Effects Of DEHP Exposure On Thyroid Hormone Levels In Adolescent Students

Objective:The purpose of this study was to determine the DEHP exposure level in adolescent students,and analyze the effects of DEHP exposure on thyroid hormone levels in adolescent students.Methods:The method of cluster random sampling was used to select the adolescent students in a university in Jilin province.Urine and blood samples of the basic situation of the subjects were collected.A total of 347 cases were included in the study.The levels of five DEHP metabolites,namely MEHP,MEOHP,MEHHP,MECPP and MCMHP,in the urine of the study subjects were detected by high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS).The levels of five thyroid hormones,namely TT3,TT4,TSH,FT3 and FT4 in the blood samples of the study subjects were detected by radioimmunoassay.The mRNA expression levels of thyroid hormone metabolism key genes TPO,TG,NIS,TTF-1 and PAX-8 in peripheral blood leukocytes were determined by quantitative real-time PCR.IBM SPSS24.0 was used to statistical analysis,independent sample T test was used to compare the distribution of DEHP exposure,mRNA levels of thyroid hormone and genes between gender,age,household location and per capita income.Spearman correlation analysis was used to analyze the correlation between the levels of DEHP metabolites.The relationship between urinary DEHP metabolites and thyroid hormone levels was analyzed by multiple linear regression.Multiple linear regression model and ordered multiple logistic regression model were used to analyze the correlation between DEHP exposure and mRNA expression levels of thyroid hormone and genes.Results:1.DEHP metabolites can be detected in the urine of Chinese adolescent students.The geometric mean of ?DEHP was 94.72 nmol/g Crea.MECPP is the highest concentration of DEHP metabolites in the urine of adolescent students and the geometric mean was 9.43 ?g/g Crea.The geometric mean of other metabolites were MCMHP(5.79 ?g/g Crea),MEOHP(4.55 ?g/g Crea),MEHHP(3.37 ?g/g Crea)and MEHP(2.43 ?g/g Crea)from high to low.2.The TT4 levels of adolescent students were negatively correlated with the levels of DEHP metabolites MEOHP,MEHHP,MECPP,MCMHP and ?DEHP(P < 0.05).There was a significant negative correlation between MEOHP levels and TT4 levels in male subjects(P < 0.05).The TT4 levels of female subjects were negatively correlated with MECPP,MCMHP and ?DEHP(P < 0.05).There was a significant negative correlation between the ?DEHP levels and TSH levels in female subjects(P < 0.05).The levels of FT4 in male subjects were positively correlated with the levels of MEHP,MECPP,MCMHP and ?DEHP(P < 0.05).3.The mRNA levels of TG were positively correlated with the levels of MECPP,MCMHP and ?DEHP.The mRNA levels of NIS were positively correlated with MEOHP.The mRNA levels of TTF-1 were positively correlated with MEOHP,MECPP,MCMHP and ?DEHP(P < 0.05).In males,the TG mRNA levels were positively correlated with MECPP and MCMHP levels(P < 0.05).The mRNA levels of TTF-1 were also positively correlated with the levels of MEOHP,MECPP and ?DEHP(P < 0.05),and the mRNA levels of PAX-8 were positively correlated with the levels of MEOHP,MCMHP and ?DEHP(P < 0.05).4.In adolescent students,TG mRNA levels of peripheral blood leukocytes were negatively correlated with plasma FT3 levels(P < 0.05).The levels of TT4 in male were negatively correlated with the relative mRNA levels of TG,NIS and PAX-8(P < 0.05).In female,TG mRNA levels were negatively correlated with FT3 levels,and NIS mRNA levels were negatively correlated with FT4 levels(P < 0.05).Conclusion:1.DEHP metabolites were detected in the urine of adolescent students,among which MECPP concentration was the highest.2.DEHP exposure can affect the blood TT4 level of adolescent students,and TT4 level is negatively correlated with the DEHP metabolite levels.DEHP exposure can affect the blood FT4 level of adolescent males,and FT4 level is positively correlated with the urine DEHP metabolite levels.3.DEHP exposure can affect TG and TTF-1 mRNA levels in peripheral blood cells of adolescent students,and the levels of TG and TTF-1 mRNA in peripheral blood cells are positively correlated with the levels of DEHP metabolites in urine.4.DEHP exposure may influence the TT4 level of adolescent students by affecting the expression of TG and TTF-1 mRNA.