Reduction of Radiocesium Transfer to Animal Products Using Sustained Release Boli with Ammoniumiron(III)-Hexacyanoferrate(II)

Abstract

A sustained release bolus with the cesium binder ammoniu-miron(III) - hexacyanoferrate (AFCF) has been developed as a countermeasure for small ruminants grazing pastures contaminated by radiocesium (¹³⁴Cs+¹³⁷Cs). The boli (40-50 g) are produced by compression of a mixture of AFCF, barite and wax. The release of AFCF from boli labelled with 137Cs-iron-hexacyanoferrate complex was studied in laboratory sheep. The release rate followed first order kinetics during the 108 d of observation and decreased from 40 to 22, 110 to 35 and 280 to 25 mg d⁻¹ in sheep treated with 1, 2 or 3 boli respectively. The efficiency of boli in reducing radiocesium transfer to meat and milk was tested in laboratory studies with goats fed ¹³⁴Cs tracer. Until 40 d after treatment the transfer of radiocesium to milk was reduced by 35%, 60% and 85% in goats given 1, 2 or 3 boli, respectively. The reduction in radiocaesium transfer persisted for 90 d but with a lower efficiency. A similar relationship was found between number of boli and the reduction in radiocesium transfer to meat with an observed maximal reduction of 60%.