I've got poison bombs equipped as my lethal bomb type, but I'm a little wary using them around my allies, for fear that perhaps the poison would effect them as well.
It seems like my fellow assassins might be immune (seeing as I can generally throw one point blank and not be effected by it), but I'm not 100% sure. My survivability and theirs is sometimes inconsistent.
What about normal NPC companions, such as people I'm supposed to escort? Will they die if I throw poison at them? Not directly, mind you, that would be murder. I mean if they happen to be within the radius of my poisonous explosive device that was clearly thrown at a nearby hostile. Clearly.