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

Medical Aspects of Chemical Warfarestates to judicially execute murderers provide informationon the effect of HCN. In US gas chambers HCNwas usually released by dropping a bag of sodium cyanideinto sulfuric acid. Unconsciousness was thoughtto be instant, with death following in 5 to 10 minutes.In 1994 District Judge Marilyn Hall Patel ruled that thegas chamber was an inhumane method of punishmentand outlawed its practice in California. Two years laterthe 9th US Ciruit Court of Appeals supported Patel’sdecision and ruled that gas chambers violated theEighth Amendment to the Constitution because of thehorrible pain observed for several minutes. However,in several states, death row inmates still have the rightto choose the gas chamber over lethal injection, asWalter LeGrand did in Arizona in 1999.Cyanide has often been used by individuals andgroups to commit suicide. 13 One of the most notoriousof such events happened in 1978 near Port Kaituma,Guyana, when the followers of Jim Jones drank agrape-flavored drink laced with cyanide, resulting inthe deaths of more than 900 children and adults. 14Cyanide Sources and Accidental PoisoningAlthough there are many chemical forms of cyanide,HCN (or the cyanide anion CN - ) is the primarytoxic agent, regardless of its origin. Military personneland civilians may be exposed to common naturaland anthropogenic sources of cyanide through edibleand nonedible plants, industrial operations, fires, andcigarette smoke. Ongoing low-level cyanide exposuresare managed by the body through reaction pathwaysthat detoxify amounts in excess of biological tolerances.Much of the medical information on cyanide poisoninghas come from civilian experiences of poisoning, fires,and industrial accidents.HCN is released into the atmosphere from volcanoes,plants, bacteria, and fungi. 15–21 However,the primary natural source of cyanide poisoning inhumans and animals is from plants. Over 2,000 plantspecies, including edible fruits and vegetables, containcyanogenic glycosides, which can release cyanidewhen ingested. 18,22,23 Rapid hydrolysis of cyanogenicglycosides and release of HCN occurs when the plantcell structure is disrupted. Thus consumption of improperlyprocessed plants with cyanogen-containingglycosides will release HCN and may result in illnessor death. Some common cyanogenic edible plantsreported to cause cyanide poisoning include cassava,sorghum, sweet potatoes, yams, maize, millet, bamboo,sugarcane, peas, lima beans, soybeans, almond kernels,lemons, limes, apples, pears, peach, chokecherries,apricots, prunes, and plums. 18,22–30 Cassava (manioc)and sorghum are staple foods for hundreds of millionsof people in many tropical countries and are blamedin part for the high incidence of central and peripheralneuropathies in those areas. 31 Known cyanogenicglycosides in plants include amygdalin, linamarin,prunasin, dhurrin, lotaustralin, and taxiphyllin.Worldwide manufacturing of cyanide to supportindustrial and agricultural demand is in the rangeof 2.5 million US tons annually. In industries usingcyanide, occupational exposures occur primarily bythe dermal and inhalation routes. Nonindustrial accidentalexposures of clinical significance are typicallyassociated with commercial fires involving the burningof plastics. 32,33Inhalation of tobacco smoke, another source ofcyanide, has been associated with tobacco amblyopia,a syndrome of visual failure occurring in associationwith the use of tobacco, thought to result from nutritionalor idiopathic deficiencies in certain detoxificationmechanisms, particularly those that target thecyanide component of tobacco smoke. 34 Cyanidelevels in smokers versus nonsmokers are often usedas a sensitivity test in analytical methods for determinationof cyanide or its metabolites in biologicalfluids. 35 HCN concentrations in inhaled smoke fromUS-manufactured cigarettes range from 10 to 400 µgper cigarette. In non–US-manufactured cigarettes,cyanide concentrations range from 280 to 550 µg percigarette in inhaled smoke and from 53 to 111 µg percigarette in second-hand smoke. 15,36–38 Cyanide hasalso been found to be a metabolic product of certainpharmacological preparations such as laetrile, nitroprusside,and succinonitrile. Some of these formulationshave caused cyanide poisoning, in some cases resulting21, 39–43in death.BIOCHEMICAL BASIS FOR POISONINGCyanide is known to bind and inactivate severalenzymes, particularly those containing iron in theferric (Fe 3+ ) state and cobalt. It is thought to exert itsultimate lethal effect of histotoxic anoxia by bindingto the active site of cytochrome c oxidase, the terminalprotein in the electron transport chain located withinmitochondrial membranes (Figure 11-1). By this means,cyanide prevents the transfer of electrons to molecularoxygen. Thus, despite the presence of oxygen in theblood, it cannot be utilized toward adenosine triphosphate(ATP) generation, thereby stopping aerobic cellmetabolism. 44,45 Initially cells attempt to replenish theATP energy source through glycolysis, but the replenishmentis short lived, particularly in the metabolically374