The Radiosensitizing Actions of Ketonic Agents and Oxygen in Bacterial Spores Suspended in Aqueous and Non‐Aqueous Milieux

Increasing concentrations of the ketonic agents, diacetyl, acetone, acetophenone and p‐nitroacetophenone, cause regular increases in the radiosensitivity of aqueous anoxic spores to an extent that is some 40% of that achieved by O2 alone; no effect on radiosensitivity is observed with agents in the presence of O2. The effectiveness of these agents and O2 as radiosensitizers ranks on a molar basis in the same order as that of their electron affinities, indicating that their modes of action are in some way associated with radiation‐induced electrons. A lack of radiosensitizing action of diacetyl and p‐nitroacetophenone in dried spores and of p‐nitroacetophenone in suspensions of spores in non‐aqueous liquids supports the notion that the origin of their actions is within the water inside the cell.