-irradiation has remote consequences for mammalian cells cultivated invitro. Many generations in the progeny of cells surviving acute and chronic irradiation at high and low doses are char-
acterized by a number of abnormalities, including delayed cell death, the formation of micronuclei and giant
cells, an increased frequency of sister chromatid exchanges, a reduced potential for repair, the loss of adaptive
response, and increased radiosensitivity. These phenomena are regarded as manifestations of genomic instabil-
ity induced by ionizing radiation.