exposed on Rongerik. It was reported that the gross beta activity in urine obtained from
the Ailingnae group was about 50% of that of the Rongelap group. Thus, it can be
surmised that a rough estimate of thyroid dose to the Ailingnae people was about 0.75 Gy
(75 rad). The radiation dose received from external exposures must be added to these
numbers to estimate the total thyroid dose. However, when observations of thyroid
abnormalities began, a more careful evaluation of the dosimetry was made, including the
contributions from iodine-131, 132, and 135. Revised estimates of the thyroid doses in the
Marshallese by James (36) and Lessard et al. (37) are shown on Table 4. The dose
reassessment by Lessard et al. suggested higher absorbed doses than those estimated by
James because of differences in assumed isotopic ratios.
TABLE 4, Estimeies ofThyroid Dose [Gy,(rad)} in tbe Exposed Populations By Age (Years) at Exposure
Abell
Rongelep
Gy
Karty
Eothnetes*
<lé yr
50
(rad)
Ailingnae
Gy
16-18 yr
81-18
(810-1800)
7S
(rad)
Rongerik
»
Vari
Gy
_
(tad)
L450
(1964)
>18 yr
3.48.1
(334-810)
335
(335)
al.
10-18 yr
>13 yr
18-50
12-17
)
(190)
(135)
135
7.40-13.0
NID
_
_
_
_
—
060-095
3.040
27-67
15-25
27-47
(30-40)
(270-670)
1611
(1800-$000) (1200-1700) (1000-1100 f
(275-450)
(95)
L¢
<10 yw
(740-1300)
(150-250)
(7-46)
|
-23
(280-290)
~
LS-Lé
(150-160)
* Original dose estimate (rad), adult population only.
N/D = No Data
The doses to skeleton and marrow initially were assumed to be small compared to the
external doses received. Actually, before the thyroid abnormalities became apparent, it
was assumed that "the internal hazard to the contaminated inhabitants of the Marshall
Islands is minimal both from the acute and the long range point of view" (5). However,
the long-term doses to the skeleton and marrow might be importantin assessing of
stochastic effects (see 4.4.4). Also, doses to the gastrointestinal tract may have been
significant if these nuclides were inhaled in an insoluble form. (Approximately 61% of
inhaled insoluble aerosols >1 micron in diameter will be returned into the pharynx and
swallowed). Indeed, high amounts ofactivity were detected in the gastrointestinal tracts of
23