High dose-rate dependence of early skin reaction in mouse.

Early skin reactions in the legs of mice were studied as a function of average and instantaneous dose rate. A dose-rate dependence of the reaction score was found at instantaneous dose rates higher than 10(7) rad/min, regardless of the average dose rate. The skin reaction was greatest at an instantaneous dose rate of around 10(8) rad/min. The 95 per cent significance of the instantaneous dose-rate dependence was confirmed by the Mann-Whitney rank-order test (U-test).