Document K6rw1VKwDG5DER4D05ZYXaE52

FILE NAME es DATE 0000 DOC RK301 DOCUMENT DESCRIPTION e ses ses s SS s es S e s . References 1. Brake Lining Decomposition Products by Jeremiah R. Lynch National Center for Urban and Industrial Health U.S. Public Health Service Journal of the Air Pollution Control Association Vol 18 No. 12 pp 824-826 1968 2. Brake and Clutch Emissions Generated During Vehicle Operation by Michael G. Jacko Robert T. DuCharme and Joseph H. Somers presented at Automobile Engineering Meeting Society of Automotive May 14-18 Engineers Inc. Detroit Mich 1973. Study sponsored by U.S. Environmental Protection Agency 3. Asbestos The Need For and Feasibility of Air Pollution Controis Committee on Biologic Effects of Atmospheric Pollutants National Academy of Sciences ISBN 0-309-01927-3 1971 4. Report of the Advisory Committee on Asbestos Cancers to the Director of the International Agency for Research on Cancer British Journal of Industrial Medicine Vol 30 pp 180-188 ' - 1973 5. Asbestos Emissions from Brake Dynamometer Tests by A. E. Anderson R. L. Gealer el R. C. McCune and J. W. Sprys presented at Automobile Engineering Meeting Society of Automotive Engineers Inc. Detroit Mich May 14-18 1973 Asbestos . and Brake Linings | Additional Copies of This Pamphiet Are Available Asbestos Information Association America 1660 L Street N.W. ~ Washington D.C. 20036 by AAC AA AA ASBESTOS | INFORMATION ASSOCIATION ASBESTOS ANDa BRAKE LININGS | Thecontribution of asbestos from brake lining wear to ambient air pollution infin- itesimal even in urban areas and is ood an " poliution oe, ae. Brakes Rely On Asbestos The use of high heat and friction resistant- chrysotile asbestos in the manufacture of motor an vehicle brake linings was developed in Great Britain ',. in 1908. Today more than 65 years later other material has been found which will provide the same :: degree safe dependable stopping performance . --: as asbestos Throughout the world than 300 million vehicles of all automobiles; trucks :buses rely on asbestoscontaining brake | linings to bring them tosafe sure stops after time after time While formulations vary consider ably average automobile brake lining contains ;;<: approximately 55 percent asbestos by weight while the asbestos in a truck lining constitutes around 33 ' of the total Approximately 50,000 tons of percent asbestos is used in the manufacture of brake in the United States each year.2 in year.2 linings Health Questions Arose The inhalation of excessive quantities of asbestos fiber in occupational settings can cause respiratory disease and cancer In the sixties speculation arose whether the gradual in service wear of containing brake linings would release potentially harmful amounts of asbestos fiber into the ambient air This concern was heightened by repeated findings of small amounts of asbestos fiber in the lungs of some city dwellers not known to have had occupational exposure to asbestos While it is now generally recognized by the worldwide asbeshealth medical community that these small amounts of fiber do not constitute a hazard to the health of the general public the question still remained unanswered what contribution emissions from containing brake linings made to urban air pollution The results of research undertaken to answer this question are now available Natural Sources fe Asbestos exists naturally in small though detect- .-- able amounts in serpentine rock formations through- out the world and is constantly being released into the atmosphere through erosion by wind and water Asbestos is thus natural to our environment and as analysis of dated ice from the polar caps have revealed has been for thousands or even millions . of years Thus the mere presence of asbestos in --. ambient air is not prima facie evidence of pollution from brake linings or other sources For this reason investigations into this question have had to be |. < conducted either on specially equipped cars and trucks under actual driving conditions or the mometers .. Emissions Not Significant - projects projects The results of three such research projects projects carried out over the past six years support the - wear conclusion that emissions from brake lining are not a significant source of asbestos in the envi the three ronment.1.2.5 Some of the results of studies are summarized as follows * When brakes are applied the high heat of friction converts more than 99 percent of the asbestos in the lining to a fibrous toxic material : ' called forsterite The two most recent investiga- percent tions showed conversion ratios of 99.7 and 99.95 percent respectively rane Total airborne emissions of free asbestos fiber | from brake lining wear amount to approximately)-- 2tons each year for the entire United States.2| This is less than half of one percent the| sizeof total particulate emissions in a city the Los Angelesin a single day fey from The calculated contribution of asbestos ot brake lining wear to the air in a typical urban area- +: is less than 0.07 nanograms per cubic meter of 3 air a nanogram is billionth of a gram Sci- -* entists estimate that asbestos fiber concentra- tions in urban areas average between 5-10 nano- @ 2 grams per cubic meter is therefore clear that the wear of brake lining produces at most a :~ small fraction of the asbestos fiber in urban air