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Re: Prussian Blue
-----Ursprüngliche Nachricht-----
Von: Bjorn Cedervall <bcradsafers@HOTMAIL.COM>
An: radsafe@list.vanderbilt.edu <radsafe@list.vanderbilt.edu>
Datum: Sonntag, 11. August 2002 07:28
Betreff: 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)
>
-----------------------------------------
Björn,
I am a chemist and I knew before the Chernobyl accident that Prussian Blue
could be used to remove Cs-137 from drinking water and it actually has been
used to concentrate Cs-137 in order to measure traces of it.
As one consequence of the Chernobyl accident in countries much affected by
fallout the concentration of Cs-137 and Cs-134 in animals and also milk was
rising. In order to counteract it was considered to feed various cesium
binding chemicals to animals or to mix it directly with their feed. I had
the same concern as you and was not so sure about the stability of this
complex. Anyway it turned out, that the use of hexacyanoferrates for removal
of Cs-137 had been investigated carefully since a long time, especially by
Prof. Giese in Germany. He obtained the best results not with Prussian Blue,
but another hexacyanoferrate (I believe to remember it was ammonium the
ammonium salt), which was known by the name of "Giese salt". I was with my
laboratory involved in tests - which had to be done very quickly, so they
were not really carefully planned and the results were somewhere between
quantitative and semiquantitative. Animals involved were cows, pigs and
roedeer. We had "Giese salt", bentonite and two other substances, which I do
not remember by heart. Giese salt was clearly superior to bentonite and the
two other substances hardly showed any effect. Nevertheless the Giese salt
did not reduce the Cs-137 and Cs-134 from muscle very fast. I know for sure,
that no animal died, (and it is known from other research as well) therefore
the hexacyanoferrate complex must be extremely strong.
Most contaminated in Austria were wild animals, especially roedeer.
Therefore Giese salt was mixed with rock salt and pressed into so called
"lick stones", which were then put out into the woods, so that roedeer and
red deer would take up the Giese salt by licking.
Another project was carried out in north-east Austria, which was relatively
highly contaminated. Cows were fed Giese salt in order to reduce radiocesium
in milk - the dairy there had a contract with an Arabian country and milk
with the "natural" radiocesium contamination would not have been accepted.
The project was successful, but another story is, how much this did cost the
taxpayer, because the project was paid for by the federal government. Even
more, since there was at this stage already milk available in Austria, which
would have fulfilled the criteria of the importers.
A big project was carried out in Norway, where sheep were treated with a
so-called "bolus", which is in my understanding a kind of cloth, impregnated
with hexacyanoferrate and inserted into the sheeps stomach through mouth and
throat. I am sure you could get good information by contacting the Norvegian
Radiation Protection Institute.
During a visit in Kiev in 1987, I heard about a project there, to use
filters impregnated with hexacyanoferrates in order to remove Cs-137 and
Cs-134 from milk by filtration. I do not know whether this was practiced in
reality.
>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.
I do not believe, that this would be very healthy!!!
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 (?).
>
-----------------------------------------------
Yes, I described it above.
Fortunately Chernobyl has happened quite a time ago, so I described what I
still have in my head. I can only conclude, that without any doubt
hexacyanoferrates like Prussian Blue have no adverse effect on the health of
animals. (That the radiocesium is excreted and again put into the ecological
cycle is another story!!!) I have a lot of material, buried somewhere, from
those times, because I do not work in this field anymore and I prefer to
forget as much as possible about the Chernobyl accident, because these were
no nice times, when everybody got mad - including so-called scientists - and
finally all those who had only produced bull-s**t were promoted and the ones
who did serious and reliable work and tried to calm down the population and
the administration, because there was no danger, were degraded. So if you
need some more specific information I could try to dig into my old reports.
Best regards,
Franz
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