Toxicology

Definition:

Toxicology is the scientific study of the effects of poisonous substances on living organisms, including:

• Physicochemical properties: Structure, chemical properties, degradation, absorption, metabolism, and excretion of toxins.

• Mechanism of action: How toxins affect the body at the cellular, tissue, organ, and whole-body levels.

• Symptoms of poisoning: Signs, symptoms, and progression of poisoning.

• Diagnosis and treatment of poisoning: Methods of diagnosis to identify the type of toxin and the severity of poisoning, treatment methods, and rehabilitation.

• Prevention of poisoning: Measures to prevent poisoning such as controlling the source of toxins, protecting health, and educating people about toxic substances.

Roles of Toxicology:

• Protecting human health: Establishing hygiene standards for the environment, food safety, and developing methods for preventing and treating poisoning.

• Supporting medical practice: Diagnosing and treating diseases related to toxins, researching and developing antidotes.

• Environmental protection: Studying the effects of toxins on the environment and developing solutions to control pollution.

• Occupational safety: Assessing the risks of toxic hazards in the workplace and implementing occupational safety measures.

Classification of Toxicity:

• Based on lethal dose:

• Highly toxic (LD50 < 5 mg/kg): Toxins with very low lethal doses, only a small amount can be fatal. Examples: Cyanide, Strychnine.

• Toxic (LD50 5 – 50 mg/kg): Toxins with low lethal doses, small amounts can be dangerous. Examples: Atropine, Nicotine.

• Moderately toxic (LD50 50 – 500 mg/kg): Toxins with moderate lethal doses, larger amounts are needed to be dangerous. Examples: Aspirin, Morphine.

• Slightly toxic (LD50 > 500 mg/kg): Toxins with high lethal doses, very large amounts are needed to be fatal. Examples: Ethanol, Caffeine.

• Based on mechanism of action:

• Neurotoxins: Affect the central nervous system, causing neurological dysfunction. Examples: Nicotine, Atropine.

• Cardiotoxins: Affect the cardiovascular system, causing arrhythmias and heart failure. Examples: Digitalis, Quinidine.

• Hepatotoxins: Affect the liver, causing liver damage. Examples: Acetaminophen, Carbon tetrachloride.

• Nephrotoxins: Affect the kidneys, causing kidney failure. Examples: Mercury, Lead.

• Based on origin:

• Natural toxins: Originate from plants, animals, and molds. Examples: Venomous snakes, Poisonous mushrooms.

• Chemical toxins: Synthesized by humans. Examples: Pesticides, Herbicides.

Notes:

• LD50 (lethal dose 50%) is the dose of a toxin required to kill 50% of a test population.

• Toxicity classification based on LD50 is only a relative indicator and does not fully reflect the risk of a toxin.

• The Gosselin, Smith, and Hodge toxicity classification table is just one of many used, and there may be differences between classification tables.

• Sensitivity to toxins can vary between individuals, depending on age, gender, health, nutritional status, and other factors.

Answering questions:

• Question 1: c. Toxicology is the study concerned with the detection, manifestation, affecting properties, and regulation of toxic substances.

• Question 2: a. Highly toxic.

According to the Gosselin, Smith, and Hodge toxicity classification, a substance with a lethal dose of 0.5 g/kg belongs to the highly toxic group (LD50 < 5 mg/kg).

Conclusion:

Toxicology is an important branch of science that helps protect human health, protect the environment, and ensure occupational safety. Understanding toxicology helps us prevent poisoning, respond promptly to poisoning, and minimize the harmful effects of toxins on health and the environment.