Conductive Thread - non toxic?
I believe that the thread sold by Sparkfun is made by ShieldEx. According to the material safety data sheet for the silver-coated thread:


  Eye Protection: SHIELDEX® silver
  coated non-woven/or/woven nylon fabric
  and yarns does not cause significant
  eye irritation or eye toxicity
  requiring special protection. Use good
  industrial practice to avoid eye
  contact.
  
  Skin Protection: SHIELDEX®
  silver-coated non-woven/or/woven nylon
  fabric and yarns does not present a
  significant skin concern requiring
  special protection.


Comprehensive review of other conductive threads