Document jyLnkkdvN7pGEEzezegaQyQvZ

f\ / MVA, Inc. t-- Excellence in---- Microanaiysis 20 January 1993 Mr. Robert T. Cheng Chevron Corporation P.O.Box 7924 San Francisco, California 94120 Des- Mr. Cheng, Some time ago I read with interest the 1991 paper you co-authored with Henry McDermott entitled "Exposure to Asbestos from Asbestos Gaskets" which appeared in Applied Occupational Environmental Hygiene. I found it to be very well written and informative. It inspired me to take a close look at some asbestos sheet gaskets to see if asbestos fibers were protruding from the surfaces or whether they were fully encapsulated in the binder. The results were published last year and copies are enclosed. . Our work shows that not all the asbestos fibers in the gaskets are bound in the organic matrix and are, therefore, available to be abraded from the surface. It reinforces your conclusion that potential, short term, high exposure can be eliminated by working with the materials in a wet condition as you wouid with friable material. I noticed that your paper did not include any information about analyses which identified the gaskets as asbestos-containing. Were such analyses done? If you still have the air samples and would like some additional information about the types of fibers present, I would be happy to analyze a few by the NIOSH 7402 (TEM) procedure at no charge. Comparison of PCM and TEM counts of asbestos fibers is of particular interest to me. If you are interested in pursuing this effort please call. Sincerely, JRM/ds =r>cfcsures Barnes R. Millette, Ph.D. Executive Director MILLE7TE: CHENG120 5500 Oak brook Park wav =200 H G I' II llna /(l?-1 V Sim I iiinnu M, CA IM I' Nr\) O VD*