f^SS^l UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C, 20460
SAB-RftC~88-QQl
October 9, 1987
The Honorable Lee M. Thomas
Administrator
U.S. Environmental Protection Agency
401 M Street S.W,
Washington, DC 20460
Dear Mr. Thomass
The Science Advisory Board's Radiation Advisory Cotanlttee lias reviewed
the revised plan for the Idaho Radlonucllde Exposure Study at the request
of the Office of Radiation Programs (OEP).
The request for review was received September 5, 1986 and the work
plan was first presented at the Radiation Advisory Comftittee meeting
October 1-2, 1986. A revised plan for the study was presented at the
December 17, 1986 meeting and the final document describing the study,
sent to the Committee March 30, 1987, was reviewed at the June 12, 1987
meeting*
The objective of the Idaho Radionuclide Expogttre_Study Is "to
determine the magnitude and relative importance of the various Industrial
sources of radiation and to estimate the dose to the populations of Soda
Springs and Pocatello, Idaho from these sources." This objective is
more limited than that found in the September 5, 1986 work plan, and the
Committee believes that it is achievable.
The Committee finds that the current version of the study plan is
of sufficient quality and detail to achieve the study's objective. This
conclusion is due primarily to changes iti approaches to sampling and
neasurement of radlonuclides, enhanced use of existing data, and Improved
use of meteorological Information.
There are two additional Comlttee comments, neither of which will
affect the overall plan, that will be relatively easy to address in the
final report.
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These comments include:
1. The March 30, 1987 OKP transmittal memorandum states (on page 2,
item 7) that, in the absence of information on indoor/outdoor polonium-
210 ratios, it will be assumed that the indoor polonium-210 concentration
is the same as the outdoor concentration; the memorandum points out that
this assumption will result in a conservative estimate of dose. However,
this estimate may also be incorrect because it is generally accepted that
indoor concentrations of any aerosols originating outdoors are lower than
the outdoor concentrations. A better approach would be to take a
conservative value for the indoor/outdoor ratio based on literature
values, rather than to assume the ratio is unity.
2. The Committee hopes that in the final report of the Idaho
Radionuclide Exposure Study lung doses due to inhalation will be converted
into effective dose equivalents to permit these doses to be added to the
external dose from gamma rays originating in slag* Since these two
pathways are expected to be the principal modes of exposure, it is important
that they be expressed in comparable units.
Thank you for the opportunity to present our evaluation of this
study plan. Vfe request and look forward to the Agency's response to our
report.
Sincerely,
Norton Nelson
Chairman
*Executiv
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