Unless someone happened across a record of how to make it and thought they ought to...but I trust those who destroyed what was made that any traces of it have been stamped out.

[That's not to say someone couldn't make something else terrible in the same vein, but if you sit around worried about everyone making new terrible biochemical weapons, you're going to drive yourself to the brink.]

I suppose...my memories can be quite potent, in this regard. When our dreams are pushed to such lengths.