Lead toxicity in the pregnant rat. I. The effect of high-level lead on delta-aminolevulinic acid dehydratase activity in maternal and fetal blood or tissues.

A study was made of the effects of administration of 500 ppm of lead in the drinking water of pregnant rats and their fetuses. The delta-aminolevulinic acid dehydratase (ALAD) activity of erythrocytes in lead-treated dams showed 82.7 and 74.8% inhibition on Days 18 and 21 of pregnancy, respectively. ALAD activity of erythrocytes in the lead-treated fetuses showed 59.7 and 73.0% inhibition on Days 18 and 21 of pregnancy, respectively. ALAD activities in the liver and placenta were not significantly different between the lead-treated and control animals. The lead concentrations of blood and liver in the lead-treated dams and fetuses were higher than in the control animals, but the lead level of amniotic fluid was not significantly different from that of the control animals. Significant correlations were observed between maternal and fetal blood lead, liver lead, and erythrocyte ALAD, but there was no significant correlation between maternal and fetal liver ALAD.