I have often seen referencs to argyria and the 'the sun' in medical, and other 
reports about argyria or siver toxicity.
Heres just one example from a google search on argyria/photographic.
"In argyria, silver deposited in the body reacts with
the sun through a process similar to that of the development of a photographic
negative. This leads to permanent discoloration of the skin."
http://www.rense.com/general12/blueasdf.htm

David

   * From: Marshall Dudley (view other messages by this author
     
<http://www.escribe.com/health/thesilverlist/index.html?by=Author&a=Marshall%20Dudley>)
   * Date: Tue, 3 May 2005 07:08:32

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Ode Coyote wrote:

##  I don't recall any mention of using UV light one way or the other, but
since agyria is well known to be a photographic process, I can't imagine
that a frustrated researcher with an agenda wouldn't figure that out.

Where else have you seen it? I have never seen argyria referred to as a
photographic process except by me in this group or papers I have written, and
others in this group.  Do other researchers share this view?  Do you have any
urls?

Thanks,

Marshall