Radioactivity in the Service of Humanity

Abstract

The ready availability of inexpensive radioisotopes from the Oak Ridge reactor at the end of World War II led to the burgeoning application of these materials in biomedical investigation and the development of a new medical specialty, Nuclear Medicine. Much of this specialty is concerned with imaging, that is, administering a radioactive material to a patient and tracing its behavior in the body. Another important application is radioimmunoassay (RIA) an in vitro test that has become a major tool in thousands of laboratories around the world to measure concentrations in body fluids of hundreds, if not thousands, of substances of biologic interest. The concentmtion of an unknown substance is determined by comparing its inhibition of binding of a radioactively labeled tracer to specific antibody with the inhibitions observed with known standards. Whether these uses of radioisotopes will remain viable in the face of the pervasive fear of radiation exposure at any level is a cause for concern. The general public is not aware of the large number of investigations that are consistent with an absence of detectable adverse consequences to human health when the integrated exposure to ionizing radiation is low and/or when it is delivered at a low dose rate. Although it is impossible to design a study to determine unequivocally whether there is or is not a threshold for radiation iniury, it is necessary to establish the concept of ade minimis, an amount of radioactivity or radiation exposure so low as to present no cause for concern.