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Re: Prussian Blue
Bjorn,
While I'm not a medical doctor, I have had interest in this area for some
time, and have done quite a bit of reading on the subject, and participated
in several studies related to this issue.
Cesium is an biologic analogue of potassium. It appears to tightly bind to
the transfer pores on the cell surface. (Surprisingly) in adults it is not
displaced by increased dietary intake of K or Na; there were several papers
published on this point in the 1960s. Further, there are other downsides
from oral supplementation with KCl and NaCl; other compounds may be
preferable.
There is some evidence that increased K supplementation may accelerate Cs
elimination in children, but it is not a profound acceleration. It doesn't
seem to have any effect in adults. This suggests that puberty may cause
certain physiological changes that alter the behavior of cesium.
The last I heard, Prussian Blue is still an experimental drug, and FDA has
not given permission for its widespread use for humans. I am not aware of
its specific pharmacology, but it appears to be relatively safe. [Perhaps
there are other listmembers who could amplify the current status and
behavior of the substance]. It is chemically specific for cesium; it binds
the cesium into an insoluble complex, which then passes through the gut into
the feces. This binding interferes with the bilatory recycling of the
cesium, which drops the body burden over a few days. Given the fact that
Cs-137 is not a particularly "dangerous" isotope, the use of PB would
probably not be justified unless the Cs-137 burden was quite high.
Bentonite has been used for reduction of toxic effects in the GI tract. I
don't know if it is effective for cesium due to the fact that I'm not sure
it interferes with the bilatory recycling. If you don't bind cesium to
something, it gets reabsorbed and recycled fairly readily.
Similarly, just increasing water intake doesn't appear to have much effect
either (recall the cesium becomes tightly bound to the cell walls).
I believe there was a very good discussion of these types of substances in
the first HPS Summer School on Internal Dosimetry. Check the textbook that
was published from that session.
Jim Barnes, CHP
james.g.barnes@att.net
----- Original Message -----
From: "Bjorn Cedervall" <bcradsafers@HOTMAIL.COM>
To: <radsafe@list.vanderbilt.edu>
Sent: Saturday, August 10, 2002 10:18 PM
Subject: Prussian Blue
> >who may become inadvertently internally contaminated, were KI (which we
can
> >buy), Prussian Blue (an oral drug that binds Cs-137 and promotes fecal
> >excretion), <snip>
> ---
> A question for reason of clarification:
>
> I understand that Prussian Blue, KFe(III)[Fe(II)(CN)6], is very stable and
> guess that the mechanism is replacing the K with Cs.
>
> The hexacyanide complex is, however, possible to break up with strong warm
> acid - potentially releasing HCN. As decontamination experiments have been
> made with mammalians Prussian Blue obviously passes through the stomach
> without any problems. In order to understand this from a chemistry point -
> can anyone shed light on the stability as a function of pH and
temperature?
> (37 C, 1 M HCl does not seem to be enough)
>
> I guess that some HCN is released - depending on the quantity taken in -
so
> for a low level of say a Cs-137 contamination I might prefer to keep the
> Cs-137 and just try to wash it out faster with a combination of heavy
> drinking (not exactly whiskey) and increased intake of potassium/sodium
> chloride. An alternative to Prussian Blue is bentonite which I think
> (=probably something my professor in nuclear chemistry told me 20 years
ago)
> has been tried on sheep or some other larger mammal (?).
>
> Please comment, add or correct whatever is necessary.
>
>
> My personal reflections only,
>
> Bjorn Cedervall bcradsafers@hotmail.com
> http://www.geocities.com/bjorn_cedervall/
>
>
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