Read the whole thing by following the link, but here is the reader's digest version
From Shane's site
http://www.ki4u.com/#6
Topical Iodine Applications
There has been some interesting research, though, with both humans and dogs into topically (on the skin) applied Povidone-Iodine (10%) solution (such as Betadine® or Povidex® solutions), and also with tincture of iodine, to test the absorption rates of iodine directly through the skin. But, it was found not to be as quick in providing thyroid blocking as oral Potassium Iodide (KI) or KIO3, nor as consistent, and then, often, at lower levels of protection. Questions remain of skin irritation, determining the amount of Iodine solution to apply, where best to apply it, how long to apply it, and the effects of temperature and humidity on absorption through the skin. Also, insufficient testing has been done on specific groups, such as infants, children, and pregnant and nursing women to know how effective it would be and the full range of complications that could be expected with repeated applications. For instance, the skin absorption of iodine products in neonates with inhibition of thyroid function has been documented in the past. The use of Povidone-Iodine is the most frequent cause of this type of intoxication. Another study showed that Povidone-Iodine did not significantly influence neonatal thyroid function if they were used to a full term neonate only once and even to a wide skin surface.
Another source, non-medical, claims that by using the stronger 7% tincture iodine and just dipping the index finger of the person being treated up to the first knuckle (just above the fingernail) would provide the proper dosing. They claim this would work for all people as our fingers are roughly proportionate to our size and weight. That may be true, but that this technique would actually provide sufficient quantity and effective absorption of iodine for thyroid-blocking has not been verified. (Additional documentation and source references have been requested of that author. And, will be promptly posted here if provided.)
Clearly more research is needed before embracing the topically applied techniques as a one-size-fits-all solution, as its limitations must first be more fully understood. However...
According to research by Health Physicist Ken Miller, Hershey Medical Center, using 24 healthy adult male subjects, an adult could get a blocking dose of stable iodine by painting 8 ml of a 2 percent tincture of Iodine on the abdomen or forearm approximately 2 hours prior to I-131 contamination. The abstract of his study titled "Effectiveness of Skin Absorption of Tincture of I in Blocking Radioiodine from the Human Thyroid Gland" from Health Physics, June 1989, Vol. 56, No. 6, pages 911-914, (To read abstract, search the title of the article here <http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?TOXLINE>) states:
"Although there were large variations within each subject group in regard to serum-I levels and thyroid uptakes, the increase in serum-I concentration after topical-I application was effective in reducing the thyroid uptake of I131. The authors conclude that in the absence of KI, most humans would benefit from topical application of tincture of-I, and that in some the effectiveness would equal that of oral KI."
Hmmm... interesting Plan "B"(Betadine®) possibilities here, if in a pinch!