Document N2vQbnwk9XO6qVJp0kQEbOkME

(36) department op health, education, ano welfare PUSLIC HEALTH SERVICE centc* row oiiaj control A, ugust .S, .1.3.7.3 NATIONAL INVTI TVITt COR OCCUPATIONAL tRRCrr ANO HCALTH JU0 PIINCRS lanc aockvill* marvlamomim ( l Dear Colleague: This communication is Intended to elect you to recently gathered informa tion Indicating a potential health hazard or parsons exposed to asbestos during Che servicing af motor vehicle brake and clutch assemblies. On July 21, 1973, the National Instltite lor Occupational Safety and Health convened a meeting of government and university scientists, Induscry representatives, and labor union officials to discuss the present state of knowledge vith respect to this problea. Data was presented by investigators from the Mount Slant School of Medicine in New Torts City indicating chat workers Engaged in the maintenance and repair of alocomobile and truck brake linings ara 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 eir -concentra tions for these three activities based on personal samples taken within ten feet of the operator were, reapectlvely, 10.5, 3.73, and 37.3 fibers (>5 microns in length) per ml. An analysis of samples of brake drum dust revealed that almost all of che 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 of the original asbestos content of the brake lining is found in brake drua dost (Ref. 1-3). It was presumed that this is due to thermal degradation of the fibers during braking. The present findings indicate chat 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 of the scientific literature on the association between asbestos exposure and mesothalisl tumors of the pleura and peritoneum has revealed at least four cases of these rase tumors in parsons who were employed In jobs Involving automobile brake servicing (Ref. 4-6). I 061683 PRODUCED BY FORD