Radiation chemistry. II. Elementary processes in the radiation chemistry of water and implications for radiobiology.

Abstract

Understanding of elementary processes of radiobiology is confused by complexity both of phenomena and of systems involved. Even the simplest biological material is a complicated aqueous system containing various inorganic solutes, including air, and a variety of organic substances which may be combined to give a single macromolecule or a mixture of such molecules. Water both surrounds and pervades such organic material and only in relatively simple cases are the building blocks known. Nevertheless, a sufficiently simple model may make possible the application of our knowledge of the radiation chemistry of water in interpretation of some radiobiological processes. For the purpose of this limited survey we consider a single biological entity of macromolecular dimensions suspended in and aqueous system. At first, we shall treat the biological entity as if its only contact with water is at its surface, but this restriction will be removed later and we shall make no other limitations on its structure or its composition. However, the effects of variations in composition will be considered. For interpretation of the effects of high-energy radiation on such a system we consult our knowledge of the radiation chemistry of water and aqueous systems and examine how this chemistry is affected by the presence of an essentially organic entity.