The 'oxygen-effect' in ionizing irradiation

Abstract

IT is a well-established fact that ionizing irradiation damages a variety of cells to a greater extent if the irradiation takes place in presence of oxygen than under anaerobic conditions. The mechanism of this 'oxygen-effect' is not yet fully understood. It is generally believed1-4 to be due to the deleterious effect on cells by the strongly oxidizing radical HO2 and, to some extent, by hydrogen peroxide, which are formed on X-ray irradiation in aqueous media containing oxygen, as compared with the less powerful OH radical which, in addition to reducing hydrogen atoms, is formed on irradiation in nitrogen. The exception, so far, is a bacteriophage, for which evidence has been adduced5,6 that it has a far greater sensitivity to reducing than to oxidizing radicals. © 1954 Nature Publishing Group.