What is poison? Do not rush to answer, it is not so obvious.
The great Paracelsus (1493–1541), who lived nearly five centuries ago and was a man of the Renaissance who dared to explore the hidden mysteries of human nature, did not overlook the topic of poisons. After deep research, he formulated the conclusion: “Sola dosis facit venenum,” which translates from Latin as “Only the dose makes the poison.” In a broader form, his thought sounds like this: “All things are poison, and nothing is without poison; only the dose makes a thing non-poisonous.”
It cannot be said that nothing has changed in toxicology since then, but we have progressed very little in terms of definition.
In the early 19th century, the defining characteristic of poisons was their ability to harm in small amounts. In 1814, the founder of toxicology, Spanish physician Mathieu Orfila, wrote: “Poison is a substance which, in small quantity, when brought into contact with a living organism, destroys health or life.” However, the definition of what constituted a “small quantity” was not clarified.
Poison is everywhere
In the end, under certain conditions, any substance can become a poison. Today, about 10 million chemical compounds are known worldwide. Of these, more than 60,000 are widely used in households, medicine, industry, and agriculture. This number increases by about 1,000 new substances annually. There is reason to believe that, under certain conditions, any of them could pose serious harm to health, even because water and oxygen can poison us.
“35-year-old American Ashley Miller died from… water poisoning. No, she was not swimming in the Seine during the Olympic Games. She felt dehydrated after boating on a hot day. According to her brother, she drank about two liters of pure drinking water from a bottle in less than 30 minutes, then lost consciousness and soon died. The doctors’ verdict: death from water intoxication, specifically due to a set of bodily reactions triggered by a sharp drop in potassium levels in her blood serum.”
“Oxygen is also a poison if in excess. The oxidation of chemicals in our bodies is a finely-tuned system. During inhalation, oxygen mixed with other atmospheric gases enters the lungs. Oxygen attaches to red blood cells and is distributed throughout the body. Oxidative reactions in cells produce carbon dioxide, which is transported to the lungs by the blood and exhaled. An excess of oxygen complicates the removal of carbon dioxide. Due to the unusual regime, the whole chain breaks down: lung ventilation is impaired, causing edema and hemorrhages in internal organs, seizures, and loss of consciousness. In severe cases, the heart stops, leading to death.”
Not just the dose
The cases with water and oxygen vividly illustrate the relevance of Paracelsus’ maxim about the importance of dose. However, modern toxicologists assert that focusing solely on dose as the determining factor for a substance’s harmfulness is incorrect.
A living organism is a complex biological system, not just a receiver of a certain amount of substance with predictable effects. The outcome is influenced by individual factors: age, genetic makeup, circadian rhythms, lifestyle, current health, and sensitivity to various substances. Moreover, the toxicity of a specific substance depends on the method and duration of exposure.
The paths of poison are known
The speed at which poison begins to affect the body largely depends on how it enters. Whether by chance or not, poisons have found the same entryways as medicines. There are, with slight generalization, only four of these methods.
Swallowing, when poison is absorbed in the gastrointestinal tract, like food or liquid.
Inhalation, when poison in the form of gas or fine dust enters the lungs and passes through the alveoli into the bloodstream.
Through the skin, when poison penetrates the skin pores to reach the subcutaneous tissues and enter the bloodstream.
Injections: intravenous and intramuscular, the first going directly into the blood, the second into muscle tissue first.
Once inside the body, poisons disrupt its functions, usually through chemical reactions or actions on a molecular level.
Intravenous injection works the fastest, followed by inhalation, abdominal injection, intramuscular injection, swallowing, and finally absorption through the skin.
There are poisons that act very quickly regardless of how they enter the body, such as the famous cyanides. However, poisons also include heavy metals like lead (Pb) or strontium (Sr), which can accumulate in certain tissues over years. These metals exploit the natural bone formation mechanism and integrate into the bone structure similarly to calcium.
The issue of poisons
Medical professionals have managed to accept the complexity of defining poisons and agreed to stop debating the topic. They call poisons harmful substances that cause poisoning or death when introduced into the body in the same small quantity. For those who find the criterion of “small quantity” too vague, it is recommended to understand the concept of “toxicity.”
Toxicity is the property of a chemical compound to cause damage or death to a living organism when it affects it. The less substance needed to damage a biosystem, the more toxic it is.
Poisons, toxins, and toxicants
There are many classifications of poisons – practical, clinical, forensic. Specialists categorize toxic substances in ways that help them solve specific tasks: doctors to save lives, forensic experts to uncover crimes, and governments to regulate usage, storage, and transportation.
