Internal Exposure Level And Health Risk Analysis Of Nitro Polycyclic Aromatic Hydrocarbons In Human Plasma In Tianjin Area

This study selected 104 adult males aged 20-45 in some areas of Tianjin as the research object.A fasting peripheral blood sample from the morning of the study subject was collected.Qualitative and quantitative determination of 40 NPAHs was performed by gas chromatography-mass spectrometry（GC-MS）in order to determine the internal exposure levels of NPAHs.A total of 12 nitro polycyclic aromatic hydrocarbon components were detected in this study,namely:1-Nitronaphthalene,2-Nitronaphthalene,5-Nitroacenaphthene,2-Nitrofluorene,9-Nitroanthracene,3-Nitrophenanthrene,9-Nitrofluoranthene,1-Nitropyrene,7-Nitrobenzo[a]anthracene,6-Nitrochrysene,6-Nitrobenzo[a]pyrene.The total average exposure concentration ofΣ₁₂NPAHs was 82.15 ng/m L.Among them,the internal exposure level of the6-Nitrochrysene component was the highest,with an average concentration of 18.78ng/m L.The average exposure concentration of 9-Nitroanthracene was 10.57 ng/m L.The internal exposure level of 2-Nitronaphthalene was the lowest with an average concentration of 2.51 ng/m L.This study further extracted plasma mitochondrial DNA and used pyrosequencing to determine the methylation levels of four specific gene fragments（MT-COX1,MT-COX2,MT-RNA1,MT-RNA2）.It was found that the methylation level（%）of MT-COX1 was the lowest,which was around 0.MT-COX2 has the highest methylation level（%）,with an average of 13.54.The average MT-RNA1methylation level（%）was 7.22,and the average MT-RNA2 methylation level（%）was 1.64.In the analysis of the correlation between the internal exposure levels of NPAHs and specific fragments of mitochondrial DNA,we found that the total exposure concentration ofΣ₁₂NPAHs and the methylation level（%）of MT-COX1 showed a significant positive correlation（P=0.013）.The single-component 9-nitroanthracene（9N-Ant）exposure concentration also had a significant positive correlation with MT-COX1 methylation level（%）（P=0.007）.There was a significant correlation between MT-COX2 methylation level and the risk of high blood pressure（P=0.04）.This study found that the total exposure concentration of 12 nitro polycyclic aromatic hydrocarbons would affect the methylation modification of MT-COX1,a specific fragment of mitochondrial DNA.Among them,a single component of9-nitroanthracene（9N-Ant）will affect the methylation modification of specific fragment of mitochondrial DNA MT-COX1.MT-COX2 methylation modification may cause abnormal expression of the encoded genes,thereby participating in the development of hypertension.