And Duck, 
chemical is in reference to chemicals, like poison gas and stuff.
Biological is in reference to something living. A biological weapon could be anything from a dog with a bomb strapped to its back [Horrible, but was tested during WW2], to a genetically-engineered disease, to just rubbing one's face on a blanket and giving it to Indians, and infecting them all with Small Pox.

And what do you mean? You can't do poop if they can't do poop, and if you don't know something is wrong.