Persistent leucocyte abnormalities in children years after previous long-term low-dose radiation exposure

Two hundred and eighty-nine children who had been educated in a kindergarten during 1983-92 and received continuous low-dose whole body gamma-irradiation from ⁶⁰Co-contaminated steel window frames in their classrooms were investigated for residual effects on their haematological tissues. Another 751 children, sex and age-matched, received similar but much lower exposure in an elementary school with classrooms built with contaminated steel rebars. The peripheral leucocytes of these children were examined 5-7 years after they had stopped using these irradiated classrooms. Children who received higher exposure in the kindergarten were shown to have a significant decrease in total leucocytes and neutrophils and an increase in eosinophils. Moreover, they were shown to be at significantly higher risk of developing relative leucopenia and neutropenia, but not lymphocytopenia, than those who received a lower exposure at the elementary school. Children from the kindergarten who had much higher exposure were shown to have a significant lowering of total leucocytes and neutrophils, and an increase in eosinophils years after exposure. Residual adverse haematological effects on the exposed children are strongly suspected.