Fluoride content of water which causes fluorosis is

Options

A. 6 ppb
B. 100 ppb
C. 1 ppm
D. 10 ppm

Answer

To solve the question regarding the fluoride content of water that causes fluorosis, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Fluoride and Its Role**:
- Fluoride is a mineral that helps in preventing tooth decay by strengthening tooth enamel. It is beneficial in small amounts.

2. **Recognize the Health Risks**:
- While fluoride is helpful in small quantities, excessive fluoride intake can lead to health issues, particularly fluorosis. This condition affects the bones and teeth.

3. **Identify Safe Levels of Fluoride**:
- Normal drinking water contains about 0.3 parts per million (ppm) of fluoride, which is considered safe and does not pose health risks.

4. **Determine Harmful Levels**:
- Fluoride levels above 1 ppm can start to pose health risks. However, levels significantly higher than this are more dangerous.

5. **Analyze the Options Given**:
- The options provided are:
- A) 6 parts per million
- B) 100 parts per billion
- C) 1 part per million
- D) 10 parts per million

6. **Evaluate Each Option**:
- **Option A (6 ppm)**: This is above the safe limit and could potentially cause fluorosis.
- **Option B (100 ppb)**: This is equivalent to 0.1 ppm, which is safe.
- **Option C (1 ppm)**: This is at the threshold where health risks begin but is not as severe as higher levels.
- **Option D (10 ppm)**: This is significantly high and will definitely cause fluorosis.

7. **Select the Correct Answer**:
- Based on the analysis, the fluoride content of water that causes fluorosis is **10 parts per million (Option D)**.

### Final Answer:
The fluoride content of water which causes fluorosis is **10 parts per million**.

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