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 crossshift 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 carryover 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.

Respiratory Symptoms and Lung Functional Impairments Associated with Occupational Exposure to Asphalt Fumes

“…1,[4][5][6] Additionally, asphalt workers are exposed to emissions from the exhaust of passing vehicles. 4,[7][8][9] Respiratory effects of exposure to asphalt fume have been evaluated in a few studies. 5 However, conclusive results have not been obtained yet.…”

Detection of DNA strand breaks by comet assay in sputum leucocytes of bitumen-exposed workers: A pilot study

“…These workers were randomly selected from the workers of the German Human Bitumen Study (further details on the conduct and recruitment have been published elsewhere). 7,9 However, the preand post-shift IS samples of 42 workers contained sufficient leucocytes that comprised the material for this pilot study. Characteristics of this subgroup are summarized in Table 1.…”

“…Collection and analysis of induced sputum IS was collected pre and post shift by inhalation of isotonic (0.9%) saline aerosol for 10 min) 9 and selected sputum plugs were processed with 0.1% sputulysin (Calbiochem, Darmstadt; Germany). After centrifugation, aliquots of the cell-free supernatants were stored at -80 C until further analysis of IL-8.…”

“…In this cross-shift study, an increase of airway inflammation was detected by higher levels of sputum interleukin-8 (IL-8) and neutrophil influx in workers with high exposure levels. 8,9 This pilot study was conducted within the frame of the German Human Bitumen Study and aimed to assess the level of DNA strand breaks in cells collected from IS. DNA strand breaks in sputum leucocytes were compared with DNA strand breaks in blood lymphocytes and with the sputum concentration of IL-8.…”

“…Human and Experimental Toxicology 29 (9) for lymphocytes isolation by a standard method of centrifugation on a Ficoll density gradient. Lymphocytes suspended in the RPMI solution were counted in a hemocytometer and about 4 Â 10 4 cells were used immediately for the comet assay.…”