Physical and Chemical Characterization of Asphalt (Bitumen) Paving Exposures

Abstract

The purpose of this research was to characterize the physical and chemical properties of asphalt (bitumen) fume and vapor in hot mix asphalt roadway paving operations. Area and personal air samples were taken using real-time equipment and extractive sampling and analytical methods to determine worker asphalt exposure, as well as to characterize the properties of the particulate and vapor phase components. Analysis of personal inhalation and dermal samples by gas chromatography/mass spectroscopy showed that the polycyclic aromatic hydrocarbon profile is dominated by compounds with molecular weights below 228, and that substituted and heterocyclic polycyclic aromatic hydrocarbons comprised approximately 71% of the detectable mass concentration (vapor and particulate combined). Principal components analysis shows that the polycyclic aromatic hydrocarbons with molecular weights greater than 190 are the driving force behind the polycyclic aromatic compound exposures measured for the dermal and particulate phases; there was no clear trend for the vapor phase Most of the aerosol particles are fine (mass median aerodynamic diameter 1.02 μ m; count median diameter 0.24 μ m).

Keywords:

• asphalt
• bitumen
• polycyclic aromatic compounds
• polycyclic aromatic hydrocarbons
• aerosol size

ACKNOWLEDGEMENTS

This study was supported by a grant from the National Cancer Institute (1R01-CA74413-01) titled Identification and Control of Cancer Risks in Asphalt Workers, and research support from the Asphalt Paving Environmental Council. We also recognize the contributions of Rick Rinehart and Jen Massa (Harvard) and Kevin Dunn (NIOSH), in collecting the field data, and DataChem Laboratories and the Harvard Organics Laboratory for chemical analyses.

Notes

^A Mixed models used to evaluate the effect of five factors.

^A Comparison of the PAC concentrations at 370 nm and 400 nm as emission wavelengths.

^B Below limit of quantitation.

^A Comparison of the PAC concentrations at 370 nm and 400 nm as emission wavelengths.

^B MMD ranged from 0.30–0.7; lower MMD approximated and may be biased due to low sample loading.

^C MMD ranged from 0.15–0.6; lower MMD approximated and may be biased due to very low sample loading.