Dermal toxicity and percutaneous absorption of cadmium in rats and mice

Cadmium is a common contaminant in sawdust and other materials used in laboratory animal bedding. This study was conducted to assess the irritancy of a soluble cadmium compound to the skin and percutaneous absorption of the cadmium ion. Cadmium chloride solution was administered to the shaved skin of the dorsum of rats and mice daily for 10 days at concentrations of 1.0, 0.1, and 0.01% (wt/vol). Cadmium accumulated in the skin in association with approximately 6,000 ng/g in animals exposed to the high dose. Skin damage of hyperkeratosis and acanthosis with some ulcerative change was dose-related. The mitotic index in mouse skin was increased up to twofold. In rat blood, concentrations of cadmium, after 10 days of administration of a 1% concentration, were 11.65 micrograms/L, indicating percutaneous absorption. Clear evidence was seen of an accumulation of cadmium in the liver (526 ng/g) and kidney (216 ng/g), but histopathologic evidence of damage was absent, after this period at least. Concentrations of zinc were increased in the skin, probably as a consequence of local increases in metallothionein, a zinc-binding protein.