Re: use of topical iodine for thyroid blocking

[Shane Connor <shanec@gvtc.com>]

Radsafers,
The Potassium Iodide Anti-Radiation Pill FAQ at http://www.ki4u.com/
explores various alternatives to KI and KIO3, including iodized salt, sea
salt, kelp tablets, iodine tablets (for water purification), tincture of 
iodine,
and Povidone-Iodine (10%) solutions (such as Betadine® or Povidex®).

The potential, limitations, and in some cases dangers of poisoning,
of attempting thyroid blocking with each are detailed. (Especially of
concern is the possible public confusion during a nuclear emergency
leading some to erroneously attempt to ingest poisonous tincture of
iodine or Povidone-Iodine intended solely for topical applications.)

The FAQ also explores this interesting research, with both humans
and dogs, into topically applied Povidone-Iodine solutions, and also
with tincture of iodine, to test the absorption rates of iodine directly
through the skin for thyroid blocking.

Dr. Miller's promising topical application research is referenced there
showing that in some cases the effectiveness would equal that of oral
KI. His study titled "Effectiveness of Skin Absorption of Tincture of I in
Blocking Radioiodine from the Human Thyroid Gland" can be found in
Health Physics, June 1989, Vol. 56, No. 6, pages 911-914.

It's also noted that 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 well documented in the past. The use of Povidone-
Iodine is the most frequent cause of this type of intoxication. Yet
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.

While there is still much more to learn about the topical application
of I, in an emergency, a Plan "B" (Betadine® or tincture of iodine)
topically applied does hold promise of being a viable alternative
when oral KI or KIO3 tablets are unavailable.

Best Regards,
Shane Connor (FAQ author)
The Potassium Iodide Anti-Radiation Pill FAQ at www.ki4u.com
is an ongoing research project and we invite any suggestions or
related research for inclusion there. mailto:webmaster@ki4u.com

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html