Tin, copper, iron and calcium metabolism of rats fed various dietary levels of inorganic tin and zinc

Three studies were conducted to determine the effects of various dietary levels of tin (less than 1, approximately 100, approximately 200, approximately 500, approximately 2000 micrograms/g diet) and of zinc (approximately 15, approximately 30, approximately 52 micrograms/g diet) on the metabolism of tin, copper, iron and calcium by growing rats. The accumulation of tin in the kidneys and tibias of animals was proportional to dietary exposure. The concentration of tin in the bones of rats fed greater than 100 micrograms Sn/g diet was 5-fold and 20-fold greater than the levels found in kidney and liver, respectively. Rats fed greater than 500 micrograms Sn/g diet had plasma copper levels that were only 13% of control levels and had depressed copper levels in livers and kidneys. The activity of delta-aminolevulinic acid dehydratase in the erythrocytes of rats fed the highest level of tin was 55% of that found in control animals. The amounts, but not the concentrations, of calcium in the tibias of rats fed greater than 100 micrograms Sn/g diet were less than the levels in the bones of control animals. The moderate variations in dietary zinc levels did not affect significantly the levels of minerals in tissues.