Question

High concentration of nitrates (\(\gt 45\ \mathrm{mg/L}\)) in drinking water causes

• A. Rickets
• B. Skeletal fluorosis
• C. Minamata disease
• D. Methemoglobinemia

Hint:

Important water-quality diseases: \[ \boxed{ \begin{aligned} \text{Nitrate} &\rightarrow \text{Methemoglobinemia}\\ \text{Fluoride} &\rightarrow \text{Fluorosis}\\ \text{Mercury} &\rightarrow \text{Minamata disease} \end{aligned} } \]

Answer 1

The Correct Option is D

Step 1: Track what happens to nitrate in the body.
When water with nitrate above $45\ \mathrm{mg/L}$ is consumed, gut bacteria convert nitrate into nitrite.
Step 2: See what nitrite does to blood.
Nitrite oxidizes the iron in haemoglobin, turning it into methaemoglobin, which cannot carry oxygen properly. This condition is especially dangerous for infants and is called blue baby syndrome.
Step 3: Eliminate the other diseases.
Rickets comes from vitamin D or calcium deficiency, skeletal fluorosis comes from excess fluoride, and Minamata disease comes from methyl mercury, none of which are linked to nitrate.
\[ \boxed{\text{Methemoglobinemia}} \]