re: The Radiation Dose from a "Reference Banana."
Some time ago (when I almost had time to do such things) I calculated the dose one receives from the average banana. Here's how it goes:
On page 620 of the CRD Handbook on Rad Measurement and Protection, the concentration of K-40 in a "Reference Banana" is listed as 3520 picocuries per kilogram of banana. For those of us who are stuck in certain unit ruts, this is equivalent to 3.52E-6 microcuries of K-40 per gram of banana.
An average "Reference" banana weighs (masses) about 150 grams (I think.) So, the ICRP Reference Banana contains about 5.28E-4 microcuries of probably deadly K-40.
Federal Guidance Report #11 lists the ingestion dose (committed effective dose equivalent) for K-40 as 5.02E-9 Sv/Bq or (again, for those of us who are "unit-challenged," 1.86E-2 rem per microcurie ingested.)
Thus, the CEDE from ingestion of a Reference Banana is 5.28E-4 x 1.86E-2 = 9.82E-6 rem or about 0.01 millirem.
I have found this "Banana Equivalent Dose" very useful in attempting to explain infinitesmal doses (and corresponding infinitesmal risks) to members of the public. (Interestingly, the anti-nukes just HATE this, and severely critisize us for using such a deceptive concept.)
Would love to go into more detail, but have to get back to our DEADLY Human Radiation Experiments (i.e., eating bananas.)
The same table in the CRC Handbook lists 3400 pCi/kg for white potatoes and 4450 pCi/kg for sweet potatoes - so you could carry through the same sort of calculation for Reference Potatoes. Interestingly, raw lima beans come in at 4640 pCi/kg, "dry, sweet" coconut comes in at 6400 pCi/kg, and raw spinach
(yum!) comes in at 6500 pCi/kg.
Considering the fact that the DOE has officially stated that "there is no safe dose of radiation" my advice to you all is to stop eating immediately.
Oh yes! Almost forgot. Regarding K-40, go into your local grocery store, buy some salt-substitute (there are two common brands, and the one in the white and orange labeled container works best) spread some out on a table and check it out with a GM survey instrument. There it is folks, deadly radioactivity in your grocery store!
Yours for healthful diets . .
Captain Internal Dosimetry
aka Gary Mansfield, LLNL, (email@example.com)
Neither Lawrence Livermore National Laboratory, the University of California, nor the Department of Energy recommends eating bananas.
The point of course, is to make people realize that the notion that "there is no safe dose of radiation" isn't necessarily correct. Your granite countertops have trace particles of uranium in them. The Capital Building in Washington DC has so much granite in it that it wouldn't be qualified as a nuclear facility because it already emits too much radiation. We consume radiation all of the time from a variety of sources and our bodies rid themselves of it naturally.