A Physico-chemical Method of Testing the Protective Action of Chemical Compounds against the Lethal Effects of Ionizing Radiations

Abstract

The decrease in viscosity of .025% solns. of polymethacrylic acid (P. M. A.) produced by 1000 r of X-rays was studied. In decreasing order of effectiveness the following compounds protected P.M.A. against degradation: KCN, thiourea, NaN3, sodium thiosulphate, methanol, glucose, and methyl amine. The protective action of a number of amines paralleled, in order of effectiveness, their protective action in vivo. No degradation of P.M.A. was obtained in air free solns. or by the action of 10-3[image] H2O2 alone. The effects of radiation are ascribed, therefore, to HO2 radicals, and the protective action of the compounds is ascribed to competition for HO2. The effect of OH radicals was studied by following the X-ray induced polymerization of methacrylic acid. No parallelism was observed between the action of the 12 compounds tested in protecting the polymer against degradation and in inhibiting polymerization.