Associate Certified Entomologist (ACE) Practice Exam

How is LD50 typically measured?

1. In moles per liter

2. In milligrams per kilogram

3. In liters per square meter

4. In percentage concentration

The correct answer is: In milligrams per kilogram

LD50, or lethal dose for 50% of the test population, is a standard measurement used in toxicology to assess the toxicity of a substance. It quantifies the amount of a substance required to kill half of a test population, usually expressed in relation to the body weight of the organism being tested. The measurement in milligrams per kilogram effectively provides a clear and concise means of indicating how much of a chemical is harmful relative to body weight, which is crucial for understanding its potential risks and effects on various species. This measurement helps researchers and regulatory agencies determine safe exposure levels for humans, animals, and the environment. Understanding LD50 in this context allows for comparative analysis between different substances and their associated risks, provided in a way that is standardized and easily interpretable for safety assessments. The other units listed, such as moles per liter or liters per square meter, are not applicable to the assessment of toxicity in this manner, as they pertain to concentration or volumetric measurements, rather than dose-response relationships necessary for calculating LD50.