Measurement of genotoxic air pollutant exposures in street vendors and school children in and near Bangkok

Abstract

The effects of air pollution on human health are a great concern, particularly in big cities with severe traffic problems such as Bangkok, Thailand. In this study, exposure to genotoxic compounds in ambient air was studied by analysis of particle-associated polycyclic aromatic hydrocarbons (PAHs) and benzene through direct measurement of concentrations in air as well as through the use of different biomarkers of exposure: urinary 1-hydroxypyrene (1-OHP) for PAHs and urinary t,t-muconic acid (t,t-MA) for benzene. The study was conducted in various susceptible groups of the population with different occupations in 5 traffic-congested areas of Bangkok, as well as in primary school children. The level of total PAHs on the main roads at various sites ranged from 7.10 to 83.04 ng/m(3), while benzene levels ranged from 16.35 to 49.25 ppb. In contrast, ambient levels in nearby temples, the control sites, ranged from 1.67 to 3.04 ng/m(3) total PAHs and 10.16 to 16.25 ppb benzene. Street vendors selling clothes were exposed to 16.07 +/- 1.64 ng/m(3) total PAHs and 21.97 +/- 1.50 ppb benzene, levels higher than in monks and nuns residing in nearby temples (5.34 +/- 0.65 ng/m(3) total PAHs and 13.69 +/- 0.77 ppb benzene). Grilled-meat vendors in the same area were exposed to both total PAHs and benzene at even higher levels, possibly due to additional formation of PAHs during the grilling of meat (34.27 +/- 7.02 ng/m(3) total PAHs; 27.49 +/- 2.72 ppb benzene). At the end of the workday, urinary 1-OHP levels in street vendors (0.12 and 0.15 micromol/mol creatinine in clothes and grilled-meat vendors, respectively) were significantly higher than in controls (0.04 micromol/mol creatinine; P < 0.01). Afternoon urinary t,t-MA levels in both groups of street vendors (0.12 mg/g creatinine) were also significantly higher than in controls (0.08 mg/g creatinine; P < 0.05). School children from two schools in Bangkok were exposed to total PAHs and benzene at levels of 6.70 +/- 0.47 ng/m(3) and 4.71 +/- 0.25 ppb, respectively, higher than those to which children living outside the city were exposed (1.25 +/- 0.24 ng/m(3) total PAHs; 2.10 +/- 0.16 ppb benzene). At the end of the school day, levels of urinary 1-OHP and t,t-MA were significantly higher (P < 0.001 and P < 0.01, respectively) in Bangkok school children (0.23 micromol/mol creatinine and 0.27 mg/g creatinine, respectively) than in school children from outside Bangkok (0.10 micromol/mol creatinine and 0.08 mg/g creatinine, respectively).