Cadmium and Zinc in Pregnancy and Lactation

Abstract

Radioactive cadmium (¹⁰⁹Cd) and zinc (⁶⁵Zn) were injected subcutaneously into pregnant rats. More cadmium than zinc was found in the placentae. After birth, newborns showed detectable ¹⁰⁹Cd only in liver, gastrointestinal tract, and in the brain tissue. Zinc 65 was present in all newborns’ tissues. During lactation, highest output of ⁶⁵Zn was in colostrum and, on subsequent days, ⁶⁵Zn in milk declined rapidly. Cadmium 109 in milk was present in low concentration throughout the lactation period. Rats injected with ¹⁰⁹Cd and ⁶⁵Zn after parturition excreted these isotopes in milk in a similiar pattern. Newborns nursed on radioactive milk showed rapid absorption of ⁶⁵Zn, whereas ¹⁰⁹Cd accumulated primarily in the intestinal tract; a lesser quantity of ¹⁰⁹Cd was deposited in the liver. In other organs, only ⁶⁵Zn was found. The lactating mammary gland contained more ¹⁰⁹Cd than ⁶⁵Zn; after lactation, ⁶⁵Zn was depleted, whereas ¹⁰⁹Cd remained in mammary tissue.