The use of an in vitro technique to predict the absorption of dietary radiocaesium by sheep.

The validity of an in vitro extraction technique to predict the availability for absorption of radiocaesium in the sheep gut has been assessed. The technique (a 2-h extraction with caesium chloride) was found to be valid for sources with a low availability for transfer across the gut, but inappropriate for ionic radiocaesium or radiocaesium incorporated internally within herbage. For such radiocaesium sources, which have a high in vitro availability, no correlation was found between in vitro extraction and true absorption measurements. A true absorption value of 0.80 is recommended for these sources, although values for individual sheep in the range 0.60 to 1.00 should be expected.

Countermeasures for reducing radioactive contamination of farm animals and farm animal products.

A summary is given of the range and effectiveness of different available countermeasures which can reduce the radiation dose arising from the radioactive contamination of food products from animals. The choice of which countermeasure is suitable for each particular situation will depend on many factors. Consideration should be given not only to the effectiveness of each countermeasure in terms of reduction of radionuclide content, but also to its practicality and cost, particularly where deposition levels are high or where high contamination levels in animal food products persist for a long period of time. Effective countermeasures which can reduce radiocaesium contamination of milk and meat from farmed animals by more than a factor of 10 have been developed, tested and used during the last 30 years. Less progress has been made in identifying effective binders for reducing levels of the other important contaminating radionuclides, such as I and Sr, in animal food products.