What may happen if pesticides move too rapidly in the environment?

Pesticides that move too rapidly in the environment pose a significant risk of contaminating water sources. This rapid movement can occur through various pathways, including surface runoff, leaching into the soil, or drift in the air. When pesticides reach rivers, lakes, or groundwater, they can harm aquatic ecosystems and present health risks to humans and wildlife that rely on these water sources. The potential for contamination can create long-term environmental issues and is a critical concern for regulatory agencies.

In contrast, the other options suggest outcomes that are often desirable but do not align with the consequences of rapid pesticide movement. Increased effectiveness of pest control generally would derive from proper application and targeting rather than rapid movement. Lower costs for pesticide application and enhanced soil fertility may also be influenced by appropriate pesticide use, but these outcomes would not result from rapid movement in the environment. Instead, they could be side effects of careful, sustainable management practices.