Genetical Instability induced by Low Doses of Radations

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We have reported that chronic radiations with low doses of X-rays affected to several biological responses in human cells. For example, repeated-irradiation with 1 cGy per week of gamma-rays was significantly prolonged over that of control. Although non-irradiated control and acute irradiated cells at passage 26 (about 10 passages to senescence) were normal karyotype and number, chronic-irradiated cells at the same passage showed numerical, rather than structural, abnormalities. We also found that chromoshone aberration frequency of a cell irradiated with low doses of X-rays is high around 50 times of the unirradiated cells at 14 days after irradiation.These results can best be interpreted by assuming that ionizing radiation at low doses induces a stress response, probably an epigenetic one, which is responsible for the majority of the genetic instability. We speculate that non genetic materials, such as cell membrene and cell division apparatus may be important target of low dose radiations.