Oregon Pesticide Practice Test

Which of the following describes the behavior of pesticides that can lead to contamination of water sources?

1. Only those applied in large quantities

2. Pesticides with high solubility and volatility

3. Pesticides that dissolve and leach through soil

4. Pesticides used in agricultural settings exclusively

The correct answer is: Pesticides that dissolve and leach through soil

The behavior of pesticides that can lead to contamination of water sources is best described by the characteristic of pesticides that dissolve and leach through soil. When pesticides are applied to the soil, particularly if they are water-soluble, they can easily be taken up by water as it moves through the soil profile. This process is known as leaching. Leaching occurs when rainfall or irrigation causes water to move through the soil, carrying dissolved substances with it. If pesticides are highly soluble, they can readily dissolve in this moving water and be transported away from the treated area, potentially reaching groundwater or surface water bodies. This has significant implications for environmental health, as it can lead to the accumulation of pesticides in water sources, impacting ecosystems and human health. The other choices do not fully encapsulate the mechanisms that lead to contamination. For example, pesticides applied in large quantities might increase the risk but are not the sole factor involved in contamination. Pesticides with high solubility and volatility imply potential for airborne transport but do not capture the crucial element of how they can leach into water sources through soil. Lastly, limiting the concern to pesticides used exclusively in agricultural settings overlooks the broader context that any pesticide, regardless of its application area, can result in contamination if