International studies to compare methods for personal sampling of bitumen fumes

A newly recommended Institute of Occupational Medicine (IOM) sampler, optimized for the inhalable fraction, was compared with 'total particulate' samplers currently used by five laboratories in different countries for the analysis of bitumen fumes. Using a laboratory fume generator, all samplers were uniformly exposed to bitumen fumes from typical USA bitumen (commercial Pen 65). The results show that, for laboratory-generated bitumen fumes, benzene-extractable inhalable particulate data for the IOM sampler are consistent with benzene soluble matter data from the other samplers. Direct comparison of the IOM sampler with the 37 mm closed-face cassette (USA sampler) using an identical protocol in a single laboratory gave a ratio of 1.05:1 (USA:IOM). Similarly, for total particulate matter, the standard previously recommended by the American Conference of Governmental Industrial Hygienists (ACGIH), an average value of approximately 1 between the IOM and the five samplers was obtained. For unadulterated bitumen fumes, the geometry of the cassettes does not appear to affect entry of the particles into the sampler. Field studies may show differences in results as other factors, e.g. wind and its effect on sampling efficiency, and also particulates originating from sources other than bitumen, such as dust, are involved. These will require thorough investigation prior to the assessment of the impact of the new sampler and prior to any reconsideration of occupational exposure limits taking into account practical feasibility. Other tests were conducted on the bitumen fume samples including total organic matter, simulated distillation and polycyclic aromatic compound analysis. These additional tests were performed on the fume collected on the filter plus the volatile portion that passed through the filter and was captured on various adsorbent materials. Protocols for sample collection and analysis varied in different countries with results reflective of these differences, suggesting the need for standardization.