Preliminary Study Of Genotoxicity Of Different Fractions In Air Particulate Matters From Guangzhou

Guangzhou is facing serious air pollution due to particulate matters (PM) and increasing haze episodes in recent years. The health effects of air particle pollution are of great concern. In the present study, PM (TSP, PM₁₀, PM_2.5) samples in urban Guangzhou were collected to genotoxic effects (DNA and chromosome damage) of their different fractions by comet assay, cell-blocked micronucleus (CBMN) and flow cytometry (FCM) on human peripheral blood lymphocyte. The organic and inorganic fractions were also analysed for their chemical compositions by GC-MSD, ICP-MS and IC. The study helps to explore the relationships between genotoxic activity and compositional fractions for PM, and therefore bears valuable information for the control of particle air pollution and the assessment of related health effects, air pollution. Major results of this study are present as below.1. For organic fractions in TSP and PM₁₀ with exposre doses of 4, 12 and 20 m³air eq/mL, genotoxicity tetsts revealed that comet assay was more sensitive than CBMN; and even at the lowest dose of 4 m³ air eq/mL, comet assay revealed significant difference with the the negative control (p<0.001). FCM indicated increased apoptotic cells with the increase of organic extract concentrations.2. Comparisons between haze days and non-haze days found significantly higher (p<0.05) fine particle (PM2.5) levels during haze episodes, but whether there were haze episodes or not, daily mean PM2.5 levels exceeded the USA air quality standard (65μg m^-3). Highly significant correlations (R=0.95-0.99, p<0.001) among the comet assay results expressed in tail length, tail DNA% and olive tail moment (OTM). Benzo[a]pyrene (BaP) increased from 4.55 ng m^-3 in non-haze days to 19.01 ng m^-3 in haze days. DNA damages were positively correlated with exposed BaP levels (R=0.71, p<0.001).3. Based on comet assay, aromatic fractions showed the highest genotoxic potencies, but polar fractions also substantially contribute to genotoxic activity of organic extracts. The sum of genotoxicity by the three fractions as OTM was usually higher than that by the total organic extratcs. For total extractable organic matters and aromatic fractions, significant dose-response effects were observed (R=0.84～0.98, p<0.05).4. Whether there was haze or not, water soluable factions in PM induced significant DNA damage at doses above 10m³ air eq/ml compaed to negative controls (p<0.05). Exposed doses of water soluable Ni, Mn and Zn significant relations with DNA damages; The concentrations of Zn were the highest among all heavy metals, and they were also highly correlated with genotoxicity as OTM, therefore Zn might be among the most important species responsible for the genotoxicity of water soluable factions.