Cadmium accumulation in rat organs after extended oral administration with low concentrations of cadmium oxide.

Abstract

Rats were exposed to dietary cadmium oxide (CdO) (2.80 and 7.15 ppm Cd) for 60 days. Between days 20 and 36 of the feeding experiment, only 7.15 ppm Cd significantly reduced body weight, while an improved food utilization was recorded at both dietary Cd concentrations between days 36 and 50. After 40 and 60 days of exposure, Cd concentrations of selected organs and tissues and the excreta were recorded by atomic absorption spectroscopy. Compared to the control animals, Cd levels of hair, bone (femur), blood, and testes did not increase. Soft tissues (liver, kidney, lung, and spleen) displayed significantly elevated Cd concentrations after 40 and 60 days in both dosage groups. An increased level of Cd in muscle was observed in one group only (7.15 ppm, day 40). Maximum Cd levels were 11.6 ppm in liver and 9.75 ppm in kidney on a dry weight basis, reflecting a 68- and 50-fold accumulation of the metal compared to the controls. Only absolute weights of lung and liver decreased slightly in the higher dosage group, while relative weights of all organs investigated were not affected by Cd. The ratios in fecal Cd levels between control and CdO-treated animals partly reflected the Cd concentration ratio between the respective diets. No increase in the urinary Cd level was found during the feeding trial. The significance of Cd accumulation in organs, tissues, and excreta and their value as indicators for CdO exposure are discussed.