Occupational exposure to bitumen during road paving.

The exposure of road pavers to total particulates, bitumen fumes, semivolatile organic compounds (SVOCs), polycyclic aromatic hydrocarbons (PAHs), low-molecular-weight amines, styrene, and 1,3-butadiene was studied at 13 paving sites where 11 different asphalt mixtures were laid. Researchers analyzed 1-hydroxypyrene in the workers' pre- and postshift urine samples. The arithmetic mean concentrations of total particulates, bitumen fumes, SVOCs, and PAHs in the breathing zone of road pavers were 0.6 mg/m3, 0.29 mg/m3, 5.6 mg/m3, and 5.03 microg/m3, respectively. The highest bitumen fume concentrations (2.65 mg/m3) were measured in manual mastic laying, that is, when the paving temperature was highest. More than 90% of air impurities measured were in the vapor phase. Workers laying surface dressing were exposed to the highest SVOC concentrations (27.8 mg/m3). The paving temperature and the concentrations of bitumen fume correlated positively, but the weather conditions significantly affected the workers' exposure; for example, increased wind velocity resulted in lower concentrations of SVOCs and PAHs. Job title was not found to be a significant determinant of exposure, but exposure to bitumen fume and greater than or equal to four-ring PAHs among manual mastic pavers, and that to SVOCs and total PAHs among surface dressing workers, were significantly higher than among other pavers. Exposure during road paving operations was, on average, more than 10-fold higher to PAHs than was the exposure of a traffic controller (0.34 microg/m3) caused by automobile exhausts from background traffic. The PAHs were comprised mainly of two- and three-ring compounds. The concentrations of amines, and impurities from polymer modified bitumens, styrene, and 1,3-butadiene were below detection limits. Urinary 1-hydroxypyrene concentrations were higher among road pavers than among office workers serving as referents.