Abstract
Benzene exposure data, submitted by nine petroleum refining companies, were studied with the general objective of characterizing the distribution of exposures within work operations and job categories. The data were collected by company hygienists over the period of years between 1978 and 1984. All measurements were of personal exposures determined using charcoal tubes or organic vapor monitors. Of the 123 location and unit specific job groups studied, most eight-hour time-weighted average (TWA) exposures were below 1.0 ppm. For some groups, however, the variability in exposure was such that ten percent or more of exposures exceeded 1.0 ppm. For nineteen of the most highly exposed groups, sufficient data were available to study the variability in exposure associated with individual workers versus the common work environment. Results indicate that there were some cases in which variability in exposure was mostly associated with the environment and others in which it was mostly associated with differences between workers, but it was most often approximately evenly split between the two sources. This analysis provides guidance in determining whether control strategies should be targeted at the work environment or at work requirements or practices of individual workers within the group. Some short-term exposure data were included for study. It was found that most 15-minute TWA exposures were less than 1.0 ppm, but again, there were groups with highly variable exposure with some measurements in excess of 5 ppm. These were often in jobs involving loading and unloading operations of barges or tanker trucks.