Cytogenetic Effects of Low-Dose Tritiated Water in Human Peripheral Blood Lymphocytes—Experimental Studies on the Relative Biological Effectiveness and Chromosome Aberration Rate and CBMN in Human Blood Lymphocyte Irradiated by Tritium Low Dose Tritium iβ/i-Rays and sup60/supCo iγ/i-Rays

摘要

In this study, the yields of unstable chromosome aberrations in human lymphocytes induced by β particles from low-dose HTO have been measured. HTO was mixed with heparinized blood in varying amounts so that a dose of 6.24 × 10-4 Gy to 1.23 Gy were delivered in 24 and 48 h, respectively. After 72-h culture, the dicentric yield was measured as a function of dose to the blood and compared with data from 60Co γ-radiation. Using a linear-quadratic dose-effect relation to fit the experimental data, a significant linear contribution Y = 0.062D + 0.053D2 was found. The main difference between the coefficients for β and γ-radiation was in the a values, indicating that HTO β-rays were more efficient, particularly at low doses. As per the theory of dual radiation, the relative biological effectiveness (RBE) of HTO β-particles relative to γ-rays is 2.21 at 0.06 Gy and decreases with increasing dose. Micronucleus yield at low doses was fitted to a linear equation Y = C + αD, indicating that the RBE value of MN for HTO β-rays irradiation was between 1.46 and 2.17, which is similar in shape to the chromosome aberrations experiments. Thus, β-rays were found to be more efficient in producing two lesions with single ionizing tracks at low dose.