Variation of Acute Mortality with Dose-rate in Mice Exposed to Single Large Doses of Whole-body X-radiation

Summary

(1) As the duration of a continuous exposure to radiation was increased from 1 min to 8 hours, and the dose-rate of the radiation exposure correspondingly reduced, there was a progressive increase in the value of the median lethal dose for deaths within 30 days.

(2) There was a small qualitative difference attributable to dose-rate in deaths occurring up to 30 days after irradiation. In the animals given the longest exposures there were fewer deaths before 10 days than in the other groups.

(3) Deaths with a severe gastrointestinal syndrome occurring between 30 and 200 days after irradiation were much more frequent in mice irradiated at 68 rads/min than in mice irradiated at lower dose-rates.