Poisoning

Poisoning is the damage caused when a toxic substance enters the body. The word comes from "poison," which refers to any chemical that can injure or kill a living thing if swallowed. Poisoning can happen through ingestion, inhalation, injection, or skin absorption. The field of toxicology studies the symptoms, mechanisms, diagnosis, and treatment of poisoning.

The symptoms that appear after contact with a poison depend on the level of exposure. Acute poisoning occurs when a living thing is exposed to a harmful substance once or several times over a short period, with symptoms showing up within 14 days. Chronic poisoning involves repeated exposure over a long time, with symptoms developing slowly or after a long delay. This often happens with poisons that build up in the body, like mercury, gadolinium, and lead.

In 2020, America's Poison Centers reported that 76.9% of recorded poison exposures were accidental, often from taking the wrong medicine or doubling a dose by mistake. The rest were deliberate or unexpected.

Some poisons are made for industry or warfare. Nerve gases are synthetic substances designed to harm living things; they can paralyze someone in seconds or stop organ function, leading to quick death. They are considered biologically derived neurotoxins that attack the nervous system. Cyanide, inhaled or swallowed, was used in gas chambers; it starves the body of energy by blocking enzymes in mitochondria that produce ATP. Injecting a very high concentration of potassium chloride, as in some U.S. executions, stops the heart by removing the cell potential needed for muscle contraction.

Most biocides, including pesticides, are meant to poison target organisms, but they can also cause acute or chronic poisoning in non-target organisms, including humans who apply them. For example, the herbicide 2,4-D mimics a plant hormone, making it toxic only to plants; it is not a poison but is classified as harmful.

Many substances are only indirectly toxic through a process called toxication. Methanol, or wood alcohol, is not poisonous itself, but the liver converts it into toxic formaldehyde and formic acid. Many drugs become toxic in the liver, and genetic differences in liver enzymes mean toxicity varies between people.

Safety agencies worldwide require pictograms on toxic substance labels, as set by the GHS. The hazard symbol for poison shows a human skull above two crossed bones. GHS precautionary statements warn users about dangerous features, and labels often include handling instructions, what to avoid mixing, and how to treat someone exposed. Poison control centers are available by phone or website to help diagnose, manage, and prevent poisoning.

If someone may have been exposed to a poison, medical help is strongly advised, especially from a poison control center. It helps to provide the patient's age, weight, any other drugs they take, and symptoms. Try to find out what was ingested, how much, and how long ago. Keep the pill bottle, medication package, or other container if possible. Treatment depends on the substance and may include activated charcoal, inducing vomiting, or diluting or neutralizing the poison.