People have used poison throughout history for various purposes: to hunt animals for food, to treat disease, and to accomplish nefarious goals such as assassination and assassination.
But what is a poison? Do all toxins work the same way? Does the amount of poison matter in terms of its toxicity?
I’m a toxicologist which studies how chemicals affect human health, especially when they cause harmful effects. As a fan of mystery and detective stories, which often use poison, I’ve noticed a few poisons that pop up repeatedly in books, television, and movies. How they actually work is just as fascinating as how they are used in fiction for evil purposes.
What is a Poison?
The 16th century physician-alchemist Paracelsus, considered the father of toxicology, once wrote: “What is there that is not poison? All things are poison and nothing is without poison. Only the dose determines that something is not poison.” According to this adage, any substance can be a poison in the right amount.
Many people deliberately expose themselves to chemicals such as ethanol through alcoholic beverages, nicotine through tobacco products, and botulinum toxin through botox treatments at relatively low doses and experience minimal adverse effects. However at sufficiently high doses, these chemicals can be deadly. The body’s response often depends on how the chemical interacts with receptors in or on the surface of cells, or how it binds to enzymes used for biological processes. Often higher concentrations of the substance lead to stronger reactions.
Despite Paracelsus’ statement, the term “poison” is often reserved in popular culture for chemical compounds not normally found in everyday life and which can lead to adverse health effects even in relatively small amounts.
Poisons in books, TV and film
New writers and television and film screenwriters have exploited numerous poisons in their works, including those that are chemical elements, such as arsenic And poloniumand that come from animals, such as snake venom And puffer fish poison. Many poisons derived from plants have also been used in fiction for nefarious purposes.
In the AMC TV series “Break badchemistry teacher Walter White uses a compound called ricin to kill businesswoman Lydia Rodarte-Quayle. Ricin is a very powerful poison derived from the castor bean Ricinus communis and can be especially fatal if inhaled. Once this compound enters a cell, it becomes damages a structure called a ribosome that is responsible for synthesizing proteins essential for cell function. Ingestion of ricin can cause intestinal bleeding, organ damage, and death.
Sometimes certain organs are much more sensitive to the effects of a poison. Doctors use digitalis drugs such as digoxin, which are derived from members of the foxglove family of plants, to treat congestive heart failure and heart rhythm problems. However, when administered in high enough doses, they can lead to heart failure and death. By interfering with a protein in heart cells called the sodium-potassium pumpthey can decrease the rate of electrical impulses in the heart and increase the strength of the contractions. This can result in a dangerous type of irregular heartbeat called ventricular fibrillation and can lead to death.
The villain of the James Bond movie “Casino royaleLe Chiffre has his girlfriend try to kill Bond by poisoning his martini with digitalis. At high doses, digitalis drugs can alter the activity of the autonomic nervous system, which controls unconscious bodily functions such as the pumping of the heart.
TV characters are not immune to the dangers of poisonous mushrooms. A particularly powerful fungus, Amanita Verna, is known as the “destroying angel”. In the ITV TV series “Midsomer murders“Evenelyn Pope, puppet show owner and supposedly upstanding citizen, uses this mushroom to fatally poison Chef Tristan Goodfellow as part of her murder spree of the heirs of an estate. This mushroom contains several chemicals called amatoxins thought to inhibit the activity of a specific enzyme critical for the production of messenger RNAor mRNA, a molecule essential for protein synthesis in cells. Because ingested amatoxins primarily target the liver, these toxins can seriously interfere with the liver’s ability to repair itself, leading to a loss of function that will be fatal without a liver transplant.
Another very popular poison in detective and mystery stories is strychnine. In the Agatha Christie Story “The mysterious affair at Styles”, Alfred Inglethorp and his lover Evelyn Howard use this poison to kill Inglethorp’s wife and wealthy manor, Emily Inglethorp.
Strychnine, which comes from seeds of the Strychnos nux vomica tree, affects the nervous system by blocking a neurotransmitter called glycine in the spinal cord and brain stem. Normally, glycine slows the activity of neurons and prevents muscle contractions. By blocking glycine, strychnine intake can result in over-activation of neurons and muscles, leading to a series of whole-body muscle spasms that can become so intense as to cause respiratory arrest and death.
There are many more toxins in nature than described here. Aside from potentially increasing the enjoyment of detective and mystery stories, understanding the mechanisms of how these toxins work can provide an additional appreciation for the complexity of the effects foreign chemicals have on the human body.