Here is a bit from a chapter on health for my platinum book.
There are several caustics involved in noble metal printing.  One of 
the most common is potassium oxalate.  Another common form of 
potassium oxalate when dissolved in water is oxalic acid, which has an 
OSHA PEL of 1 mg/m3 for airborne contaminants.   This is also a skin 
hazard due to the caustic nature of the material.  If ingested, or 
absorbed through the lungs or skin, damage may result to the kidneys 
and liver as a systemic toxin.  This compound can be controlled by 
good chemical hygiene, as in use of gloves or tones to prevent skin 
contact and good ventilation in the workroom.
This information was privided to me by Howard Etkind.  There is also a
web site that list hazards of many chemicals used by artist. Michael
McCann, Ph.D runs a world wide web site for the Center for 
Safety in the Arts at http://artswire.org:70/1/csa.
Judy Seigel wrote:
> 
> This came to me.  I can't answer it, but perhaps someone else can.
> 
> ---------- Forwarded message ----------
> Date: Wed, 13 May 1998 23:52:15 EDT
> From: V6263 <V6263@aol.com>
> To: jseigel@panix.com
> Subject: Potassium Oxalate Hazards
> 
> Can someone tell me in what ways potassium oxalate is toxic and what might be
> done to reduce these hazards?
-- Eric J. Neilsen 505-758-8868 http://laplaza.org/~ejnasn