FGR 13 and K-40

[Chris Alston <alstonc@odrge.odr.georgetown.edu>]

I glanced through the "Interim Version" of Federal Guidance Report 13,
"Health Risks from Low-Level Environmental Exposure to Radionuclides".
Conspicuous by its (glaring) absence from the list of nuclides is K-40!!!
I'm speaking of a medium-E beta/gamma emitter (Emax = 1.3MeV / Egamma1 =
1.46MeV) that's in equilibrium in Standard Man @ 0.1 uCi. To quote the
fourth edition of Environmental Radioactivity (Eisenbud M and Gesell T.
1997): ". . . K-40 is easily the predominant radioactive component in normal
foods and human tissues." Note that the elemental specific activity is 800
pCi/g. I have used containers of orange juice to provide an E-cal point for
gamma spectrometers. I also have collected a spectrum that way to impress a
pregnant nurse, who was suffering the usual fears and anxieties.

I'm not one given to paranoia, or a devotee of conspiracy theories, but I
would love to see an authoritative explanation of this flabbergasting
omission. C-14 and Tritium are considered in the document. If K-40 were on
the list, it would be very easy for any numerate person to do
intercomparisons, and, perhaps, conclude that much of the regulatory concern
about actual (or potential) exposures may be inappropriately "scaled". Or,
maybe the information was suppressed at the instigation of lobbyists from,
e.g, Florida, California, Texas, and Hawaii!!!

chris alston
alstonc@odrge.odr.georgetown.edu
I do not here represent my employer.

P.S. Y'all down at the RIDIC should also, please, consider adding K-40 to
Table D1 of the Fetal Dose Calculation Workbook. I've found that such
information really does help concerned mothers to put things in a rational
perspective, when it's presented in a sympathetic, and intelligible, manner.
Chris Alston
alstonc@odrge.odr.georgetown.edu
I am not here a representative of my employer.