Assessment of Irritative Effects of Fumes of Bitumen on the Airways by using Non-Invasive Methods—Results of a Cross-Shift Study in Mastic Asphalt Workers

Abstract

Data concerning the irritative effects of current exposure to fumes of bitumen on the airways in humans are limited. To assess the effects of fumes of bitumen on the airways a cross-shift study was conducted with monitoring of inflammatory process in upper and lower airways of workers exposed to fumes of bitumen and a reference group. All workers were examined immediately before and after shift. At both time points, spirometry was performed and nasal lavage fluid (NALF), induced sputum and spot urine were collected. Cellular composition and inflammatory mediator profile of the NALF and sputum samples were analyzed. Personal air sampling in each mastic asphalt worker's breathing zone was carried out to measure exposure to fumes of bitumen. The present cross-shift study with 202 mastic asphalt workers exposed to fumes of bitumen and 55 roadside construction workers as the reference group showed that fumes of bitumen released under high processing temperatures by mastic asphalt handling can exert acute and (sub-)chronic irritative effects on the upper and lower airway assessed with nasal lavage and induced sputum analysis. Airborne personal exposure to fumes of bitumen was associated with significant cross-shift declines in lung function parameters. Pre-shift lung function parameters (forced expiratory volume in 1 s [FEV 1 ] and forced vital capacity [FVC]) were significantly higher in the exposure group that pointed to a “healthy worker effect.” Possible carry-over effects could be observed in elevated pre-shift levels of several inflammation parameters in exposed workers indicating a (sub)chronic inflammation in these groups. Elevated interleukin-8 and protein levels in bitumen-exposed workers in sputum samples were found, but not in the nasal lavage fluid. The results emphasize irritative effects on the upper and lower airways under high exposure to fumes of bitumen. A more detailed analysis will be provided when all workers will be enrolled in that study.