LD50 values are typically expressed in which units?

The correct unit for expressing LD50 values is typically mg/kg. LD50, or lethal dose for 50% of the population, is a common measure used in toxicology to quantify the toxicity of a substance. It represents the amount of a substance that, when administered, is sufficient to kill half of a test population (usually laboratory animals such as rats or mice).

In terms of measurement, mg/kg signifies milligrams of the substance per kilogram of body weight of the organism being tested, providing a clear understanding of the dose relative to the size of the subject. This measurement is crucial because it allows for comparisons of toxicity across different substances and studies involving different sizes of test organisms. The use of this metric is standardized in toxicology to ensure that findings can be communicated effectively and compared accurately across different studies and toxic agents.

The other units presented do not accurately reflect the typical expression of LD50. For instance, g/kg would represent a much larger dose than is typically relevant in toxicology, while mg/m³ and ppm by volume are units that would apply to exposure concentrations rather than dose-related toxicity measurements.