Levels of DDT and its metabolites in placenta, maternal and cord blood and their potential influence on neonatal anthropometric measures

Abstract

Previous studies of in utero exposure to dichlorodiphenyltrichloroethane (DDT) have shown mixed results for the harmful effects on fetal growth and development. This cross-sectional study was designed to: (1) examine the extent of DDT exposure in 1578 women, aged 28.5±6.0 who delivered between June 2005 and 2006 in the area of Al-Kharj, Saudi Arabia; and (2) assess its influence on neonatal anthropometric measurement of newly born babies. DDT and its metabolites, namely 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), 1,1-dichloro-2,2-bis (p-chlorophenyl) ethane (p,p′-DDD) and 1,1,1-trichloro-2,2′ bis (p-chlorophenyl) ethane (p,p′-DDT) were measured in cord and maternal serum as well as placenta by Gas Chromatography coupled with an Electron Capture Detector (GC/ECD). p,p′-DDE was detected in 28.3% of cord and 54.4% of maternal serum, reflecting past exposure, whereas the p,p′-DDT was only found in 0.46% cord and 1.2% maternal samples. As expected the p,p′-DDE cord levels (0.197±0.961μg/L) were 2.8 times lower than the maternal levels (0.551±1.778μg/L), and both were significantly correlated (r=0.517) suggesting its transplacental transfer. The picture was different in placental tissues. p,p′-DDE and p,p′-DDT were detected in 84% and 99% of placental tissues, with the highest p,p′-DDT in placental tissues (29.62±158.282µg/kg dry wt.) compare to p,p′-DDE (10.167±18.851μg/kg dry wt.). In general, the presence of DDT metabolites in our participants indicates that these chemicals are still relevant despite the fact that they have been banned or restricted in the study area for many years. Our results support the view for an association between low in utero exposure to DDT and the anthropometric development of the fetus leading to a reduction in its head circumference, crown–heel length, birth weight and birth height. Since the reduction in these measures was independent of gestational age and/or preterm births, our findings suggest a detrimental effect of the DDT exposure on fetal growth. Neonatal anthropometric measures are considered as an important tool to detect newborns at higher risk of morbidity and impairment of growth. Efforts should be made to decrease exposure of women of reproductive age and to examine maternal DDT exposure in relation to long-term impact on health.