Prenatal and postnatal exposure to organophosphate pesticides and child neurodevelopment in an agricultural area of Jiangsu province, China: a cohort study

Abstract

BackgroundChildren's exposure to organophosphorous pesticides attracted global concerns because of their vulnerability and physiological differences compared with adults. Few studies have examined the associations of both prenatal and postnatal organophosphorous exposure with child neurodevelopment in China. Our aim was to investigate the associations of maternal and child organophosphorous urinary metabolite concentrations with child neurodevelopment at age 2 years. MethodsTo assess exposure to organophosphorous pesticides, we measured dimethyl phosphate, diethyl phosphate, and total dialkyl phosphate metabolites in maternal urine collected before delivery and in urinary samples of their children aged 2 years (n=310). Healthy pregnant women who gave birth at local maternity hospitals without serious chronic diseases (eg, diabetes, hypertension, thyroid disease, or a serious pregnancy complication that could affect fetal growth and development) were recruited during June, 2009, to January, 2010. Neurodevelopment of children at age 2 years was assessed using the Gesell Developmental Schedules, and developmental quotients were calculated for four main categories of neurobehavioural functions—namely, motor, adaptive, language, and social functions. Multiple linear regression and logistic regression analysis were used for all children combined and also after stratification by sex. To compare effect estimates for urinary dialkyl phosphates measured in prenatal versus postnatal periods, seemingly unrelated regression estimation was used. All mothers who participated in the study signed an informed consent form and agreed to donate maternal and child urine samples. This study was approved by the health bureau of Sheyang county and the ethics committees of the School of Public Health, Fudan University, Shanghai, China. FindingsNo significant association between child neurodevelopment and urinary organophosphorous exposure was reported using multiple linear regression. Logistic regression analysis showed that elevated prenatal diethyl phosphates (odds ratio [OR] 9·75; p=0·028) and total dialkyl phosphates (9·69; p=0·072) were significantly associated with an increased probability of developmental delay in adaptive area. Elevated postnatal diethyl phosphates and total dialkyl phosphates were significantly associated with an increased probability of developmental delay; specifically, for every 10-times increase in postnatal total dialkyl phosphates, the probability of developmental delay increased by 2·58% (p=0·026) in motor area and 2·45 % (p=0·058) in social area. In relation to child neurodevelopment, the effect coefficients for organophosphorous exposure measured in children's urines were not significantly different from those for maternal metabolites. Boys showed adverse associations of both prenatal and postnatal organophosphorous exposure with developmental delay, but such associations were not reported in girls. InterpretationBoth prenatal and postnatal exposure to organophosphorous pesticides can adversely affect neurodevelopment of infants living in agricultural areas. This study added strength to the accumulating evidence on associations of prenatal and postnatal organophosphorous exposure with infant neurodevelopment. Reduction of maternal exposure to organophosphorous pesticides during pregnancy is important. FundingThis study was partly supported by grants from Shanghai Natural Science Foundation (grant number 11ZR1402200), the Chinese National 973 Project (2011CB503802), and the Shanghai Project “3-Year Year Action”.