American Chemical Society (ACS) Laboratory Safety Practice Test

What does an LD50 value of 20 in mice indicate?

1. The substance is non-toxic

2. 50% of a test population would die after exposure

3. The substance is safe for laboratory use

4. All mice will survive the exposure

The correct answer is: 50% of a test population would die after exposure

An LD50 value represents the lethal dose required to kill 50% of a test population, and in this context, a value of 20 indicates that it is the amount of a specific substance that would lead to that outcome in mice. This measurement is a standard way to assess the acute toxicity of a substance and provides important information about its potential hazards. A lower LD50 value suggests a higher toxicity, as it takes less of the substance to be lethal to half the population tested. This means that if a substance has an LD50 of 20 in mice, it implies that 50% of the mice exposed to this dose would die as a result of the exposure, giving researchers crucial insights into the risks associated with handling or using the substance in laboratory settings or other applications. Understanding LD50 values is vital for assessing toxicity levels and ensuring safe practices when working with chemicals.