the dose at all atolls using the results from the MLSC diet survey of the Enewetak ‘people
on Ujelang Atoll.
The dose is also calculated using the BNL diet results by applying the
appropriate diet to each atoll as recommended by the BNL authors. We have used the
BNL diets even though the authors feel their values probably overestimate the amount of
food actually consumed.2° The diet is, of course, very important in predicting doses to a
population because the radionuclide intake, and therefore the dose, will correspond
directly with the intake of locally grown foods.
We have mentioned in previous
assessments the importance of the diet and the uncertainty that was inherent in
previously constructed dietary patterns. /? 10 The BNL diet survey once again indicates
the atoll-specific nature of the dietary intake and supports our concern that specific
dietary information is needed for each atoll and each cultural grouping.-° As an example,
if the average coconut intake were assumed to be as high as the values listed for coconut
meat and fluid in the BNL report for community B, then the estimated maximum annual
dose rates would be about 2.7 times higher than those calculated using the MLSC results
when imported foods are available and 1.5 times higher than when imported foods are
unavailable. It is clear that more precise diet data are needed for each atoll if we hope
to develop more precise dose estimates.
The normal condition referred to in the MLSC diet is the usual and expected living
conditions in which the preferred imported foods are available.
For the situation where
imported foods are unavailable, it is assumed that there is a primary dependence on
locally grown crops for a person's lifetime.
It is again emphasized that an accurate
picture of the diet, especially the consumption rate of locally grown foodstuffs, is
extremely important in the dose predictions for current living patterns and resettlement
options at an atoll.
The maximum annual dose rates for Likiep, Wotho, Ujelang, Mejit, Ailuk, Taka,
Jemo, and Bikar for all exposure pathways excluding cosmic radiation are less than
6 mrem/y if the MLSC diet is used and are less than 30 mrem/y even when the BNL diet
is used.
The only significant source of natural external background exposure in the
Marshall Islands is the 3.5 UR/h or 22 mrem/y from cosmic radiation.© For reference,
these doses can be compared with the external background doses observed in the U.S.
The average dose from cosmic radiation for the entire U.S population is 28 mrem/y and
range as high as 50 mrem/y for Denver, Colorado to
Colorado.*?
125
mrem/y for
Leadville,
Therefore, the additional cosmic radiation doses in the U.S. relative to the
Marshall Islands range from 6 to 103 mrem/y depending on whether the U.S. population
average
or
specific
subfractions
of
the
population
are
considered.
The
external
background exposure from terrestrial sources in the U.S., which includes structural
49