How is LD50 expressed?

LD50, or "lethal dose for 50%," is a standard measure used to quantify the toxicity of a substance. It represents the dose of a substance that is expected to cause death in 50% of a defined animal population, typically laboratory animals. The measurement is expressed in terms of milligrams of the chemical per kilogram of body weight (mg/kg). This format allows for a standardized understanding of toxicity across different species and chemical substances.

By using this unit of measurement, it is possible to compare the toxic effects of various chemicals relative to their dosage and the size of the organism affected. This makes it easier to evaluate and communicate the risks associated with exposing non-target organisms, as well as to develop safety protocols in environments where pesticides are used.

Other options like parts per million, liters per hectare, and percentage of concentration do not specifically relate to the definition or standard use of LD50, as they pertain to different contexts for measuring concentration, volume, or dilution, rather than lethal dose calculations. Thus, the expression of LD50 as milligrams of chemical per kilogram of body weight is essential for accurately assessing and communicating the potential risks of chemical exposure.