islands and (2) identify those islands or atolls
where additional sampling and analysis may be
required (Robison et al., 1981a). A dose
assessment was made based on the limited data
from the screening survey to determine the dose
people living on Rongelap Island would receive
between 1978 and 2050 (Robison et al., 1982).
Estimates of the dose Rongelap inhabitants
received from 1957 through 1978 were reported
by Lessard et al. (Lessard et al., 1980a).
Since the 1978 survey, we have collected and
analyzed additional samples from Rongelap
Atoll. This has resulted in an extensive
expansion of the data base for both Rongelap and
Kabelie Islands.
In 1985, the Rongelap people w@re relocated
to an island at Kwajalein Atoll
remain today. In this report we uge data from
the 1978 NMIRS and the larger ampuntof data
developed from sampling trips to
Rangelap Atoll
from 1986 through 1993, to estimate the dose
resettle on Rongelap Atoil.
The doses are calculated
resettlement date of 1995.
As noted below, we also have
and have found useful data from
for example, those done by the
Washington (LRE) in 1959 and 1961
Gessel, 1985).
dssuming a
Had access to
eaglier surveys,
Exposure Pathways
The radiological dose to inhabitants at a
contaminated atoll occurs from both external and
internal exposure. Each of these two categories
can be broken down further into the following
exposure pathways:
(1) External Exposure
A. Natural Background Radiation
B. Nuclear-Test-Related Radiation
(2) Internal Exposure
A. Natural Background Radiation
B. Nuclear-Test-Related Radiation
1. Radionuclides in Terrestrial Foods
2. Radionuclides Inhaled
3. Radionuclides in Marine Foods
4. Radionuclides in Drinking Water
The aboveinternal exposure pathways are listed
in descending order of their contribution to the
total estimated radiological dose at the atolls
(Robison et al., 1987). The terrestrial foods are
of importance because of the uptake of 157Cs by
vegetation; these foods account for about 60% of
the total estimated effective dose
The dose
from the external gamma path way is also
primarily due to 137Cs. Consequen , about 95%
of the total estimated effective do
5% of the total estimated effective
vary at different atolls and islands
The external natural backgro
exposure in the northern Marshall
is 3.5 wR ho! or 0.22 mSv y-! (22 mr
cosmic radiation. The external bac
due to terrestrial radiation is ve low in the
Marshall Islands. The internal efféctive dose is
about 2.2 mSv y—! (220 mrem y-) for natural
occurring radionuclides such as }0-Potassium
(40K), 210-Polonium (21°Po), afd 210-Lead
(210Pp), that result from consumptidn of local and
imported foods. The natural background dose is
not included in the doses presented in this paper
unless specifically stated.
__ Data Bases
External Exposure Measurements
The external exposure rates at Rongelap
and Ailinginae Atolls were measured by EG&G
as part of the aerial survey conducted in the
1978 NMIRS (Tipton and Meibaum, 1981). The
average exposure rate on Rongelap Island as
measured by EG&G in 197@ was about
45 uR h-l. The EG&G external exposure
contours for 137Cs are shown in Fi
1. In 1988,
we made a series of extefnal gamma
measurements at the two atolls with our in-situ