Pesticides are considered as hazardous because they

Options

A. Presist in environment
B. Do not enter food chain
C. Affect target organism only
D. Do not kill natural enemy populations .

Answer

**Step-by-Step Solution:**

1. **Understanding Pesticides**: Pesticides are chemicals used to kill pests that can harm crops. However, they can have unintended consequences on the environment and health.

2. **Non-biodegradability**: One of the main reasons pesticides are considered hazardous is that they are non-biodegradable. This means they do not break down naturally in the environment through microbial action.

3. **Persistence in the Environment**: Because pesticides do not decompose, they persist in the environment for long periods. This persistence allows them to accumulate in soil and water bodies.

4. **Runoff into Water Bodies**: When pesticides are applied to crops, they can run off into nearby water bodies due to rain or irrigation. This runoff contaminates rivers, lakes, and other water sources.

5. **Entry into the Food Chain**: Once in water bodies, pesticides can be absorbed by aquatic organisms, such as fish. These organisms then become part of the food chain, leading to bioaccumulation and biomagnification of pesticides in higher trophic levels, including humans.

6. **Health Impacts**: The accumulation of pesticides in the food chain can lead to serious health issues in humans, including various diseases. This is why pesticides are considered hazardous.

7. **Conclusion**: Therefore, the correct answer to the question is that pesticides are considered hazardous because they **persist in the environment** (Option A).