Placental transfer of lead, mercury, cadmium, and carbon monoxide in women. I. Comparison of the frequency distributions of the biological indices in maternal and umbilical cord blood.

ABSTRACT

PIP 500 pregnant women living in different areas in Belgium were surveyed to evaluate the extent of environmental exposure to heavy metals (lead, cadmium, and mercury) during fetal life, possible biological effects of such exposure, and various epidemiological significances which may influence such exposure. In addition carboxyhemoglobin level was determined. And frequency distributions of these various hematological indexes were compared. Maternal and umbilical cord blood levels of these hematological parameters indicate that the 3 metals do cross the placenta, but the transfer rate differs for each heavy metal. No barrier was demonstrated for mercury transfer. A slight barrier seemed present for lead. A barrier of some importance was demonstrated for cadmium. Statistical correlations bear out these contentions; there was a lower correlation between maternal blood cadmium and umbilical blood cadmium concentrations (r + .38) than for the other 2 metals (r .6). Carboxyhemoglobin levels of mother and newborn are highly correlated (P .001), and in mothers carboxyhemoglobin levels are also associated with cadmium concentration in blood, suggesting that the source of these pollutants is the same, namely smoking. There were no significant correlations observed between blood lead concentrations and erythrocyte prophyrin level; rather, because of its high sensitivity to lead, the erythrocyte enzyme ALAD was negatively correlated with blood lead in mother and newborn.^ieng