What is used to describe the time needed for a pesticide to break down?

The term that describes the time needed for a pesticide to break down is "half-life." This concept refers to the duration it takes for half of the amount of the pesticide to degrade or dissipate in the environment. Understanding the half-life of a pesticide is crucial for determining how long it will remain effective and how long it can pose potential risks to non-target organisms, including humans and wildlife.

In contrast, while "persistence" may also be related, it generally refers to how long a pesticide remains in the environment without degrading, which may not specifically indicate the breakdown of half of the compound. The term "decomposition rate" typically pertains to the speed at which organic matter breaks down, but it is not a standardized term used in the context of pesticides. "Longevity" suggests durability or the lasting effectiveness of a pesticide rather than the specific timing of its breakdown. Thus, half-life is the most accurate term for describing the time it takes for a pesticide to break down to half its original concentration.