Document 1N5RB6epe5zLbxYw0GV805Zd

. .",- .:.,.~" Information Circular 8639 :J. . . :";--.-- :...;;,.- ....... 41 , . " . ,-. Proceedings of the Symposium on Talc, Washington, D.C., May 8, 1973 Compiled by Aurel Goodwin Metal aDd Nonmetal Mine Health aDd Safety. Washinaton D.C. ."" ~~.. ~~.."."~l , ...,..... .....:,. CAM-16 UNITED STATES DEPARTMENT OF THE INTERIOR Rogers C. B. Morton, Secretary BUREAU OF MINES Thomas V. F.lkie, Director !ZY'PItf. D t)eft. EJrhIIItt No. 8/ _1.0. Patrlel. Ruby. H.P. r-/.2-TI wtt:r.a ...2i~~~~ 1 CONTENTS Ab s tr ac t ........".................."...................................... _ lntroduc tion.......... , .. , .......... " ~ ........... " .......... Opening Statement. by Donald p. Schlick .... "........................ '" '" Opening Remarks. by Arthur P. Nelson.................................... . Mortality Experience of New York Talc Kiners and Killers j by Morris Kleinfe ld ... , .......... _......... " ... ,,Sf""~;, " Characterization of Talc Dusts, by a. S. Lamar ............... 11 Characterization and Occurrence of Talc, by H. T. Mulryan .... Discussion of the Mineralogy of Industrial Tales, by C. S. Thompson Experimental Studies on Biological Effects of Tremolite Talc on Hamsters, by WilHam E. Smith ....................................... IThe Biological Action of Talc and Other Silicate Kinerals, 16 21 q by Cerri t \i. R. Schep.rs...... . .......... _ " Applicability of Asbestos Standard to Fibrous Talc. nby William J. Nicholson ........................ Aspects of Kin.ralogy of Talc, by Arthur K. Lang.r .... II Mineralosy. Identification. and Quantification of Airborne Talc Dust. by T. D. Dulton....................... It ""Medical Aspects of Talc, by Richard K. Spiegel ............ ial tal and"; ,~ ales are -!at r, to le leneran, CHARACTER!STICS OF TALC DUSTS1 by R. S. L_~~ Ition, ch_- w111 be The Nat~e of COUID.rcbl Talc. It is important to make a clear distinction between commercial talc and I :~. mineral. Pure talc mineral is a hydrous magnesium sllicate havina the ;j",t'ition Ms. (Si~Olo) (Oft) 3 Limited isomorphous substitutions can occur .;':.in this structure. Crystal form 11 generally monoclinic. In41vidual accepte4 I .r::ctcs of pur., finely milled talc appear platy or micaceous under the . r. secpe. Commercial tales . .y or may not b. pure talc mineral. These products are 'T:.-nly mixtures of talc mineral with other related minerals that vere ::...b'ed in the paraseQuia of the talc mineral. I icroscope, g such opU~ence, and :i to much aDd 1... tic les t TIlese a.sociated mineral. are in many cases calcite, dolomite. quartz, ":""htine, magnetite, . .snesite, chlorite, tremollte, anthophyllite, and in t " cases chrysotile.' These may occur 1n various . .ounts and proportions in t '~', rc ial tales from different sources or mines. Not all of these associated ::":-:11. occur in all commercial tales. Some products are entirely free irOlD .~tiform minerals, .ad this distinction is allo important. s ble, The so-called "fibrous tales It appear fibrous because of the presence of .. "tiform miner.lI. Pure talc mineral rarely app.an fibrous 1n crystal .~!l and 11 much more commonly platy, lamillar, or micaceous. Specifically. Is by X-I'''' its 0Vft .!:~agre. with the definition of talc (fibroul)--tremolite as it appear. in ,.;~!cntation of the threshold Limit Values for Substance. 1n Workroom Air, It ns uel in yt he p..s..I-- \ : i"iled ~y' the American Conference of Governmental Industrial HYlienists . .: i tion. 1971. p'. 243. It h our opinion that this documentation for talc h~oUlh ua ':"!'l)US" should be rev1."itten to eliminate any reference to "fibrous talc" but &l parUd" I ~!d refer t~ the fact that the talc ores can contain fibrous contllminants y and not :,:: are ubeatifonl minerals. This is important in view of the fact that - ... I , , for the .... que. c oc:zIIICI'l1 -nul. 19n , , ;&tioll p. 35-36. :-.n Wney & Sons, 'Inc. Encyc lopedia of Chemical lechnololY. Talc. V. 19, 2~ ed., 1969. p. 608. :~scarch Hanager, Celit. Division. Johns-Manville Corporation. '~r. W. A., R. A. Hovie, and J. Zussman. Rock-Formina Hinerall. V.3, ~~eet Silicat. Longman_, Green and Co., Ltd London. 