radiations, and in some cases to provide information on the energy spectrum and directionality of incoming radiations. Use of this equipment would allow reasonably good description of the integrated doses received from the plume, and possibly knowledge of the time history of how the doses were received as well. In addition, im-sitz measurements of ground,air, and water contamination may provide input to various published results or computer models which predict doses to the skin and internal organs of the body from such sources external to the body. 6.1.2 Skin Dosimetry Uncertainties in the radionuclide mixtures, matrix densities, and exact distribution on the skin limit the precision of the estimates of the expected radiation doses to the sensitive layers of skin. In cases in which a well-defined monoenergetic beam or perhaps a single nuclide contributes to skin dose over a well-defined time-frame, and in a known geometry, calculations yield reasonably accurate prediction of the magnitude of radiation doses expected. In a case involving an unknown mixtureoffall-out nuclides in an unknown distribution over the skin within an ash of undetermined constitution, the best estimates of the actual doses received are obtained after the fact through observation of the severity of actual effects suffered. 6.1.3 Internal Radiation Dosimetry Substantial progress has been made overthelast ten years in the development of anatomical models for adults and children, as well as in understanding of the physiology of certain elements. The important issue in the evaluation of the internal radiation doses is accurate quantitation of the nuclides taken in and their pathways. The best input to these models is measured data on the retention and excretion of the radionuclides. This requires the availability of some equipment, including in vivo detectors, andin vitro sampling and analysis equipment. Characterization of the radionuclide content of the body and associated excretion rates can be assessed with germanium-based detector systems, some of which can give fairly accurate assessments ofactivity in the skeleton and lungs by direct measurements over these areas. Sampling of excreta also is a well38