Acute toxicity

Acute toxicity is the capacity of a substance to cause harmful effects after a single exposure or exposures over a short period. It is commonly assessed through the severity and frequency of effects at defined doses.

Dose–response relationship: The relationship between the amount of a substance received and the magnitude or likelihood of its effects. Acute effects generally become more likely or severe as the absorbed dose rises.
Exposure: Contact between an organism and a physical, chemical, or biological agent. Acute toxicity begins with exposure, whose amount and duration must be specified.
LD50: The estimated dose that kills half of a test population under specified conditions. This historical measure summarizes acute lethality for a particular species and exposure route.
Chronic toxicity: Harmful effects caused by prolonged or repeated exposure over an extended period. It contrasts with acute toxicity in exposure duration and often in the timing of harm.
Exposure route: The pathway by which a substance enters an organism, such as ingestion, inhalation, or skin contact. The entry route changes absorption speed and which organs receive the greatest dose.
Hazard: The inherent capacity of an agent or situation to cause harm. Acute toxicity describes a harmful capacity, not the likelihood of exposure.
LC50: The estimated concentration in air or water that kills half of a test population during a specified period. It expresses acute lethality when exposure is measured as a surrounding concentration.
Subacute toxicity: Harmful effects assessed after repeated exposure over a relatively short period. The term separates repeated short-term testing from single-exposure and longer-term studies.
Absorption: The movement of a substance from an exposure site into blood or another internal compartment. Rapid absorption can produce high internal concentrations soon after exposure.
Risk: The likelihood and severity of harm under specified conditions of exposure. A highly toxic substance can pose low risk when exposure is unlikely or controlled.

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