Biological monitoring of petrochemical industry workers exposed to benzene, toluene, xylenes, methyl ethyl ketone, and phenol in Southern Iran

Background: Volatile organic compounds (VOCs), including carcinogens and toxic compounds, are produced in petrochemical industries. We undertook this study in order to study workers’ respiratory exposure to different VOC concentrations and compare the results with the urinary levels of its metabolites and study the correlation between them in petrochemical industries. Materials and Methods: Exposure to benzene, toluene, xylene isomers, phenol, and methyl ethyl ketone (MEK) was evaluated in 104 male subjects using personal sampling pump and charcoal sorbent tube at the breathing zone and analyzed using gas chromatography–mass spectrometry (GC-MS). The urine samples were analyzed using high-performance liquid chromatography (HPLC-UV) and gas chromatography-flame ionization detector (GC-FID). Results: The mean concentration of urinary trans,trans-muconic acid (t,t-MA), was 1431 µg/g creatinine and hippuric acid, methyl hippuric acid, phenol, and MEK were, 0.394, 0.444, 0.098 g/g creatinine, and 0.15 mg/l. The mean concentration of benzene in the breathing zone was greater than the threshold limit value (TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). Conclusions: In this study, a more significant relationship was found between benzene in breathing zone and urinary t,t-MA in those exposed to benzene in concentrations higher than 1 ppm (r2 = 0.89) than lower than 1 ppm. Moreover, the same results were observed for other hydrocarbons and their level of urinary biological index. A more significant relationship was observed between phenol in breathing zone and urine through exposure to airborne phenol in concentrations of higher than 0.049 ppm than lower than 0.049 ppm (r2 = 0.75). The relationship between MEK in breathing zone and urinary MEK was more significant in concentrations of higher than 0.1 ppm (r2 = 0.79) than lower than 0.1 ppm.