1962, p. 121. i.:,.: 124 of wOrk cited in footnote 3. cLCS 126-129 of work cited in foocnote 3. !LC, Ben M. Talc Deposits of Steatite Grade, Inyo County, California. Div. J[ ~ine State of California. Special Rept. 8, Ausuat 1951. ~~g~t, Lauren A. Geology of the Silver Lake Talc Depo~its, San Bern,rd1no, C.lifornia. Div. of Minea, State of California, Special Rept. 38. July :'1S~ . 3 the definition of the American Conference of Governmental Industrial Hygienists il part of the Federal Mandatary Standard under the Metal metallic Mine Safety and Health Act. In addition to the mineralollca1 differences, than S-mieron maxtmum particle lize. The end determines the particle size required.? Characterization of Talc Dusts Talc dust. may be characterized cal composition, particle Ihape. and particle '{Ze. described separately. "~ :c .-"...': _..\ .. Characterization of Mineral Compolition I" ~.This may be done according to a variety of commonly used and accepte. methods. :(; , 1['Petrggraphlc Examination IA highly skilled petrographer, working with a petrographic miCrOICOp8,< can, In many cases, determine various mineral a~cles by measuring such optl~ .cal pro crystal phearbtiiets. s as index Aa the of refraction, extinction angle. birefringence. ~ particle 11ze of a mineral dust is reduced to mucb T .... :"'. , , belov 5 microns these measurements become increasingly difficult and lell reliable. Host commercial tales contain a high proportion of particles ." . ~aller than 5 microna a~d other methods are therefore more reliable. Electron Probe t ;: .t :. The basic principle underlyina the identification of . .terials by Xr~ " "Ior by electron diffraction is that each crystalline aubstance h.. ita QVQ ch.racte~iatic atomiC .tructure which diffract. X-ray. or electrons in a ~ ticular pattern. The recognition of the pattern establish uniquely the .~ fract1ng subsJance. Newly developed electron probes. operatinl through aD electron microscope. make poa.ible the identification of individual particl.. 1 small al 1 micron by this method. The equ1p~nt 1s ve~y costly and oct -,: readily adopted to routine ..aaurementa. X-Ray Diffraction 'I This i. probably the moat powerful and &aeful tool available for the .... , eral characte~ization of talc d~sta. Uaina equipment and techniques c~ -7Industrlal Kineral.. Talc: Micronl&ed Grade. Lead the Way. January 1971 .. \.: p. 9. .- -Brindley, G. W. Exper~ental Method,. Ch. I in The X-Ray Iden:tficatioU Crystal Struct\ae. of Clay Minerala. ed. by C. Brawn". 1961, P.. ' .,5-36. - Page 1 of work cited in footnote 8. ~... ~,'yed in the tdc industry, it is pos.ible to identify a. 11ttle a. 1 per- harac :-:t of tremol1te in otherwise pur, talc mineral. There 1a evidence that dif:~:-"nt tremolites respond differently and may show different lower Umit. of comp Ie tel,., .. : ...:tability dependina on cryatal size and l?erfection. ned by .;. scanniua . ~c~ential Thermal Analysts (DTAl iINO Iviaa . This procedure is useful but not as definitive a. X-ray diffrACtion . :~. chlorite. serpentine, and the carbonate ~ineral how characteristic .. A curves but lIlany of the peaks ""erlap and are not clearly defined in ..u1 mixtu1'et. Tl'emoUte shows a relatively weak n.T.A. reaction because : its low content of chemically combined water.10 While D.T.A. is a useful .; . t for qualitaU"e analysis. it is of limited value for quantitative deter- ~.: Itilms. Particle Ihe, SIImple composition, and experilD.ental and lnstru~ ~ .,-:\(.