Study on the Accumulation, Excretion, and Distribution of Cadmium in Mice After Dietary Exposure to Cadmium-Rich Swimming Crab Portunus trituberculatus

To investigate the patterns of cadmium accumulation and distribution in mice following oral ingestion of cadmium-enriched Portunus trituberculatus, this study selected 4-week-old ICR mice as a model organism. A control group was fed a standard diet, while an exposure group was fed a diet supplemented with 10% cadmium-enriched Portunus trituberculatus. After 28 consecutive days of exposure, the mice were switched to a standard diet for 7 days. Tissues and feces were collected throughout the experiment; cadmium levels were determined by inductively coupled plasma mass spectrometry (ICP-MS) following microwave digestion. The results showed that after 28 days of exposure, cadmium accumulation was observed in the kidneys (females: 0.046 ± 0.001 mg/kg, males: 0.053 ± 0.005 mg/kg) and livers (females: 0.046 ± 0.008 mg/kg, males: 0.034 ± 0.001 mg/kg), while levels in the control group were below the limit of detection; After a subsequent 7-day period of feeding standard diet, cadmium accumulation was observed in the kidneys (females: 0.070 ± 0.001 mg/kg, males: 0.047 ± 0.006 mg/kg), livers (females: 0.040 ± 0.001 mg/kg, males: 0.035 ± 0.009 mg/kg), and the intestines (females: 0.028 ± 0.006 mg/kg, males: 0.029 ± 0.001 mg/kg) still contained trace amounts of cadmium that had not been excreted. An apparent mass balance analysis suggested that more than 90% of ingested Cd was not retained in the analyzed tissues. In summary, although cadmium ingested orally is primarily excreted, the clearance rate for cadmium accumulated in the liver and kidneys of mice is relatively low, and residual levels remain in the tissues even 7 days after exposure ceased, indicating that even when the majority of ingested Cd is eliminated, the fraction retained in target organs may persist after exposure cessation and warrants further investigation under longer-term exposure scenarios.