What is one of the environmental concerns linked to insecticide use?

Groundwater contamination is a significant environmental concern linked to insecticide use. When insecticides are applied to crops, they can be carried away by rain or irrigation runoff, leading to their movement into the soil and potentially leaching into groundwater supplies. This contamination can have severe consequences for both ecosystems and human health, as groundwater is a major source of drinking water in many areas. Additionally, contamination can affect aquatic life when runoff reaches rivers, lakes, and streams, causing imbalances in local ecosystems.

In contrast, the other options relate to positive effects rather than concerns. Promoting beneficial insects, improving soil health, and increasing nutrient content are generally regarded as desirable outcomes in sustainable agriculture and integrated pest management practices. These practices can enhance biodiversity and ecosystem functionality, which are crucial for maintaining healthy agricultural systems.