in these particular compounds is not only theoretically possible, but is Indeed a commercial reality. However, many commercial users of non-asbestos patching compounds believe them to be inferior to asbestos patching compounds. "Por commercial application, manufacturers consider asbestos to be a critical constltutent which contributes to the workability and ease of appli cation of the compound and contributes to the appearance of the finished wall joint. Efforts to substitute other materials for asbestos have generally re sulted in products considered by professional dryvall finishers to be Inferior in performance and require more labor to use" (Kearney, 1977). "Formulations are closely-held secrets and have been developed after years of trial and error research and experimentation. The few formulators who were willing to discuss their work admitted a certain lack of under standing as to why asbestos uniquely seemed to impart the qualities required for an efficient and durable product" (Kearney, 1977). 270 GAF 16984 "Formulators who claimed Co have idencifled satisfactory substitutes for asbestos note that asbestos could not be replaced with one ingredient. Rather, a complex of several compounds was required to optimize the 10 to 15 desirable characteristics of a tape Joint compound. Workability (thixotropicity), water retention, decreased need for sanding, and crack-free drying properties were reported as extremely important. Further, these formulators reported their asbestos-free products were fre quently more sensitive to variations of job-site tempera ture and humidity than their asbestos containing formula tions" (Kearney, 1977). 17.2 Drilling Muds "Drilling fluids (muds) are essential for drilling oil and gas wells. The use of asbestos in drilling muds is well-established and can have a signifi cant effect on lowering the cost of drilling and completing wells. Drilling muds are pumped down through the drill pipe and back up the annulus between the drill pipe and the well bore wall. When they arrive back on the surface, they flow over a shaker screen to remove the drill bit cuttings, and into a mud pit. The fluid is then recirculated through the hole. Materials needed to maintain the properties of the drilling fluid are added in the surface pit" (Daly et al.. 1976) "The main function of the drilling mud is to remove drill cuttings from the hole and to contain formation pressures in the hole. The mud also removes heat from the drilling action, acts as a lubricant, and prevents excessive hole erosion. The drilling mud must be such that it remains fluid enough to be pumped with minimum pump pressures. It must not be lost to the formation, yet it must overcome formation pressures to prevent Ingress of oil, gas, or water" (Daly et al., 1976). "Asbestos is added to the drilling mud to improve its carrying capacity without appreciably Increasing the viscosity. Other methods of improving the 271 AF 16985 carrying capacity markedly Increase viscosity, which increases pump pressures, thus reducing the power available at the bit and slowing down drilling. Slow drilling rates Increase drilling costs. Asbestos is used In concentrations of from 2-5 pounds per barrel (1 barrel 42 gallons) of mud" (Daly et al., 1976). "Asbestos is added to the drilling fluid through a mud hopper or large funnel. Initially, a volume of mud of from 150 to 200 barrels is prepared. As drilling progresses, additions are made to the system for maintenance and to accomodate the volume of the hole being drilled. Typically, these conditions occur only once during an 8-hour shift. The amounts of asbestos added are small -- rarely exceeding 500 pounds at a time1' (Daly e jlL., 1976). "Over 30,000 wells are drilled per year in the U.S., using around 1,500 drilling rigs. The frequent moving from site to site makes fixed control equipment for asbestos fiber exposure infeasible. A normal drilling crew con sists of four men working an 8-hour shift; that is, three 8-hour crews per day. Drilling sites may be miles from any population center and are subject to ex tremes of climatic conditions (for example, the north coast of Alaska to the Gulf of Mexico)" (Daly ex al., 1976). According to the Asbestos Information Association (AIA), the quancity of asbestos fiber annually consumed for drilling fluids is approximately 10,000 cons The shorter grades of chrysotlle fibers are normally used; pelletized fiber as well as loose fiber can be utilized. 