A possible method for estimating the true absorption coefficient for radiocaesium in ruminants

A method has been described for estimating the true absorption coefficient for radiocaesium. The ratio of the excretion of 137Cs in the faeces to that excreted in the urine was estimated in housed ewes and lambs offered a radiocaesium-free diet for 16-22 days, after previously grazing a pasture contaminated with Chernobyl fall-out. There was a two-fold range in the faeces:urine excretion ratio. The ratios obtained were used to estimate the the faecal 137Cs of endogenous origin from the urinary excretion rates of ewes given diets contaminated with radiocaesium from Chernobyl or from marine effluent from BNFL, Sellafield, and hence the true absorption coefficient could be determined. The observed variations in faeces:urine excretion ratios had little effect upon the estimates of true absorption coefficient.