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Crit Care Clin 21 (2005) 691 – 705

Cyanides
Anthony P. Morocco, MD
Guam Memorial Hospital, Department of Emergency Medicine, 850 Gov. Carlos Camacho Road, Oka, Tamuning, Guam 96911

Perhaps no other poison is so universally recognized as cyanide. Since antiquity, the lethality of cyanide-containing plants has been well known. The Roman Emperor Nero dispatched his enemies with cyanogeniccherry laurel water, and other forms of cyanide have since been used by common murderers and militaries alike [1]. Hydrogen cyanide (HCN) was first isolated in 1782 by Scheele, who later died after being poisoned by the substance. The name cyanide is derived from the colorful Prussian blue from which HCN (also called prussic acid) was first synthesized [2]. Massive quantities of cyanides areproduced in industry every year, for use in metal extraction, electroplating, pesticides, metal hardening, photography, printing, dyeing, and many other manufacturing processes. In addition, cyanogenic (cyanide-forming) compounds such as amygdalin are naturally occurring in many Prunus species seeds and fruit pits, including bitter almonds, apricots, chokeberries, and apples, and in other common foodsources such as lima beans and cassava [3]. Cyanides are also produced during the combustion of many organic compounds [4]. Battlefield use of cyanides was proposed by Napoleon III during the FrancoPrussian war, to improve the lethality of bayonets. The French introduced gaseous HCN to World War I in 1915, and used 4000 tons in battle. However, it was found to be a relatively poor weapon due to itspoor persistence in open battlefields and difficulty in delivering large amounts in small artillery shells, and the Germans soon equipped their soldiers with gas masks that filtered the cyanide [5]. French attempts at an improved warfare agent resulted in the introduction of cyanogen chloride in 1916, which had the advantages of lower volatility and the ability to cause additional toxicity (mucousmembrane irritation and lung injury)

E-mail address: morocco@pobox.com 0749-0704/05/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.ccc.2005.06.002 criticalcare.theclinics.com

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at lower concentrations. A related compound, cyanogen bromide, was simultaneously introduced by Austria, but was difficult to use and subsequently abandoned. Germany didnot use cyanide during the First World War, but it did infamously use HCN, in the form of the fumigant Zyklon B, to exterminate millions of Jews and other prisoners during the Second World War. Japan may have also used cyanide against the Chinese during this era. Cyanide has since been reportedly used in the 1980s in the Iran–Iraq war, against the Kurds in Halabja, and in the Syrian city of Hama[1]. Numerous well-publicized incidents resulting in deaths, both intentional and unintentional, have occurred due to nonmilitary uses of cyanide. A mixture of toxic gases including methyl isocyanate and cyanides was responsible for up to 5000 deaths and 200,000 injuries in the Bhopal, India, chemical plant disaster [6]. In 1978, a cyanide-laced drink was used in the mass suicide of 913 followersof the Reverend Jim Jones in Jonestown, Guyana. Several well-publicized murder plots have involved cyanide-laced food or commercial products, including the adulteration of acetaminophen capsules that killed seven Chicagoans in 1982 [7]. HCN has also been used in the ‘‘gas chamber’’ for prisoner executions in the United States. Given its notorious history and notoriety as a poison, it is notsurprising that terrorists have identified cyanide as a valuable addition to their arsenals. The 1993 World Trade Center bombers may have attempted to incorporate cyanide into their attack. Although the use of sarin nerve agent in the Tokyo subway in 1995 was well publicized, less well known is that containers of cyanide precursors were discovered in subway bathrooms after the attack. More recently,...