Principles of Toxicology: A Clinical Review

Abstract

Toxicology can be defined as that branch of science that deals with poisons, and a poison can be defined as any substance that causes a harmful effect when administered, either by accident or design, to a living organism. In short, it is the study of toxic kinetics and toxic dynamic. Poison is a quantitative concept, almost any substance being harmful at some doses but, at the same time, being without harmful effect at some lower dose. Between these two limits there is a range of possible effects, from subtle long-term chronic toxicity to immediate lethality. Vinyl chloride may be taken as an example. It is a potent hepatotoxic at high doses, a carcinogen with a long latent period at lower doses, and apparently without effect at very low doses. The measurement of toxicity is also complex. Toxicity may be acute or chronic, and may vary from one organ to another as well as with age, genetics, gender, diet, physiological condition, or the health status of the organism. Exposure of humans and other organisms to toxicants may result from many activities: intentional ingestion, occupational exposure, environmental exposure, as well as accidental and intentional (suicidal or homicidal) poisoning. The toxicity of a particular compound may vary with the portal of entry into the body, whether through the alimentary canal, the lungs, or the skin. The initial approach to a person who has been poisoned should be to assess the airway, breathing, and circulation, and to take a thorough history. Less than 1 per cent of poisonings are fatal; therefore, management in most cases is supportive unless a specific antidote is available. Treatment for poisoning depends on the type of exposure (e.g., ingestion, inhalation), the specific toxin (poisonous substance), and the severity of the person's condition. Childhood poisoning that involves a foreign object (e.g., small toy, battery) may require surgery to remove the object. This review article gives you an overall view on toxicity, its principles, management and treatment.