Seasonal oscillations of the radiosensitivity of cells in culture

A comparison has been made of 112 sets of experimental data recorded over a six year period showing the survival of 60Co γ-irradiated Chinese hamster cells in culture. The survival of the cells irradiated with the same dose (1400 rad) changed periodically throughout each year. The cells were most radiosensitive in the spring, and most resistant in the autumn. Values of the cell radiosensitivity (D0) determined from survival curves showed similar seasonal changes over 3 years, although the variability of the D0 values for the same period of each year was smaller than that of the corresponding survival values. (U.K.)