Cadmium accumulation in rats treated orally with cadmium chloride for 8 months

To investigate the accumulation pattern of cadmium (Cd) in the liver and kidney following Cd intake from diet, female SD rats were fed cadmium chloride (CdCl2)- contained diets (1.24 and 4.96 ppm Cd) for 2 or 4 months. The other rats were fed CdCl2-contained diets (8, 40, 200, and 600 ppm Cd) for 2, 4 or 8 months. The control rats were given diet without Cd addition (lower than 0.01 ppm Cd). The concentrations of Cd in the liver and kidney derived from all rats were determined. The concentrations of Cd in the liver and kidney increased depending on the dosage of Cd. The concentrations of Cd in the liver did not reach plateau level even in the 200 and 600 ppm groups. On the other hand, the concentrations of Cd in the kidney in the 200 and 600 ppm groups reached a plateau level, which was approximately 250 micrograms/g. In the 600 ppm group, the concentrations of Cd in the kidney reached 250 micrograms/g at 2 months, but did not exceed that level at 4 months. In the 200 ppm group, the concentrations of Cd in the kidney increased to nearly the level of 250 micrograms/g at 8 months. The ratio of the concentrations of Cd in the kidney versus liver decreased as the dosage of Cd increased, suggesting that a low dosage of Cd was distributed preferentially to the kidney, but a high dosage of Cd was distributed to the liver. The relation curves between total amounts of Cd intake and Cd levels in the kidney in the 2-, 4-, and 8-month groups showed a parabola. The curves were shifted in parallel in the direction of higher levels of ingested Cd in order of length of Cd exposure period. These results suggested that when Cd is ingested over a long time at low concentrations, the amount of Cd accumulation in the kidney is small even for equal amounts of total ingested Cd.