Re: Prophylactic administration of potassium iodide

["Dukelow, James S Jr" <jim.dukelow@pnl.gov>]

It is discouraging, reading the recent RADSAFE messages regarding the 
prophylactic administration of potassium iodide, at how resistant 
RADSAFE readers and government agencies responsible for rad protection 
policy are to a better idea.

I will repeat a message I sent to RADSAFE in February 1996 that has 
some relevance.


>  The recent discussion of the safety (or not) of potassium iodide has 
>  been interesting, but none of the correspondents have mentioned a 
>  possible alternative.  Several years ago there was a brief report in 
>  _Science News_ (Volume 128, p. 360) about research by a group, led by 
>  Prof. Kenneth Miller, at Penn State's Hershey Medical Center into the 
>  possibility of loading the thyroid with stable iodine using topical 
>  application of iodine-based antiseptics, specifically tincture of 
>  iodine and povidone iodine.  Briefly, topical application of the 
>  antiseptics blocked thyroid uptake of injected radioiodine I-131 as 
>  well as ingestion of potassium iodide did (the experimental animals 
>  were rats).  The article ended with a note that Miller's team was 
>  planning human tests of the idea. 
>  
>  The particular charm of this idea is that it seems to avoid many of the 
>  problems or potential problems associated with prophylatic 
>  administration of potassium iodide.  The iodine-based antiseptics are 
>  non-prescription drugs.  I assume they are "Generally Recognized as 
>  Safe" (in the formal regulatory sense of that phrase).  I am not aware 
>  of any problems with allergic reaction to topical application of these 
>  products.  Finally, they are probably already found in many homes and 
>  could be easily and inexpensively stocked in the rest. 
>  
>  I was curious what subsequent research had shown, so I chased down 
>  Professor Miller's email address and asked him about the rest of the 
>  story.  He replied: 
>   
>    << Begin Miller reply >>
>  
>  Our research on effectiveness of topically applied iodine culminated in 
>  studies in humans and was published in HEALTH PHYSICS as per the 
>  following: 
>  
>  Miller, K.L.; Coen, P.E.;  White, W.J.;  Hurst, W.J.;  Achey, B.E.;  
>  Lang, C.M.:  "Effectiveness of Skin Absorption of Tincture of I in 
>  Blocking Radioiodine from the Human Thyroid Gland",   Health Physics, 
>  Vol. 56, No. 6. Pages 911-914, 1989. 
>  
>  Unfortunately, although we needed to do additional studies in order to 
>  come up with specific recommendations on optimum dose of tincture of 
>  iodine, ideal body location for application, advanages/disadvantages of 
>  occlusive dressing, etc. there were no TMI or Chernobyl accidents going 
>  on at the time and we could not obtain the funding necessary to do 
>  further studies. In all, we published the results of 3 studies, first 
>  in rats, secondly in dogs and finally, in humans. All showed promise of 
>  an alternative for those times when KI would not be sufficiently 
>  available. 
>  
>  I hope this helps. Incidentally, my phone number is (office) 717-531-
>  8027, 
>     ... . My e-mail address is kmiller@xray.hmc.psu.edu
>  
>  If you need further information, please let me know. 
>  Regards,
>  Ken
>  
>    << End Miller reply >>
>  
>  Best regards.
>  
>  Jim Dukelow
>  Pacific Northwest National Laboratory
>  Richland, WA
>  
>  js_dukelow@pnl.gov
>  
>  The message has not been reviewed and/or approved by either my 
>  management or by the U.S. Department of Energy. 
>  

A couple of responses to my earlier message and at least one recent 
message referred to "iodine allergy".  I am prepared to believe that 
the immune system will build antibodies to proteins contained in foods, 
particularly shellfish, that are high in iodine.  These allow the 
immune system to identify and tag those antigens for later destruction 
by killer cells.  I am not prepared to believe that the immune system 
can or does built antibodies to iodine atoms, particularly since iodine 
is an essential nutrient.  I am not, however, by any stretch of the 
imagination an expert on the immune system, so perhaps someone can 
convince me of the error my ways. 

The KI side effects referred to in several of the recent messages are 
most likely associated with electrolyte balance, since potassium is one 
of the most important electrolyte cations.  Topical application of an 
iodine-containing antiseptic, with passage of ionic iodine through the 
skin into the bloodstream and subsequently to the thyroid presumably 
would not carry the same risk of upsetting the electrolyte balance. 

Best regards.

Jim Dukelow
Pacific Northwest National Laboratory
Richland, WA
jim.dukelow@pnl.gov

These comments are mine and have not been reviewed and/or approved by 
my management or by the U.S. Department of Energy.