Luminescence spectroscopy as a screening tool for the potential carcinogenicity of asphalt fumes

Abstract

A subset of polycyclic aromatic compounds (PACs), which contain 4-6 annulated rings, has been documented as the source of carcinogenicity in animal skin painting studies of petroleum products and asphalt fumes (M. L. Machado, P. W. Beatty, J. C. Fetzer, A. H. Glickman and E. L. McGinnis, Fundam. Appl. Toxicol., 1993, 21, 492; T. A. Roy, S. W. Johnson, G. R. Blackburn and C. R. Mackerer, Fundam. Appl. Toxicol., 1988, 10, 466). Because of the chemical complexity of these materials, it has been difficult to identify the specific compounds within this broad range of PACs responsible for their carcinogenicity. An alternative approach using luminescence spectroscopy was taken in this study to quantify, without identification, a subset of these compounds that appears to cause cancer. The fluorescence response at a specific wavelength pair was obtained for 39 laboratory asphalt fume condensates from animal skin painting studies, yielding a linear correlation coefficient of R2 = 0.96 between the fluorescence response in these materials and the carcinogenicity found in animal studies. In the absence of other asphalt fume condensates from animal studies, 17 petroleum oils were also evaluated using this method and compared with the available animal skin painting data. The details of the method include a clean-up step that removes the highly polar compounds and spectral subtraction of two- and three-ring PAC interference, both of which add to the fluorescence response, yet were not found to contribute to a carcinogenic response from skin painting studies. Full scan fluorescence plots also produce a fingerprint which can be used to assess contamination, such as coal tar products or mixtures of materials, that are not defined as asphalt, yet may be present in the working environment.

Review and implications of IARC monograph 103 outcomes for the asphalt pavement industry

“…This subset of 4-6 ring PACs that correlate with carcinogenic potency in animal studies of petroleum products and bitumen emissions have been extensively characterised using Modified Ames and Fluorescence (FL-PACs) (21-24). Correlations of individual bitumen fume study results have been reported between these measures and carcinogenic index per gram Kriech, Kurek, Osborn, Blackburn, & Fehsenfeld, 1999;Osborn, Kurek, Kriech, & Fehsenfeld, 2001) and data from the relevant dermal cancer assay studies have been aggregated by Trumbore et al (2011).…”

“…Mutagenicity index determined by the modified Ames assay (Blackburn, Roy, Bleicher, Vijayaraj Reddy, & Mackerer, 1984) was reduced between 41% and 50% from the input asphalt to the final oxidised product. A fluorescence method tuned to a subset of PAC compounds that have been associated with carcinogenic behaviour in mouse bioassays (Osborn et al, 2001) was reduced between 39% and 71%. The decrease was largest in the first quarter of the oxidation reaction.…”

Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

“…Further work to characterize and quantify workplace exposure to the bitumen emissions chosen for study was undertaken to compare workplace samples with samples of condensed fume collected from a heated storage tank (Preiss et al 2006). Consistent with the typical application temperature in the workplace, condensate was collected from the headspace of a storage tank at 175 C. Workplace and condensate sample results were comparable based on predetermined acceptance criteria that included boiling point distribution, UV fluorescence (Osborn et al 2001) and PAC profile. Pohlmann et al 2006a showed the feasibility of collecting samples of condensed emissions from the headspace of a heated bitumen storage tank that matched closely emissions to which paving workers were exposed.…”

Personal Breathing Zone Exposures among Hot-Mix Asphalt Paving Workers; Preliminary Analysis for Trends and Analysis of Work Practices That Resulted in the Highest Exposure Concentrations

“…(20) The instrument, a Perkin Elmer LS 50 B fluorescence spectrometer, was set to 385 nm excitation and 415 nm emission making the results more selective for the PACs, in the sample, containing 4-to 6-rings than the PACs containing 2-to 3-rings and was calibrated using diphenylanthracene (DPA). Results were reported as DPA equivalents providing exposure concentrations for the workers.…”