Document bBgVJqZzzbqQ06Gem6998x920

Environmental Asbestos: Threat or Phantom The paradox of asbestos is that destroys the asbestos, converting bodies have been found in 25% although its primary uses have it into an amorphous material, or more of the general public, ac been for safety--in fire insulation forsterite. cording to autopsy studies. But and vehicle brake linings--it now "Of the total materials removed these structures have not been is widely condemned as a hazard from brake linings during their proven to be asbestos. to man's lungs. use, less thap 5% appears as ac At least 20 widely disseminated The association seems strong, tual asbestos. The number of as substances are capable of form several investigators have said, bestos fibers released by normal ing these structures in lungs, he between long-time industrial ex friction material wear must be said. One of the most common, posure to asbestos and certain small indeed," the Cleveland in- - in wider use than asbestos, is bronchial diseases, including vestigator commented. talcum powder. pleural mesothelioma. If asbestos fibers are in the air So far, no laboratory method Based or. what is known, how breathed by the general public, has been developed to determine ever, the fears about asbestos* the rare occurrence of pleural which ferruginous bodies ,in a presence in the environment seem mesothelioma unrelated to occu lung are asbestos. Until one is exaggerated, said George W. pation `'strongly suggests that developed, asbestos should not be Wright, MD, head. Department there la a tolerable level of air blamed for all the fibrous materi of Medical Research, St. Luke's borne asbestos fiber." al found in lungs, Dr. Wright Hospital, Cleveland. He spoke at Structures similar to asbestos said. the American Thoracic Society meeting in Miami Beach. The goal for the next few years, he said, should be more research about safe ways to use asbestos. "This is the only sure way to combat unwarranted apprehen . Miners Suffer Pleural Damage sion and speculation." In a group of Canadian asbestos ciation of gas-exchange impair Use Increased miners with parenchymal disease, ment with the presence of pleural pulmonary function was invaria . changes suggests that free move Asbestos use has increased in bly more impaired in the pres recent years, but most of the ad ence of pleura] disease, reports ditional material has gone into ' Margaret R Becklake, MD, as products which tightly bind the sociate professor of epidemiology fibers, preventing their escape and health, McGill University, into the atmosphere. These in ... Montreal. . clude asbestos tile and cement Physicians have tended to dis Some asbestos-containing prod regard the significance of pleural ucts do wear, however, aid the changes oh pulmonary function. fibers are released. These include This study suggests that such brake linings, siding, and shingle* ' changes have a significant effect The fibers that might be: re* rjr on all aspects of lung function. leased from aD kinds at "wear'* When 1,069 asbestos workers either become bound into the soil were surveyed, marked pulmo- or are captured in rein or deen- nary fibrosis was found in 1.4%. ing water. All were men over age 55. Asbestos is almost universally The degree of parenchymal present in river water, but in disease was rated according to very small amounts. radiological findings. When ment between lung and chest wall is necessary to preserve optimal ventilation to perfusion imbal ance," Dr. Becklake said. "In other words," she contin- . ued, "free pleural movement ap pears to be necessary for normal gas-exchange." Exposure to asbestos dust may result in diffuse generalized pul monary fibrosis. The pleural changes (thickening and/or pleural calcification) are a com mon finding among workers ex posed to asbestos dust In regard to pleural plaques, George W. Wright, MD, said "in an area where asbestos fiber is known to be present in consider That asbestos is indestructible is a fallacious concept "and the belief that it accumulates on the surface of streets, etc., seems ill- founded and will require some proof," Dr. Wright said. pleural disease also was present, pulmonary function was invaria bly leas hiy every measurement-- lung volume, flow rate; and dif fusing capacity at rest and during able concentration (such as eastmu Quebec) ... it is proper to - consider these findings as evi dence of asbestos exposure." There is no evidence associat ing the presence of pleural less than 5% of US asbestoe production goes into brake lin ings. The high heat of friction The effects of pleural changes in restricting lung volume were expected. "The consistent asso plaques with development of the much more serious disease, meso thelioma, however. L F" i i i i i JAMA, June 9, 1969 Vbl 20& No 10 Medical News 1789 HWBUI0005565