Asphalt Industry Cross-Sectional Exposure Assessment Study

Abstract

Work activities around molten or heated petroleum asphalt, such as in road paving and roofing applications, may result in worker exposure to asphalt fumes. This article presents the results from a worker exposure study, conducted in five different industries, that examined airborne and dermal exposure to asphalt fumes. The industries included road paving, hot mix plants, refineries/terminals, roofing manufacturing, and roofing application. Thirty-one sites were visited throughout the continental United States during this study. Dermal wipe samples from the back of the hand or forehead were collected from selected workers in each industry studied. Air samples were collected over full work shifts to measure concentrations of respirable particulate matter (RPM), total particulate matter (TP), benzene soluble fraction (BSF), and polynuclear aromatic hydrocarbons (PAHs). Observations were made to identify work practices, hygienic procedures, exposure control methods, and factors that could influence exposure measurements. The analysis of dermal samples for PAH compounds revealed very few detectable levels of these compounds in the samples. Air samples revealed highly variable concentrations of total particulate, with less variable concentrations of BSF and RPM. Industry mean TP concentrations ranged from 0.43 to 2.6 mg/m³, with RPM industry means ranging from 0.26 to 0.76 mg/m³. Air sample results for PAH analysis generally revealed low, and frequently nondetectable, levels of these compounds. Benzo(a)pyrene was detected in 2 of 186 air samples. Discrepancies were noted in the BSF analysis, including high field blank contamination, and the observation that BSF values exceeded TP values in the same samples in an inconsistent and unpredictable pattern. These BSF findings, which have been observed in previous studies, deserve careful consideration if this method is to be employed in petroleum asphalt fume sampling and analysis. Potential interferences were also observed, including workers smoking tobacco products during sample collection, and exposure to diesel exhaust in some of the industries studied. These factors may result in a positive bias on the sampling and analytical results, but could not be quantified in this study due to limited samples that could be collected to evaluate each of these potential interferences.