In many movies and TV shows, cyanide is portrayed as a deadly poison that causes almost instant death. But what actually happens once you take cyanide?

What is Cyanide?

Cyanide is a deadly poison that can be lethal if taken in a sufficient dose. The most common compound that is commonly used is Hydrogen cyanide (HCN). It can exist as a gas or a liquid, where it is a light blue color. Potassium cyanide (KCN) can exist as a salt (solid) (National Library of Medicine). Many common foods actually contain cyanide, including almonds, lima beans, some mushrooms, and the seeds of many fruits (NIH). It has been used throughout history as a poison, with one of the first instances being as a chemical warfare agent in World War I. It is also used in many pesticides, plastics, and for mining purposes (New York Department of Health).

How It Affects Humans

One of the most important functions of our body is cellular respiration. This is the process that provides our body with the energy it requires to function and move. It is a multi-stage process that breaks down sugars like glucose and uses oxygen in order to produce ATP, a type of energy used by the body, as well as carbon dioxide and water. Cyanide prevents this process from occurring, which, once it has spread, prohibits the body from making energy that it needs to survive (Britannica).

Cellular respiration occurs in the mitochondria, the organelle that makes energy. The first stage is called glycolysis, where the glucose is broken down into smaller sugars, making a small amount of energy. Next, it is taken through the Krebs Cycle, which, once again, creates a small amount of energy and a few important electron carriers (Khan Academy). Neither of these processes are affected by Cyanide, but the last process, the Electron Transport Chain, is affected.

The electron transport chain is a complicated series of steps that produces a large amount of ATP energy for the body. It begins with the electron carriers produced during the Krebs cycle. These carriers bring electrons to the electron transport chain where they are passed through a series of proteins found in the inner membrane of the dual-membrane mitochondria. The electrons allow these proteins to “pump” hydrogen (H+) ions from the center of the mitochondria, the matrix, into the space between the two membranes, where they later diffuse back into the matrix through an enzyme called ATP synthase. This enzyme functions similarly to a wind turbine that creates energy when H+ ions flow through. The oxygen that we breathe is used as an acceptor that allows electrons and H+ ions to bond with the oxygen, creating water (Brittanica).

With cyanide, however, the electrons are unable to be accepted by the oxygen. Cyanide binds to Complex IV (cytochrome c oxidase) in the electron transport chain that allows this oxygen to accept electrons, and it creates a blockade in the process. If the electrons cannot exit the electron transport chain via oxygen, the chain will eventually fill up and the process will halt, making the body unable to synthesize ATP energy that it uses for its processes.

Signs and Symptoms

If you are in contact with cyanide, you may experience the following symptoms: headache, anxiety, agitation, confusion, lethargy, seizures, and coma. Cardiovascular issues, lung injury, and nausea are also common. Recovery from such symptoms is very rare, and victims can be left with permanent effects. If exposed to a lethal dose of hydrogen cyanide gas, 2,500–5,000 mg•min/m3, death would be likely within the minute. Ingestion of a cyanide salt of 100-200mg would likely be fatal and would occur within a few minutes (Johns Hopkins Center for Health Security).

Cyanide is a very dangerous chemical that has lasting and immediate effects on the human body, and should be treated as such.

References

Graham, J., & Traylor, J. (2023, February 13). Cyanide Toxicity. Nih.gov; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK507796/

John Hopkins Center for Health Security. (2022). Cyanide Factsheet. https://centerforhealthsecurity.org/sites/default/files/2023-02/cyanide.pdf

Khan Academy. (2023). Khanacademy.org. https://www.khanacademy.org/login?continue=https%3A%2F%2Fpl.khanacademy.org%2Fscience%2Fhigh-school-biology%2Fhs-energy-and-transport%2Fhs-cellular-respiration%2Fa%2Fhs-cellular-respiration-review

New York State Department of Health. (2019). The facts about cyanides. Ny.gov. https://www.health.ny.gov/environmental/emergency/chemical_terrorism/cyanide_general.htm

Potassium Cyanide Powder Supplier | Stanford Advanced Materials. (n.d.). Www.samaterials.com. https://www.samaterials.com/potassium/2703-potassium-cyanide-powder.html