\1 variables ara compileatina factors. ,raqcrhati911 bI Chemical Compo.ition C(.mplete chemical analyses are useful in identifying talc dusts but are :t.' means definitive. Quantitative analyses by conventional wet methods or ~r~y fluorescent methQds only help but do not yield the type of positive .:,,ral identific:ation obtainable by X-ray c:U.ffraction. f . :~: ide Shape Partial morphololY, .hape, and .tructure are powerful tools for ident!f!- .,, .~. ~: I.'ll of mineral dUlt.. Keuurements made w1th an ordinary Uaht-mlcroscope ::' !1c misleadine. r01: ex_ple, talc platelet ob.erved on edae, 01' on an .:~. may appear to b. a fiber. Scannlna electron mic:roaraph. are far more : i .I~ Ie and reveaUna becau of greater po. .ible magnification and depth of .':J. When obrved in thl. . .nner, .~ talc platelet. appear to roll up '. a tubular .hape not unlike kaou'nhatloyslte or .erpentine-chry.otlle . t' . ': \.': ;..:r. in the ca of tale, this tubular structure i. far more rare and is ~ camp lete. .") II .,.:;.' --"-:':::e:::: .iJO ..y be deeermined by direce micro.coptc meuremene using ~~.: It" :n.icrometer eyepiece or by mE surement of particles in an electron microTelevi.lon .cannina techniques and equipment are also available . . ".,r procedures involve .ettling rate determinationa in water or other ;~las. The Andrea.en pipette 1. commonly used for this purpo.e.~a I.~ --~.-lC~kl~l!-ru-:i-e.--R-o-be-r-t ~C-.--(e-d-.-).-~~T~he--D-i~ff~e~r~en-t-:.-a-l -T-h-e~rm~a-l-I-n-v~e~s-ti-g-at~i~o~n~o-f-C~~la~y~s. ~ineral. Soc., Clay Hineral. Croup, London, 1957. :.,; len, Terence. Particle Size Measurement. Chapman and Ran Ltd . London. -" 7. '~I """.1968, pp. 45-61- rr, Clyde, Jr., and J. H. DallaVall. Fin. Particle Me .surement. ill an C""'pany. Hev York. 1959. pp. 43 -78. n-~ U _, 5 Cone lusiona We h.,.-e attempted ~o .h"" 1ft the above presentation that the charac zation of tale dusts is not stMple. No one procedure or ~thod 1. comple definitive. We believe that mineral composition can beat be determined by X-ray diffraction. Particle morphololY i. best defined by meana of electron microlraph. and particle s1ze det.~ned by .edimentaCion laval the Andreasen pipette. .A .!,'~,r.l~ . ; t" ~ tl " ~.Sl1., I~~ .11 "(" 3..: t J r..: .. n,~ n :'(-1". '. .r.11 I' . 1 ~ : . :1 ". !ll ,.... h: .. ,-!t: . .f . '': ,,:,-1 'll <. ~~~. ,r f l ;.;i.d: .'-.,;: -.~~ ~;,o.:k\ ~il ;, : 1... , 1~1 fl". :-: .:1, u- CHARACTERIZATION AND OCCURRENCE OF TALC'I""""'!'--"""'--_ _""""'_ ~PItt. 0 Deft. by Exhibit No. 8 g I.D.~ - H. T. Mulryan1 Patrkia Ruby. M.P. F'/~' ~~ . ~m.m.~~~~~~. My name i. H. T. Mulryan. I.m president of Cyprus Mine. Corporation'. ~aitcd Sierra Division. The divi.ion i. the world'. largest producer of talc tn terms of produc t v.lue. it operate. t.lc mine. in the St.tes of Montana, Nevada, California. and ';"'xAS and talc proeeuing units in the States of Montana, Californi., and s.hra:ik Belgium, and through an .ffUiate, Mexico. The divi.ion employs about 180 person t its talc production units. Ai~r~ximatety h.lf of them work in our Mont.n. mines and mill., the rem.inder , Ih' :;catterd 8Il10111 the other eisht tale loeation.. The Montana product I??t',>ac:he. the purity of pure talc adnerat and it. habit 11 platy or Iranular, 4C'1'~'ndina on the material .0UTce and fineness of grind. Figu1'es 1 and 2 11 lustrate the 'DAture of the p.rtic 1 by transmission and .canning electron :;.:r,'scope, respectively. On the other hand, mixture. of miner.l. from other sources may cont.in !!~t Lf.! or no talc mineral and .tUl be correctly known coamercially .s "talc. It il':,ures 3 and 4 show the p.rticle sh.pes of "talcs" from the Gouverneur !i)tr1ct of New YOTk Sute. The needle. or fibers are mai.nly tremolite with ~thophyllite also cOlllll1only pA.ent. This type of commercial talc 1. not confined to New York State, beinl txt~'nsively mined and procened in Ca11fornia. Table 1 cOUlpares the mineral ;Jnt~nt of talc from N.w York, California, and Kontana. The Silver L.ke. Calii., tremo11tic talc 1 imil.r to typic.l New York State talc except for :~~. :::issina anthophyllite and quartz impurities. , 6,0GI).. TABLE 1: - Comparison of mineral content of talc from New York, California. and Montana, in percent - Tale type Talc Carbonate Tremolite Anthophyllite !Quartz Other - - -5t'\;' york ..... _. 