wed induced activity. Although these materials emit only radiations with which we are already familiar -+ gamma rays and beta particles -- it appears at first glance to be almost an impossible task to consider them individually and in the aggregate for an appraisal of their health hazard. Fortunately, for an analysis, most of the radio- nuclides have short radioactive half-lives and soon decay away or have other characteristics such as being highly insoluble so that pei jrea they are of little health consequence. In fact, it is possible te-esti- mate the radiation doses to various organs of the body by considering only five principal radionuclides in fallout that are deposited internally, i.e., iodine-131, strontium-90, strontium-89, cesium-137 and unc carbon-14. To these doses are added those to the whole body due to the radiations from fallout material outside the body. The problem of estimating these latter radiation doses is again similified by conthen sidering fits cesium-137 and/lumping all of the remainder radionuclides together. (O