thus far I've had no dwarven casualties, but keep in mind that this is testing on a fresh fort when the dwarves still have all their clothes. In later forts where clothes have deteriorated/gone missing, chances could be pretty high, but as long as they are well clothed I don't think there's anything to worry about but freak accidents. And as for syndromes in workshop, I think they're in stasis, as it's shown as a "stack" of the liquid, I.e. "Giant Cave Spider Venom[300]". If anyone else wants to play around with it, here's the code I used for the workshop. It's probably easiest to just assign it to the screw press, though we should probably test distribution field with larger and smaller workshops.
[REACTION:POISON]
[NAME:poison an area]
[BUILDING:POISON:CUSTOM_P]
[PRODUCT:100:3000:LIQUID_MISC:NONE:CREATURE_MAT:SCORPION_DESERT_GIANT:POISON]
[SKILL:COOKING]
I'm just going to assume that most people here know enough about modding to change the building and add the reaction to the entity file.