EFFECT OF NATURAL CHELATING-AGENTS ON THE INTESTINAL-ABSORPTION OF RADIOSTRONTIUM IN RATS

Chitin is a cellulose-like biopolymer distributed widely in nature, es pecially in crustaceans, insects, fungi and yeast. Its derivative, chi tosan is known to be a natural chelating agent. The purpose of the pre sent study was to investigate whether this naturally occurring biopoly mer can be used to reduce the bioavailability of radiostrontium in foo d in the gastrointestinal tract of animals and humans. The whole-body retention of Sr-85 was monitored in rats given chitosan orally. The re tention of Sr-85 in the chitosan-treated rats was lower than the contr ols, with a corresponding increase in Sr-85 in the faeces. Other rats were kept for 50 days on a powdered diet which contained 10% w/w of ch itosan before oral administration of Sr-85. The whole-body retention o f Sr-85 decreased sharply compared with the controls. Trace element co ncentrations and other variations in components of blood were measured in the rats to which the low molecular weight chitosan was given in o rder to investigate the cause of the rapid decrease in the retention o f radiostrontium. The concentrations of phosphorus and calcitonin in b lood decreased significantly with the feeding time. The results sugges t that chitosan can be used to reduce the bioavailability of radiostro ntium in ingested food. Chitosan may form an insoluble phosphate compl ex with Sr in the gastrointestinal tract.