Cadmium absorption and tissue distribution in rats provided low concentrations of cadmium in food or drinking water

Tissue Cd levels were determined 1, 2, 4, 8, and 12 wk after weanling rats were provided with food or water containing 1-1000 ng/g Cd as 109CdCl2. No differences in growth rate or organ weight were observed over the concentration range tested. Kidney accumulated the highest concentration of Cd, followed by liver with values one-third to one-fourth those found in the kidney. Liver, however, accounted for 35-55% of the total body burden, while kidney contained only 35-45%. Cd concentrations in the various tissues increased with time and the Cd concentration of the food or water. The percentage of the ingested dose absorbed in a given time was relatively constant over the tested Cd concentration range. However, for each metal concentration, the percent of Cd absorbed decreased with exposure time. Regression analysis established that female rats accumulated Cd at a higher rate and retained a greater percentage of the ingested Cd than did male rats and that tissue concentrations were higher in rats exposed to Cd in the water. The differences in tissue Cd levels are probably related to proportionally higher metal intake by females and to higher intake from water than food at equivalent concentrations. It is uncertain whether the greater retention of ingested Cd by females is due to more efficient absorption or a reduced rate of excretion of the metal.