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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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