Placental transfer of lead and its effects on the newborn.

Following delivery, blood was taken from 122 mothers and their infants' cords for estimation of lead, haemoglobin, packed cell volume and mean corpuscular haemoglobin concentration. All were resident in Kasanda, a township within a radius of 3000 metres of Brokin Hill Lead Mine and Smelter, Zambia, where the annual mean atmospheric lead concentration was 9.6 microgram/m3 and the soil lead concentration 100-9400 p.p.m. Their mean blood levels were high, being 41.2 microgram and 37 microgram/dl for mothers and infants respectively, with a significant correlation (r = 0.77, P less than 0.001). Thus an infant's blood lead at birth closely follows that of its mother even at high values. The increased lead level transfer, however, did not appear adversely to affect the birth weight or red cell values of the newborn. Cord blood lead levels are being used in Broken Hill to monitor a community's exposure to lead.