Effects of Low Concentrations of Organochlorine Compounds in Women on Calcium Transfer in Human Placental Syncytiotrophoblast

For most Canadians, food represents one of the major sources of environmental contaminants. Among them, organochlorine compounds (OCs) are known to affect calcium (Ca2+) homeostasis. They are neurotoxic by perturbation of Ca2+ channels and pumps, and they interfere with protein kinase C (PKC) and Ca2+ binding protein (CaBP). Ca2+ is an essential element to adequate fetal growth and development. The aim of the present study is to determine the relation between low environmental maternal exposure to OCs, such as polychlorinated biphenyls (PCB 153), Aroclor 1260, p,p'-dichlorodiphenyltrichloroethane (DDT) and p,p'-dichlorodiphenyl-dichloroethane (DDE), Ca2+ levels in serum and placenta, placental Ca2+ transfer, and newborn development. Total Ca2+ and OCs were measured in women's serum samples, as well as in umbilical cord's serum and placenta at term. Placentas were taken for trophoblast cells isolation and Ca2+ incorporation kinetic experiments. Our results were obtained from 30 pregnant women from the southwestern area of Quebec. Concentrations of Aroclor 1260, PCB 153, DDE, and DDT were respectively 6.1, 6.0, 3.1, and 2.9 times lower in the umbilical cord serum than in the mother's serum at term. In the placenta, DDE was accumulated at higher levels than other contaminants. A tendency towards an inverse relation was observed for in OCs found in three compartments and Ca2+ levels in maternal serum and in placental tissues. Maternal Ca2+ concentrations do not influence Ca2+ uptake by syncytiotrophoblast. Only DDE (>/=0.70 mug/l) in maternal serum significantly was associated with a small increase in Ca2+ uptake by syncytiotrophoblast. This study will help us determine if low OC contamination significantly modifies Ca2+ transfer in syncytiotrophoblast.