Cytogenetic Effects of Strontium-90 on the Bone Marrow of the Chinese Hamster

Abstract

NUMEROUS studies have been made with the ultimate goal of establishing dose effect models that will enable quantitative assessments of the damage inflicted by various types of radiation exposures. In most, the animals were exposed to whole body gamma or X-irradiation delivered at high dose rates. The number of chromosome aberrations changes as a function of total radiation dose, radiation dose rate and time after exposure^1–3, so it is not clear how these criteria apply in interpreting aberrations produced by internally deposited radionuclides which give low, continuous and non-uniform radiation dose rate exposures. Several workers have used in vivo or in vitro exposure to internal emitters and in vitro cell sampling to determine radiation damage^4–7. These are relatively indirect, so we have tried to evaluate the influence of an internally deposited radionuclide on the frequency of chromosome aberrations produced and sampled in vivo. We selected ⁹⁰Sr (in equilibrium with its daughter ⁹⁰Y) because it exists in abundance in a number of nuclear processes, and localizes selectively in osseous tissues, resulting in beta irradiation of both bone and bone marrow. Aberrations in bone marrow cells are readily studied in vivo and may also be significant in the development of haematopoietic tissue neoplasms. We took two time periods, 2 and 14 days after injection, because differences in the aberration frequency which may be observed as a function of the total radiation dose and dose rate change with time.