Why is cyanide poisoning lethal

After exposure, cyanide quickly enters the bloodstream. The body handles small amounts of cyanide differently than large amounts. In small doses, cyanide in the body can be changed into thiocyanate, which is less harmful and is excreted in urine.

In the body, cyanide in small amounts can also combine with another chemical to form vitamin B 12 , which helps maintain healthy nerve and red blood cells.

Large doses of cyanide prevent cells from using oxygen and eventually these cells die. The heart, respiratory system and central nervous system are most susceptible to cyanide poisoning. The health effects from high levels of cyanide exposure can begin in seconds to minutes. Some signs and symptoms of such exposures are:. The severity of health effects depends upon the route and duration of exposure, the dose, and the form of cyanide.

Moving away from the point of exposure to fresh air is an important first step in treating cyanide exposure. Cyanide poisoning can be further treated by medical professionals.

Often patients are given oxygen. Two antidotes sodium nitrite and sodium thiosulfate are usually used to stop the effects of serious cyanide poisoning. Other drugs may be necessary to control additional health effects of cyanide such as seizures. People who experience serious signs and symptoms will need immediate hospital care, especially individuals who have "passed out" or are unconscious. Any delay could result in death. While an elevated blood cyanide concentration may indicate that someone has been exposed to cyanide, laboratory testing for cyanide exposure will not be useful in making emergency treatment decisions.

A patient exposed to cyanide should not expect medical personnel to do these tests before treatment. Treatment should not be delayed if signs and symptoms are present and exposure is believed to have occurred. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Cyanide. Division of Toxicology, U. Department of Health and Human Services. Medical Management Guidelines for Hydrogen Cyanide.

Centers for Disease Control and Prevention. Emergency Preparedness and Response. Chemical Casualty Care Division. This fact sheet is based on the most current information. 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 swallowed, chemicals found in acetonitrile-based products that are used to remove artificial nails can produce cyanide when metabolized by the body.

Reports have indicated that during the Iran-Iraq War in the s, hydrogen cyanide gas may have been used along with other chemical agents against the inhabitants of the Kurdish city of Halabja in northern Iraq. How you could be exposed to cyanide You could 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. When present in air, it is usually in the form of 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. How cyanide works The extent of poisoning caused by cyanide depends on the amount of cyanide a person is exposed to, the route of exposure, and the length of time that a person is exposed.

Breathing cyanide gas causes the most harm, but swallowing 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 gas is less dense than air; so it will rise. Cyanide prevents the cells of the body from using 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 lot of oxygen. Immediate signs and symptoms of exposure to cyanide 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 signs and symptoms within minutes: Dizziness Headache Nausea and vomiting Rapid breathing Rapid heart rate Restlessness Weakness Exposure to a large amount of cyanide by any route may cause these other health effects as well: Convulsions Loss of consciousness Low blood pressure Lung injury Respiratory failure leading to death Slow heart rate Showing these signs and symptoms does not necessarily mean that a person has been exposed to cyanide.

Long-term health effects of exposure to cyanide Survivors of serious cyanide poisoning may develop heart, brain and nerve damage. How you can protect yourself, and what to do if you are exposed to cyanide Since breathing it is likely to be the primary route of exposure to cyanide, leave the area where the cyanide gas was released and get to fresh air. Quickly moving to an area where fresh air is available is highly effective in reducing exposure to cyanide gas.

If the cyanide gas was released outdoors, move away from the area where it was released. If you cannot get out of the area where the cyanide gas was released, stay as low to the ground as possible. If the release of cyanide gas was indoors, get out of the building.

For more information on evacuation during a chemical emergency, see Facts About Evacuation. For more information on sheltering in place during a chemical emergency, see Facts About Sheltering in Place. Fact sheet as PDF. Cyanide is a naturally occurring chemical, found in many plants, that has been used in conventional warfare and poisoning for 2 millennia.

It is highly lethal, whether inhaled as a gas, ingested in solid form, or absorbed through topical exposure. Two notorious incidents in recent history-the Jonestown Massacre in and the Tylenol poisonings in highlight the lethality of this poison.

First isolated in , cyanide is a compound composed of carbon triple bonded to nitrogen CN. Cyanide can be released from natural sources, including some foods, and it is contained in several industrial chemicals and in cigarette smoke.

It is also used in manufacturing and in pesticides. In medicine, cyanide can be found in the widely used anti-hypertensive, sodium nitroprusside, each molecule of which contains 5 molecules of cyanide. The most common cause of cyanide poisoning is smoke inhalation in fires.

The use of cyanide in warfare dates to the Franco-Prussian War , during which Napoleon III urged his troops to dip their bayonet tips in the poison. Roman Emperor Nero also used cyanide-containing cherry laurel water as a poison.

This poisonous compound poses an ongoing threat as a weapon of terrorism, whether it is delivered in oral form via sodium cyanide and potassium cyanide or as a gas via hydrogen cyanide and cyanogen chloride. Cyanide poisons the mitochondrial electron transport chain within cells and renders the body unable to derive energy adenosine triphosphate-ATP from oxygen.

Specifically, it binds to the a3 portion complex IV of cytochrome oxidase and prevents cells from using oxygen, causing rapid death. When ingested as sodium or potassium cyanide, the lethal dose is mg. Cyanide kills quickly: death occurs within seconds of a lethal dose of cyanide gas and within minutes of ingestion of a lethal dose of cyanide salt. The central nervous system CNS and cardiovascular systems are chiefly affected.

Signs and symptoms of cyanide poisoning include the following:. Cardiovascular : decreased inotropy, bradycardia followed by reflex tachycardia, hypotension, and pulmonary edema; and.