What does LC50 represent in toxicology?

LC50, or lethal concentration 50, is a critical parameter used in toxicology that quantifies the concentration of a substance in the environment that is expected to be fatal to 50% of a test population, typically within a specified time frame. This measurement is particularly relevant for assessing the toxicity of chemicals in aquatic environments, where it denotes the concentration of a substance in water that is toxic to half of the test organisms.

The designation "lethal concentration" makes it clear that LC50 focuses specifically on concentration levels rather than dosage, making it distinct from other metrics like LD50, which refers to the lethal dose leading to 50% mortality. Choosing this option reflects an understanding of how toxicological assessments are designed to quantify risks associated with exposure to hazardous substances, allowing scientists and regulators to evaluate safety thresholds and the potential human and ecological impacts of chemicals.