[tomp]

If we banned all uses of harmful substances, many things (e.g. spaceflight) wouldn't be possible (or at least much more expensive) (e.g. most hypergolic propellant used for fine maneuvring e.g. during docking are extremely poisonous - alternatives are being tested but aren't there yet).

[boobsbr]

Yeah, hydrazine came to my mind instantly.

That stuff is scary.