This publication provides valuable information to those interested in food irradiation especially scientists in regulatory authorities for food safety and radiation applications as well as consumers who may be interested in the scientific aspects of this subject. Clear explanations are given not only of why radioactivity cannot be induced in food irradiated by the radiation sources considered but also the extent to which the increase in dose or energy level of radiation sources would induce significant radioactivity in food. The compilation of such data was prompted by a desire to increase the energy limit and the absorbed dose based on the need to irradiate thicker samples of food and on the use of sterilizing doses up to 60 kGy.