1982 Volume 28 Issue 2 Pages 31-42
The target organ of inorganic tin and its toxic action are described in this review. Tin has some toxic effects on gastrointestinal function, blood cells, hepatic enzymes, endocrine secretion from pancreas, renal calcium metabolism and its related enzymes, bone metabolism, central nervous system, and reproduction function. In bone, however, a marked deposition is caused by the ingestion of inorganic tin compounds, while a slight deposition is observed in other soft tissues. The acute toxic studies of inorganic tin on various biochemical indices suggest that the critical organ of tin is bone with a decrease in the femoral calcium content. Furthermore, from the subacute toxic experiment by oral administration of stannous chloride for 90 days in weanling rats, the decrease of calcium content in the femoral epiphysis is regarded as the most specific biochemical manifestation of the toxic action of inorganic tin. On the basis of the sign of this manifestation, the nonobserved-effect level of inorganic tin is estimated to be lower than 0.6 mg Sn/kg/d. Also, the maximal allowable concentration of inorganic tin contained in the diet would be lower than 50 ppm Sn. On the other hand, as a possible mechanism of the toxic action of inorganic tin on bone metabolism, it seems that tin induces the obstruction of proliferation of the bone cells accompanied with the prevention of DNA synthesis succeeded to the inhibition of protein synthesis, i.e. alkaline phosphatase and collagen, and as the result the bone formation is suppressed. This review emphasizes that a primary target organ of inorganic tin is bone, and the metal may cause fragile bone.
