Blue-baby syndrome is caused by

Options

A. Nitrates
B. Mercury
C. Cadmium
D. Arsenic

Answer

**Step-by-Step Solution:**

1. **Understanding Blue Baby Syndrome:**
- Blue baby syndrome is a condition observed in infants where their skin appears blue. This is primarily due to a lack of oxygen in the blood.

2. **Identifying the Cause:**
- The main cause of blue baby syndrome is related to the consumption of substances that affect the oxygen-carrying capacity of hemoglobin, the protein in red blood cells responsible for transporting oxygen.

3. **Role of Nitrates:**
- Nitrates, when ingested in high amounts (often through contaminated water or vegetables), can convert hemoglobin into methemoglobin. Methemoglobin cannot effectively carry oxygen, leading to a condition known as methemoglobinemia.

4. **Effects of Methemoglobinemia:**
- As a result of methemoglobinemia, the blood takes on a blue color instead of the normal red, which is why the syndrome is referred to as blue baby syndrome.

5. **Evaluating Other Options:**
- **Mercury:** Causes Minamata disease and affects the kidneys but does not cause blue baby syndrome.
- **Cadmium:** Leads to Itai Itai disease, which involves joint pain, but is not related to blue baby syndrome.
- **Arsenic:** Causes arsenicosis, affecting the nervous system and gastrointestinal tract, but does not cause blue baby syndrome.

6. **Conclusion:**
- Therefore, the correct answer is that blue baby syndrome is caused by **nitrates**.

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