RE: Ammoniacal Silver - Safety Concerns

From:"Nick Kirk"

Although there is a theoretical risk of explosion, the very fact that you
don't see headlines saying "Technician blown up by silver solution" suggests
that most of the so called "evidence" is anecdotal.
In fact most of the so called "evidence" seems to stem from an era when
general safety conditions in labs were considerably less than they are
today, so it was more likely a combination of factors rather than this
single one.
The same is true for other substances such as Picric acid which is also
supposed to be explosive, but you have to dry it out and hit it with a very
heavy object like a moving express train to get it to do anything.
As with all these things a risk assessment should be completed as to how you
use the substance and a means of safely using it should be devised.
We keep ammoniacal silver in the fridge for several days with no problems,
although it must be said that it always works better if you make it up fresh
each time.
If you precipitate the silver out of the solution and keep it you then have
to consider the toxicity of the residue, where you store it and the fact
that it is much more difficult to dispose of the solid residue safely than
the dilute liquid one.

Nick Kirk
Hinchingbrooke Hospital

-----Original Message-----
From: Kelly Booher (by way of Histonet) []
Sent: 08 August 2003 03:08
Subject: Ammoniacal Silver - Safety Concerns

In reviewing our procedures, we recently came across a
warning in the latest Freida Carson book regarding the
potential explosivity of ammoniacal silver, as is used
in Gomori's Reticulin staining.  We have in the past
reused the ammoniacal silver solution for up to one
week, refrigerating it between uses.

What are the protocols for dealing with this
substance?  Are you reusing the ammoniacal silver, or
preparing it fresh each time?  How are you disposing
the waste?  Should we be treating the solution by
precipitating out the silver prior to disposal?  Does
anyone have a procedure for this?

Thanks in advance.

Kelly Booher, BS, HTL (ASCP)
Anatomic Pathology
Swedish Medical Center, Providence Campus
Seattle, WA  98122

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