Radioiodine in cows

[Lorna Bullerwell <ljb1@cornell.edu>]

Hi all,

We have a researcher here who wants to inject 10 mCi of I-125 into a cow.
He is telling us that almost all of the iodine will be excreted out of the
cow via milk, urine and feces within a 36 hour period.  He is basing this
on the iodine being bound to bovine Luteinzing Hormone and studies of the
hormone in rats.  This has brought about a few questions that I hope
someone out there in RADSAFEland may have some insight into.

I was Skrable-ized at Lowell, so I am fully aware of retention functions,
etc.  I also know that based on compound, there are different classes for
inhalation, depending on how long material stays in the lung.  I don't
recall any discussion about different forms of isotopes behaving
differently in the body based on certain compounds being injected into an
animal, human or otherwise.  I couldn't find any discussion of this type of
thing in any of my reference books, which are all based on human exposures
anyway.  Does anyone know how differently radioiodine behaves in cows vs
people?  Is anyone aware of any references for stay times for different
compounds?  Do pretty much all compounds end up with the same behavior in
regards to radioactivity in the body?  Our main problem at the moment is
trying to determine ahead of time how long the cow needs to remain in an
isolated stall before it can rejoin the herd and release all excreta
directly to the environment.  While in the stall, we can deal with any
wastes generated, so that isn't really the issue.  Based on what I have
looked up in the human data, a significant amount of iodine should still be
in the cow after 36 hours, especially when you are talking about
environmental levels.  Can anyone offer any insight?

Please respond directly to me, unless you feel others may be interested in
this topic.  Thanks in advance.  Liz, any ideas?

Lorna
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Any statement above is 100% my responsibility.  
Don't blame Cornell!
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Lorna Bullerwell			Phone:  (607) 255-8816
Radiological Safety Specialist		Fax:  (607) 255-8267
Cornell University			mailto:ljb1@cornell.edu
Department of Environmental Health and Safety
Laboratory and Radiation Safety Section
125 Humphreys Service Building,  Ithaca, NY  14853
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