A Study On Urinary Methyl Tert-butyl Ether Exposure And Influencing Factors Among Pupils In A District Of Beijing

PurposeThrough panel study,analyze the exposure level and influencing factors of methylbutyl tertiary ether(MTBE)in primary school children’s urine,and to understand the correlation between the primary urinary MTBE exposure level and individual PM 2.5 external exposure level,atmospheric PM2.5/PM10/O3/CO/NO2/SO2.Method(1)Respondents:Select students who have a fixed lifestyle,less lifestyle changes,regular school hours,good compliance,and few confounding factors.This study excludes factors such as poor compliance,residency at school,inability to attend full time,and travel.Ten male and ten female students from Changping District Zhixing Elementary School were randomly selected as survey objects(2)Questionnaire survey:Collect the basic personal information(age,gender,residential address,etc.)of the respondents through the questionnaire survey,collect the living environment and daily lifestyle,and analyze the influencing factors(mixing factors)of the mtbe exposure level in urine.All the respondent had no organic disease(3)Real-time monitoring of individual PM2.5 external exposure levels through intelligent air quality detector individual monitoring equipment.At the same time,combined with data from environmental monitoring fixed stations,record PM2.5/PM10/O3/CO/NO2/SO2 content in the atmosphere(4)The urine of the subject was collected when he getting up,then at 11 and 16 o’clock.Picric acid spectrophotometry was used to detect the urine creatinine content of the subject,and gas chromatography-mass spectrometry was used to detect the urine MTBE.Urine MTBE levels are corrected by urinary creatinine to reflect exposure throughout the day and during daytime activities.The test cycle is seven days from Monday to Sunday(including working days and rest days)(5)Statistical analysis:SPSS 19.0 software was used for statistical analysis.Geometric mean and percentiles were used to describe the MTBE exposure level in urine;non-parametric tests were used to compare the differences in MTBE in urine between different groups;Multivariate regression analysis and mixed linear model were used to analyze the influencing factors involved in the questionnaire,to screen out statistically relevant factors,and to explore the personal and environmental influencing factors of MTBE in urine(distance from the traffic trunk line,etc.);using Spearman rank correlation Analyze the correlation between MTBE level in urine and PM2.5,PM10,CO,SO2,NO2,O3 in atmospheric environment.Test level α=0.05ResultThe monitoring period was 7 days,a total of 420 urine samples were detected,and the exposure levels showed a log-normal distribution.The geometric mean of MTBE exposure levels in morning urine,instant urine at 11:00,and 16:00 were 0.109μg/L,0.110 μg/L,0.104 μg/L;geometric mean of MTBE exposure levels in creatinine-corrected morning urine,11:00,and 16:00 instant urine were 0.117 mg/g creatinine,0.121 mg/g creatinine,0.120 mg/g Creatinine.The exposure level of MTBE in urine is affected by the distance between the student’s home address and the main road in the traffic,and the distance from the main road to the road is<150 m and≥150 m.There is a statistically significant difference in the exposure level of MTBE in the urine;The effect of the time of outdoor activities every day and the time of daily use of air purification equipment in the class.When students’ outdoor activities are 0 minutes,0-60 minutes,and 60 minutes or more,the MTBE exposure levels of students have statistically significant differences.;When the ventilation time in the class of the student is 0 minutes,0-60 minutes,and more than 60 minutes,there is a statistically significant difference in the exposure level of MTBE in urine.The exposure level of MTBE in urine of urine and the external exposure level of PM2.5 in students no significant statistical correlation.There was a significant statistical correlation with SO2 in the atmosphere,r=0.188,P=0.026;and a weak correlation with O3,r=0.016,P=0.056.ConclusionThe influencing factors of urinary MTBE exposure in students include whether the home is close to the main road,daily outdoor activity time,and the daily use of air purification equipment in the class.There is no significant statistic relationship on urinary MTBE exposure levels and individual PM2.5 external exposure levels.It has a weak correlation with SO2 in the atmospheric environment and a weak correlation with O3.