What does a lower LD50 value indicate about a pesticide?

A lower LD50 value indicates that a pesticide is more toxic because LD50, which stands for "lethal dose for 50% of the population," is a measure of the toxicity of a substance. Specifically, it represents the amount of a substance required to kill half of a given population (often laboratory animals) that have been exposed to it. When the LD50 value is lower, it means that a smaller quantity of the pesticide is needed to cause lethal effects, which directly denotes a higher level of toxicity.

In contrast, a higher LD50 value suggests that a greater amount of the substance would be needed to achieve the same lethal effect, indicating lower toxicity. Other choices like higher efficacy and safety in handling are not directly related to LD50 values, as they pertain to different characteristics of pesticides that are not solely defined by toxicity alone. Understanding these metrics is crucial for evaluating pesticide safety and ensuring responsible use in various applications.