Abstract
The direct effect of cadmium on bone metabolism and interaction between cadmium and zinc or copper in tissue culture are described in this review. One ppm cadmium stimulated 45Ca release from 45Ca-prelabeled bone from 9-d-old chick embryo, but 30 ppm cadmium inhibited 45Ca release. Mineralization and collagen synthesis were inhibited by cadmium of 1 ppm and above. Since Cdtreated bones in the culture system showed a decrease in both mineral and collagen, the change in the cultured bone is not osteomalatic but osteopororic and agrees with the bone change of cadmiumtreated animal rather than with that of Itai-itai diseased patient. The difference in bone lesion between humans and cadmium-treated animals suggests that factors other than cadmium participate in the etiology of Itai-itai disease. We gave attention to zinc, copper and lead as factors other than cadmium, which were found in the bones of Itai-itai diseased patients and in cadmium-polluted rice. A cadmium-induced decrease in collagen content was protected by zinc but enhanced by copper. A cadmium-induced decrease in mineral content was unaffected by zinc and copper. These results point out that copper aggravates cadmium-induced osteoporotic change and cadmium plus zinc-treated bone shows a decrease in mineral without a decrease in bone matrix to give an osteomalacia-like change. Therefore, it is suggested that a ratio as well as each dose of three metals influences whether bone damage in vivo is osteoporotic or osteomalatic.
