Medical Definition of Cyanide
Cyanide: Poisoning with cyanide, a rapidly acting, potentially deadly chemical that can exist as a colorless gas, such as hydrogen cyanide (HCN) or cyanogen chloride (CNCl), or a crystal form such as sodium cyanide (NaCN) or potassium cyanide (KCN). Cyanide sometimes is described as having a "bitter almond" smell, but it does not always give off an odor, and not everyone can detect this odor. Cyanide is also known by the military designations AN (for hydrogen cyanide) and CK (for cyanogen chloride).
Cyanide is naturally present in some foods and in certain plants such as cassava. Cyanide is contained in cigarette smoke and the combustion products of synthetic materials such as plastics. 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 for electroplating, metal cleaning, and removing gold from its ore. Cyanide gas is used to exterminate pests and vermin in ships and buildings. If accidentally ingested (swallowed), chemicals found in acetonitrile-based products that are used to remove artificial nails can produce cyanide. Hydrogen cyanide, under the name Zyklon B, was used as a genocidal agent by the Germans in World War II.
People may be exposed to cyanide by breathing air, drinking water, eating food, or touching soil that contains cyanide. Cyanide enters water, soil, or air as a result of both natural processes and industrial activities. In air, cyanide is present mainly as gaseous hydrogen cyanide. Smoking cigarettes is probably one of the major sources of cyanide exposure for people who do not work in cyanide-related industries.
Poisoning caused by cyanide depends on the amount of cyanide a person is exposed to and the route and duration of exposure. Breathing cyanide gas causes the most harm, but ingesting cyanide can be toxic as well. Cyanide gas is most dangerous in enclosed places where the gas will be trapped. Cyanide gas evaporates and disperses quickly in open spaces, making it less harmful outdoors.
Cyanide prevents the cells of the body from getting oxygen. When this happens, the cells die. Cyanide is more harmful to the heart and brain than to other organs because the heart and brain use a great deal of oxygen.
People exposed to a small amount of cyanide by breathing it, absorbing it through their skin, or eating foods that contain it may have some or all of the following symptoms within minutes: rapid breathing, restlessness, dizziness, weakness, headache, nausea and vomiting, and rapid heart rate. Exposure to a large amount of cyanide by any route may cause these other health effects as well: convulsions, low blood pressure (hypotension), slow heart rate (bradycardia), loss of consciousness, lung injury and respiratory failure leading to death. Survivors of serious cyanide poisoning may develop heart and brain damage.
To protect oneself against cyanide:
Cyanide poisoning is treated with specific antidotes and supportive medical care in a hospital setting. The most important thing is for victims to seek medical treatment as soon as possible.
Last Editorial Review: 5/13/2016
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