The six major forms of asbestos (1332214) were reviewed and then the most widely used form, chrysotile (12001295), was examined in more detail. The three largest industries using chrysotile include the asbestos/cement pipe industry, the asbestos friction products industry, and the asbestos textiles industry. A discussion was given for the production operations and products made in each of these industries. A brief comparison was included of the optical and electron microscopy techniques used in asbestos exposure evaluation. Since the invention of the steam engine, the uses for asbestos in the modern world have dramatically increased. Asbestos/cement pipe has become commonplace for water and sewage piping. The purpose of the asbestos mixed with the cement was to provide more strength and flexibility. The friction products industry involved the manufacture of brake linings, clutch facings, and transmission bands. In the asbestos textile industry both asbestos cloth and tape were produced. The United States Public Health Service, in 1964, initiated a comprehensive industrial hygiene study of these three industries to characterize the exposures to chrysotile asbestos and to establish a new sampling and analytical methods. Some recent research based on samples collected during this study was reviewed as well. In comparing the usefulness of phase contrast microscopy and electron microscopy, it was determined that the phase contrast microscopy technique provided relatively good indications of asbestos fibers greater than 5 micrometers in length.
Division of Surveillance, Hazard Evaluations, and Field Studies, NIOSH, Cincinnati, Ohio, 18 pages, 11 references