Health Risk Assessment and Urinary Biomarkers of VOCs Exposures among Outdoor Workers in Urban Area, Bangkok, Thailand

Abstract

Volatile organic compounds (VOCs) are major source of ambient air pollutants in Bangkok, Thailand. Humans can be exposed to these pollutants by inhalation, ingestion, and dermal contact but mainly by inhalation. The scientists have paid much attention to the study of exposure to air pollutants in outdoor air because they have realized the seriousness of outdoor air pollution problems of acute and chronic health effects as cancer. The measurements of benzene, toluene, ethylbenzene, xylene (BTEX) and carbonyl compounds (CCs) at 16 sites with 144 subjects of 3 classes (motorcycle drivers, security guardsmen and street venders) were performed in Pathumwan district, central Bangkok during September and October 2012 by Gas Chromatography/Flame Ionized Detector (GC/FID) and High Performance Liquid Chromatography/Ultraviolet-Visible Detector (HPLC/UV-VIS). The ambient air concentrations of benzene, toluene, ethyl benzene, xylene, formaldehyde and acetaldehyde in urban area were 46.13, 91.10, 4.55, 58.27, 11.98 and 5.85 µg/m3 respectively. The outdoor workers had average lifetime cancer risk of benzene, ethylbenzene, formaldehyde and acetaldehyde at 1.67E05, 2.11E-07, 3.38E-06 and 7.93E-07 respectively which cancer risk of benzene and formaldehyde were higher than acceptable limit (1.00E-06). The security guardsmen, motorcycle drivers and street venders who work in the same area had cancer risk at 3.65E-05, 1.76E-05 and 1.01E-05 respectively The hazard quotient (HQ) of benzene, toluene, ethylbenzene, xylene, formaldehyde and acetaldehyde of all workers were 9.43E02, 9.57E-04, 4.43E-04, 4.04E-02, 1.42E-01 and 7.64E-01 respectively which all of them were lower than acceptable limit (HQ<1.00). In addition, the urinary biomonitoring concentrations of outdoor workers of trans,trans-muconic acid (tt-MA), hippuric acid, formaldehyde, acetaldehyde and formic acid were 1.66 mg/gCr, 0.51 g/gCr, 0.85 mg/gCr, 15.9 mg/gCr and 20.57 mg/gCr respectively. The tt-MA was strongly associated with benzene exposure (p<0.001) as well as hippuric acid was associated with toluene (p=0.001).