The Biological and Toxin Weapons Convention (BTWC), which went into effect in 1975, has aims similar to those of the CWC but is directed toward biological weapons.  It, too, is built around a general purpose criterion.  Although established long before the CWC, the parties to the BTWC have thus far not been able to agree on verification and inspection mechanisms, and there is no multilateral (international) administrative structure comparable with the OPCW.  The two conventions overlap in that toxins produced by microorganisms are also chemicals within the meaning of the CWC.