Chemistry Blog #3: The Chemistry of Poison
Kathryn Ahearne
Two of the most common poisons that have been used throughout history to kill poeple are Cyanide and Arsenic. Both of these poisons are used less today, however, due to advancements in science and chemistry that we have made that make it possible to detect Cyanide and Arsenic poisoning in a person as well as reverse its effects on the body. Although there are many similarities in the history and effects of these poisons, there are also many differences between the two.
Cyanide, also known as the polyatomic ion CN– is one of the deadliest poisons known to man and has been used for centuries as a method to kill people and animals. Cyanide was first identified in 1782 by the chemist Scheele and has since been used for a variety of reasons including rat poison and pest control as well as chemical warfare in WWI. The seeds of many fruits contain a substance known as amygdalin which, when it comes into contact with stomach acid produces cyanide. When someone ingests cyanide, it inhibits the cytochrome oxidase enzyme, which then prevents the body’s cells from using oxygen. The effects of this include: Dizziness and headache, nausea and vomiting, rapid breathing and heart rate, low blood pressure, loss of consciousness, respiratory failure, and then convulsions and death. The effects of cyanide can be somewhat reversed through compounds of nitrite which remove the cyanide from cytochrome oxidase, however, cyanide is a very fast acting poison and often the effects of it are too severe for doctors to help the patient by the time they get to the doctor.
Arsenic is another poison that has been around for a very long time. White arsenic was used by many poisoners throughout history and has also been nicknamed, “The King of Poisons.” There are even documents of ancient Greeks and Romans using arsenic as poison in myths and stories. During the 17th and 18th centuries arsenic was used very often as a poison as well until advancements in chemistry made it easier to test for arsenic poisoning. The chemical formula for arsenic is As2O3 and its technical name is Arsenic (III) Oxide. In order to test for Arsenic poison, the Marsh Test is used. In this test, a reaction between the sample, zinc and acid is performed. If the sample contains arsenic, arsenic gas is formed when this reaction takes place. Then, upon cooling, scientists look for a silver-black layer of deposit to form. More recently, scientists have developed methods of detection involving spectroscopy that are now used more frequently. The effects of arsenic poison include headache, discoloration of nails, vomiting and metallic taste, breath smells of garlic, stomach pain and diarrhea, hair loss, convulsions, coma, and death. Arsenic interferes with cell enzymes as well as respiration and mitosis which then causes all of the above symptoms to occur.
These are very interesting topics to compare due to how similar they are in their history and use. Both were used as rat poison at some point, both have been used as poisons for a very long time and both of them are seen less today due to the advancements in medicine and chemistry we have made that allow for detection and reversal of the effects of the poison. Another interesting topic of comparison to these two articles about poison is the use of drugs and alcohol by people in the world and the effects that these drugs have on individuals’ bodies. For example, alcohol, which is used by individuals to feel drunk, affects the body in certain ways based on its chemical makeup, which is similar to the way that poisons affect the body based on their chemical makeup. The chemical present in alcohol is ethanol, or C2H6O, which limits the actions of neurotransmitters in the brain. It is interesting that many of the side effects of these drugs and poisons are the same. For example, almost all of them include headache and stomach ache or vomiting. This is perhaps because these are two of the bodies primary responses to poison or unwanted substances in the body and mind.
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