Fill in the following blank with suitable words:
Untreated human excreta is a …………………….hazard.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks us to fill in a blank regarding untreated human excreta. We need to think about the implications of untreated human waste.

2. **Identifying the Risks**: Untreated human excreta can lead to various health issues. It can contain harmful microorganisms that can cause diseases.

3. **Recognizing the Type of Hazard**: Since untreated human excreta can lead to diseases such as cholera, typhoid, and meningitis, it poses a risk to human health.

...