Assessment of Exposure to Polycyclic Aromatic Hydrocarbons (PAH) in Italian Asphalt Workers

Abstract

The purpose of the work was the assessment of exposure to Polycyclic Aromatic Hydrocarbons (PAH), a family of ubiquitous pollutants of which some are carcinogens, in 100 Italian asphalt workers (exposed to bitumen fumes and diesel exhausts) and in a reference group of 47 ground construction operators (exposed only to diesel exhausts, reference group). The protocol included interview via questionnaires, environmental air-monitoring (active personal sampling during the work shift), dermal contamination measures (six pads placed on worker's wrist, neck, arm, chest, thigh, and ankle), and biological monitoring (determination of 1-hydroxypyrene in urine spot samples collected three at different moments: baseline after two days of vacation, before shift, and at end shift on a day in the second half of the week). Analysis of the most relevant PAH, according to the American Environmental Protection Agency, EPA, was performed by High Performance Liquid Chromatography (HPLC) by fluorimetric detector. Median airborne levels of PAH ranged from 426 to below 0.03 ng/m3. Vapor-phase PAH, apart from naphthalene, were significantly higher in asphalt workers than in the reference group. Particle-phase PAH were similar and very low (< 1 ng/m3) in both exposure groups. Exposure levels did not vary in different work-tasks. Excretion of urinary 1-hydroxypyrene (expressed by ng/g creatinine) showed a significant increase at different sampling moments in asphalt workers, smokers, and non-smokers: baseline was lower than at the beginning of the workshift, and values were even higher in the end workshift sample. Comparing the two groups, a significant difference in the levels of metabolite does not appear, whereas this trend can be viewed observing the non-smokers. All body regions monitored by pads showed equivalent values levels of Dermal Deposition Density in both exposure groups. The measured amount of dermal contamination was significantly higher in asphalt workers than in ground construction operators. In asphalt workers, skin contamination was significantly higher during asphalt paving than during asphalt mixing. Dermal Exposure Rate was calculated about threefold higher than Airborne Exposure Rate; whereas considering toxicokinetical information (Kp, lag time, experimental dermal absorption data) and hygienistic data (particle size of bitumen fume), the relevance of dermal absorption is lower than respiratory. The results of this study demonstrate that asphalt workers experience slight occupational exposure to PAH, both by inhalatory and dermal routes, resulting in a significant increase of urinary 1-hydroxypyrene during the workweek.