17.2.1 Environmental Emissions Asbestos is added to the drilling fluid at the job site; there fore, manufacturing emissions, in the conventional meaning, are non-existent. During the addition of asbestos to the drilling fluid, an undetermined quantity 272 GAF 16986 of fibers becomes airborne. Release may be partially dependent upon weather conditions; for example, a greater number of fibers may be released during windy weather. Once Che fibers are encapsulated by the mud, however, airborne releases are unlikely to occur. Also, use of pellecized asbestos should significantly reduce airborne emissions. Lacking monitoring data, it is judged that perhaps 0.5:; of the asbestos consumption for drilling fluids is lost during on-site mixing, or roughly 50 tons per year. These releases will probably settle on the ground or be washed by rain, etc. from the air and eventually become stabilized in ground or river sediments. When drilling fluid is used, mud pits are usually dug or set up next to the drilling rig (see Figure 17.1). Discussions with drilling contrac tors indicate that when drilling operations have been completed, the mud is usually dumped or left in the mud pit and covered over with dirt; a sort of on site landfill. Occasionally, the mud may be transported to a new drilling site when the new sice is nearby. Airborne release of asbestos fibers from drilling muds would appear to be unlikely because the fibers are encapsulated. 17.2.2 Alternatives Asbestos is added to drilling fluids to Increase the density, to improve viscosity, and to reduce whole fluid loss. Asbestos is apparently unique in being able to add to all three of these characteristics of drilling fluids. However, many other materials are commercially used to give these properties to drilling fluids. Choice of drilling fluids is apparently determined by appli cation of the Individual job, soil characteristics, materials being drilled for, and cost-effectiveness. Asbestos apparently comprises leas than 2Z of all drilling fluid materials (SRC estimate). 273 GAF 16987 OriMtfif hot* Aimp Figure 17.1. A Circulatory System for a Rotary Drilling Rig (Huebotcer and Gray, 1965) GAp l69aa 274 c. i. T . > riser l:-.; to lr. Gil?':: of C-.-:'.:::', rr. cr.ir ".cl;- dust;- yc- :? hs:'d. c: c riled i - :-.i 3 1? . lore d t-.:-t r.rt in fc.:t visited the c ! : r.; s .. Tr . d-_ .pir.;.. cl fl: re lend?- to sc"? dus;, esproiaV'.y in. the dry cor.: it i vir.db];/ firro a:.d rcoh cost, the surliC; '.rill to vrcvtid tr.d covered vith The Gold reir.ee around J oh Mines burg have made rt.esr'table irprove...s"tc to the dures in this vay. Waste dumps have been flattened, and covered vith g-'ass. effect is crrtrerr.ely pleasing, ar.d successful in eliminating vindblovn dust these durvs. GAF 16989 Ef."]; lf.il- J-Ci-r 1 SC.:t 310. 'i i--.' Til I. the Slf-.i.vE -..W'.i.'. ' f . : ' , u:-:ci for i'.c deter-J.nnticr. of cUi3t concentrrtior..*. in the C;ucbec .-irs iiicv-itry. Tt's mct'.ccl was svi;.plid by Hr. II. Lachance. S vsr'.'y the f. -E'.---- techriiqja huve no.. been tuber. in the mills in Cyprus and their; -.-ere d.'.*cvr..- ;i. . limbre11 described the appearance of tha fibre in some of tb.es-? sr. -_>r. a. anc'i it vas agreed that he vrcjld send sene samples to Canada for us to co: ;'rr type of airborne dust found ir. the ttills in Quebec. The storage of the U7CC (International Union against Cancer) chrysotile samples '.:es also discussed. Dr. Ti told r-.e that large samples were originally !<=pt in large paper bags in Job innerbur Dr. B.T. Comins in England who I visited on ny return Journey fro-. Johannesburg, said that these paper bags samples had beer, in polyethylene bogs at some time and this is why small amounts of the diphenocuiroae are reported even in specimens re stored in paper bags. The presence of the diphenoc-uinone present in the paper bag. samples reported by Dr. Tirbrell in his paper at the Cor.ferer.ee did not near, the dipheno<;uinona originated from these bags, but rather that these samples had been stored at some time in polyethylene. The majority of the samples, which were shown to r.e letcr by Mr. R.E. F.cndall, were stored in paper bags and the UZCC samples r.o being distributed are in tin cans lined with brcr..-n paper. The trace metal contents of the U1CC samples were a subject of discussion by a number of delegates to the v GAF 16990 I C'j: *j ' ' ? t C i'--r r.i :. c." C' '-.tcr.ixc AbscrmLion Dr. Cm] lay 795 om l.x-'::: 4 -'3 ppm Atomic Absorption (E;:dar.iology tad Health, McGill) 7S0 ppm 2. IV, 475 ppm Activation analysis (Kart-ell) S90 ppm 2. 6?: 510 ppr. I The analysis reported by the Department of Epidemiology has only been carried out once, but will be repeated shortly to verify these values vhich should be tahen as tentative. Dr. C.G. Addlnalev and Dr.S. Eol~.es - 3ritish Asbestosis Research Council Ip. the survey carried cut by the Department of Epidemiology and Health in the Quebec asbestos mills durins lest year the thermal precipitator had been used as era method for the collection of asbestos dust samples. The publication by the British Occupational Hyjitnc Society of reference hygiene standards for the vorhinj e-.vironmar.t rupcsctsi that the thermal precipitator vas not a suitable GAF 16991 1 n.. Sc titty. 7 c vis he. ee in agr'.-u. :-pc sc eke Conference. I .