Document NN2qpRJ2Xjm9vEyKjXzmg6Zg8

JDHHS (NIOSH) Publication No. 78-127 Page 2 of 5 automobile drum brake assemblies, grinding ofused truck brake linings, and bevelling of new truck brake linings. Average peak asbestos air concentrations for these three activities based on personal samples taken within ten feet of the operator were, respectively, 10.5,3.75, and 37.3 fibers (>5 microns in length) per ml. An analysis of samples ofbrake drum dust revealed that almost all of the asbestos fibers found were shorter than 0.4 microns in length. Previous studies of the extent of asbestos emissions from automobile brake lining wear showed that only a very small fraction ofthe original asbestos content ofthe brake lining is found in brake drum dust It was presumed that this is due to thermal degradation ofthe fibers during braking. The present findings indicate that enough asbestos is preserved to produce significant exposures during certain brake servicing procedures. The full extent of asbestos-related disease in brake servicing personnel is not known at present because this particular occupational group has not been studied systematically up to now. However, a review ofthe scientific literature on the association between asbestos exposure and mesothelial tumors of the pleura and peritoneum has revealed at least four cases ofthese rare tumors in persons who were employed in jobs involving automobile brake servicing For your information and guidance, we are enclosing pertinent references, estimates of the population at risk, a NIOSH interim recommendation for brake and clutch servicing procedures, and a copy of the Department of Labor standard covering exposure to asbestos in the work place. The environmental studies ofbrake lining servicing operations outlined above together with observations ofmesothelial tumors in persons so employed affirms the necessity for instituting and maintaining recommended control measures in this industry so that the health hazards of asbestos are minimized. [signature] J. William Lloyd, Sc.D., Director Office of Occupational Health Surveillance and Biometrics Estimates of the Workforce Potentially Exposed to Asbestos in the Manufacturing and Servicing of Brake Linings and Clutches Auto Mechanics 833,535 Garage Workers 67,679 Manufacture (original and rebuilding) 6.657 907,871 [Source:] from 1972 Census ofManufacturers, 1972 County Business Patterns, and Census of Population: 1970 Occupation by Industry (all are Department ofCommerce, Census Bureau publications) http://www.cdc.gov/niosh/78127_5.html 10/24/2001