Unmetabolized VOCs in urine as biomarkers of low level occupational exposure

Objectives: To compare the usefulness of determining unchanged forms of volatile organic compounds (VOCs), namely toluene (TOL), ethylbenzene (EB) and xylene (XYL), in urine with the effectiveness of the already used biomarkers of occupational exposure. Materials and Methods: Surveys were conducted in two workplaces (paint factory and footwear factory). In total, 65 subjects participated in the study. Air samples were collected using individual samplers during work shift. Urine and blood samples were collected at the end of work shift. Urine samples were analyzed for unchanged compounds and selected metabolites, while blood samples were tested for unchanged compounds. VOCs in blood and urine were determined by solid phase microextraction gas chromatography (SPME-GC-MS). Results: In the paint factory, the geometric mean (GM) concentrations of VOCs in the air ranged as follows: 0.2-4.7 mg/m3 for TOL, 0.4-40.9 mg/m3 for EB and 0.1-122.6 mg/m3 for XYL. In the footwear factory, the GM concentration of TOL in the air amounted to 105.4 mg/m3. A significant correlation (p < 0.05) was observed between VOCs in blood, urine and air. The regression analyses performed for paint factory workers showed that TOL-U and TOL-B were better biomarkers of exposure (r = 0.72 and r = 0.81) than benzoic acid (r = 0.12) or o-cresol (r = 0.55). Conclusion: The findings of the study point out that the concentration of unchanged VOCs in urine can be a reliable biological indicator of low level occupational exposure to these compounds.