Temporal and Spatial Distribution of Particulate Carcinogensand Mutagens in Bangkok, Thailand

To investigate the level of genotoxicity over Bangkok atmosphere, PM10 samples were collected at the KlongchanHousing Authority (KHA), Nonsree High School (NHS), Watsing High School (WHS), Electricity GeneratingAuthority of Thailand (EGAT), Chokchai 4 Police Station (CPS), Dindaeng Housing Authority (DHA) andBadindecha High School (BHS). For all monitoring stations, each sample covered a period of 24 hours taken at anormal weekday every month from January-December 2006 forming a database of 84 individual air samples (i.e.12×7=84). Atmospheric concentrations of low molecular weight PAHs (i.e. phenanthrene, anthracene, pyrene andfluoranthene) were measured in PM10 at seven observatory sites operated by the pollution control department ofThailand (PCD). The mutagenicity of extracts of the samples was compared in Salmonella according to standardAmes test method. The dependence of the effects on sampling time and on sampling location was investigatedwith the aid of a calculation of mutagenic index (MI). This MI was used to estimate the increase in mutagenicityabove background levels (i.e. negative control) at the seven monitoring sites in urban area of Bangkok due toanthropogenic emissions within that area. Applications of the AMES method showed that the average MI ofPM10 collected at all sampling sites were 1.37±0.10 (TA98; +S9), 1.24±0.08 (TA98; -S9), 1.45±0.10 (TA100; +S9)and 1.30±0.09 (TA100; -S9) with relatively less variations. Analytical results reconfirm that the particulate PAHconcentrations measured at PCD air quality monitoring stations are moderately low in comparison with previousresults observed in other countries. In addition, the concept of incremental lifetime particulate matter exposure(ILPE) was employed to investigate the potential risks of exposure to particulate PAHs in Bangkok atmosphere.