An approach to the characterization of silica exposure in U.S. industry.

Quantitative evaluation of worker exposure to silica in nine Standard Industrial Classification (SIC) codes was conducted, using data derived from OSHA compliance inspections, in order to assess the silica exposure problem in the U.S. The nine SICs studied were those in which OSHA inspections were concentrated. They include: construction; chemical manufacture; stone, glass, and clay manufacturing; primary metal industries; metal fabrication; machinery; transportation; and miscellaneous manufacturing industries. High exposures to silica were documented in each industry, with the number of test samples over the permissible exposure limit ranging from 14% (aluminum foundries) to 73% (pottery). An estimation is made that 24,889 workers employed in ferrous and nonferrous foundries are at risk of silica-related pulmonary effects. The data developed in this analysis also indicate the need to investigate certain industries that had high exposures but few inspections. The limitations of the data base for estimating the scope of the silica problem, including lack of data on mining and milling, are discussed. We conclude that exposure to silica represents a continuing and significant problem in a number of U.S. industries.