Examination of in utero exposure to arsenic, placental permeability and birth outcomes in South African population

Abstract

Introduction: Early life exposure to arsenic has shown to interfere with foetal and early childhood development. The purpose of this study was to evaluate exposure to arsenic in utero, to assess placental permeability and birth outcomes in South African populations. Methods: Arsenic (As) was measured in maternal blood of total cohort (n=650) and in paired cord blood and urine of subset cohort (n=317). Bivariate analyses between As exposure, sizes at birth and covariates were evaluated by Spearman’s correlation coefficient. Association between maternal blood As levels and size at birth and other factors were further evaluated using mixed-effects modelling. Results: The geometric mean (GM) of the As in maternal blood was 0.62 µg/L (n=650; 95%CI, 0.58-0.66), in cord blood 0.78 µg/L (n=317; 95% CI, 0.74-0.83) and in urine (creatinine – corrected) was 14.26 µg/L (n=317; 95% CI, 12.64-16.09). Linear correlation was found between maternal blood and cord blood As, indicating placental permeability and some protective mechanism to foetus. Birth outcomes showed geographical differences in gestational age (p<0.001), birth length (p=0.028), head circumference (p<0.001), Apgar score at 5min (p<0.001) and parity (p<0.002). In univariate analyses older age, having secondary education, consuming fresh fish, consuming root, leafy and vine vegetables, and dairy products as well as bottled water, were associated with lower As blood levels. Both in univariate and multivariate analyses being single, drinking outdoor tap water, borehole and river water resulted in higher As levels. In the higher percentile head circumference was positively correlated with maternal blood As levels both in total cohort (β=0.19, p=0.049) and in female babies (β=0.40, p=0.007). Conclusions: Exposure to arsenic in utero differed by geographical positions. The placental permeability for As was confirmed and some effect on birth anthropometry in girls was found that requires further investigation.