Estimation of radiation doses on lymphocytes and their progenitors after ingestion of strontium-89,90

Abstract

In radiobiology circulating T-lymphocytes are used as “natural biodosimeters” since the frequency of chromosomal aberrations that occur in them after radiation exposure is proportional to the accumulated dose. In addition, stable chromosomal aberrations (translocations) are detected in them years and decades after radiation exposure. Estimation of doses to circulating lymphocytes requires consideration of two dose components: the dose accumulated by the lymphocyte precursors (progenitors) in the red bone marrow; and dose accumulated by the lymphocytes in the lymphoid organs/tissues during circulation. A recently created model of T-lymphocyte exposure takes into account all these dose components, as well as the age-dependent dynamics of T-lymphocytes. The use of a model approach is especially important in assessing doses from osteotropic beta emitters (89,90Sr). They accumulate in the bone and locally expose predominately bone marrow. The dose to other lymphoid organs and tissues is much lower. The objective of this study is to evaluate the conversion factors from ingested 89,90Sr to the cumulative dose to circulating T-lymphocytes and their progenitors (DCL). For calculations, the previously developed model of T-lymphocyte exposure and new dose coefficients for the red bone marrow, estimated on the basis of a sex-and-age-dependent biokinetic model and a new dosimetric model of the human skeleton were used. As a result, the DCL values were evaluated for the first time. The age at the time of 89,90Sr intake varied from a newborn to 35 years, the age of T-lymphocyte examination (blood sampling age) was up to 75 years. The maximum values of DCL for both 90Sr and 89Sr were typical of children in the first years of life. It has been shown that doses to circulating T-lymphocytes from these radionuclides are lower than those to bone marrow, but are significantly higher than doses to other lymphoid tissues. The effect of sex on DCL is manifested for children 10 years of age and older. The area of DCL application covers the population of radioactively contaminated territories (the Urals region, the zone of the Chernobyl accident), as well as personnel of the nuclear industry enterprises.