Biokinetics of 90Sr after chronic ingestion in a juvenile and adult mouse model
The aim of our study was to define the biokinetics of 90Sr after chronic contamination by ingestion using a juvenile and adult murine model. Animals ingested 90Sr by drinking water containing 20 kBq l−1 of 90Sr. For the juvenile model, parents received 90Sr before mating and their offspring were killed between birth and 20 weeks of ingestion. For the adult model, 90Sr ingestion started at 9 weeks of age and they were killed after different ingestion periods up to 20 weeks. The body weight, food and water consumption of the animals were monitored on a weekly basis. Before killing and sampling of organs, animals were put in metabolic cages. 90Sr in organs and excreta was determined by liquid scintillation β counting. Highest 90Sr contents were found in bones and were generally higher in females than in males, and 90Sr retention varied according to the skeletal sites. An accumulation of 90Sr in the bones was observed over time for both models, with a plateau level at adult age for the juvenile model. The highest rate of 90Sr accumulation in bones was observed in early life of offspring, i.e. before the age of 6 weeks. With the exception of the digestive tract, 90Sr was below the detection limit in all other organs sampled. Overall, our results confirm that 90Sr mainly accumulates in bones. Furthermore, our results indicate that there are gender- and age-dependent differences in the distribution of 90Sr after low-dose chronic ingestion in the mouse model. These results provide the basis for future studies on possible non-cancerous effects during chronic, long-term exposure to 90Sr through ingestion in a mouse model, especially on the immune and hematopoietic systems.