Associate Certified Entomologist (ACE) Practice Exam

What does LC50 measure in toxicology?

1. Dosage of a substance by weight

2. Concentration of a substance in the environment

3. Volume inhaled needed to kill 50% of a population

4. Quantity of a substance absorbed via the skin

The correct answer is: Volume inhaled needed to kill 50% of a population

LC50, or lethal concentration 50, is a key metric in toxicology that quantifies the concentration of a substance required to kill 50% of a test population, typically within a specified time frame. This measurement is crucial for understanding the potency and risk posed by various chemicals to organisms in their environment. It allows researchers and pest management professionals to assess and compare the toxicity of different substances, providing insight into the potential impact of these substances on health and ecosystems. In the context of the question, the correct answer emphasizes the concept of concentration rather than volume or dosage. Other choices focus on aspects such as weight or surface absorption, which do not directly pertain to the definition used in toxicology. Thus, understanding that LC50 reflects the lethal concentration in an environment helps in evaluating the safety and environmental effects of chemicals, making it an essential parameter in both research and applied entomology.