Removal of Plutonium by a New Type Calcium and Combination of the Calcium and Ca-DTPA in Rats.

Abstract

Effects of a new type of calcium product (Seaweed-calcium complex: SWCa) and combination of SWCa and Ca-DTPA on removal of injected 239Pu were examined in rats. SWCa is a natural product consisting of mixed calcined oyster shell (COS) which is composed of calcium salt probably in the form of calcium oxide and a natural material extracted from seaweed to transport calcium actively throughout the small intestine. In experiment I, a 2% solution of SWCa, COS, CaO, CaCl2 or CaCO3 was injected into the small intestinal loops of rats to compare the intestinal absorption rate of each calcium salt. In experiment II, 25 male Wistar rats, 3 months of age, were divided into five groups given; a control diet with 1% CaCO3 (group A), a SWCa diet with 1% SWCa to replace the 1% CaCO3 after plutonium injection (group B), a SWCa diet 1 week before plutonium injection until the end of the experiment (group C), a SWCa diet and intraperitoneal injections of a daily dose of 150μmol/kg of Ca-DTPA (group D), and a control diet and intraperitoneal injections of the same dose of Ca-DTPA as group D (group E). The rats were injected intravenously with plutonium, 1.85×104Bq/kg, and killed 14 days later and the femur and liver were excised. All excreta were collected at 24-h intervals during the experimental period. The plutonium concentration was measured by a liquid scintillation spectrometry after a wet ashing treatment.The levels of serum total and ionic calcium were elevated more rapidly and were higher after the injection of SWCa than after those of COS, CaO and CaCO3. The percent of plutonium content to administered dose in the skeleton was 69.3, 63.6, 58.8, 10.4 and 19.0%, and that in the liver was 7.74, 6.93, 6.43, 0.22 and 0.35% for groups A, B, C, D and E, respectively. The plutonium contents in the urine and feces were increased during the first 2-3 days after plutonium injection in the SWCa groups. The results indicated that the elevation of serum calcium by the oral administration of SWCa could lower the plutonium content in the skeleton and liver both before and after plutonium injection and the effects were increased by the combination of SWCa and Ca-DTPA. In conclusion, SWCa not only lowered the plutonium content after exposure but also prevented plutonium deposition in the bones and liver.