so before anyone thinks im making viruses, i downloaded this linux iso meant to be used as a rescue disc and it occured to me, if i use it to rescue a linux system, is it possible to get viruses on the disc, thus not being able to use it anymore?
In practice, rootkits and viruses for Linux aren't very common.
If you burn the ISO to a CD or DVD, it can't get "infected" later because for all practical purposes that sort of media is read-only. So it boils down to how much you trust the makers of that Linux distro not to put nasty stuff in it.