we should like to tell you something of the relatively brief history of this fascinating subject as well as the present-day status and problems in the field, particularly as they apply to the various aspects of public health and environmental sanitation. About sixty years ago, Roentgen 13 discovered x-rays and Becquerel 1 discovered radioactivity. Within the next decade pioneer investigators in fundamental and applied bacteriology had begun to experiment with this new form of energy and soon observed its bactericidal properties. However, it was not until World War II, or shortly thereafter, that reserch was initiated in earnest in an attempt to ascertain whether practical utilization could be made of the bactericidal, fungicidal, and chemical properties of these radiations. During World War II developments in the field of particle accelerators made available, for the first time, large quantities of ionizing radiations and reopened research in the general area of food and drug sterilization. Special emphasis