What is meant by acute toxicity?

Acute toxicity refers specifically to the degree of harmfulness that a substance can inflict on an organism following a single exposure or a short-term exposure. This is characterized by the immediate effects that occur soon after the exposure to a high dose of the substance, typically within 24 hours. In laboratory testing, acute toxicity is often assessed by determining the dose of a substance that results in toxicity or death in a significant percentage of test animals after a single dose.

The other options describe concepts that are related but distinct from acute toxicity. Long-term effects and cumulative effects pertain to chronic toxicity, which involves the consequences of repeated or prolonged exposure over a duration rather than a single instance. Additionally, resistance of pests to certain chemicals refers to the ability of pest populations to survive exposure due to genetic changes or adaptations, which is not directly related to the immediate toxic effects of a substance.