Sorry, but they weren't. If you are referring to the 500 sarin canisters then they were not lethal at all. Look, I was standing right there when they were drilled and tested and the chemist made the statement "You'd have to drink this to get sick." It was about 40 canisters and we were being directed to more on a regular basis with the same results. These reports went directly the Gen Casey. But, let me ask you this, does it make any sense that having found 500 lethal sarin canisters the White House, or the Pentagon, or the Republican leadership would have simply sat on that information. It simply doesn't follow. Do you wonder why the White House and Pentago have been so quiet on the Santorum claims?
According to this Al-Reuters article, it was sarin AND mustard gas. The mustard gas being extremely lethal (not that I would take a sip of old sarin...)
http://www.freerepublic.com/focus/f-news/1658384/posts