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