-20- (one-third the guide for the individual) is to be used. This operational technique may be modified to meet special situations. The FRC primary numerical guides, expressed in rem, are provided in two reports, FRC Nos. 1 and 2, summarized in Table III. Secondary numerical guides developed by FRC are expressed in terms of daily intake of specific radionuclides corresponding to the annual RPG's. Consideration is given to all radionuclides through all pathways to derive a total annual exposure for comparison with FRC guides. How- ever, for many practical situations a relatively few radionuclides yield the major contribution to total exposure; by comparison, exposures from others are very small.