Internal Dose Of The Chlorinated Disinfection By-product Trichloroacetic Acid During Pregnancy And Influencing Factors

Chlorination is widely applied to disinfect drinking water in many countries.However, a series of chlorinated disinfection by-products (CDBPs) are formed whenchlorine reacts with organic matters in water. Many CDBPs can cause health hazards forhuman, for example, cancers and adverse pregnancy outcomes. Recently, a number ofepidemiological studies have been conducted to explore the possible associationbetween exposure to CDBPs in drinking water and the increased risk of human adversepregnancy outcomes. Most of the studies assessed the individual exposure of CDBPsonly based on the monitoring data of CDBPs levels in distribution system, and didn’ttake the special and temporal variations of CDBPs levels, and subject water-usebehaviors during pregnancy into account comprehensively. As a result, the exposureassessment of these studies wasn’t accurate enough. Therefore, the relationship betweenCDBPs exposure and adverse pregnancy outcomes remains unclear. So the exposureassessment of CDBPs has become an urgent problem in current researches.Objectives:In order to provide a basis for exposure estimates to CDBPs in drinking water, weconducted a study to investigate the factors influencing urinary trichloroacetic acid(TCAA), an internal dose of the CDBPs, during pregnancy.Method: A total number of729pregnant women, whose daily drinking water source was tapwater during pregnancy and waiting for deliver in a hospital in Wuhan during the periodfrom July2011to June2012, were recruited in our study. Among them,198were livingand working in the supply areas of the same water plant during pregnancy. Weconducted a face to face questionnaire survey for each participant to collect theirinformation of demographic characteristics, disease history, reproductive history,lifestyle, occupational exposure, and water-use behaviors, and collected their firstmorning urine. The urinary TCAA levels were measured by liquid-liquid extraction,derivatization with acidic methanol and gas chromatography with electron-capturedetection. The urinary creatinine levels were detected by sarcosine oxidase method. Thefactors influencing the internal dose of TCAA during pregnancy were analyzed byone-way ANOVA analysis and general linear regression.Results:(1) The internal dose of TCAA of participantsFor the729pregnant women, the urinary TCAA concentrations ranged from lowerthan the limitation of detection(1.60μg TCAA/g creatinine) to102.88μg/L (150.42μgTCAA/g creatinine), the median concentration was7.19μg/L (8.28μg TCAA/gcreatinine). For the198pregnant women, the urinary TCAA concentrations ranged fromlower than the limitation of detection (1.37μg TCAA/g creatinine) to82.36μg/L(83.41μg TCAA/g creatinine), and the median concentration was6.81μg/L (8.29μgTCAA/g creatinine).(2) The results of one-way ANOVA analysisFor all of the729participants, the pregnant women who shower with hot water insummer (P<0.05), winter (P<0.05), spring and autumn (P<0.05), had a higher urinaryTCAA concentration than the ones who shower with warm water. For the198participants, the pregnant women aged30and older than30had a higher urinary TCAAconcentration than the ones younger than30(P<0.01), and the women whose bodymass index (BMI) before pregnancy were20or more had a higher urinary TCAAconcentration than the ones whose BMI before pregnancy were less than20(P<0.05). (3) The results of general linear regressionThe analysis of general linear regression for729pregnant women shows thatnone of the independent variables including individual factors (such as maternal age andBMI before pregnancy) and subject water-use behaviors (such as the average dailyamount of drinking water, the temperature of showering in spring, summer, autumn andwinter, the bath time in spring and autumn, and the weekly washing time for clothes)had effect on urinary TCAA concentrations. But the analysis of general linear regressionfor the198pregnant women who were living and working in the supply areas of thesame water plant during pregnancy indicated the urinary TCAA concentrations waspositively correlated with maternal age (β=0.304，P<0.05), and the urinary TCAAconcentrations of the pregnant women whose weekly washing time for clothes less than40minutes are higher than that of the women who did not wash clothes (β=0.237,P<0.05).Conclusion：Maternal age and the weekly washing time for clothes may influence the internaldose of urinary TCAA during pregnancy.