-'<3d Drs. Kol* 23 rnd Aicing'.ay checker reass samples ;:rre likely : oi urea in future for Chi collection ar.d control of esa isros fort. ireV. lad that the horizontal elutriator mhich he lias used for tine col faction of tr r respirable fraction of asbestos dust, led to problems of clogging. '.'.e vns alco worried about the fibre released from the elutrlator ducts by vibration rnd sampled together.with the respirable fraction. The use of glycerine to ratair the non-reso^rable fibre ir. the elutriator was r.ot a solution because it tended to increase the clogging effect. Dr. Kolr.es thought that the most suitable mass sampling instrument was the TIRE sampler although it did not supply c large quantity of duct and so night entail caroling for considerable periods of time in the less dusty areas. Although a method other than dust counting mas desirable, r.o suitable technique existed for the determination of fibre other than membrane dust courts. Dr, J.S. Paring ton - South Africa Institute for Cancer Research. Johannesburg Discussion was centered around the prosar.ee of oils end maxes in asbestos. Arrang'-juts wavs made to obtain t"0 large sa-ples of C'-T/sotila f;b>a from the Trans veal. One of these specimens will be shipped to the Department of epidemiology ar.d health at '.'cGlll University and tha ccher mill be broken open GAF 16992 r . . i - - * - - ' ; \ ; :* /ic/r . r . . . S' ' of croci' '-li. i by 2. .1*0 J-.C I r./.-= :'i. J. c-vfcn. 1. encountered by s;:o*:i}3 /.is Sir pies of oil ir. ce siccafors :zz discus:: 1. 0:1 allowed to in \;ei3*-:i/. j v trials ir. caiiccf :ors rich phSip'.ertJS ;t. l.v a: I'orsic'.r.t c ccraftjsd in quite r. f'.ly 017 ir tha per iot of several day.-: Possibly this is to a radretion in vapour pressure sc.d the ev.-.t:'.-.-.:si alion of the compounds by the dessicant. Ia Ccnada samples have act he2.1 store:' in desiccators over phosphorous psntoxide so this problan has not arisen. X bare11 a~ procedure for treatment of specimens of asbestos for oil analysis, and the very great problen of suitable containers for storing the fibre were also discussed. At..the present tir.a he keeps all samples in paper bags, and avoids the use of marker pens or grease pencils because of the likalihood of contar.ination. Dr. V. Tlm.brell feed 1'r R.E. P.andall (?R.U. Johannesburg) The possible use of D.I.S1A.* for the sizing and counting asbestos fibres was discussed. Dr. Randall agreed with na that the instrument did not appear to be measuring surface area as was described in the paper but only a rough approximation to it based on an assumption of particle shape. Dr. Tinbrell felt that the ratl-.cd night be applied tc asbestos and was going to have further discussions with the manufacturers of this instrument after the conference to investigate this potential. ''Diffraction siac-freqv.oncy Analyser GAF 16993 &n. i. .> o ^ -1 , Cw-/*- cci >i .... l ;;.i: z. z ;, .. _. fishes in the lung /ay b:- :..ove renlist 1c. then to starth for th; p r a. c/ of ferruginous bodies, u-hicb pr&s.-nt so i.try pro's?/.s cs to th-:.i.- r.rtvr?, .--..i r/- difficult to analyse. Th? elccrrm-microyrob? or.i ol `ntron r'iffv.-.cticn v.c'---: t. ( applicable to such studies. Dr. J.C. Kroner Phau-occniasis he/errch lr.it Cardiff (V.-tlas) I spoke to Dr. J.C. issuer with a viv: to subsistin' that naw sample-; which had only been in contact with glass night be suitable tor any further a/.ir.a.l studies. !'e however expressed the vie-/ that the polyethylene conte.rinr.tion of the asbestos was not important. I attempted to point out that the presence of the absorbed oil right be note important than the dipher.oquino-ie, in via:; of the fact that the letter was only present in vary small amounts. He told its that Dr. Co/.nins had changed his opinion on the importance of this contamination so I raised this with Dr. Co.rmins when I was in England. He still .like myself had an open mind on the effects of these adsorbed compounds end felt that this problem would only be resolved when sufficient controlled experiments with animals 3how the effects of th contaminating cow-pounds to ba negligible. GAF 16994 Brief discussions vara held during the Con far erica with many of the deleg.-.tcs, but it is not possible to rop-rt ell those conversations.  -- -- ..v. e*. . of Lh: !'iyZ, cl V.i:'.-5 ,\:.i Lb ' i to i *. c rri: . cm . ......-> f' * * -s\t . GAF 16995 / I! // . l-.V. le.'nsi: 7hi F j: cr\ if ; : iter'.' 're Inst:'-;-....c- s:' Cic.'.t-. Fnviron: . ertal I-iealoh n-.cc viiii : v:-ic- i-.'oslreal, Quetsc l>, i?6? Dear Sir: I vish to then!-: the Institute of Occepe.tior.il er.d E.iivirore:.entr.1 Heeltr. end the C.uebee Asbestos '.'inir r Association for mahir.g cy attendance at the Inter.-.etionai Vonfertr.ee on Pneurcconiccis in Johannesburg possible. The enclosed report on the nesting considers prcblens of dust assessment er:d control only end attempts to highlight the r.ore important end xost recent edvences in this field. GTCsjh Enel. Yours sincerely, C'/ W/ Graham f. Gibbs, S.Se o \ GAF 16933