What type of pesticide has an acute oral LD50 of between 501-5,000 ppm?

The correct choice is based on the classification system for pesticides that utilizes the concept of LD50 (lethal dose for 50% of a test population). Pesticides categorized as Category III are those that have an acute oral LD50 ranging from 501 to 5,000 mg/kg (not ppm).

In this classification system, a Category III pesticide represents a lower toxicity level compared to Categories I and II, which have LD50 values that are more toxic, while being more toxic than Category IV, which is the least toxic. Understanding this scale is crucial for applicators as it helps them identify the potential health risks associated with various pesticides, guiding safer handling, application, and safety protocols.

Therefore, recognizing that a pesticide with an LD50 in the specified range signifies moderate toxicity aligns with the classification of Category III effectively and underscores the importance of using pesticides responsibly while considering their potential health impacts.