shielding, does not exist in the Marshall Islands. It is 26mrem/y for the U.S. population-weighted dose and about 57 mrem/y for Denver and Leadville, Colorado. 43 Therefore, the total external background dose in the U.S. is 54 mrem/y based on the U.S. population-weighted average; 107 mrem/y for Denver, Colorado, which has a population of about 500,000 (urban population of about 1,500,000); and about Leadville, Colorado, which has a population of about 10,000. 182 mrem/y for Thus, depending on the diet, most of the atolls have estimated doses from all exposure pathways excluding cosmic radiation that range from about 4 to 57% of the U.S. population-weighted background dose; from about 2 to 29% of the Denver, Colorado dose; and from about | to 17% of the Leadville, Colorado dose. When the 22 mrem/y of cosmic radiation background dose in the Marshall! Islands is added, the total doses at the atolls for all exposure pathways range from 45 to 100% of the U.S. population weighted external background dose; from about 23 to 50% of the Denver, Colorado external background dose; and from 13 to 29% of the Leadville, Colorado external background dose, depending on which diet is employed. The natural internal dose will be similar in the U.S. and the Marshal! Islands. For additional reference, these estimated doses for the various atolls can be compared to the U.S. Federal guideline of 500 mrem/y above background for an individual.** The doses at most atolls are from | to 5% of the guideline, depending on which diet is assumed to apply. The highest estimated doses for an inhabited atoll are for the southern islands at Rongelap where the doses range from about 10 to 50% of the guideline, depending on the diet. The 30- and 50-y integral doses provide a similar picture. The 30-y integral doses for Likeip, Wotho, Ujelang, Mejit, Ailuk, Taka, Jemo, and Bikar for the MLSC diet are less than 0.14 rem and for the BNL diet they are less than 0.7 rem. This is less by a factor of 20 to 33 than U.S. Federal guidelines of 5 rem/30 y for a population ad and less than the integrated 30-y external background dose in the U.S., which ranges from 1.6 to 5.5 rem.1? The 30-y integral doses for the MLSC diet are less than 0.25 rem for Utirik, less than 0.49 rem for Ailinginae, less than 1.3 rem for the southern islands of Rongelap and for Rongerik, less than 7.4 rem for Naen Island on northern Rongelap, and less than 3.3 rem for the other northern islands of Rongelap if they were to be continuously inhabited. Similarly, for the BNL diet the doses are less than 0.72 rem for Utirik, less than 2.1 rem for Ailinginae, less than 2.5 rem for the southern islands of Rongelap, less than 14 rem for Naen Island at Rongelap, and less than 7.6 rem for the other northern islands at Rongelap for continuous occupation. 50