When fluoride ion concentration in water is more than 2 ppm them it causes
I. tooth decay
II. brown mottling of teeth
III. harmful effect to bone
Identify the correct option.

Options

A. I and II
B. II and III
C. I,II and III
D. None of the above

Answer

To solve the question regarding the effects of fluoride ion concentration in water when it exceeds 2 ppm, we can analyze each of the given statements step by step.

### Step 1: Understand the Effects of Fluoride
Fluoride is a compound that can have both beneficial and harmful effects on health, particularly concerning dental and skeletal health. The key is to determine what happens when fluoride levels exceed certain thresholds.

### Step 2: Analyze Each Statement
1. **Tooth Decay**: The first statement claims that fluoride ion concentration above 2 ppm causes tooth decay. However, fluoride is known to help prevent tooth decay at lower concentrations (up to 1.5 ppm). Therefore, this statement is incorrect.

2. **Brown Mottling of Teeth**: The second statement refers to brown mottling of teeth, which is a condition known as dental fluorosis. This condition occurs when fluoride levels are too high during the development of teeth, leading to discoloration. This is indeed a consequence of fluoride levels exceeding 2 ppm. Thus, this statement is correct.

3. **Harmful Effect to Bone**: The third statement discusses harmful effects on bones. Excessive fluoride can lead to skeletal fluorosis, which is characterized by an increase in bone density but a decrease in bone quality, making bones more brittle and prone to fractures. Therefore, this statement is also correct.

### Step 3: Conclusion
Based on the analysis:
- The first statement is incorrect.
- The second and third statements are correct.

Thus, the correct option is that fluoride ion concentration above 2 ppm causes:
- II. Brown mottling of teeth
- III. Harmful effect to bone

### Final Answer
The correct option is **II and III**.

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