Ingestion doses from 609 are negligible and therefore do not appear in any of the tables. It is observed at low concentrations in soil samples, but incorporation in plants is such that concentrations rarely exceed the detection limit. The 60 ~~Co contribution to the external gamma dose is about 5% or less. 905, 1376, and 60 Doses from Co via the inhalation pathway are two to four orders of magnitude smaller than doses from the transuranic radionuclides and are therefore not listed in the dose tables. The global deposition of 1376, in the 10 to 15° N. latitude of the Pacific region through 1974 was about 30 mCi/kmn? (Ref. 45). Adjusting this to 1978 and comparing it with the concentrations of 13"Cs determined here, we see that 30% of the 13 7Cs soil concentration (and therefore the dose) listed for Likiep, Wotho, Ailuk, Mejit, Ujelang, Bikar, Jerno, and Taka is from worldwide fallout and is not specific to the Marshall Islands. The worldwide fallout of 137 Cs 137.65 at Utirik and 1376, and 98% of the accounts for about 7% of the about 2% at Rongerik and Rongelap Islands. The other 70, 93, concentrations, respectively, is due to intermediate range and global fallout. The global deposition of 13 7Cs between 30 and 50° N., which includes the United States, is greater by more than a factor of 3 than that in the 10 to 15° N. latitude. Thus, the deposition of 1376, from global fallout between 30 to 50° N. is nearly equal to the total 1376. observed at Likiep, Wotho, Ailuk, Mejit, Ujelang, Bikar, Jemo, and Taka. The deposition of other radionuclides follows a similar pattern. Another comparison for this latitude and this area of the Pacific is the background concentrations of 137 Cs in the soils at Ponape, Truk, Palau, and Guam. 6 concentration averaged over !0 cm range from 0.1 to 0.5 pCi/g.* The 1376s soil The range of 1376, concentrations in the 0- to 10-cm soil averaged for Likiep, Wotho, Ailuk, Ujelang, Mejit, and Jemo is 0.2 to 0.7 pCi/g, very similar to the background levels at the other areas of Micronesia, although slightly higher. Uncertainty in the final dose values can result from uncertainty in three sources of input data: (1) radionuclide concentration in food (or soil); (2) dietary intake; and (3) the biological parameters such as radionuclide turnover times in the body, fractional deposition in various organs, and body or organ weight. First, the distributions of radionuclide concentration data in relatively large vegetation and soil sample populations from Bikini and Eneu Islands at Bikini Atoll is discussed in Ref. 5. The distributions are log-normal; the arithmetic mean x includes some 68% of the population, 2 x includes 88% of the population, and 3 X includes better 51