Radiation Sensitivity of Escherichia coli to β-Rays in Dry and Wet Condition

Abstract

THE greater sensitivity of biological material to irradiation in the wet condition is due to the formation of radicals in the water surrounding the vital molecule. However, all the volume is not effective, since these radicals have a definite life-time and can diffuse only to a distance allowed by that time. This diffusion distance has variously been estimated from different types of inactivation studies in the wet and in the dry state of the molecules. Recently, the dependence of this distance on the shape of the molecule has been reported, and it has been shown that as the asymmetry of the target increases, the diffusion distance decreases¹. In the present report this idea has been applied to the calculation of diffusion distance for the inhibition of colony-formation by E. coli exposed to β-rays from strontium-90.