Revisiting the Historic Strontium-90 Ingestion Beagle Study Conducted at the University of California Davis: Opportunity in Archival Materials.

Strontium-90 is a radionuclide found in high concentrations in nuclear reactor waste and nuclear fallout from reactor accidents and atomic bomb explosions. In the 1950s, little was known regarding the health consequences of strontium-90 internalization. To assess the health effects of strontium-90 ingestion in infancy through adolescence, the Atomic Energy Commission and Department of Energy funded large-scale beagle studies at the University of California Davis. Conducted from 1956 to 1989, the strontium-90 ingestion study followed roughly 460 beagles throughout their lifespans after they were exposed to strontium-90 in utero (through feeding of the mother) and fed strontium-90 feed at varying doses from weaning to age 540 days. The extensive medical data and formalin-fixed paraffin-embedded tissues were transferred from UC Davis to the National Radiobiology Archive in 1992 and subsequently to the Northwestern University Radiobiology Archive in 2010. Here, we summarize the design of the strontium-90 ingestion study and give an overview of its most frequent recorded findings. As shown before, radiation-associated neoplasias (osteosarcoma, myeloproliferative syndrome and select squamous cell carcinomas) were almost exclusively observed in the highest dose groups, while the incidence of neoplasias most frequent in controls decreased as dose increased. The occurrence of congestive heart failure in each dose group, not previously assessed by UC Davis researchers, showed a non-significant increase between the controls and lower dose groups that may have been significant had sample sizes been larger. Detailed secondary analyses of these data and samples may uncover health endpoints that were not evaluated by the team that conducted the study.