DYNAMIC RADIOCESIUM DISTRIBUTION IN SHEEP - MEASUREMENT AND MODELING

An experiment was carried out to provide a data set specifically desig ned to allow the development of a model to describe the dynamic behavi our of radiocaesium in sheep tissues. A single intraruminal dose of (C sCl)-Cs-134 was given to each of 15 Scottish Blackface ewes, aged 1-2 years. Radiocaesium activity concentrations were measured at various t ime intervals after dosing in blood, faeces and urine and, after slaug hter, in a range of tissues and digestive tract contents. A first orde r compartment model was developed comprising nine compartments represe nting various organs and tissues in the body. Rate constants for the m odel were obtained by optimisation to the experimental results. A limi ted validation of the model was carried out by using it to calculate t issue transfer coefficients (F(f)) and biological half-lives (T0.5) of radiocaesium in sheep. The values generated compare favourably with p ublished figures. Applications for the model and constraints on its us age are examined along with possibilities for further development.