Non-carcinogenicity of cadmium-free ferritin

Abstract

IT was reported in 1964 that rats which received repeated subcutaneous injections of cadmium-precipitated ferritin developed sarcomas at the site of injection, interstitial cell (Leydig cell) tumours of the testes and testicular atrophy (Haddow, Roe, Dukes and Mitchley, 1964;Roe, Dukes, Cameron, Pugh and Mitchley, 1964). Previous and parallel observations demonstrated that simple inorganic cadmium salts were carcinogenic-both at the site of injection (Kazantzis, 1963;Haddow et al., 1964) and in the testis (Parizek and Zahor, 1956; Meek, 1959;Kar and Das, 1960;Gunn, Gould and Anderson, 1963)-and it thus seemed likely that some or all of the effects of cadmium-precipitated ferritin were due to its content of cadmium. To confirm this hypothesis, cadmium-free ferritin was tested for carcinogenic activity in rats and mice. MATERIALS AND METHODSExperiments were carried out on 48 male CB Wistar rats and on 64 male CB stock mice. The rats, which were 6 weeks old at the beginning of the experiment, were divided into test and control groups, each consisting of 24 animals. The mice, 11 weeks old, were divided into a test group of 24 animals and an untreated control group of 40 animals. The rats and mice were housed in metal cages and maintained on cubed Diet No. 86 (Messrs. Dixon, Ltd., Ware, Herts.) and water ad libitum.