What is one of the defining features of a poison based on LD50 values?

One of the defining features of a poison is characterized by its lethal dose values, specifically the LD50 (lethal dose for 50% of the population). The LD50 is a measure used to determine the toxicity of a substance, with lower values indicating higher toxicity. When a substance has an LD50 of fewer than 50 mg per kg, it qualifies as highly toxic and is considered a poison in many toxicology contexts.

Substances with an LD50 below this threshold pose significant risks to health even at relatively low doses. Thus, the classification of a poison primarily hinges on this metric, making an LD50 under 50 mg per kg a clear indicator of high lethality. This parameter is crucial for toxicologists, regulatory agencies, and safety professionals assessing the risks associated with various chemicals and compounds.

While other ranges, such as greater than 500 mg per kg, or fewer than 100 mg or 200 mg per kg, indicate varying levels of toxicity, they do not fulfill the stringent criteria needed to classify a substance as a poison as rigorously as an LD50 below 50 mg per kg does.