Document ymMqDgQnbdkv0ZOqQXyB3dXnX

Reprinl5 from the collection of the University of Michi~aJlI.ihrarv CAM-2 16 CHARACTERIZATION AND OCCURRENCE OF TALC by H. T. Mulryan1 My name is H. T. Mulryan. I am president of Cyprus Min.s Corporation'. United Sierra Divilion. The division i. the world'. largest producer of talc iu terms of product value. It operates talc mines in the States of Montana, Nevada, California, and Texas and talc procelsing units in the States of Montana, California, and Nebraska, Belgium, and through an affiliate, Mexico. A The divis pproxtmately ion hal f emofplotyhs~ about work 180 persons at in our Montana itl talc production unita. mines and milts, the'reuainder are scattard HUang the other eight talc locations. The Montana product approaches th. purity of pure talc mineral and its habit is platy or granular, depending on the material source and fineness of grind. Figures 1 and l illustrate the nature of the particles by transmission and scanning electron microlcope, respactively. On the other hand, mixtures of minerals from other sources may cDntain little or no talc mineral and still be correctly known ccmnercially &I "talc." Figures 3 and 4 show the particle shapes of "talcs" from the Gouverneur district of Nev York State. The needles or fibers are uainly tremolite with anthophyllite allo commonly present. Thil type of commarcial talc is not confined to New York State, being extenaively mined and proce.sed in California. Table 1 comparas the minerat content of talc from New York, California, and Montana, The Silver Lake, Calif" tremolitic talc is similar to a typical New York State talc axcept for the milaing anthophyllite and quartz impurities. TABLE 1: _ Comparison of mineral contlnt of talc from New York, California, and Montana, in percent Talc tvoe - -New york........ - - -Silver Lake, Calif ... - -Panlllllint, Calif ...... Talc [Carbonate 62 54 3 82 12 TremoITte 30 43 AnthoDhv' 5 H tB IOuartz 3 Trac. Other 2 Mont. 4 Mica. Yell"".ton., Mont ... 99 lIeaverhaad Mont .... 98 1 1 -- -<0.5 -- 1 Chlorita ion. ,, .~ , :,~:;?~: ~j'(:~! " ~ .... crometers 1. . Nature 01 particles by transmission end s:enning electron microscope (X 6,000).  or"- .~i! ~~~ip=x,- ~ .:'" ..... 3~~{~~~~\:?~:~;;:~" I:........ _ ....:. ..'...i.. :!.j 20 21 :" Another California talc, the Panamint, contains calcite Ind mica a. principal impurities with no asbestos minerals present. rh~ two Montana talc., Yellowstone and Beaverhead, are high purity and also free of asbestos minerals. It has been the policy of the Cyprus Min Corporation to X-ray the 0- production workers at all of our operations annually. This policy has been in c0o0 effect for 5 years and these examinations have not turned up any lung or ..~ pleural cancer among our talc workers, nor have they reveslud chronic respiratory disea of any kind . c Vi Seven of the employees were first exposed to talc dust 25 to 44 year. ago. --" !5 All the long service group were California worker. who had been ~xpused ~o ..>- tremolitic talcs as well as tremolite-free materials. ~ z When the threshold limit values for tremolitic tales were first made pub- 0 lic, we became concerned about the possibility that our people had been inad- .~ vertently expo d to a health hazard and we took two steps . ~ .~ c First, the division ceased production of all talc. containing detectable amounts of tremolite and established an X-ray diffraction facility at our 5 II California mine. to a.sure control. ,.E II , Second, the seven long-service employee. together with four retirees and "0 ex-employees were subjected to exhaustive physical examinations with emphasis I.!) on the respiratory system, chest, and abdomen.. This group'. first exposure to ~ talc duat ranged from 25 to 49 years ago. There are no records to tell us E what conditions were like in the talc mines and mills of the 1920'. and 1930's, ..0.: but neither were mining nor milling techniques designed with dust control as a '" [: major objective. The oldtime worker was, therefore, exposed to vastly greater ~ amounts of dust than hi. modern counterpart. .!1 Nevertheless, these exhaus tive examinations failed to de tee t any ign of 0 cancer among any of the long-service group. One of the retirees did reveal "8. signs of possible pneumoconiosis. "..z0:. Cyprus Minea Corporation'. interest in this proceeding is one of concern ...!! for the welfare of it. workers and for the truth. Although the medical data .!:! presented are admittedly limited, they contain no indication that tales of ~ 0 either the pure Montana type or less pure California varieties are ~ carcinogenic. We .hould emphasiza that Cyprus' talc operations are in compHanc'e with thralhold limit value. both as relates to dust from nonasbestiform talc and fiber count. We realized that any du.t in axc.ssive amounts cannot be a positive health factor and are making every effort to minimize employee exposure.