In the late 1960s, a number of congressional committee hearings were held on the problem of medical radiation exposure in this country. In these hearings, considerable testimony was delivered by selected radiation experts concerning excessive use of medical radiation under conditions which created unwarranted hazards to patient and operator. These hazards were documented by data such as that presented in the 1964 X-Ray Exposure Study conducted by the United States Public Health Service (USPHS). In the 1964 USPHS study, the genetically significant dose (GSD) was computed as 55 mrems for medical radiation exposure in this country, as compared to a medical GSD on the order of 20 mrems for other countries of similar technical sophistication. This difference. in IGSDs was represented as illustrative of unwarranted exposure of U.S. residents to medical radiation, and contributed significantly to establishment by Congress of Public Law 90-602: The Radiation Control for Health and Safety Act of 1968.