Effects of marginal zinc deficiency on subclinical lead toxicity in the rat neonate.

Influence of maternal dietary zinc intake on tissue distribution of lead and zinc in neonatal rats administered lead acetate by gavage during lactation was examined. Milk from dams fed a marginally deficient diet (6 micrograms Zn/g diet) contained a lower zinc concentration at the beginning of lactation than did that from control dams (30 micrograms Zn/g diet); no differences were seen by d 11 of lactation. Dams fed the deficient diet had lower plasma zinc values in comparison with pair-fed or ad libitum-fed dams and lower femur zinc concentration in comparison with pair-fed dams. Pups suckling marginally deficient dams had lower concentrations of zinc in plasma, femurs and kidneys although hippocampal and cerebellar zinc were unaltered. Body weights of pups from marginally zinc-deficient dams were lower than those from ad libitum-fed dams, but similar to those from pair-fed dams. Lead ingestion had no effect on body weight. Marginally zinc-deficient pups had greater lead accumulation in blood, femurs, hippocampi and cerebella, but not kidney, than did zinc-adequate pups. Marginal zinc deficiency during lactation increases the body lead burden of suckling rats, an effect not attributable to increased transfer of lead into milk in response to suboptimal maternal zinc status.