Internal Exposure Assessment And Exposure Characteristics Of Arsenic In Pregnant Women

Objective:Arsenic is a ubiquitous,naturally occurring environmental toxicant which is highly carcinogenic to human.Arsenic pollution has been a serious public health concern.Arsenic can methylate to different species in human which have different toxicity.Arsenic exposure levels and metabolism efficiency during pregnancy are closely related to maternal and child health which period is vulnerable to external toxicants.This study aims to establish a method for determination arsenic species in urine.Then based on a cohort study to evaluate arsenic exposure levels,metabolism efficiency and its influencing factors in the 1^st,2^nd,and 3^rd trimester during pregnancy.Methods:HPLC-ICP-MS method was applied to detect the content of arsenobetaine（As B）,arsenite(As³⁺),arsenate(As⁵⁺),dimethylarsinic acid（DMA）,and monomethylarsonic acid（MMA）in urine.A total of 2,008 pregnant women recruited from April 2014 to December 2016 and their urinary arsenic species exposure level during three trimesters were measured.The ratio of MMA to DMA concentration（MMA/DMA）was calculated to measure arsenic methylation efficiency.Spearman correlation analysis was conducted to assess the correlations of arsenic species concentrations in three trimesters.Consistent concentration of arsenic species during pregnancy was evaluated by the intraclass correlation coefficient（ICC）based on the mixed linear model.The effects of physiological and socioeconomic status of pregnant women on the concentration of arsenic species in urine during pregnancy were analyzed by the generalized linear model.Results:（1）We established the HPLC-ICP-MS method which can determine five arsenic species within 11 minutes simultaneously.The limit of detection（LOD）of As B、As³⁺、DMA、MMA and As⁵⁺were 0.1,0.3,0.1,0.1,0.3μg/L,respectively.And the limit of quantitation（LOQ）were 0.2、0.6、0.2、0.3、0.8μg/L,respectively.The recovery rate of this method was between 98.4-111.4%,the intra-day variation and inter-day variation coefficient were less than 15%.（2）The detection rates of MMA,DMA,As B and As⁵⁺were all above 60%,while the average detection rate of As³⁺was less than 3%.The geometric means concentrations of arsenic species corrected for specific gravity different in the 1^st,2^nd,and 3^rd trimester were as follows:i As(As⁵⁺+As³⁺)were 3.41,3.03,3.17μg/L,respectively.DMA were 10.02,7.76,7.58μg/L,respectively.MMA were 1.27,1.00,0.99μg/L,respectively.As B were 2.29,2.02,1.80μg/L,respectively.The median of MMA/DMA in the three trimesters were 12.76%,12.79%and 13.13%,respectively.The ICCs of specific gravity corrected As B,i As,MMA,DMA concentrations were 0.24,0.21,0.44,0.19,respectively.（3）Parity,household income,education level and folate,multivitamin supplements were negatively related to arsenic exposure levels and positively correlated with arsenic metabolism efficiency during pregnancy.Conclusion:The concentrations of urinary arsenic species were higher in the early pregnancy and lower in the 2^nd and 3^rdtrimesters.Urinary arsenic metabolism efficiency in the 1^stand 2^ndtrimesters were higher than in the 3^rd trimester.In addition,levels of maternal urinary arsenic species during pregnancy were affected by many factors,including maternal physiological and socioeconomic status and nutrient supplementation during pregnancy.