62 - -Sllver Lake, CaUf ... 54 - -?r.~int. C.lif .... 82 3 12 30 43 53 - Trace 2 Mont. :"llowstone, HQnt .. 99 ~.\'erhead Mont ..... 98 1 1 - - -- -<1>.5 4 Hica. - 1 Chlorite I-"-.-'i~d~e-n-t-,-C-y-p-r-u-. -H-i.-.-.--C-o<~p-o--t-i-o-n~'-. -U.n-i~te~d~~5~ie-r-r-.-D~i~v~is-i-o-n,--- 1 7 .r. epi 4.. : 11 all ent Cr''''t --, l~ S11 len "s ,."lerome ters' '~s.- FIGURE 1. - Nature of particles by transmission and scanning .Iectron microscope (X 6,..- - -. 8...,. !o. U oI..t.t t "ue -..oc u ..!! v 0> C C Co U Itt ~ C C u i o :11;.1 zo , La 5 micromtter' FIGURE 3. - Partie'le shapes af IItales" from the Gouverneur District of New YOI'k Stat. (X 6,000). 10 t. !o> .t as pria- ~ talcs, ~ mineral:: che " 'S been 1Il~~ Iorerspira- 'f.~. y.ars ...; ed to "I...... pub- !en inad- !tectable : our ,I I .rees mel hlphasia :posure to !ll us - In.i 1930' :rol ... .y greater I f I, , sign of reveal : concan :&1 data .cs of I 1 ,I lee with lic and - ~: )e a poal. !xpoau:r ~ i I t I . Q CID -CID )( -o. -.~ ..:: Q c!..5:.: :. o::t (.!) .! ..oE:: '0 WI It -=a 111 ~ -..~.. If .... .. a:w:::>: ~~ .u... ].~oE .E, 11 Another California talc. the Panamint. contains calcite and mica as c1pal impurities ~ith no asbescos minerals present. The tvo Montana talc., Yello~.tone and Beaverhead. are high purity and also free of asbestos mi It has been the policy of the Cyprus Mines Corporation to X-ray the production ~orkers at all of our operations annually. This policy has been effect for 5 years and these examinations have not turned up any lung or pleural cancer among our talc ~orkers. nor have they revealed chronic re tory disease of any kind. . Seven of the employees were first expo'sed to talc dust 25 to 44 years All the long service group were California workers who had been exposed to tremolitic tales as well as tre~lite-free mat~rials. When the threshold limit values for tremolitic tales were ltc, we became concerned about the possibil:ty that our people vertently exposed to a health ha1ard and we tooK ewo steps. First, the division ceased production of all talc. containing .mounts of tremolite and established an X-ray diffraction facility California mines to sure control. Second, the seven 10ng~service ~ployees together with four retirees .a4' exemployees were subjected to exhaustive physical examinations wteh empha'1~'ik on the respiratory aystelll, chest, and abdomen. This group'S first exposur. ~ talc dust ranged from 25 to 49 years ago. There are no records to tell us wat conditions were like in the talc mines and mills of the 1920's and 1930' . but neither were mining nor tni ning techniques designed with dust contro 1 as . major objective. The oldtime worker w , therefore. exposed to vastly greatar amounts of dust than hi. modern counterpart. Ne~ertheless. these exhaustive examinations failed to detect any sign of cancer among any of the long-service group. One of the retirees did reveal ligns of possible pneumoconiosis. Cyprul Mines Corporation's interest in this proceeding is one of concern for the welfare of its workers and for the truth. Although the medical data # presented are admittedly limited. they contain no indication that talcs of '~Ii":_. either the pure Montana type or le pure California varieties are careioolenic. We should emphasize that Cyprus' talc operation. ar. in compliance ~ith threahold limit value. both al relate. to dust from nona.bestiform talc and fiber count. We realized that any dust in excessive .mounts cannot be a posi. tive health factor and are making every effort to minimize e=ployee exposur r, ii 12