Health Hazard Evaluation Determination Report No. 79-45-649, The Timken Company, Canton, Ohio

摘要

The concentration of crystalline silica (free silica) in five personal breathing zone samples exceeded both the NIOSH recommended time-weighted average standard of 50 micrograms of free silica per cubic meter of air and the OSHA standard (respirable dust permissible exposure limit 10 milligrams per cubic meter of air divided by the % Quartz plus 2). Laboratory analysis revealed that the bulk refractory material did not contain asbestos or fibrous glass. The fiber-like material present in the refractory material was mineral wool fiber. The results of the personal air sampling for coal tar pitch volatiles (CTPV's) indicated levels of benzene extractables which were below the 0.2 mg/cu. m. evaluation criteria yet, laboratory analyses of the powdered coal tar pitch mixture identified known and suspected carcinogens as components of the mixture. Recommendations have been offered in this report for reducing worker exposure to free silica, mineral wool fibers, and coal tar pitch volatiles.