toxicants

Toxicants are substances that can cause harm to living organisms when exposure occurs. The term covers a wide range of chemicals, including naturally occurring compounds and man-made substances. In toxicology, a toxin is a toxicant produced by a living organism; toxicants include inorganic metals, solvents, pesticides, industrial chemicals, and environmental pollutants. Effects depend on dose, exposure duration, route of entry, and individual susceptibility. Common exposure routes include inhalation, ingestion, and dermal contact.

Toxicants are evaluated by origin (natural vs synthetic), mechanism of action, and potential health outcomes. They can cause acute effects after high-dose exposure or chronic effects after prolonged or low-dose exposure. Effects may be organ-specific or systemic; some toxicants are carcinogenic, mutagenic, or teratogenic. Examples include lead, arsenic, mercury, benzene, carbon monoxide, pesticides, dioxins, and polychlorinated biphenyls.

Assessment and regulation rely on hazard identification, dose–response assessment, exposure assessment, and risk characterization. Public health and occupational safety programs strive to limit exposure by substitution with less toxic substances, improved ventilation or containment, product labeling, and monitoring of environmental levels.

Understanding toxicants supports efforts to protect ecosystems and human health by reducing sources of exposure and mitigating effects.