Abstract

A series of controlled experiments was carried out on rats to study the effects on the kidneys of the repeated administration of small doses of cadmium for periods of up to 12 months. Renal lesions consisting essentially of tubular atrophy and interstitial fibrosis were produced, and the evidence that these lesions were due solely to cadmium is discussed. No similar lesions occurred in a series of control animals, litter mates of the experimental animals. The lesions were shown to be reproducible in two prolonged experiments on two strains of rats. The relationship between the lesions and the concentration of cadmium in the tissues of the rats is discussed and a comparison is made with tissues from human cases of chronic cadmium poisoning. It is of interest that the cadmium concentration of human tissues and rat experimental tissue is of the same order of magnitude. Animals in which the administration of cadmium was discontinued after five months of the experiment had developed as severe lesions seven months later as those animals which had received cadmium for 12 months. It has been shown previously that the first sign of chronic cadmium poisoning can occur in man for the first time many years after the last exposure, and that the disease once established in man is progressive despite the absence of further exposure.