Study On The Mechanism Of DNA Oxidative Damage Induced By Diesel Engine Exhaust Exposure

Objective:Diesel engine exhaust(DEE)is a common air pollutant resulting from incomplete combustion of diesel fuel.DEE is a complex mixture comprising of Nitrogen oxides.carbon monoxide,unburned and partially burnt hydrocarbons,soot(mainly elemental carbon and organic particles combined with carbon)and some nitrates.Diesel exhaust particles(DEP)are centered on elemental carbon and adsorb a variety of toxic organic substances.Therefore.particulate matter is generally considered to be the main toxic part of diesel exhaust,especially PM2.5.In addition to particulate matter,diesel exhaust includes polycyclic aromatic hydrocarbons,nitropolycyclic aromatic hydrocarbons and other carcinogens.Therefore.DEP can cause health damage by increasing DNA oxidative damage.In order to study on the mechanism of DNA oxidative damage induced by diesel engine exhaust,this study took particulate matter and nitro polycyclic aromatic hydrocarbons as exposure markers of diesel engine exhaust,8-OHdG and etheno-DNA adduct as biomarkers of DNA oxidative damage.Methods:In this study,a diesel engine automobile factory was selected,in which,114 male workers were chosen to conduct cross-sectional epidemiological studies.The individual air sampling pump were used to sample the breathing air of the workers,and the particle size distribution of DEE in different work sites were determined by APS3321 aerodynamic particle size spectrometer.The GC-NCI-MS method was used to detect Nitro-PAHs in air samples.The UPLC-MS/MS method was used to detect 8-OHdG levels and Etheno-DNA adduct levels in plasma and urine samples.Then the samples were grouped and statistically analyzed based on particle size distribution and Nitro-PAHs contents.The comparison of the count data rate was carried out by Pearson χ2 test.T-test was used to compare the mean between the groups.Those who did not conform to the normal distribution were described by median(M)and 0-100th percentile(P0-P100).The Median comparison between two groups was performed by Wilcoxon rank sum test;the Median comparison among three groups was based on Kruskal.Wallis H test.The test level is a=0.05(both sides).The statistical analyses were performed using SPSS 19.0.Results:1.The particle size distribution of the air in the three positions(Assembly.Adjustment and Inspection)were different.The concentration of PM2.5 and PM10 in the inspection post was higher than the other two groups.2.The concentration of Nitro-PAHs in the high exposed position of DEE was increased(the mean value of 1-NP concentration in theree posts were 26.62 pg/m3.164.82 pg/m3,126.08 pg/m3,respectively;the mean value of 6-NCh concentration were none,22.46 pg/m3.and 13.41 pg/m3,respectively).3.The level of sdA adduct in the blood of Inspection position workers was significantly higher than that in the other two groups.4.The urinary 8-OHdG median level was significantly higher in the Nitro-PAHs high-exposure group(2.54 μg/g Cr vs 2.03 μg/g Cr,P<0.05).5.There is a positive correlation between blood 8-OHdG and εdA levels in the sample.Conclusions:Our study found that Nitro-PAHs content increased in the DEE exposure environment.DEE exposure could induce the oxidative damage of DNA in the body through different pathways.