How is a persistent pesticide defined?

A persistent pesticide is defined as one that remains active in the environment for an extended period, typically more than one growing season. This characteristic means that such pesticides do not break down quickly after application and can continue to affect target and non-target organisms over time. The long-lasting nature of persistent pesticides raises concerns regarding their potential environmental impact and the possibility of residues accumulating in the ecosystem, which is why it's crucial for those applying these substances to have a deep understanding of their properties and behaviors.

In contrast, other definitions focus on shorter durations of activity or other characteristics. For instance, a pesticide active for less than a growing season would not be classified as persistent, since it dissipates relatively quickly. Similarly, the notion of accumulation in soil pertains to a chemical's tendency to build up over time but does not necessarily indicate how long it remains active. Lastly, a pesticide being biodegradable means it can decompose, but this characteristic is not synonymous with persistence; a pesticide can be biodegradable yet still be persistent if it takes a long time to break down.