[ RadSafe ] Banana Equivalent Dose - erroneous?

[shima]

Mike, thanks for your reply.

Clearly  homeostasis will cause a fairly rapid evacuation of the excess 
K ingested. Also ingesting K in the normal isotope ratio will not change 
the ration in the body in either long or short term.  This makes this 
situation different from ingesting a quantity of K-40 alone which would 
alter the body's ratio for a time and that would remain on a longer 
time-scale that evacuation of a naturally balanced excess.

The main question I am seeking to clarify is:

does this mean that applying the dose given in FGR #11 for K-40 is 
incorrect in this case?

Is using the dose from exposure to K-40 given in FGR #11 valid in the 
case of ingestion of a large mass (circa 500mg) of a natural mix of 
potassium isotopes.

In particular any ref to any documentation explaining whether or not 
this is correct use of the dose tables would be most helpful

best regards.


On 03/25/11 17:22, McNaughton, Michael wrote:
> Shima
>
> Thank you for the link to the amusing message.
>
> Every living cell (eukaryote or prokaryote, animal or vegetable) contains potassium, and the concentrations are generally within about a factor of three. Most fruits and leafy vegetables contain less potassium than bananas because bananas have less water. Nuts,  meat, and human tissue contain somewhat more potassium than wet fruits and vegetables.
>
> The problem with calculating a potassium dose from food is: homeostasis. Every living cell, tissue, or organism regulates the amount of potassium and rejects the excess. So ingesting extra bananas, or nuts, or beans, is not going to make much difference in the amount of potassium retained in the body.
>
> mike
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of shima
> Sent: Friday, March 25, 2011 8:31 AM
> To: radsafe at health.phys.iit.edu
> Subject: [ RadSafe ] Banana Equivalent Dose - erroneous?
>
> re http://health.phys.iit.edu/extended_archive/9503/msg00074.html
>
> Subject: Banana Equivalent Dose
>
>
> Hi, sorry to dig up such and old message but this rather humorous post
> has just dug itself up and is going viral due to current interest in all
> things radioactive and appeal of the idea.
>
> It is also included in a more recent (2004) document that is still being
> given prominent position by U.Nevada's Environmental Health and Safety
> unit (though no explanation of the derivation is given there).
>
> http://www.ehs.unr.edu/radiationsafety.html
> http://www.ehs.unr.edu/Documents/RadSafety.pdf
>
>
> As far as I can tell, this list is the origin of this calculation. In
> any case the above post certainly details how it was calculated, even if
> this is not the origin of the concept.
>
> Could someone please state whether using the dose from exposure to K-40
>    given in FGR #11 is valid in the case of ingestion of a large mass
> (circa 500mg) of a natural mix of potassium isotopes.
>
>
> Many thanks for any advice in using this data correctly.
>
> Best regards, Shima.
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