Influence of a chronic 90Sr contamination by ingestion on the hematopoietic, immune and bone systems

• Main Author: Synhaeve, Nicholas
• Language: ENG
• Published: Université Paris Sud - Paris XI 2011
• Subjects: [SDV:SA] Life Sciences/Agricultural sciences; [SDV:MHEP] Life Sciences/Human health and pathology; Strontium 90; Chronic ingestion; Biokinetics; Low dose; Bone physiology; Hematopoietic system; Immune system
• Online Access: http://tel.archives-ouvertes.fr/tel-00656935; http://tel.archives-ouvertes.fr/docs/00/65/69/35/PDF/VA_SYNHAEVE_NICHOLAS_15122011.pdf

Strontium 90 (90Sr) is a radionuclide of anthropogenic origin released in large quantities in the environment as a result of nuclear atmospheric tests or accidents at nuclear facilities. 90Sr persists on a long-term basis in the environment, leading to chronic contamination by ingestion of populations living on contaminated territories. The induction of bone tumours associated with the fixation of 90Sr has been widely described. However, the occurrence of non-cancer effects is much less known. We used a mouse model with chronic contamination by ingestion of water containing 20 kBq/l of 90Sr. A biokinetic study confirmed the accumulation of 90Sr in the bones, with an increased rate of accumulation during bone growth. This accumulation was higher in the bones of females than in males. The whole-body absorbed doses ranged from 0.33 ± 0.06 mGy (birth) to 10.6 ± 0.1 mGy (20 weeks). The absorbed dose for the skeleton was up to 55 mGy. Ingestion of 90Sr induced a change in the expression of genes inducing an imbalance in favour of bone resorption, but without effect on bone morphology. No significant effect was observed for the hematopoietic system. On the other hand, minor modifications were observed for the immune system. To evaluate the functionality of the immune system, a vaccination test with TT and KLH antigens was used. Results showed in contaminated animals a significant decrease in the production of specific immunoglobulins, changes in the Th1/Th2 balance in the spleen and a disrupted B lymphocyte differentiation. These results improve the understanding of some of the non-cancerous consequences of chronic exposure at low dose of radionuclides with a long half-life, which can be accidentally released.