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

Chitin is a cellulose-like biopolymer distributed widely in nature, especially in crustaceans, insects, fungi and yeast. Its derivative, chitosan is known to be a natural chelating agent. The purpose of the present study was to investigate whether this naturally occurring biopolymer can be used to reduce the bioavailability of radiostrontium in food in the gastrointestinal tract of animals and humans. The whole-body retention of Sr-85 was monitored in rats given chitosan orally. The retention of Sr-85 in the chitosan-treated rats was lower than the controls, 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 chitosan before oral administration of Sr-85. The whole-body retention of Sr-85 decreased sharply compared with the controls. Trace element concentrations and other variations in components of blood were measured in the rats to which the low molecular weight chitosan was given in order to investigate the cause of the rapid decrease in the retention of radiostrontium. The concentrations of phosphorus and calcitonin in blood decreased significantly with the feeding time. The results suggest that chitosan can be used to reduce the bioavailability of radiostrontium in ingested food. Chitosan may form an insoluble phosphate complex with Sr in the gastrointestinal tract.