Friday, October 15, 2004

Where cyanide is found and how it is used

Since the days of ancient Rome, cyanide and the derivates of this highly toxic substance have been used as weapons. Nero used cherry laurel water, which contains cyanide as its principal toxic component, to poison members of his family and others who displeased him. Napoleon III proposed the use of cyanide to enhance the effectiveness of his soldiers` bayonets during the Franco-Prussian war3.
Although substances containing cyanide had been used for centuries as poisons, it was not until 1782 that cyanide itself was identified. It was first isolated from cherry laurel by the Swedish chemist Scheele, and in 1786 he was feared to be the first victim of this rapid poison in a laboratory accident. Later in 1795 Fontana investigated its mechanism of action, followed by Blakes`s attempts to antagonize its toxic effects3,4.
During World War I, in late 1915 and early 1916, the French were the only proponent for using cyanide and its derivative, hydrocyanic acid. This was made by distilling a concentrated solution of potassium cyanide with dilute sulfuric acid. Its use, however, proved to produce less than its desired effect. A highly volatile gas and lighter than air, hydrocyanic acid persisted for only a few minutes in the open air; this made it difficult to disperse a lethal concentration. The effect of cyanide were not cumulative. So these combined factor made hydrocyanic acid less effective as a weapon3.
About September 1916, the French tried another cyanide based poison, cyanogens chloride, which is heavier and less volatile than hydrocyanic acid and which had a cumulative effect on its victims. Cyanogens chloride was produced by chlorinating a saturated solution of potassium cyanide at 0ºC (32ºF). its toxicity was similar to that of hydrocyanic acid, but cyanogens chloride was more effective at low concentrations ( it irritated the eyes and lungs ). At high concentrations, cyanogens chloride is capable of killing by rapidly paralyzing the respiratory system`s nerve centre3.
At about the same time that the French launched cyanogens chloride, the Austrians introduced their own poisonous gas, which was derived from potassium cyanide and bromide. The resulting cyanogens bromide was highly volatile, nevertheless it had only a quarter of the volatile of hydrocyanic acid and was less toxic. Cyanogens bromide had a strong irritating effect on the conjunctiva and on the mucous membranes of the respiratory system. But, finally the Austrian abandoned its use. Cyanogens chloride can produce irritation of the eyes and mucous membranes similar to that produced by riot control agents3.
Hydrogen cyanide, under the name Zyklon B, was used as a genocidal agent by the German in World War II. The Nazis employed hydrocyanic acid adsorbed onto a dispersible pharmaceutical base (Zyklon B) to exterminate millions of civilians and enemy soldiers in the death camps. Zyklon B was a fumigant and rodenticide3-5.
In addition, cyanide is used by governments, terrorists , corporations, and individuals to achieve various economic, beneficial, humanitarian, or harmful ends. In 1978 near Port Kaituma, Guyana, the followers of reverend Jim Jones drank a grape-flavored drink mixed with cyanide, and more than 900 children and adult members of the People`s temple committed mass suicide3.
Reports have indicated that during the Iran-Iraq War in the 1980s, hydrogen cyanide gas may have been used in addition to other chemical agents against the inhabitants of the Kurdish city of Halabja in northern Iraq and the inhabitants of the Syrian city of Hama and possibly in Shahabad, Iran. Based on this recent history, acute cyanide poisoning continues to constitute a threat for U.S. soldiers in future conventional or non conventional conflicts3,6.
Cyanide is the agent used in “gas chambers” in which a cyanide salt is dropped into an acid to produce HCN. These chemicals –an acid and a cyanide salt- were found in several subway restrooms in Tokyo, Japan, in March 19953.
The cyanide have no therapeutic value, but in manufacturing, cyanide is used to make paper, textiles, and plastics. It is present in the chemicals used to develop photographs. Cyanide salts are used in metallurgy in a number of chemical processes, including electroplating, case hardening of iron and steel metal cleaning, and removing gold from its ore. Cyanide gas is used as a fumigating agent to exterminate other animal pests and insect in ships and buildings1,3,6-7.
Certain rare plants containing cyanide include apricot pits, wild cherry, peach, plum pits, corn (sorghum), chickpeas, cashew, chickpeas, some other fruits and vegetables contain cyanogenic (i.e., cyanide-forming) glycosides (such as amygdalin) that release hydrogen cyanide when chewed or digested. A type of potato called cassava contains cyanide too. Cassava is a staple in several tropical countries and is blamed for the high incidence of tropical ataxic neuropathy in these areas1,3,6,,8 . Beside that cyanide can be produced by certain bacteria, fungi, and algae. In the body, cyanide combines with chemical to form Vitamin B128. Cyanides are present at low concentrations in several naturally occurring environmental sources, it is not surprising that most animals have intrinsic biochemical pathways for detoxification of the cyanide ion7.
The supposed cancer-fighting substance called laetrile (made from apricot pits) used to be sold to desperate cancer patients as a cancer chemotherapeutic, have been responsible of the death of some patients who took this substance3,4,7.
Certain chemicals, after ingestion, can be changed by the body into cyanide. Most of these chemicals have been removed from the market, but some old artificial nail polish remover or chemicals found in acetonitrile-base products, solvents and plastics manufacturing solutions can contain these substances,7,9,10 . In 1989, the food and Drug Administration quarantined all fruit imported from Chile after traces of cyanide were found in 2 Chilean grapes9.
Combustion of synthetic product that contains carbon and nitrogen, such as pyrolysis of plastic and nitrile-based polymer fibers (synthetic fibers) can create cyanide fumes. Cigarette smoke contains cyanide; the nonsmoker averages 0.06 µg /mL of cyanide in blood, whereas the smoker has 0.17 µg/mL. The effects of cyanide and of carbon monoxide, also formed in fires, they both contribute to tissue hypoxia by different mechanisms. The two gases are major causes of combustion-related fatalities. In residential fires, cyanide poisoning may be more significant than has previously been esteemed. The short half-life of cyanide in blood contributes to the low concentration of cyanide found in fire victims when blood is checked after victims reach the hospital3.
From April 1988 to April 1989, a team of French investigators collected samples-on the scene-from 109 victims of residential fire in and around Paris, France. The data they gathered were compared with data from a control group (N=114) of individuals whose injuries were not caused by fire.
Blood cyanide concentrations were much higher in the fire victim than in the control group (Table 2 ) and victim who died had significantly higher levels ( > 5-fold) than victim who survived. Contrary to what previous researchers have concluded that cyanide may a few substances in contributing cause of death. Even it can be said that many deaths to cyanide poisoning is a mistakes, but the result from this study “suggest that cyanide poisoning may more predominant factors than carbon monoxide poisoning as the caused of death in some fire victims3,5,9.

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