Electron-beam sterilization of laboratory animal diets--sterilizing effect of 10-MeV electrons from a linear accelerator.

Abstract

Electron beam sterilization for laboratory animal diets was examined as an alternative to 60Co gamma rays. Solid, powder diets for "mice and rats" and solid diets for "rabbits and guinea pigs" which are the main products sterilized by 60Co gamma rays were irradiated with 10-MeV electrons from a linear accelerator at the Research Institute for Advanced Science and Technology, Osaka Prefecture University. At least 20 kGy was required to sterilize the samples irrespective of solid or powder diets, which was in good accordance with the results for 60Co gamma rays. Using a set dose of 30 kGy, a thickness of 45 mm for solid diets and 30 mm for powder diets could be sterilized by "one-sided" irradiation. "Dual-sided" irradiation could sterilize all the solid diets and the powder diets contained in the thicknesses of 90 mm and 75 mm, respectively. Irradiation effects of 10-MeV electrons on the nutrient quality of each diet were almost equivalent to those of 60Co gamma rays. These results suggest that commercially adopted sterilization doses for 60Co gamma rays are applicable to electron sterilization without modification if the depth-dose profile and the minimum dose of irradiated samples are precisely assessed.