Evaluation of Bricklayer Exposures to Airborne Asbestos in Steel Mills (1972-1981)

Abstract

P-609 Introduction: Although there have been a number of studies of worker exposure to chemicals in steel mills, less attention has been devoted to characterizing the exposure of craftsman in these facilities. For example, the exposure to asbestos by bricklayers in steel mills has been suggested as being possibly significant. The objective of this analysis was to characterize the airborne concentrations of asbestos of these craftsmen as reflected in samples collected in two steel mills between 1972 and 1981. Methods: An asbestos air monitoring database was created from industrial hygiene surveys conducted during repair and/or maintenance work on open hearth furnaces and stoves. Personal (n=110) samples were collected while bricklayers and bricklayer helpers handled asbestos millboard and asbestos expansion allowance sheets. Some area (n=11) samples were collected in the vicinity of the work environment. The sample durations for all personal and area samples averaged 22 min (range 9-50 min) and 37 min (range 13-95 min), respectively. Most air samples were analyzed using phase contrast microscopy (PCM). Descriptive summary statistics were conducted to characterize both personal and area airborne asbestos concentrations. These data were combined with time-motion information to estimate 8-hour time-weighted average (TWA) concentrations, and these were compared to the contemporaneous OSHA permissible exposure limit (PEL) for asbestos. Results: Results of all personal air samples ranged from 0.03-3.2 f/cc (average: 0.3 f/cc; standard deviation (SD): 0.5 f/cc). These samples were collected during the periods of the day during which exposure was expected to be the highest and don't reflect the 8 hr-TWA. Of all the personal samples, six had results greater than or equal to 1 f/cc, but all were below the contemporaneous OSHA 15-min ceiling limit of 10 f/cc. Four of these relatively high samples were associated with the relining of a stove and the remaining two were associated with relining an open hearth furnace. Neither task is normally performed by bricklayers or masons. The estimated 8-hr TWA concentrations for these workers ranged from 0.04-1.34 f/cc (average: 0.33 f/cc; SD: 0.348 f/cc) for those days when mason were rebuilding furnaces. These values can not be used to depict the typical daily exposures of masons since fraction of their careers were involved in lining furnaces. Conclusions: Based on these results, it appears that bricklayer exposure to airborne asbestos, in these steel mills during this period of time, were generally below the contemporaneous OSHA permissible exposure limits (PELs).