The Pollution Characteristics And Exposure Risk Of Polycyclic Aromatic Hydrocarbons(PAHs) Bound With Fine Particulate Matter In Coke Plant

With the rapid economy development of China,the demand for coking products keeps increasing,and the number of coking plants and employees gradually increases.As one of the main by-products in the process of coking,Polycyclic aromatic hydrocarbon（PAHs）was likely to cause serious damage to the occupational health of workers in coking plants due to the teratogenic,carcinogenic and mutagenic effects.At present,the studies about occupational exposure in coking plants mainly focused on the concentration level of pollutants in environmental media,but the specific mechanism between the exposure level of pollutants and the occurrence of diseases is still unclear.Therefore,it is significant to grasp the exposure level of pollutants in vivo and in vitro,and analyze the reaction mechanism through statistical analysis combined with epidemiology for the occupational health of people at risk of exposure in the industry.In this study,the particulate matter in different exposure levels of a coking plant was collected and analyzed.It was found that there was a large difference in the concentration of PM_2.5 samples collected in the control group,low-exposure group and high-exposure group,the median concentration of PM_2.5 in the two exposure groups was 2.78,4.99 times higher than that of the control group,respectively.It is proved that PM_2.5 is one of the main by-products of coking process.Among the three groups of PM_2.5 samples,there were significant differences in the composition of 14 kinds of PAHs,between the control group and the exposure group,with the largest proportion of low molecular weight PAHs（LMW-PAHs）in the control group,which was 41.03%.The proportion of high molecular weight PAHs（HMW-PAHs）was the largest in the low-exposure group and the high-exposure group,which were 70.06%and 71.51%,respectively.From the composition of different molecular weight PAHs,it can be seen that the main emission of PAHs during coking is HMW-PAHs.The components of 1-OHPyr（1-Hydroxy Pyrene）in urine were analyzed by high performance liquid chromatography-mass spectrometry（HPLC-MS/MS）,and the exposure level of PAHs in the participating population was evaluated.The results showed that the concentration of 1-OHPyr in urine of the workers in the high exposure group was the highest,which was 1563.18 nmol/mol creatinine,which was 54.91 times that of the control group.In this study,two gene fragments of platelet mitochondrial DNA（mitochondria DNA,mtDNA）from workers in the factory were selected to detect their methylation levels by polymerase chain reaction（PCR）and pyrophosphate sequencing（Pyrosequencing）,and the exposure response relationship between pollutants and target gene fragments was analyzed statistically.The results showed that most of PAHs.For example,Flu,Pyr,BaA,Chr,BbF,BkF,BaP,IcdP,BghiP,DBahA and 1-OHPyr have significant negative correlation with ATP6 gene,and all pollutants except 1-OHPyr have significant negative correlation with ATP8.It is proved that PAHs exposure can affect the expression level of mtDNA,and then have potential effects on health.By calculating the equivalent toxicity concentration of PAHs in low-exposure group and high-exposure group,it was found that the concentration of PAHs in the environment of both groups was higher than the limit of national ambient air quality standard,and the concentration of PAHs metabolites in urine of workers also exceeded the limit,which had a significant effect on the level of mtDNA methylation,which proved that the exposure risk of the coking plant was high and did great harm to the occupational health of workers.