ABSORPTION OF RADIOCESIUM BY SHEEP AFTER INGESTION OF CONTAMINATED SOILS

The absorption of Cs-137 by sheep following ingestion of contaminated soil was studied using an established dual isotope method. Two agricul tural soils were studied: an alluvial gley contaminated by discharges to the sea from the Sellafield Reprocessing Plant, and a lowland organ ic soil that had been artificially contaminated. Values of the true ab sorption coefficient of radiocaesium of 0.19 +/- 0.03 and 0.03 +/- 0.0 1, respectively, were obtained for these soils. This implies that avai lability of soil-associated radiocaesium for uptake following ingestio n is up to about 20% of that when the activity is incorporated in vege tation. These results have been compared to estimates of availability made using an in-vitro approach described previously and found to be i n good agreement. However, comparison with in-vitro data obtained for an upland peat indicated that absorption from some upland organic soil s could be greater than from the lowland organic soil.