| In recent years,with the intensification of human activities and the rapid development of urbanization,the concentration of PM2.5 nationwide has risen sharply.As one of the important cities in the northwest,Shihezi City is extremely polluted during the heating period,which not only affects urban traffic,but also poses a certain hazard to human health.PM2.5 loaded organic matter and heavy metals can produce a large amount of reactive oxygen species?ROS?,which is an important cause of oxidative stress,and the generally recognized mechanism of PM2.5 damage to human body is oxidative stress and inflammatory response.Therefore,through the detection of PM2.5 and its heavy gold,this research conducts health risk assessment of heavy metal exposure in PM2.5,obtains important heavy metals and PM2.5 for animal experiments,and the studies of genetic mechanism of PM2.5 on lung injury in rats.In this study,PM2.5 was tested in real time from May 2017 to April 2018,and PM2.5 samples during heating were collected for heavy metal detection by ICP-MS.The health risks of the tested heavy metals were evaluated by the US Environmental Protection Agency's recommended health risk assessment model.SPF male rats were divided into 13 groups,and different concentrations of PM2.5,Al,Fe,and Zn were exposed to rats by tracheal instillation.After the instillation was completed,the rats were sacrificed to obtain bronchoalveolar lavage fluid?BALF?,lung tissue,testis and epididymis of the rats,and the remaining rats were caged with female rats at a ratio of 1:1 to obtain lung tissues of the offspring rats.ELISA,colorimetry and HE staining were used to detect proinflammatory factors?IL-6,IL-1?,TNF-??,oxidative stress indicators?SOD,MDA,GSH-Px?in rat lung tissues and testis tissues.Pathological changes of rat lung tissue and testicular tissue were observed.The results of this study are as follows:?1?The PM2.5 concentration in Shihezi City during 20172018 is the heating period>the non-heating period,and the average concentration of PM2.5 during heating(109.86±58.76?g·m-3)is 1.46times that of China's air quality secondary standard(75?g·m-3).The average concentration of PM2.5 during non-heating was 18.87±4.86?g·m-3.In Shihezi City from January to March 2018,the average concentration of heavy metals in PM2.5 was Al(98.351?g·m-3)>Fe(27.766?g·m-3)>Zn(3.484?g·m-3)>Pb(1.444?g·m-3)>Cu(0.628?g·m-3)>Ni(0.094?g·m-3).The order of non-carcinogenic risk of heavy metals is Pb>Cu>Zn,HQ is less than 1,there is no non-carcinogenic risk,and the lifetime risk of Ni is1.97×10-6,which has certain cancer risk.?2?PM2.5 and its Al,Fe and Zn elements can cause oxidative stress in the lungs of rats and further cause lung injury in rats,and these damage effects are dose-dependent.And Al,Fe,Zn elements play an important role in the process of PM2.5 damage to the lungs of rats,but in the case of the same content of Al,Fe,Zn(PM2.5 high dose group and Al,Fe,Zn medium dose group),PM2.5 damage to rats is more serious.?3?Adult male tracheal instillation of PM2.5 can cause sperm deformity and structural changes of testis tissue,and can significant inhibition of SOD and GSH-Px activity,significant increase in MDA content,significant decrease mRNA expression of SOD and GSH-Px,significant increase in IL-1?and TNF-?levels and mRNA expression in rat testicular tissue.With the increase of the amount of tracheal infusion of the parent PM2.5,it can cause the lung tissue of the offspring rats to have lesions.The activity of SOD and GSH-Px in the tissues of the offspring rats was significantly inhibited,and the MDA content was significantly increased,SOD and GSH-Px mRNA expression was significantly decreased,IL-6,IL-1?and TNF-?levels and mRNA expression increased.The pollution of PM2.5 and heavy metals during the heating period in Shihezi City is very serious.The health risk assessment indicates that Ni has certain cancer risk.Animal experiments have shown that PM2.5and its heavy metals can cause damage to the lungs of rats,and that the offspring of adult male rats exposed to PM2.5 also have lung damage.These data can provide a basis for PM2.5 heating and pollution prevention of heavy metals in Shihezi City. |
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