DNA Damage Of Population Exposed To Fine Particulate

Airborne particulate is an important kind of air pollution, its effect on human health correlate with the size and chemistry components. The most harmful kind of particulate is PM2.5, particles with an aerodynamic diameter of less than 2.5μm. As the harm of PM2.5 was realized widely, American published the stander of airborne PM2.5 in 1997, which was 15μg/m3 and 65μg/m3,respectively for the annual and 24-hour standards and the 24-hour standard was adjusted to 35μg/m3 in 2006.China published the stander of airborne PM10 in 1996, but hasn't enacted air quality standards of fine particles up to now. PM2.5 is attached to massive metals, hydrocarbons and their derivatives which may represent a serious harm to health. Many in vitro and animal studies have demonstrated that PM2.5 can cause DNA damage. Studies on DNA damage by PM2.5 in population in foreign countries were reported recent years, but such studies were rarely reported in china till now.Our study was in Shanghai, where the air pollution of PM2.5 was mainly from soot and exhaust gas, therefore, traffic policemen were selected as exposed group to study DNA damage in population both exposed to higher and normal concentration of airborne PM2.5, and research for exposure and effect biomarkers of DNA damage induced by PM2.5.Exposure to PM2.5 in both groups was measured on the first part of our study. The study consisted of two phases in winter and summer respectively, in each phase, 24h continuous monitoring of PM2.5 by individual samplers were operated to measure exposure to PM2.5. The results showed that exposure to PM2.5 in exposed group was significantly higher than that in control in both phases. In winter, exposure to PM2.5 was 1.33 times to that in summer in exposed group, which was 1.25 times in control, the exposure was significantly different in two seasons. By the standard of 65μg/m3, published by EPA in 1997, exposures in exposed group were 0.78 and 0.43 times higher than standard in winter and summer respectively. Though the exposure in control was only 0.15 times higher in winter and slightly lower than standard in summer, by the standard of 35μg/m3, published by EPA in 2006, exposures were more than 70% higher than standard in control, so airborne PM2.5 pollution remained serious in Shanghai, particularly for the outside workers exposed to high concentration of PM2.5 such as traffic policemen, health effects of airborne PM2.5 exposure can not be ignored.The most harmful components of PM2.5 are heavy metal and PAHs.I-OHP was used widely as a biomarker of population exposed to PAHs. In atmosphere, PAHs exists in the form of solid particles, most of which are attached to PM2.5.In our study, exposure to PM2.5 had a fine linear correlation to concentration of 1-OHP in urine in both seasons. The r was 0.45 in winter and 0.56 in summer(P<0.05).The result showed that without special exposure to PAHs, concentration of 1-OHP in urine could be used as a exposure biomarker of PM2.5.DNA damage and its relation to PM2.5 were researched on the second part of our study. Comet cell percentage was 15.20% in winter and 12.64% in summer in exposed group, which were significantly higher than that in control(10.05% and 7.83%, P<0.05), and the difference became larger as the damage level increased.The results suggested that in exposed group, the cells with DNA damage were more and the damage level was higher than those in control.OMT and DNA-in tail were both significantly higher in exposed group than those in control in both seasons, and OMT had a fine linear correlation to DNA-in tail.The influence factors on OMT with multiple Logistic regression showed that the level of DNA damage became higher as the exposure to PM2.5 increased excluding the effect of age and length of service. BPDE-DNA adducts in white blood cells were significantly higher in exposed group than that in control in both seasons. The influence factors on BPDE-DNA adducts with multiple Logistic regression showed that excluding the effect of age and length of service, the OR of BPDE-DNA adducts positive was 1.04 in winter and 1.03 in summer as the exposure to PM2.5 increased by 1μg/m3. The results suggested that DNA damage was significantly higher in exposed group than that in control, DNA damage in population will reduce effectively if concentration of airborne PM2.5 decrease.For the complication of components and instability in different times and locations, no highly specific effect biomarker has been found. Our study showed that OMT of peripheral blood lymphocyte could be used as effect biomarker of DNA damage in population by PM2.5, but considering the massive DNA damager factors in environment, it might had weak specificity. BPDE-DNA adducts in white blood cell could be used as effect biomarker of DNA damage in population by PM2.5 without special exposure to PAHs.