I once had to transport a patient that had done the bleach/ammonia thing. Funny, I was the only guy in the responding units (ambulance, fire truck, and a paramedic ambulance unit) that had the necessary background to say "Hey, you know, I'm pretty sure that was chlorine gas he decided to fumigate himself with - you know, the stuff from WW1." I got a bunch of blank stares in return. (Please don't construe this as a slam against medics or firefighters - the ones that do get additional training are WAY smarter than I am in that field.)

The patinet turned out OK, AFAIK.

Cyano just means a carbon and nitrogen linked together (Blast, correct me if I'm wrong). There's stuff in the human body that uses cyano groups, but as Blast said, when they're bound with other things they tend to be less offensive.