What does LC50 measure?

LC50 is a standard measure used in toxicology to express the lethal concentration of a substance in the air that is estimated to cause death in 50% of a test population, typically in a controlled environment. It is a critical value for assessing the potential hazard of airborne substances, including gases, vapors, and aerosols, indicating how toxic a substance is when inhaled.

When a substance has a lower LC50 value, it means that a smaller concentration of that substance is required to achieve lethality, which implies a higher toxicity. This measure is especially useful in determining safe exposure levels for workers and in emergency response scenarios where hazardous materials may be present in the air.

In contrast, the other choices focus on different aspects of toxicity or safety. One option describes a lethal dose via injection, which does not pertain to airborne concentrations. Another option refers to exposure limits in workplaces, which are important but distinct from the specific lethal concentration measure. Lastly, the mention of long-term health effects addresses chronic exposure rather than immediate lethality, which is what LC50 specifically quantifies. Understanding LC50 is essential for the assessment and management of risks associated with exposure to hazardous materials in various environments.