An optimized sampling and GC–MS analysis method for benzene in exhaled breath, as a biomarker for occupational exposure

Benzene is known to be toxic and carcinogenic: therefore, in case of exposure to benzene vapours, a reliable biological monitoring procedure is needed, particularly in the field of occupational hygiene. The determination of the concentration of benzene in the exhaled air 8 h after the exposure has been demonstrated to be a significant biomarker, even for low concentrations of airborne benzene vapours. This work presents a sampling and analysis method that optimizes previously described procedures: in the sampling phase, a double-step sample collection in Tedlar bags is used, in order to remove the breath moisture and to standardise the sample volumes. The analytical phase uses a cryogenic trap for the concentration of the air samples to be injected in the GC–MS, without the need for trapping materials, significantly reducing time and costs of the analysis and improving sensitivity. The presented method has been successfully applied to the biological monitoring of a mixed population (occupationally exposed and not exposed subjects, smokers and non-smokers), with a lower detection limit of 1.5 ng of benzene per litre of exhaled air, that is 1/200 of the biological exposure index recommended by the American Conference of Governmental Hygienists.