Dear
Colleagues,
In regard to
chemical agents used for treating certain types of RAM exposures, are there
any substitutes available for the following two chemicals
?
Ferric ferrocyanide (Prussian
Blue), a blocking agent for Cs-137, is not recognized by the U.S.
Pharmacopeia and is not approved by the
FDA.
DTPA, a chelating agent, is
not commercially available either. I believe it is only available under
Investigational New Drug (IND) permits for treatment of persons contaminated
internally with plutonium. However, calcium EDTA is available and has
effectiveness for the transuranium metals, but DTPA is generally more
effective.
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Dave,
I
cannot recommend you any substitutes, but I offer you the possibility to
think a little about the use of such chemicals.
Regarding Prussian Blue: It is not really a "blocking
agent", but complexes caesium (also Cs-137 and Cs-134) strongly - this
is known since decades and has been used to remove Cs-137 from drinking
water and milk and has actually been used to enrich Cs-137 from drinking
water in order to measure its concentration. It has been used after the
Chernobyl accident to reduce Cs-137 levels in meat (for instance in Norway,
where sheep were treated with ferrocyanides) and the levels in milk. For the
latter purpose, which actually did use a slightly different ferrocyanide
("Gieses salt") I recently found a paper which I had not had track
of for years, so if somebody is interested I could forward the site, where
it can be retrieved.
However, the efficiency of reducing Cs-137 levels in meat and milk is
rather limited. A reduction by a factor of two or at most three in meat and
milk is something, which is in my opinion not worth the effort. In case of a
very severy case of internal contamination by Cs-137, which might result in
extremely high doses I personally would not hesitate to swallow
ferrocyanides, whether they are approved or not.
Regarding DTPA: It is of course commercially available
as well as all kind of ferrocyanides. Contamination with plutonium or
americium should not occurr frequently unless in places with a potential for
it and there health physicists should be prepared to it, so I personally
would swallow that stuff, if such internal contamination - in a range of
causing very high doses - occurred to me.
I
would be very surprised, if it would not be possible to use in a real
emergency situation - not ingestion of femto-Becquerels - such agents. I
remember an Austrian Standard for Internal Decontamination I have worked
with many years ago. I would have to look it up, but as far as I remember we
recommended the use of complexing agents and we did not bother about their
official approval. Moreover I think to remember that Health Physics has
published during the last 20 years several papers on the decorporation of
radionuclides.
Best regards,
Franz