Affiliations: Research Lab Supervisor, Urban Environmental
Engineering and Management Program, School of Environment, Resource and
Development, Asian Institute of Technology, G.P.O. Box 4, Klong Luang,
Pathumthani 12120, Thailand | Affiliated Research Associate, 216 Soi Satsana 5, Phya
Thai, Bangkok 10400, Thailand
Abstract: Four environmental and biological monitoring sites were
strategically established to evaluate benzene and lead exposure assessment at
various traffic zones of Bangkok Metropolitan Region (BMR). Biological
measurement of 48 non air-conditioned, male bus drivers was carried to study
the relationship between individual exposure levels and exposure biomarkers.
The study group was further subdivided into four age groups (16–25, 26–35,
36–45 and 46–55 years old) to monitor the age-related exposure effects. A
total of 12unexposed persons were deliberately chosen as the control group.
Measurement of unmetobolized benzene in blood and analysis of urinary
tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of
benzene exposure. Measurement of lead in blood and urine is also recommended
for the biological monitoring of lead exposure. During the monitoring period,
benzene and lead levels at Yaowarat Road was
C_6H_6: 42.46 ± 3.88
μg/m^3, Pb: 0.29 ± 0.03
μg/m^3 and decreased to
C_6H_6: 33.5 ± 1.35
μg/m^3, Pb: O.13 ± 0.01
μg/m^3 at Phahonyothin Road. Significant difference was
established between the nonsmoking exposed group and nonsmoking control group
for blood benzene concentrations (P < 0.001, two-tailed, Mann-Whiteney U
test). Strong correlations were also found between trans-trans-Muconic acid
concentrations in post shift samples and atmospheric benzene concentrations.
Similarly, good correlation between all of biomarkers and lead level in air is
established from automobile emissions. The analysis revealed that among the
occupational population in the urban sites, the driver groups were found to
have the highest risk of benzene and lead exposures derived from automobile
emission.
Keywords: benzene and lead measurement, biomarkers, exposure assessment, human biomonitoring
