Retention, distribution, and excretion of repeatedly administered cadmium-109 in the albino rat

This study was initiated to investigate uptake, distribution, and excretion of cadmium after prolonged intravenous and oral administrations. In both the intravenous and the oral studies cadmium was administered at 48 hr intervals for 30, 60, and 90 days to the first, second, and third animal groups, respectively. The total cadmium administered to each rat equaled 1/10 of the acute LD50 (the intravenous LD50 = 2.0 mg/kg, and the oral LD50 = 150 mg/kg). In the excretion groups, urine and feces were collected every 48 hr during the experiment. All tissues and excreta were assayed for cadmium-109 activity by internal liquid scintillation counting. In the intravenous study the liver showed the highest cadmium retention. There were no significant differences between the mean retention values for liver in the intravenous study. Renal cadmium levels in the 120-day group were significantly higher than that of any of the other groups. In the oral study, the liver showed a mean retention of 0.90 percent on day 30, 0.96 percent on day 60, 0.68 percent on day 90, and 0.61 percent on day 120. The kidneys retained 0.13 percent, 0.19 percent, and 0.20 percent for the 30-day, 60-day, 90-day, and 120-day groups, respectively. In both the intravenous and the oral studies hepatic and renal cadmium levels were highly correlated. Cadmium excretion during the first three months of the intravenous study was cyclic in nature. After three months, about 22 percent of the total amount of intravenously administered cadmium had been excreted. In the oral study, almost all the administered cadmium was excreted