Effects of Chromium, Cadmium and Lead on the Growth and Survival of Rats

Abstract

Eight groups of more than 50 hooded rats were each given (at 5 ppm) cadmium, trivalent chromium or lead in drinking water while fed a diet of rye flour, dried skim milk and corn oil containing no detectable cadmium and only small amounts of chromium and lead. Extensive precautions were taken to avoid environmental metallic contamination. The diet was nutritionally adequate for survival, all but 7 control animals surviving 21 months. Mortality of rats receiving chromium was equally low. Although those given lead and cadmium grew normally, survival was considerably reduced when their tissue concentrations of metal were approximately similar to or less than those of adult human beings. No metallic toxicity appeared. Growth of males was stimulated by chromium and mature animals were larger than the controls. Cadmium was not detected in the livers and kidneys of animals not given it, although they grew normally and survived. Cadmium is not an “essential” trace metal for rats in terms of growth and survival; it shortens their lives at less than human renal concentrations. Lead at human tissue concentrations has a similar innate toxicity in terms of survival. If chromium has a metabolic function, these experiments confine it to male rats.