Generation of Bitumen Fumes Using Two Fume Generation Protocols and Comparison to Worker Industrial Hygiene Exposures

Abstract

This study had two fundamental goals. The first was to collect sufficient quantities of bitumen fumes used in both the roofing and paving industry in the United States to do detailed chemical and biological testing in preparation for a two-year animal skin painting study on select samples. These bitumen fumes need to be similar to the fumes to which workers in these industries are actually exposed. In this first phase, bitumen from four geographical regions of the United States were selected, which produced bitumen from four different major crude sources in roofing and four sources in paving. Each source was supplied to projects where workers were monitored for exposure. The industrial hygiene samples from workers were then tested for physical and chemical properties. These results were used to guide collection of fumes from each source using the vapor headspace of tanks containing each bitumen. Bitumen fumes were collected using the same protocol that the Fraunhofer Institute of Technology and Medicine employed in a recent animal inhalation study. The second goal of this study was to better understand previous studies conducted by NIOSH which generated fumes for mouse skin painting studies using a roofing bitumen in a laboratory fume generator. In the current study, bitumen fumes from the four roofing sources were generated using the NIOSH protocol and compared to fumes collected in the roofing work sites and taken from the tank headspace. One of the sources was selected to generate enough fumes for a chronic two-year animal skin painting study. Results from an array of physical, chemical and biological tests were used to characterize the subsequent fumes. Acceptance criteria were designed to match parameters that could be analyzed both on the workplace samples and the bitumen fumes collected from the tank and involved three basic categories: simulated distillation, fluorescence and gas chromatography/mass spectroscopy for polynuclear aromatic hydrocarbon analysis and extracted ion fingerprinting. Methods employed for the collection of these fumes were selected to optimize the capture of the most toxicologically relevant components.Distinctions between paving and roofing fume samples are outlined. Bitumen fumes from the paving sources produced from four different crude sources were quite similar to each other in a number of the tests performed. Bitumen fumes from the roofing sources also were very similar to each other. On the other hand, fumes generated using the NIOSH protocol show results that significantly differ from the corresponding worker exposures.

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

“…The higher the temperature of preparation of the bitumen emission condensates, the greater tumorigenic activity observed. Kriech et al (2007) showed that these emissions were not the same as worker exposures and that the high temperature and continuous agitation contributed to significantly higher levels of 4-6 ring PACs than seen in worker exposures. A follow-up mouse study was conducted in 1989 by Sivak et al on five fractions of this same fume condensate -with increasing polarity A, B, C, D and E. The carcinogenic activity was limited to Fractions B and C, which represented only 10.2% of the total fume condensate.…”

“…Much of the polycyclic aromatic compound (PAC) composition is in the form of alkylated species (primarily alkyl-naphthalenes, alkyl-fluorenes and alkyl-anthracenes) and includes sulfur heterocyclic materials (primarily alkyl benzothiophene and alkyl-dibenzothiophenes). The most prominent of the parent, unalkylated PACs detected in workplace exposures for paving and roofing workers include acenaphthene, anthracene, fluoranthene, fluorene, naphthalene, phenanthrene and pyrene (Kriech et al 2007;Cavallari et al 2012a). Normal paving worker exposures contain only trace levels of parent unalkylated PACs, primarily of the 2-and 3-ring variety.…”

“…No adducts were seen in blood lymphocytes. These bitumen emissions were not representative of worker exposure (Kriech et al 2007). Fume generation temperature was at the extreme end of the fume-generation spectrum for bitumen and furthermore intratracheal instillation is an extreme exposure route by which to evaluate pulmonary DNA adduct-forming potential of bitumen emissions.…”

“…The objective of the study was to investigate the carcinogenic potential of US Performance Grade (64-22) paving grade bitumen and type III, built-up roofing [BUR] bitumen fume condensates and compare this with results of laboratory-derived roofing fume condensate; samples of the latter have previously proved carcinogenic in skin painting studies (Niemeier et al 1988;Sivak et al 1997), although their composition was not representative of normal worker exposure (Reinke et al 2000;Kriech et al 2007). To select the paving and roofing grade bitumen samples for the study, four commercially available products of each type, representing four different crude oils from four distinct regions of the USA were collected and analyzed (Kriech et al 2007).…”

“…To select the paving and roofing grade bitumen samples for the study, four commercially available products of each type, representing four different crude oils from four distinct regions of the USA were collected and analyzed (Kriech et al 2007). For the laboratory-derived condensate samples, generation of emissions was performed on the four type-III BURA products according to the method described by Sivak et al 1989.…”