Transport of radiocaesium from a sheep's diet to its tissues

Radiocesium transfer rates among pigs fed haylage contaminated with low levels of cesium at two differentiation stages

The objective of this study was to determine the radiocesium transfer rates of pigs fed haylage contaminated with low levels of cesium at different growth stages. We measured the body weight of juvenile and adult pigs during the treatment period to confirm their health status. We also performed pig blood hematologic and biochemical analyses at both growth stages. To our knowledge, this is the first study to report pig radiocesium transfer coefficient rates after 1 month of chronic oral treatment, which is the period assumed to be required for body equilibrium under a diet of radiocesium-contaminated food. The results showed higher radiocesium retention rates in the kidneys, liver, spleen, genitals, psoas major, bladder, thyroid, and urine than in the blood and bone (tibia and femur) of pigs at both growth stages. The radiocesium retention levels were generally higher in juvenile pigs than in adult pigs, with the highest transfer coefficient ratio in the kidneys (16.2%).

Determination of the (137)Cs and (90)Sr radioisotope activity concentrations found in digestive organs of sheep fed with different feeds

In this study, 12 weanling lambs were fed for 6 months at the Vetenary Control and Research Institute of Elazığ in Turkey. Sheep were divided into two groups according to feeding type. Each group of sheep was fed a different amount of feed. The activity concentrations of (137)Cs and (90)Sr were determined in rumen, small intestine and large intestine tissue samples of sheep fed various feeds and quantities. Transfer coefficients and concentration ratios were estimated. The highest average (137)Cs and (90)Sr activity concentrations were 82 ± 22 Bq kg(-1) fw in the straw group small intestine sample and 74 ± 9.0 Bq kg(-1) fw in the fresh lucerne group rumen sample, respectively. Radioactivity levels for (137)Cs and (90)Sr are under the maximum permitted radioactive pollution level for all the samples. The transfer coefficient of (137)Cs and (90)Sr in the samples of sheep ranged from 1.0 × 10(-1) to 2.1 × 10(0) d kg(-1) and 1.7 × 10(-1) to 2.3 × 10(0) d kg(-1), respectively. Calculated transfer coefficients of (90)Sr and (137)Cs in the samples of sheep were higher than the expected values. Geometric means of Ff and CR for (137)Cs were maximum in the fresh lucerne group large intestine sample. Geometric means of Ff and CR for (90)Sr were maximum in the fresh lucerne group small intestine sample.

The transfer of radionuclides from saltmarsh vegetation to sheep tissues and milk

Radionuclides released into the Irish Sea by the Sellafield reprocessing plant are deposited onto tide-washed pastures along the western coast of the United Kingdom. Many of these pastures are grazed by sheep or cattle. This paper describes a controlled feeding study, in which saltmarsh vegetation harvested from close to the Sellafield plant, was fed to lambs and adult female sheep for a period of 8 weeks. Activity concentrations of (60)Co, (95)Nb, (106)Ru, (134)Cs, (137)Cs, (238)Pu, (239,240)Pu and (241)Am were determined in edible tissues and transfer parameters estimated. The activity concentrations of some of the radionuclides will not have been in equilibrium with those in the diet. Nevertheless, the study was reasonably realistic in terms of agricultural management as the period of the study was similar to that for which lambs graze on the saltmarshes. A field study to determine the activity concentrations of (137)Cs and (239,240)Pu in the milk of ewes grazing a saltmarsh close to Sellafield is also described.

Transfer coefficient measurements of uranium to the organs of Wistar rats, as a function of the uranium content in the food

Groups of animals (Wistar rats) were fed with rations doped with uranyl nitrate at concentrations ranging from 0.5 to 100 ppm. The uranium content in the ashes of the organs was measured by the neutron-fission track counting technique. The most striking result is that the transfer coefficients, as a function of the uranium concentration, exhibit a concave shape with a minimum around 20 ppm-U for all organs. Explanations to interpret this finding are tentatively given.

A new statistical method for transfer coefficient calculations in the framework of the general multiple-compartment model of transport for radionuclides in biological systems

A new and simple statistical procedure (STATFLUX) for the calculation of transfer coefficients of radionuclide transport to animals and plants is proposed. The method is based on the general multiple-compartment model, which uses a system of linear equations involving geometrical volume considerations. By using experimentally available curves of radionuclide concentrations versus time, for each animal compartment (organs), flow parameters were estimated by employing a least-squares procedure, whose consistency is tested. Some numerical results are presented in order to compare the STATFLUX transfer coefficients with those from other works and experimental data.

Development and testing of a revised dynamic model of radiocaesium transfer to sheep tissues

The model of radiocaesium transfer to sheep presented by Galer et al. provides reliable predictions only for sheep of a similar body weight to those used in the development of the model (approximately 30 kg). To extend the applicability of the model, it was necessary to re-parameterise it in terms of activity concentrations in tissues rather than total activities within them (although for gut compartments the use of activity has been retained). The rate coefficients for the new model have been estimated by fitting the model to the data used by Galer et al. which was derived from a single "calibration" experiment. The new model was found to account for 94% of the observed variation in the data (n = 42), a result similar to that obtained by Galer et al. The model has also been tested against data not used in its development but obtained from four separate experiments undertaken by three different laboratories. Good agreement between the predictions of the new model and observations was found for most circumstances and for several breeds of sheep with different body weights. It is concluded that the new model provides a useful dynamic description of radiocaesium transfers to the tissues of sheep of different breeds and under different contamination scenarios.