Toxicity
Toxicity is the capacity of a substance to cause harmful effects in living organisms. Its effects depend on exposure, dose, route, and the organism.
Dose–response relationship: The relationship between the amount of an agent an organism receives and the magnitude or probability of its effects. It describes how toxicity changes as exposure increases.
Hazard: A property or condition with the potential to cause harm. Toxicity is one kind of hazard, independent of how likely exposure is.
Toxicology: The scientific study of harmful effects caused by chemical, physical, or biological agents in living organisms. Toxicity is the central property investigated by this field.
Toxicity versus toxic hazard: Toxic hazard is the potential of a substance to cause harm, considered separately from exposure and resulting risk. The distinction prevents intrinsic harmfulness from being mistaken for likely harm in actual conditions.
Toxicokinetics: The study of how toxic substances enter, move through, are transformed by, and leave the body. Absorption, distribution, metabolism, and excretion determine how much reaches vulnerable tissues.
Exposure assessment: The process of estimating how much of an agent reaches people or ecosystems, by which routes and over what time. A toxic substance can pose little risk when exposure is negligible.
Environmental toxicology: The study of harmful effects of pollutants and other agents on organisms, populations, and ecosystems. It examines toxicity beyond individual human exposures.
Poison: A substance capable of causing illness, injury, or death when introduced into an organism in sufficient amount. “Poison” usually names a harmful substance, while toxicity describes its capacity to cause harm.
Toxicodynamics: The study of how toxic substances interact with biological targets and produce effects. It connects a substance’s presence in the body to cellular injury or dysfunction.
Risk assessment: A structured evaluation of potential harm that combines hazard information with exposure estimates. It turns toxicity evidence into an estimate of harm under specified conditions.