Document 5rOOVLzx90rRrqKVY5Mky3w8

'* 10/08/2001 15:58 312-996-7822 SCIENCE LIBRARY DEFORMATION OF CHRYSOTILE ASBESTOS PAGE 1l Fic. 7. Sample (D); Automobile brake drum dust after use- (a) Dark field and (b) bright field. This show* that relatively usdefonued fibers survive ia the brake drum duet. The grain sites in the darkfield images (a) are comparable to those in the burnishing dust (Fig. 5ft) or the UJCC sample* (Fig- 4a), indicating tittle deformation during use. This preliminary study also shows the need to study details of the growth of the cbrysotiie asbestos and the nature of the defects involved, ifall the diffraction and deformation effects are to be understood. ACKNOWLEDGMENTS I thank Q. R. Smith of the Ait Industrial Hygiene Laboratory (AIHL) Berkeley for bringing this problem to my attention and preparing the samples. I acknowledge useful discussions with him and Dr Walter John and thank Professor J. Washburn for encouragement. This work was supported financially by die U.5 Energy Research and Development Administration. REFERENCES Alste, J,, Watson, D., and Bagg, J. (1976). Airborne asbestos in the vicinity of a freeway, Atmos Environ. 10, 589- Hatch, D. (1970). Possible alternatives to asbestos as a friction material. Ann. Occup. Hyg. 19, 25. Hickish, D. E., and Knight, K L. (1970). Exposure to asbestos during brake maintenance Ann- Occup. Hyg. 19, 17. Hlrsch, P- B., Howie, A., PasMey, D. W,. and Whelan, M. J, (1965). "Electron Microscopy of Thin Crystals." Butterwonhs, London. Langer, A. M., Muckier, A. D., and Pooley, F. D. (1974). Electron microscopical investigation of asbestos fibers- Environ. Health Prnptct. 9, 6). Lynch, i. R. (1968). Brake lining decomposition products. J, Air foUut. Control Assoc. IS, 824. Rohl, A- N , Langer, A. M,, Wolff, M. 5 , and Weisman, I. (1976). Asbestos exposure during brake lining maintenance and repair. Environ. Hts. 12, 110. Seyhan, K., and Smith, C. R.(J977), Characterization ofchrysotlle asbestos in automobile brake drum