Early signs of oral and inhalative cadmium uptake in rats.

Female wistar rats, 170--190 g, were exposed for 90 days to cadmium oxide aerosols containing 25 and 50 microgram Cd/m3 and for 63 days to 100 microgram Cd/m3. Simultaneously female wistar rats, 170--190 g, were fed 25, 50, and 100 ppm cadmium in drinking water for 90 days. After inhalation and ingestion of the metal, there were comparable kidney cadmium levels, but higher liver and blood levels after oral uptake. Coincident with the higher blood cadmium concentrations, proteinuria was observed only after oral administration. Likewise, there was a significant decrease of serum iron after ingestion and no lowering of the serum iron after inhalation of the metal. The inhalation led to a marked dose dependent weight increase of the lungs, which was followed by an impairment of gas exchange. Obviously, after inhalative cadmium uptake of 90 days pulmonary changes precede renal damage.