Medical Aspects of Chemical Warfare (2008) - The Black Vault

Medical Aspects of Chemical WarfareTable 19-1 continuedRicin, amorphous and crystallineRussell’s viper venomSalmonella toxin, cytotoxin, enterotoxinSaxitoxinShiga toxinStaphylococcus aureus α-toxinStreptolysin OStrychnineTaipoxinTetanus toxinTetrodotoxinTextilotoxinTityustoxinTrichothecene Mycotoxin (T-2)VeratridineWestern diamondback rattlesnake venomcastor beans, the seeds of Ricinis communisVipera russelliSalmonella Typhimurium and S EnteritidisDinoflagellate marine algae, Gonyaulax catenella and G tamarensisEscherichia coli/Shigella dysenteriaeStaphyloccocus aureusStreptococcus pyogenesStryhnos nuxvomica bark or seedsaustralian taipan snake, Oxyuranus scutellatusClostridium tetani bacteriaPuffer fishes and certain salamandersaustralian common brown snake, Pseudonaja textilisBrazilian scorpion, Tityus serrulatusFusarial species of fungusliliaceaeCrotalus atroxand readily absorbed through dermal layers (posingcontact hazards), most are water soluble. Water-solubletoxins can be aerosolized for delivery to target populations,which allows toxin access to the more vulnerableinner surfaces of the lung. Aerosol particles between0.5 and 5 µm in diameter are typically retained withinthe lung, but smaller particles are not retained in theairway and most are exhaled. Particles between 5 to 15µm are generally sequestered in nasal mucosa or in thetrachea. A large percentage of aerosol particles largerthan 15 µm drop to the ground or onto flat surfaces inthe environment. Water-soluble toxins are generallynot volatile, and those particles falling onto the groundno longer pose a respiratory threat. 2Many cases of accidental exposure to toxins in humans,especially from marine toxins, occur by ingestion.Intoxication by agents such as tetrodotoxin (TTX;isolated from the Japanese puffer fish) or brevetoxin(PbTx), implicated in neurotoxic shellfish poisoning(NSP), suggest that water or food supplies could betargeted for large-scale delivery of weaponized toxinsto civilian populations. Several recent publicationshave presented mathematical models of toxin weaponsdelivered into food or water supplies. 3 These data suggestthat this means of toxin delivery would impose asignificant financial burden to diagnose and treat theaffected population, a compromise to key infrastructure,and a reallocation of resources to deliver cleansupplies to the effected population.Established ThreatsToxins of concern to the US military and the Departmentof Homeland Security comprise a groupof structurally diverse substances that share manyfeatures with chemical warfare agents. Toxins andchemical warfare agents interfere with importantbiological processes (eg, synaptic transmission, DNAreplication, and protein synthesis) and produce incapacitationand death following acute exposure. 4 Toxinsthat are generally considered to be battlefield or bioterroristthreats include anthrax, botulinum neurotoxin,staphylococcal enterotoxin B, T-2 mycotoxin, and ricin.These five biotoxins are thought to be most likely usedin the event of warfare or bioterrorism, although theyrepresent a small subset of all lethal toxins known. 5Potency, ease of production, stability, and prior historyof weaponization are all factors hostile forcesmust consider before deploying bioweapons. 4–6 TheCenters for Disease Control and Prevention (CDC)have designated anthrax and botulinum neurotoxinas category A threat agents, and staphylococcal enterotoxinB and ricin as category B agents (Table 19-2). 7 Category A agents are defined as those that “canbe easily disseminated or transmitted from personto person; result in high mortality rates and have thepotential for major public health impact; might causepublic panic and social disruption and require specialaction for public health preparedness.” 7 Category Bagents are defined as those that “are moderately easyto disseminate; result in moderate morbidity rates andlow mortality rates; and require specific enhancementsof CDC’s diagnostic capacity and enhanced diseasesurveillance.” 7 For example, T-2 mycotoxin, a categoryB agent, is specifically addressed by the CDC as a selectagent and toxin and additionally regarded as a threatbecause of its documented use in Laos, Vietnam, andCambodia during 1975–1978. 8 Category C agents, thethird highest priority, “include emerging pathogensthat could be engineered for mass dissemination in616