Transplacental kinetics of lead in pregnant mini-pigs

This study examined the maternal and fetal blood kinetics of lead in pregnant, near term mini-pigs. A lead dose of 1 mg/kg was administered to the animals by i.v. injection as bolus. During the 5-h sampling period, the two-compartment maternal pharmacokinetics demonstrated a rapid phase T1/2 of 8 min and a slower phase T1/2 of 199 min. Lead reached the fetus with a time lag of 81 min. At 24 h after administration the ratio of fetal to maternal blood lead concentration seemed to become stable. When lead was injected directly into the fetal blood circulation, the decay of fetal blood lead fitted one-compartment model. The disappearance half-life was 92 min. Lead can obviously accumulate in fetal liver; the lead level in fetal brain showed no detectable changes. This study confirmed that lead can also pass through the epitheliochorial placenta.