Ag and Cu ions/disinfection

David Snyder dasnyder at uci.edu
Wed Oct 18 17:17:37 EST 1995

In article <462o67$hnl at brachio.zrz.TU-Berlin.DE>, Michael Gregory
<gregeccd at sp.zrz.tu-berlin.de> wrote:

> I am interested in obtaining information about the effectiveness of sivler and
> copper ions against bacteria and fungi.  Also, are such ions toxic < if so at
> what level > to human if consumed regularly through the drinking water supply?
> -- 
> :::::::::::::::::::::::::::::::::::::::::::::::::::::::::
> Michael Gregory         gregeccd at sp.zrz.tu-berlin.de    :
> Biotechnology,          gregory at hera.bsq.fta-berlin.de  :
> Technical University Berlin, Germany                    :
>         "Wer nicht fragt, bleibt dumm"                  :

Silver is toxic to many bacteria at very low concentrations and is quite
suitable for disinfection of the human body, etc. because of the small
amounts of silver needed to denature proteins.  Silver is, however, too
toxic to be used in drinking water purification, or at least I think it
would build up in humans and cause toxic reactions.  However, colloidal
silver may be used to disinfect water supplies and presumably be filtered
out, but there are more cost effective means of disinfection than this.

Copper, I know, is actually required by humans but at higher levels is
also fairly toxic.  Moreover it is not as effective in colloidal form. 
While silver compounds have been traditionally used to disinfect the eyes
of newborns, copper is mainly used against fungi that attack plants.  As a
whole, bacteria seem to be more sensitive to silver and fungi more
sensitive to copper, but there are historical reasons for the use of
silver against bacteria and copper against fungi as well.  Also, some
bacteria are very tolerant of metal ions, but most of those are harmless
to humans.  

Much of this information is available in textbooks on toxicology as well
as microbiology textbooks.  And I am sure you will get more helpful
responces than this one.

David Snyder
dasnyder at uci.edu

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