Document JN3jo7m3VLLvyp93LZn1x3gMv

memorandum San Francisco, CA October 28, 1985 CERAMIC FIBERS SF&H CONTACTS: Two recent toxicological studies have implicated ceramic fiber to be an animal carcinogen. While the results from the two studies conflict in many ways, there is little doubt that a higher level of caution now exists about exposures to ceramic fibers. Ceramic fibers, sometimes referred to as refractory fibers, are amorphous, glassy, alumina silica products (AI2O3, SiC>2) which are created from molten masses of synthetic raw materials or naturally occurring-kaolin clays. Ceramic fibers have been used as refractory linings and in other high-temperature operations. During the last 15 to 20 years, they have been widely used as substitute for asbestos insulation. Two well-known brands of ceramic fiber are Kaowool by Babcock & Wilcox and Fiberfrax by Carborundum, Other trade-name ceramic fiber products include Greencote, Unifelt, Pyro-Bioc, inswool, etc. Members of the "Thermal Insulation Manufacturers Association" (TIMA) have chosen to alert their customer's of the new toxicological findings (see attached letters from Babcock & Wilcox and A. P. Green Refractories Co.). TIMA has established a work place exposure guideline of 2.0 fiber/cubic_centimeter as the recommended Threshold Limit Value (TLV) for ceramic fibers. As lyou can see from the attached Babcock & Wilcox publication, the suggested TLV and therrecommended handling procedures, work practices, personal protective equipment, and other industrial hygiene guidelines are similar to those recommended for asbestos. ~ TIMA is funding further toxicologicaLstudies of ceramic fibers. Results from these studies will not be available for another 3 to 5 years. In the meantime, based on the currently available toxicological findings, we recommend that the TIMA recommendations be followed where dust of ceramic fiber can be generated, e.g., when removing ceramic fiber insulation. If you should have further questions^ or if you need assistance in identification or evaluation of ceramic fiber exposure, please contact Mr. N. C. Zeiser (894-6916) or Mr. R. T. Cheng CTN 894-5844. RTC:sey Attachment: Chevron BB 015748