Ambient and Biological Monitoring of Exposure and Genotoxic Effects in Mastic Asphalt Workers Exposed to Fumes of Bitumen

Abstract

Mastic asphalt workers may be exposed to polycyclic aromatic hydrocarbons (PAH) present in bitumen. We conducted a cross-shift study to determine genotoxic effects after exposure to bitumen. For this purpose, external and internal exposure of 202 mastic asphalt workers exposed to bitumen and 55 construction workers without exposure to bitumen was assessed. Exposure by inhalation to fumes of bitumen during the shift was measured by personal ambient monitoring. To assess overall exposure to bitumen (by inhalation and dermal absorption), 1-hydroxypyrene (1-OHP) and the sum of 1-, 2 + 9-,3-,4-hydroxyphenanthrene (OHPhe) were determined in pre- and postshift urine. 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) adducts, anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (anti-BPDE) DNA adducts, DNA strand breaks and alkali-labile sites, and micronucleus frequencies were determined as biomarkers of genotoxic effects in white blood cells (WBC). Concentrations of fumes of bitumen were correlated with a moderate association with 1-OHP and OHPhe after work shift (r _s = 0.25, P < 0.001 and r _s = 0.36, P < 0.001). Significantly increased 8-oxodGuo adduct levels were observed after shift in both exposure groups (P < 0.0001). Paradoxically, decreased DNA strand break frequencies were observed after shift in both groups (P < 0.05). Postshift values in DNA strand break frequency were associated with 1-OHP (Spearman rank correlation coefficient 0.19, P = 0.01). Significantly more 8-oxodGuo adducts and DNA strand breaks were found in workers exposed to bitumen before and after shift compared with the reference group. However, no dose-dependent association was observed between exposure and genotoxic effects. Nevertheless, the findings indicate that workers exposed to bitumen exerted a higher level of DNA damage (8-oxodGuo and DNA strand breaks) in WBC compared with reference subjects.

Keywords:

• fumes of bitumen
• ambient monitoring
• biological monitoring
• genotoxic effects

ACKNOWLEDGMENTS

We thank R. Rühl (BG Bau, Frankfurt, Germany), R. Rumler, H. P. Schicker, K. Schott, and G. Zoubek (BG Bau, Munich, Germany) for support in the conduct of this study, and A. Düker, B. Engelhardt, A. Erkes, A. Flagge, E.-H. Lee, E. Schomberg, B. Teschner, and B. Vosshans for technical assistance.

This work was supported by the Hauptverband der gewerblichen Berufsgenossenschaften (HVBG, German Federation of Institutions for Statutory Accident Insurance and Prevention), St. Augustin, Germany.

Notes

^A Adjusted for smoking status (non smoker, smoker), age (< 30 years, 30– < 50 years, 50+ years) and German nationality.

^B Relative changes by exposure and during shift were expressed as factors for log-transformed variables.

^C Values lower than the limit of detection were replaced by normally distributed random numbers.

^A Calculated as postshift minus preshift levels.

^A Effect estimate

^B Interaction term between time of measurement (preshift or postshift) and exposure to fumes of bitumen (mg/m³)