Weapons of Mass Destruction...
include chemical and biological weapons in addition to nuclear weapons. Saddam has used chemical weapons, both against Iran and his own people on multiple occasions. That's a documented fact.
I've read that he may have used biological weapons, too, but don't have confirmation at the moment. It is certain that Iraq had a very active biological weapons program.
Saddam was caught trying to develop nuclear weapons in the early 1990s, as documented here.