Are the Members of a Paving Crew Uniformly Exposed to Bitumen Fume, Organic Vapor, and Benzo(a)pyrene?
The goal of this investigation was to assess if and when a crew of paving workers is uniformly exposed to bitumen fume, organic vapor, and benzo(a)pyrene. Data on paving workers with up to six repeated exposure measurements were extracted from a database of exposure measurements developed within a study of the European asphalt industry (N = 591). The uniformity of exposures to bitumen fume, organic vapor, and benzo(a)pyrene was evaluated while grouping individuals by job title, primary tasks, crew membership, and use of coal tar (discontinued in Western Europe). The estimated ranges within which 95% of individual mean exposures were expected to fall (BWR0.95) were used to assess exposure uniformity. Variance components were estimated by constructing mixed-effects models, with grouping variables as fixed effects and worker identity as random effect. The influence of duration of the sampling survey on estimates of exposure variability for a crew was also examined. There was a substantial variability in exposures between paving crews, as well as persons holding the same job or doing the same task, but each crew was uniformly exposed to bitumen fume and benzo(a)pyrene (BWR0.95 2 and 1, respectively). Workers within the same crew engaged in paving with coal tar – containing binders were not, however, uniformly exposed to benzo(a)pyrene. Also, organic vapor exposures were not uniform among the members of a paving crew (BWR0.95 = 15). Sampling campaigns of up to 7 months had little impact on the estimates of within- and between-worker variability. These findings should assist investigators studying paving operations in optimizing their sampling, exposure assessment, and risk evaluation protocols. The results support the notion that only empirically determined predictors of exposure can yield optimal grouping, unlike a priori grouping strategies based on general descriptors such as jobs title or tasks performed.