| Objective:To explore the relationships of Benzo (a) pyrene (BaP) in blood as biomarker of total exposure of BaP,3-hydroxyl benzo (a) pyrene (3-OHBaP) and1-hydroxyl pyrene (1-OHP) in urine to determine the exposure biomarker of BaP in urine.To explore the relationships of BaP exposure, gene polymorphisms and DNA oxidative damage to provide data support to establish health risk assessment methods of BaP based on early genetic damage.Methods:1. Subjects aged45-65years with no cancer were selected from rural, residential and traffic districts in the non-heating period and heating period in Taiyuan.A questionaire surveys were conducted to understand the general condition, occupation, living environment and living habits, personal history and family history of disease etc. At the same time blood and urine samples were collected through physical examinations.2.HPLC-fluorescence method was used to determine the concentrations of BaP in blood,1-OHP and3-OHBaP in urine.Giemsa staining method was used to determine micronucleus rate of white blood cell.Elisa kits were used to determine concentrations of8-OHdG in urine. DNA extraction kits were used to extract DNA from white blood cell. PCR-RFLP method was used to determine polymorphism of gene CYP1A1, GSTT1, GSTM1, UGT1A7and XRCC1, Capillary electrophoresis-laser induced nuorescence immunoassay method was used to determine the concentrations of BPDE-DNA adducts.3. Epidata software was used to create database, SPSS statistical software was used for statistical analysis.T test was used to compare differences of biological markers in rural, residential and traffic districts. Paired t test was used to compare differences of biological markers of the same group in non-heating period and heating period.Correlation analysis was used for the relationships of different biomarkers. Multivariate statistical analysis methods and mixed effects model analysis were used to explore the relationships of BaP exposure, gene polymorphism and genetic damage combining with questionnaire information.Results:1.85people in rural district,80people in residential district and80people in traffic district were selected in non-heating period.83people in rural district,80people in residential district and80people in traffic district were selected in heating period.46people were surveyed in non-heating period and heating period both.The living habits of residents in residential and traffic districts was similar,so the two districts were analyzed as a whole.2. In non-heating period the mean concentrations of BaP,1-OHP and8-OHdG in rural district were higher than that in city. In heating period the mean concentrations of BaP and1-OHP in rural district were higher than that in city.The mean concentrations of all the biomarkers in non-heating period were higher than that in the heating period.3.The ratio of GSTT1gene deletion type was above50%, whereas GSTM1deletion type was only10%.The ratio of CYP1A1heterozygous gene was above50%.The ratio of UGT1A7gene of wild type is higher than50%.The wild, homozygous and heterozygous type of XRCC1have the similar proportion.4. In non-heating period, coal-fired cooking may increase the level of BaP in blood, whereas the main factor was coal heating in heating period.5. Linear correlation analysis showed the concentrations of BaP had no correlation with1-OHP and3-OHBaP, whether in the non-heating period or heating period. Multivariate statistical analysis revealed the concentration of BaP in blood and CYP1A1, GSTT1, GSTMland UGTlA7gene polymorphism had no correlation with1-OHP and3-OHBaP. Mixed effects model analysis indicated there was a positive correlation between BaP and3-OHBaP.6. The micronucleus rates of rural residents in non-heating period and heating period were2.48‰and2.32‰respectively. Mixed effects model analysis indicated there was a negative correlation between micronucleus rate and1-OHP.7. The concentration of8-OhdG of rural residents was higher than that in city in non-heating period.There was no statistically significant difference,though the concentration of8-OhdG of rural residents was higher than that in city in heating period. There was a negative correlation between8-OHdG and1-OHP by mixed effects model analysis. 8. Linear correlation analysis showed there was no correlation between1-OHP and BPDE-DNA adducts, whether in the non-heating period or heating period.In non-heating period there was a positive correlation between3-OHBaP and BPDE-DNA adducts. In heating period BaP, XRCC1and CYP1A1had effect on BPDE-DNA adducts. Mixed effects model analysis indicated there was a correlation between sampling season and BPDE-DNA adducts.Conclusion:1.3-OHBaP in urine has a positive correlation with BaP in blood, and can be biomarker of total exposure of BaP, when blood samples can not be acquired.2. BPDE-DNA adducts as BaP biomarker of effect, can specificlly be a very good biomarker of early genetic damage.3. Micronucleus rate cannot accurately response to total exposure of BaP, and can not be the biomarker of BaP.4.8-OHdG in urine cannot accurately response to total exposure of BaP, and can not be the biomarker of BaP.5. In certain exposure level of BaP, metabolic enzymes and DNA repair enzymes can influence BaP metabolism and repair of genetic damage.6. Mixed effects model can be widely used to evaluate dose-response relationship. |
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