HEALTH RISK ASSESSMENT OF BTEX EXPOSURE TO PARKING WORKERS AT ONE OF PARKING STRUCTURE IN BANGKOK THAILAND

Abstract

This study aimed to estimate the level of Benzene, Toluene, Ethylbenzene and Xylene (BTEX) exposure and identified a health risk assessment related to BTEX exposure via inhalation for workers at a car parking. Measured personal exposure, air samples were collected by using active diffusion sampling tubes and analyzed by Gas Chromatography, with Flame Ionization Detector (GC-FID). Urine samples were collected from workers at post-shift and analyzed by High Performance Liquid Chromatography with Ultraviolet Detection (HPLC-UV). The mean concentrations (±SD) of benzene, toluene, ethylbenzene, and xylenes (m,p,o-xylene) were 11.282 (±5.033), 56.129 (±73.963), 7.166 (±9.198), and 10.587 (±6.324) µg/m3 respectively. Then, a risk assessment methodology was employed to evaluate the potential adverse health effects of the individual BTEX compounds according to their carcinogenic and non-carcinogenic effects. Cancer risk for benzene was estimated to be 4.37×10-6, indicated developing cancer over lifetime exceeding 5 people in a million which considered an unacceptable level (acceptable level, cancer risk < 10-6). Non-carcinogenic risks (Hazard Quotients; HQ), were considered an acceptable level (HQ < 1), which the results were 0.360, 0.010, 0.006, and 0.105 for benzene, toluene, ethylbenzene, and xylenes respectively. The mean concentration of t,t-Muconic acid, Hippuric acid, and Methylhippuric acid in urine were 177.07 µg/g creatinine, 0.39 g/g creatinine, and 0.11 g/g creatinine, respectively. Analysis of correlation between air benzene, toluene, and xylene concentrations and their urinary metabolites concentrations was found no correlation. Increasing ethylbenzene exposure was associated with increased likelihood of exhibiting nausea (OR = 1.14; 95% CI, 1.008 - 1.288), and increasing xylene exposure was associated with increased likelihood of exhibiting cough (OR = 1.137; 95% CI, 1.012 - 1.278).