safe ways to etch at home for printmaking?

I’ve heard of some safe ways to etch a plate without using acid. I was wondering if there is any way I could make safe prints at home without exhaust fans or health concerns, one that I can etch with, I have no problem etching something overnight or over a period of a few days. I’m more concerned with the ability to do it at home safely than I am with speed of etch. For instance, I heard of someone who used ordinary tap water (but I don’t know if this is true)…Just curious if anyone has tried something like this. I am a safety FREAK, so I want something that is super safe. I normally use zinc plates, but I have no problem using copper ones if need be.