The relation of sex, age, and weight of mice to microwave radiation sensitivity.

It is of interest to determine whether the weanling mouse, the sexually mature mouse, or the aged mouse of both sexes are similarly sensitive to microwave radiation. This study included 114 male and female mice irradiated to death with 2450 MHZ microwave radiation at 7.5 watts forward power, a minimum of 14 mice being used for any single set of variables. Weanling mice of 1 month of age are fully developed with respect to most organ systems except the reproductive. Two month old mice are sexually and otherwise mature, fully capable of survival and reproduction. The age mice of both sexes were ex-breeders which had been used for constant litter production for at least 12 months, and had waning reproductive potential. They were therefore about 14 months of age. It was found that the male mice on the average weighed more than the females (least difference at weaning) and both showed considerable weight increase with age; that weanling males irradiated to death absorbed slightly more radiant energy than did the weanling females, but they were also slightly heavier; that time to death under constant exposure from the beam increased with age for both sexes, indicating increasing microwave resistance with age and/or weight; that the mean absorbed dose at death did not show significant differences related to age or weight within the same sex; that the males showed slight increase in radio-tolerance with age and/or weight as measured by the absorbed dose at death when compared with the females which showed a decline in radio-tolerance with age and/or weight; that in all cases sex seemed to be somewhat more important than did age or weight in determining the lethal absorbed dose at death; and that it took longer longer for the older mice to die due probably to the fact that the rate of absorption of radiation was slower with their increased weight. It is the absorbed dose in joules per gram that is biologically significant and the data shows that the mean absorbed dose to death within either sex shows no significant difference with respect to age or weight, but that the difference between the sexes are significant, particularly among the aged ex-breeders.