The simplest classification of poisons is by origin. If the poison is of biogenic origin, meaning it is produced by living organisms – bacteria, fungi, plants, or animals – it is called a toxin.
A poison of non-biogenic origin is called a toxicant. This group includes heavy metals, compounds of arsenic, fluorine, bromine, phosphorus, mercury, chlorine, sulfur and nitrogen oxides, hydrocarbons and their chloro- and fluoroderivatives, aldehydes, alcohols, and many more. In some sources, the term “toxicant” is used more broadly, including poisons in general.
Toxins against nerves, cells, and blood
The way each toxin interacts with the body is biochemically unique, but toxins can generally be divided into three large groups, based on which system of the body they target.
- Neurotoxins “shut down” the victim’s nervous system. Under the influence of the poison, nerve cells stop transmitting signals that control the entire body. Without these signals, organs fail – the heart stops beating, and the lungs stop breathing. Destroyed nerve cells result in paralysis, seizures, death. Many everyday substances we forget are toxic, such as ethyl alcohol, nicotine, monosodium glutamate, and botulinum toxin (used in Botox injections and causing botulism). Many famous poisons are also neurotoxins, like tetrodotoxin (from the pufferfish) or alpha-latrotoxin (from the black widow spider).
- Cytotoxins attack tissue cells, slowing down enzyme action, disrupting cellular metabolism, modifying cell DNA, and blocking cell division. In the end, they kill cells. This group includes the poisons of many snakes, such as cobras and vipers. At the bite site, the poison causes pain, swelling, bleeding, and blistering followed by necrosis (tissue death), but this is not all. As it spreads through the body, the poison provokes internal bleeding and organ damage.
- Hemotoxins target the blood, destroying red blood cells responsible for supplying oxygen to tissues. This type of poison is used by rattlesnakes and copperheads against their prey. Bacteria like staphylococci and streptococci also release hemotoxins.
Antidotes
For followers of Paracelsus’ maxim that everything is poison, there is good news: everything can also become an antidote. For example, in cases of methanol poisoning, one should drink… ethanol.
The oldest known antidote recipe was created by the court physician of Pontic King Mithridates VI Eupator (2nd–1st century BC). The mixture contained 54 components, including opium, various plants, and snakes, ground into powder. The king, paranoid about being poisoned, took it for many years, starting with a few grains and gradually increasing the dose. The result was a tolerance to many poisons.
“The famous Mithridates antidote wins in antiquity but falls short in the number of ingredients. The leader in that respect is the medieval antidote of Mattiomos (17th century), described as containing about 250 components.”
The term “antidote” was first used by the Roman physician Claudius Galen, a follower of Hippocrates. In his work dedicated to antidotes, he classified toxic substances into cooling, warming, and decaying categories. For treatment, he suggested “using opposites against opposites.” This principle by Galen largely holds true today: antidotes are selected based on their ability to counteract and neutralize the poison. The simplest antidotes bind with poisons, forming insoluble compounds, which reduces the absorption of poison into the bloodstream from the gastrointestinal tract. More complex antidotes neutralize the poison on a deeper level.
The antidote for the poison of the death cap mushroom is the dye indocyanine green (its effect was discovered last year; there was no antidote before). For heavy metal compounds, arsenic, mercury, lead, and copper, the drug unithiol is used, forming non-toxic, water-soluble compounds with the poisons. Hydrocyanic acid and cyanides are neutralized with amyl nitrite, which temporarily binds the poison ions, forming non-toxic compounds.
A new step in the fight against poisons came with the creation of synthetic atropine in the 1960s, which did not interact with the poison itself but instead eliminated the effects of its action on the body. Atropine proved to be an excellent antidote against the effects of organophosphorus chemical weapons (OPCs).
A Bit of Hope
It’s impossible to finish the story of poisons. Countless incredible facts, fascinating stories, and scientific discoveries lie ahead, once we start exploring this topic. The only thing that might dampen the joy of literary immersion into the world of poisons is the refrain Memento mori.
However, a comforting thought could be the dangerous and highly venomous striped scorpion. No antidote exists for its sting; the victim faces death from anaphylactic shock or lung edema, but… it was recently discovered that one component of its venom has shown remarkable potential in fighting malignant brain tumors, and scientists have developed a prototype drug based on it to treat autoimmune diseases and cancer. See, the story of poison can indeed have a positive ending.
