BROOKHAVEN NATIOP AL LABORATORY
ASSOCIATED EINIVERSITIES, INC.
ton. New York 17973
Safety & Enwironmentai Protection [vision
570) 346 4207
AOR GSO
December 17, 1980
Jacob Thiessen, MD, CHP
Director, Human Health &
Assessments Division
Office of Health & Environmental Research
U. S. Department of Energy
Washington, D.C.
BEST COPY AVAILABLE
20545
Dear Dr. Thiessen:
Congratulations on your new role as Director of the Huma. Health and Assessments Division.
I would like to take this opportunity to oresent a synopsis of Brookhaven's Marshall Islands Radiological Safety Pro:;ram activities
which are related to dose reassessment since our research proj:cts in this
area are in part supported by your Division.
The purpose of tis research tis
to refine the previous estimates of dose equivalent which were received by
members of the Rongelap and Utirik Atoll populations in the Ma shall Islands
of Micronesia who were exposed to ionizing radiation as a resu t of the U. S.
weapons testing provram.
As you are probably aware, their cur ‘ent medical
histories indicate a statistically significant elevation above the spontaneous
thyroid nodule incidence in the acutely exposed population, re‘ative to a
comparison Marshallese and the United States population.
This information 1s
shown in Tables 1 and 2, along with dose equivalent estimates
sources.
The acute dose estimates are based
on reports
rom two
by Conird
upon calculations which utilize our I-129 in soil samples studv.
(Co 75)
and
The chronic
dose estimates are obtained from Conard (Co 75) and Lessard (Li: 80). The
thyroid nodule prevalence in the Marshallese exposed populatio: and the
comparison population is taken from a draft of Conard's 25 yea
review (Co
80).
Since the Marshallese comparison population was also exp sed to chronic
low level radiation from the weapons testing propram, another «stimate of the
spontaneous number of benign and cancer nodules {fs base? on Un-ted States
incidence and is indicated in parenthesis.
Although there are uncertainties in the mean values repo ted in Tables 1
and 2, these data may be used to derive a cancer incidence per unit dose
equivalent which would have practical impact on human health a sessment with
regard to the uses of radiation and radivactivity.
In order ts estimate a
range and a true mean value for the incidence of nodules per wit dose equivalent
and
to establish the associated confidence
following projects have been undertaken:
level
of
the
e: timate,
the