INFLUENCE OF DIETARY ZINC ON LEAD TOXICITY DURING GESTATION AND LACTATION IN THE FEMALE RAT

Confirmed pregnant female albino rats received a purified diet containing either 12 or 120 ppm zinc with or without lead (0 or 500 ppm) from day 0 gestation through day 16 of lactation. An 11% reduction in dam weight gain during gestation and a 12% reduction in average pup weight in rats fed the low zinc plus lead diet was markedly different compared to controls not receiving lead and lead supplemented rats receiving supplemental zinc. Milk lead concentration was reduced in rats receiving additional dietary zinc and lead which was reflected in a 15% reduction in pup tibia lead concentration, a 20% reduction in inhibition of pup liver delta-aminolevulinic acid dehydratase activity and a 31% reduction in pup blood porphyrin concentration. Some of the beneficial effects of supplemental zinc on lead toxicity of pups may be explained by a reduction of both liver lead (40%) and blood lead (32%) concentration of dams. However an interaction betwen lead and zinc at the placental and mammary barriers must also be considered. The results of this study suggest that nutritional status of zinc may be an important factor in modifying lead burden of infants borne by women occupationally and environmentally exposed to lead.