Document MJqepMMyEqdwXEDNM4QL6dmyy

DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE CENTER TOR OUEA9E CONTROL (36) August 8, 1975 NATIONAL INSTITUTE FOR OCCUPATIONAL SAFETY AND HEALTH 9600 FISHERS LANE aoss* .Rockville,Maryland Dear Colleague: This communication is Intended to alert you to recently gathered informa tion indicating a potential health hazard for persons exposed to asbestos during the servicing of motor vehicle brake and clutch assemblies. ^ On July 21, 1975, the National Instltlte for Occupational Safety and Health convened a meeting of government and university scientists, industry representatives, and jLabor union officials to discuss the present state of knowledge with respect to this problem. Data was presented by Investigators from the Mount Slanl School 6f Medicine in New York City indicating that workers engaged in the maintenance and repair of automobile and truck brake linings are exposed to potentially hazardous levels of airborne asbestos dust. Specific brake servicing operations studied Included blow-out of automobile drum brake assemblies, grinding of used truck brake linings, and bevelling of new truck brake linings. Average peak asbestos air concentra tions fob 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 of brake drum dust revealed that almost all of the asbestos fibers found vere shorter than (J.4 microns in length. Previous studies of the extent of asbestos emissions from automobile brake lining wear showed that only a very small fraction of the original asbestos content of the brake lining is found in brake drum dust (Ref. 1-3). It was presumed that this is due to thermal degradation of the 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-reiated 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 of the scientific literature on the association between asbestos exposure and mesothellal tumors of the pleura and peritoneum has revealed at least four cases of these rare tumors in persons who vere employed in jobs involving automobile brake servicing (Ref. 4-6).