Document 2q4gGwDxB8g65ODKVbkNEBd4r

Environmental Asbestos: Threat or Phantom The paradox of asbestos is that although its primary uses have destroys the asbestos, converting it into an amorphous material, bodies have been found in 25% 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 than 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 is 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 pleural 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. Then in MontreeL ............. clude asbestos tile and cement Physicians have tended to dis Some asbestos-containing prod regard the significance of pleural' ucts do wear, however, and die changes on pulmonary function. fibers are released. These indude t This study suggests that such brake Iminse, sidingand shingles- V changes have a significant effect The fibers thkfc ndghfc bo ro- &: on all aspects of lung function. leased from eB Had* of "wear" ?*. When 1,000 asbestos workers either become booed Into the soft - were surveyed, marked pulmo ment between lung and chest wall is necessary to preserve optimal ventilation to perfusion imbal ance," Dr. Becklake said. "In other worda," 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 fibresia. The pleural *hs"g-- (thickening and/or pleural calcification) are a com mon finding among workers ex or are mg water. Asbestos is almost universally present in river water, but in* very small amounts. That asbestos is indestructible is a fallacious concept "and the belief that it accumulates on the surface of streets, ete^ seems iHfout-ded and will require soma proof," Dr. Wright said. txss than 5% of US asbestos production goes into brake linings. The high heat of friction nary fi&roeia was found in 1.4%. All were men over age 55. The degree of parenchymal disease was rated according to radiological findings. When pleural disease also was present, pulmonary function was invaria bly leas by every measurementlung volume, flow rate, and dif fusing capacity at rest and during The effects of pleural changes in restricting lung volume were expected. "The consistent 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 able concentration (such as east ern Quebec) . . . it ia proper to ' consider these findings as evi dence of asbestos exposure" There is no evidence associat ing the presence of pleural plaques with development of the much more serious disease, meso thelioma, however. i JAMA June 9, 1969 Vol 208, No 10 1789 HWBUI0005559