Carcinogenicity of cadmium in animals: What is the significance for man?

The carcinogenic potency of cadmium injected into rats and mice has been demonstrated 20 years ago. In contrast, chronic dietary intake of cadmium‐containing food by laboratory animals did not induce any tumors. With regard to inhalation of aerosols of different cadmium compounds, there is now an extensive data base which shows that inhaled cadmium does induce lung tumors in laboratory rats. Even the highly insoluble CdS was found to induce lung carcinomas in rats, although it appears at a first glance that higher inhaled concentrations of CdS are needed to give the same pulmonary carcinogenic response as inhaled CdCl2 or CdO dust. In fact, an exposure concentration‐lung tumor relationship for the rat can be established which can be transformed into a dose (in terms of cadmium per gram lung tissue)‐response curve for the rat by applying lung dosimetric principles. However, the question arises as to whether and how the results of the rat studies should be extrapolated to humans since chronic inhalation exp...