What is the primary environmental concern regarding pesticide use?

The primary environmental concern regarding pesticide use is contamination of air and water. Pesticides, when applied, can drift through the air or be washed away into water bodies through runoff. This can lead to detrimental effects on aquatic ecosystems and the quality of drinking water. Additionally, pesticide residues can affect non-target organisms, including beneficial insects, wildlife, and human populations who may come into contact with contaminated air or water sources.

In contrast, the enhancement of soil nutrients is often a benefit associated with organic farming practices, rather than a concern linked to pesticide use. Improved crop yield is a desired outcome of pesticide application, and while it can have positive economic implications, it does not address the environmental risks. Similarly, increased biodiversity is generally considered a favorable outcome of healthy ecosystems but is not a direct benefit of pesticide application; often, pesticide use can negatively impact biodiversity by harming non-target species. Thus, the potential for air and water contamination stands out as the main environmental issue associated with pesticide usage.