The last ten years have seen a resurgence in the socio-political focus on biological weapons (BWs) as a result of a perceived increase in the threat from nation-state and terrorist quarters. The formation of the Ad Hoc Committee, under the chairmanship of Ambassador Tibor Toth, to develop the 1975 Biological Weapons and Toxins Convention into a more effective and pragmatic international tool for combating the future threat of BWs has highlighted many issues, not least the difficulty of making informed threat assessments/risk stratifications in this field. There is also a vast corpus re-inforcing the potential of various microorganisms to be weaponized. The open literature has, by and large, focused on the hostile use of replicating biological agents: bacteria, viruses and rickettsiae. However, biological toxins have also been weaponized for assassination and mass destruction. The huge repertoire of biological toxins, coupled with their unique properties, evolving developments in toxin biomedical research and the complexity of the associated science necessitate a balanced understanding of their peaceful uses and potential misapplication on the part of those involved in policy decisions within this area. This article concludes that threat assessments of toxins as potential BWs will require a network of interdisciplinary expertise that crosses traditional boundaries and areas of responsibilities, with access to classified and unrestricted information, in order to tackle the evolving asymmetry of capabilities and motivation.