Exposure duration: 7 days
Cell growth rate was significantly reduced after 7 or 15 subculture passages under exposition. Chromosome aberrations emerged after the cells had been microwave-irradiated for about 20 passages. The long-term exposition caused 0.84 chromosome breaks per cell in RH5 cells and 0.10 breaks per cell in RH16 cells. The number of chromosome breaks was greatly reduced in both cell cultures after the cells had been returned to the conventional incubator and maintained for 30 passages. The number of polyploid cells was increased during the irradiation, and was significantly reduced in the conventional incubator. Many RH5 cells lost one chromosome and became 10-chromosome cells (the number of 10-chromosome cells increased during irradiation and continued to increase after being returned to the conventional incubator).