High sensitivity of chromatin conformational state of human leukocytes to low-dose X-rays.

Changes in the chromatin conformational state (CCS) of human leukocytes were detected by the anomalous viscosity time dependence (AVTD) method. The dose dependence was studied for seven donors with doses of up to 10 cGy. X-rays caused no statistically significant changes in the leukocytes of two of the donors. The dose dependences registered on leukocytes of the other donors showed some distinctions which may be due to individual traits of the donors. Extrapolation of all the results produced a nonlinear dose dependence which consisted of two sections. The first one was characterized by a fast growth of the effect, the second section was extrapolated to a slightly sloping linear dependence which was close to a plateau. It was shown that the AVTD method was highly sensitive to X-rays and can register changes in the CCS of leukocytes exposed to doses of about 0.5 cGy. The possible role of DNA breaks and processes of ionization and excitation are analyzed.