Variation in individual sensitivity to ionizing radiation

Observations at Hammersmith Hospital that not all radiation-sensitive radiotherapy patients show increased cellular sensitivity in laboratory tests are in accord with findings of Weichselbaum et al. (1976). Two of three clinically sensitive patients they studied had fibroblast D0 values of 101 and 108 rads, below their subsequently established normal range but interpreted then as within normal limits. Such tests are slow, laborious and expensive, and there is need for easy and rapid tests of cellular sensitivity so that individuals who may be exposed to radiation can be screened in advance of exposure. Rapid tests using lymphocytes, the radiosensitivity of which in colony-forming experiments is comparable with that of fibroblasts, have been developed by Harris et al. in the investigation of rheumatic disease. A range of findings has been shown in population studies on the elderly, but no correlations with fibroblast D0 values have been made and these tests have yet to be validated. (U.K.)