Chemical weapons are special subtype of WMDs as the only subtype that was extensively used in wars between states. Technically any toxic chemical that can cause death, injury, temporary incapacitation or sensory irritation through chemical action can be considered chemical weapon. Many substances that are widely available in industry can be used as non-sophisticated chemical weapon making chemical weapons available for even for less advanced countries and non-state actors. While the robust taboo on their use arguably exists now and most countries joined Chemical Weapons Convention, which prohibits production, stockpiling and use of chemical weapons occasional incidents of use still appear in the world.