Potassium iodide, continued: response to Dr. Marcus

[Peter Crane <pgcrane@erols.com>]

Dr. Marcus's posting of September 19, 1999, includes the following
paragraph:

"Notice how Mr. Crane, a lawyer, not a scientist or a physician, fails
to admit his error concerning the use of the Physician's Desk Reference
(PDR) rather than the United States Pharmacopeia-Drug Information
(USP-DI) for information on the adverse effects and adverse drug
interactions of supersaturated potassium iodide (SSKI).  His statement
that a comment letter confused side effects of iodinated contrast
material with those of SSKI gives the illusion that no side effects of
SSKI occur, especially as he states that the PDR does not list any.  My
comment letter, submitted some years ago, described in detail the
adverse effects and adverse drug interactions of SSKI; if someone else
confused SSKI with iodinated contrast material, I have no knowledge of
it.  However, I doubt that this happened, and would like to see that
comment letter."

Reading the above paragraph, I wondered at first whether Dr. Marcus had
confused my posting to Radsafe with someone else's, because there is so
little congruence between what I wrote and what I am described as
writing.  Specifically:

1.  I did not mention "iodinated contrast material."
2.  I did not mention "SSKI."
3.  I did not say or imply that anyone's comment letter confused SSKI
with iodinated contrast material. 
4.  I did not say or imply that the Physician's Desk Reference was the
ultimate authority on drug safety.

What I did say was that Draft NUREG-1633, issued by the NRC staff in
July 1998 and withdrawn at the direction of the NRC Commissioners a few
weeks later, quoted from the PDR in a misleading way:  it quoted from a
PDR description of a prescription drug containing high amounts of KI,
used for the treatment of certain pulmonary illnesses, in such a way
that the reader would have thought that the warnings referred to KI
pills prepared for thyroid protection.  (These 130 mg pills have FDA
approval for over-the-counter sale.)   

I am at a loss to understand how this could have been understood as a
"statement that a comment letter confused side effects of iodinated
contrast material with those of SSKI."
  
In fact, far from regarding the Physician's Desk Reference as the be-all
and end-all on drug safety, I have in the past criticized the authors of
NUREG-1633 for relying on the PDR rather than on peer reviewed medical
journal articles.  As to the possible adverse effects of KI, this is a
serious issue, one that we can expect to see addressed when the World
Health Organization issues new guidance in the near future.  The most
recent information I have is that WHO believes that side effects in
children (other than newborns, who are a special case) are sufficiently
minor that the benefits of KI administration in this age group heavily
outweigh the likely adverse effects.  With increasing age, the benefit
of KI administration diminishes and the risk increases, until by age 40
or 45, the balance has tipped, and the possible harm of KI is thought to
outweigh the likely benefit.  (This is already the policy in Germany, I
believe.)  On this point, Dr. Keith Baverstock of WHO would be an
authority to consult.  

I do not plan to prolong this debate.  I am happy to give Dr. Marcus the
last word.  I hope that Radsafers will read it, and my own postings too,
with a critical eye.  

Peter Crane
pgcrane@erols.com
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