Road pavers’ occupational exposure to asphalt containing waste plastic and tall oil pitch

Abstract

Waste plastic (WP) and tall oil pitch (T), which are organic recycled industrial by-products, have been used as a binder with bitumen in stone mastic asphalt (SMA) and asphalt concrete (AC). We compared the exposure over one workday in 16 road pavers participating in a survey at four paving sites, using mixes of conventional asphalt (SMA, AC) or mixes containing waste material (SMA-WPT, AC-WPT). The concentrations of 11 aldehydes in air were 515 and 902 μg m⁻³ at the SMA-WPT and AC-WPT worksites, being 3 and 13 times greater than at the corresponding worksites laying conventional asphalt. Resin acids (2–42 μg m⁻³), which are known sensitizers, were detected only during laying of AC-WPT. The emission levels (μg m⁻³) of total particulates (300–500), bitumen fumes (60–160), bitumen vapour (80–1120), naphthalene (0.59–1.2), phenanthrene (0.21–0.32), pyrene (<0.015–0.20), benzo(a)pyrene (<0.01) and the sum of 16 PAHs (polycyclic aromatic hydrocarbons, 1.28–2.00) were similar for conventional and WPT asphalts. The dermal deposition of 16 PAHs on exposure pads (on workers’ wrist) was low in all pavers (0.7–3.5 ng cm⁻²). Eight OH-PAH biomarkers of naphthalene, phenanthrene and pyrene exposures were quantified in pre- and post-shift urine specimens. The post-shift concentrations (mean ± SD, μmol mol⁻¹ creatinine) of 1- plus 2-naphthol; 1-,2-,3-,4- plus 9-phenanthrol; and 1-hydroxypyrene were, respectively, for asphalt workers: 18.1 ± 8.0, 2.41 ± 0.71 and 0.66 ± 0.58 (smokers); 6.0 ± 2.3, 1.70 ± 0.72 and 0.27 ± 0.15 (non-smokers); WPT asphalt workers: 22.0 ± 9.2, 2.82 ± 1.11 and 0.76 ± 0.18 (smokers); 6.8 ± 2.6, 2.35 ± 0.69 and 0.46 ± 0.13 (non-smokers). The work-related uptake of PAHs was low in all pavers, although it was significantly greater in smokers than in non-smokers. The WPT asphalt workers complained of eye irritation and sore throat more than the pavers who had a much lower exposure to aldehydes and resin acids.