Document 449rVLevnXD28291wXEbB9Qdj

ST0000020 MIDLAND, MICHIGAN October 31, 1968 R. C. Middleton Safety Department Ludington Plant LETTER DATED OCTOBER 7, CONCERNING HAZARDS DUE TO HANDLING PIPE COVERING MATERIAL CONTAINING ASBESTOS Asbestos has long been known as a material capable of causing a discrete disease called asbestosis (which is somewhat similar to silicosis - caused by crystalline quartz). In the more or less recent past the subject of hazard due to asbestos has been further complicated by reports in the literature of malignant growths which were associated with the presence of asbestos bodies. The whole subject is presently under study by the U.S. Public Health Service. I feel that at this point in time our best bet is to control asbestos dust exposures according to the Threshold Limit Values suggested by the American Conference of Governmental Industrial Hygienists. This Threshold Limit Value is five million particles per cubic foot of air (mppcf). We have done some dust sampling during a variety of operations carried out by pipe coverers. I'll include a summary of this work for your information. You will see that there are some jobs where the numbers of particles in the air are above the 5 mppcf mentioned here. Jobs such as this should be done using a dust respirator which is approved by the U.S. Bureau of Mines for protection against toxic dusts, including silica. Another approach to the dust hazard is to contrive better control of the dust so that measurements will show less than the 5 mppcf and there will, therefore, be no need for respiratory protection. Generally this is best accomplished by the use of exhaust ventil ation at the point where the dust is being generated. H. R. Hoyle Biochemical Research Laboratory 1701 Building HRHtreh Enc. cc: R. P. Palk