Abstract: Purpose:To explore the changes of chromosome number and chromosome non-disjunction in human lymphocytes treated with low dose ionizing radiation. Methods: The changes of chromosome number were measured by metaphase chromosome counts, and statistic an analysed with χ 2 test. Results: After treated whole blood with 0, 0.1, 0.25, 0.5, 1.0, 2.0 Gy γ-rays, aneuploidy rate increased from 21.30 ％ to 55.56 ％ as dose increased, so did hyperdiploid / aneuploid, which increased from 8.70 ％ to 44.00 ％. After treated with 0.5 Gy at different time, the two targets were significantly higher than control(P<0.01), and the degree of increasing of the culture radiated was higher than that of the whole blood radiated. When the culture was radiated,the two targets had no difference in different radiation time. When the whole blood was radiatied, the two targets had the tendency to increase as the radiation times increased. Conclusion: The effect of low dose γ-rays on aneuploid, especially chromosome non-disjunction is dose-dependent and time-dependent. And the effect is outstanding when the culture radiated than when the whole blood was radiated.

Key words: low dose ionizing radiation, human lymphocyte, aneuploidy, chromosome non-disjunction