Dynamics of blood cell composition in residents of the techa riverside villages

The present paper focused on the analysis of data resulting from 50-year studies involving assessment of the hemopoiesis state in 2,739 Techa riverside residents chronically exposed to radiation in the range from low to intermediate doses. The highest bone marrow doses (mean value: 0.66 Sv) were due to intake of 90Sr in drinking water and local food products, and to external γ-exposure. The status of peripheral blood and bone marrow has been monitored since 1951. Peripheral blood cell counts performed for exposed riverside residents during the period of maximum radiation exposures (1951-1953) displayed a significant (p<0.0001) decrease in the proportion of leukocytes (neutrophils and lymphocytes) and thrombocytes. Peripheral blood erythrocyte count was maintained at the normal level, owing to the efficacy of compensatory processes in the bone marrow, including increased rates of erythrocaryocyte proliferation and maturation. The development of peripheral blood granulocytopenia resulted from delay in the differentiation of neutrophilic bone marrow granulocytes, a marked increase in the frequency of lethal abnormalities in bone marrow neutrophils, pathological mitoses, and activation of apoptosis. The time necessary for the blood cell composition to return to normal varied significantly in different blood cell series, depending on exposure dose-rate, extent of the initial hemopoiesis inhibition and individual physiological characteristics of exposed individuals. Thus, under a combined chronic exposure at equivalent doses to red bone marrow reaching 1.79 Sv, a stable reduction of neutrophil, thrombocyte and lymphocyte counts was observed. Neutrophilic granulocyte series were noted to require the longest time (12-17 years) to recover. (author)