Transfer of Chernobyl fallout radionuclides from feed to growing rabbits: cesium-137 balance

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Intake, excretion and retention of gamma-emitting radionuclides were assessed in male rabbits fed a radioactive pelleted diet ( 137Cs = 858 Bq kg −1 as fed) containing 40% dehydrated alfalfa meal contaminated by Chernobyl fallout. In order to evaluate radionuclide retention, an experiment was carried out on 33 animals as follows: nine rabbits were slaughtered at the beginning of the trial, six were fed a radioactive diet for 42 days, six a radioactive diet for 21 days, six a radioactive diet for 21 days and a normal diet ( 137Cs = 112 Bq kg −1 as fed) for the following 21 days and six a normal diet for 42 days. All the animals were housed in individual metabolism cages throughout the trial. All faeces and urine were collected and analyzed separately and live weight and feed intake were measured on a weekly basis. At the end of the trial all the animals were slaughtered and the activities of net body and muscles were determined. Cesium-137, 134Cs, 103Ru, 106Ru, 125Sb, 110m Ag, and 40K were measured by gamma spectroscopy. More than 85% of ingested cesium was excreted through faeces and urine (fecal ⪢ urinary) and the retained 137Cs in the carcass of the more contaminated animals was only 3% of the total ingested. The concentration of total cesium in muscle reached a maximum value of 156 Bq kg −1, much lower than the EEC guideline (600 Bq kg −1), and the biological half-life for 137Cs was calculated to be 11 days. The feed-body accumulation factors were determined in net body and muscle.