The knowledge of the absorbed radiation dose is essential in order to interpret theresults of animal experiments with chronic ingestion of radionuclides by rodents. In orderto evaluate this absorbed dose, we applied the dose conversion factors proposed by ICRPpublication 108 to mouse chronic ingestion experiments with 20 kBq.L-1 137Cs-or 90Sr-contaminated water. The results indicated that whole-body absorbeddoses were 9 mGy and 10 mGy by the end of 20 weeks of 137Cs or 90Sringestion, respectively. These results of dose calculations were compared with resultsobtained with a more refined method using published organ-specific absorbed fractions ofenergy. There was good agreement between the two methods, indicating that, despite thesimple hypotheses used to apply the ICRP 108 dose conversion factors to our mouse model,this method allows one to calculate in a simple and reliable way the absorbed radiationdose received by the rodents during long-term experiments on chronic ingestion ofradionuclides.

For a few years, the biological effects on ecosystems and the public of the bioaccumulation of radionuclides in situations of chronic exposures have been studied. This work, in keeping with the ENVIRHOM French research program, presents the uranium microdistribution by secondary ion mass spectrometry (SIMS) technique in the renal cortex of rats following chronic exposure to this low level element in the drinking water (40 mg/L) as a function to exposure duration (6, 9, 12, and 18 months). The SIMS mass spectra and 238U+ ion images produced with a SIMS CAMECA 4F-E7 show the kinetic of uranium accumulation in the different structures of the kidney. For the rats contaminated up to 12 months, the radioelement is mainly fixed in the proximal tubules; then after 18 exposure months, uranium is detected in all the segments of the nephron. This work has also shown that ion microscopy is an analytical method to detect trace elements and give elemental cartography at the micrometer scale.