Basic investigation for an epidemiological study on cadmium contamination of wildlife - Cadmium distribution in the rat body after intravenous cadmium exposure

The authors have recently developed a new cadmium (Cd) index (Cd standard regression line; CSRL) based on data from uncontaminated samples from many species. However, the samples from wildlife organs are often, and sometimes, we can not remove the blood in the tissues. The Cd remained in the blood may affect the content of the organ. Thus, preliminary work for an epidemiological study was performed upon a laboratory animal, the rat. After establishment of a constant level of Cd in rat serum, the Cd contents of various organs were compared following perfusion with 0.8% NaCl, with 1mM EDTA, or without any treatment. No significant differences were found among these organs, and the Cd levels in the organs were dependent on the infused Cd concentration. These results suggest that the Cd content in the blood did not affect the evaluation of the Cd content of the organs investigated. After the infusion of Cd, The ratio of liver and renal cortex was separated from the slope of the CSRL and was located at the upper part of the CSRL, while the data for the liver and renal medulla were located on the CSRL. From the results, we assumed that the assessment was correct, even if the content in the kidney cortex was considered to represent the Cd content of the whole kidney, when we could obtain the data only from the cortex. Furthermore, significant correlations were observed among the other organs, and strong multiple correlation was obtained among the Cd contents in liver, renal cortex, adrenal, renal medulla, pancreas, spleen and testis. These results suggest that contamination can be evaluated by measurement of the Cd content in these organs, even if samples of liver and/or kidney cannot be obtained.