Mori, C; Sakurai, K; Iguchi, T
Introduction: Low-level exposure to endocrine disruptors (EDs) occurs throughout our lives from food, air, water, soil, household products and probably during gestation and lactation. The risks associated with this low-level but constant exposure remain largely unknown and highly controversial. Disturbances of hormonal regulation during fetal or postnatal development in humans have been thought to induce adverse effects on health. However, the adverse effects of EDs on humans are less clear, characteristically slow to develop, and difficult to detect. Therefore, we have continued to investigate fetal exposure to EDs in Japan by analyzing umbilical cords and cord serum. Our studies have been approved by the "Congress of Medical Bioethics" of Kyoto University and Chiba University. In addition, we obtained mothers' consent to collect umbilical cords and cord serum. In our previous studies on the presence of many EDs in the human fetus, we detected dioxins, PCBs, DDTs, hexachlorocyclohexane (HCH), chlordanes, heavy metals (Cd and Pb) and bisphenol A in human umbilical cords collected from normal newborns in Japan. Here, we report some EDs which have not been detected in human umbilical cords. Moreover, we analyzed the relationship between concentrations of EDs and maternal age when the first baby was born. Results and Discussion: 1) In addition to dioxins (PCDDs + PCDFs + co-PCBs), PCBs, DDTs, HCH, chlordanes and HCB, we detected DDEs, endosulfan and phytoestrogens (genistein, daidzein and equol) in human umbilical cords and cord serum. By studying umbilical cord tissue and cord serum, we found that fetuses in Japan were exposed to several EDs. 2) We examined the concentration of EDs (dioxin, PCB and DDE) in human umbilical cords of first, second and third babies. The concentration of dioxins, PCBs and DDEs in first babies seems to be higher than that in second or third babies. 3) There is a correlation between the concentration of PCBs and DDEs/HCB/HCH in human umbilical cords. 4) We also investigated the relationship between maternal age and the concentration of dioxins in umbilical cords. Our study indicates that fetal exposure to dioxins is correlated with maternal age. As dioxins accumulate in the human body, previously stored dioxins are transferred from the mother to the fetus even if the compounds are avoided during pregnancy. Our data clearly show that many chemicals transfer transplacentally from mother to fetus. Therefore, we need to pay much more attention to risk management for the diminution of fetal exposure to EDs.
