Document 3jOaBDXpgqQ4Xy4Eg77Xjw2J

John s-iVl cnviSIaCcrporation 22 fins! dOlh Stro&l New York, N.Y. 10016 Executive Offices June 28, 1971 PLAINTIFF'S EXHIBIT JM-2498 Mr. Samuel G. Warr, Buyer U. S. Steel Corp. 600 Grant Street Pittsburgh, Penna. 15230 Dear Mr. Warr: Recently you requested toxicological information concerning JohnsManville Chrysotile Asbestos Fibre. It is a pleasure to provide you with this information. Asbestos is the ivmie given a family of mineral fibers comprised of three major types -- chrysotile, crocidolite and amosite - each of which differs from the other; physically and chemically. Studies of the relationship between asbestos and health arc complicated by this diversity. Chrysotile is a white magnesium silicate, which can be attacked by acids, has a positive electrical charge and is flexible and not easily pulverized. Crocidolite is a blue ferrous sodium silicate, is acid-resistant, has a negative electrical charge, and is less flexible than chrysotile. Amosite is a brown ferrous magnesium silicate, has a negative electrical charge and is brittle and easily pulverized. In the United States, chrysotile, amosite and crocidolite asbestos are all used. Chrysotile is by far the most common, is primarily mined in Canada and the U.S., and accounts for about 90% of the asbestos consumed in this country. For workers who handle asbestos fibres in mines, mills, factories, and some building and insulation trades, the industry shares with doctors, Public Health officials, and others involved in industrial medicine, a concern about possible health effects from excessive on-the-job exposure to asbestos dust. Wo have 1 mi}' rcco(;nf 7t>tl tho risk of a p.irt 1 cul a r lung dirse.if'.c c.-jllrd "A'.hfM a;, j " .iiiiong :.oiiie workers. Thi:; nun-in. 11 i j'li.ui i <11 is l/rougli l on .liter i nli.i I .i L I on nl iiri'ii'.ivr concent r-i L i on . ol i\|,i . to-: dur.L ov< r i p'ri'..' of many years. Asbestosis is one of the lung diseases called "Pneumoconiosis". PRODUCED Jill - 33 Mr. Samuel G. Warr -2- June 28, 1971 Recent medical studies have indicated that the disease "Asbestosis" and other pulmonary diseases claimed to be associated with Asbestosis, are dose and time related. The occupational use of asbestos fibre, therefore, can achieve the same degree of safety as the use of any other potentially toxic material,providing adequate control measures are taken. The current threshold limit value (TLV) for asbestos dust as stated in the Federal Occupational HcaLth and Safety Act, Federal Register, Saturday, May 29, 1971, Volume 36, No. 105, Parc TI, Page 10506, is 12 fibres per millllicer of air greater than 5 microns in length ..s uetcrinined by Uio membrane filter method at 430X Phase Contrast Magnification, or 2 million pareiclos per cubic foot of air as determined by the i.rapinger method of sampling. To control asbestos dust to within the prescribed threshold limit value, we recommend that operations which present a source or dust should be equipped with mechanical ventilation exhausting into a collector; utilize wet processes where possible; maintain good housekeeping throughout the work area, including removing scrap material from floor and other hori zontal surfaces. Scrap should be disposed of in closed containers. - A program of industrial hygiene environmental monitoring is highly desirable to determine that threshold limit values are not being exceeded. If dust concentrations cannot be controlled to within the threshold limit value, U. S. Bureau of Mines approved types of respirators for pneumoconiosis producing dusts should be worn. I am attaching the following medical references that substantiate dose and time relationship of exposure, as related to the development of disease: 1. "Mortality in the Chrysotiie Asbestos Mines and Mills of Quebec" J. Corbett McDonald, M.D. ' Archives of Environmental Health, Volume 22, June 1971 2. "A Study of Mortality of WorUcro in an Asbestos Factory" M. L. Newhouse, M.D. British Journal of Industrial Medicine, 1969, 26, 294-301 3. "IdcntiCicucion and Control of Asbestos Exposures" [.. J. Dailey, I'li.D., (t. S. Public Ileal Lit Service American Industrial Hygiene Journal, February 1971 PRODUCED JM 33 hr. ShmucI 0. Warr -3- Juna 23, 1971 4. "Asbestos and Health in 1969" , G. W. Wright, M.D. American Revicv' of .'Mapiratory Diseases volume 100 - no. 4 r October 1969. 5. "Epidemiology of Asbestos Cancers" -Drs. Wsgnor, Gilson, 3erry & Timbre11 British Medical Journal - January, L971 Also for your further -information I am enclosing the following papers and booklets: 1. Asboa toe and Human Health. 2. Asbestos - A Family of Minerals. 3. Asbestos .ind the General Public. 4. RccomiondoU Saioty Practices for IMiullim; Asbestos Fibre. 5. Recommended Health Safety Practices Cor Handling and Applying Thermal Innut.'.Lion Producer. Containing A-.boston. "~ 6. Recommended I'r.ietxces xor fabricating. Handling and Applying Asl>l>?> Cemenr. products in tile iiuxlcUng & Construction Industries. 7. Recommended Health Safety Practices for Handling and Fabricating Asbestos Textile Products. 8. Why Asbestos? 71 you require any additional information, or I can bo of further assistance, plcaso contact mo. Very truly yours. C. L, Shccklor Manager, Accident Prevention and Health Administration CLiiunw cc: j.r.m. Hutcheson - AFD Asbestos N. W. Ilondry - AKD Aubescos 11. G. Donovan - Research PRODUCED JM-83