Spontaneous micronucleus frequencies in human peripheral Mood lymphocytes as a screening test for an individual variation in a different population and radiation-induced micronucleus induction

Abstract

Our studies were to evaluate the role of epigenetic factors in the variation of radios ens itivity on human peripheral blood lymphocytes by measuring the frequencies of micronucleus (MN) from 293 healthy subjects of different population for assessing the radiation health risk in Korea. We analyzed the frequencies of both spontaneous and in vitro 60Co y-rays or 50MeV neutron-induced MNs. The frequencies of spontaneous MNs not only vary greatly between individuals, but also working or living areas. The increased levels of cells with spontaneous MNs were observed with an increasing age. The frequencies of spontaneous MNs were significantly higher in females than in males. For both sexes, MN frequency was significantly and positively correlated with age. Age and gender are the most important demographic variables impacting on the MN index. Donors who had ever smoked showed significantly increased frequencies of MNs compared to nonsmokers. The main lifestyle factors influencing the MN index in the subjects are correlated significantly and positively with smoke while measuring the spontaneous frequencies of micronuclei. Therefore, it is evident that with regard to the application of MN assay all future studies to evaluate the association between radiosensitivity and susceptibility for radiation health risks in different populations should take into account the effect of age, gender and lifestyle. For the dose-response study, the induced MNs were observed at all doses, and the numerical changes according to doses. The dose-response curves were fitted with a linear-quadratic forms of the dose, and the results were different for y-rays and neutrons significantly. Neutrons were more effective than y-rays in producing MN with a dose-dependent manner. The frequency of MN varies with dose. The RBE for a micronuclei was 2.37±0.17. The results suggested that the MN assay have a high potential to ensure appropriate quality control and a standard documentation protocol, which can be used to monitor a large population exposed to radiation epidemiologically. We conclude that the determination of individual radiosensitivity with the MN assay is reliable, rapid, sensitive and accurate when used to monitor a large population exposed to radiation.