Question

Methemoglobinemia disease is caused by

• A. Lead levels in ground water
• B. Mercury levels in ground water
• C. Nitrate in ground water
• D. Iron in ground water

Hint:

Methemoglobinemia is universally linked to Nitrate ($\text{NO}_3^{-}$) contamination in drinking water, leading to "blue baby syndrome" in infants.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Methemoglobinemia is a blood disorder characterized by an abnormal accumulation of methemoglobin, which is a form of hemoglobin that cannot bind or release oxygen effectively.
Understanding the environmental chemical triggers of this disease is critical for groundwater quality monitoring and public health management.

Step 2: Detailed Explanation:
Let us analyze the physiological impact of the listed contaminants:
Lead and mercury are heavy metals that cause neurological and systemic toxicity, but do not directly cause methemoglobinemia.
Iron overload causes hemochromatosis but does not alter hemoglobin's oxygen affinity in this manner.
Nitrate ($\text{NO}_3^{-}$) contamination in groundwater, primarily arising from agricultural fertilizers, animal wastes, and sewage, is the primary driver of methemoglobinemia.
When nitrate-rich water is ingested, bacteria in the digestive tract reduce the nitrates to highly reactive nitrites ($\text{NO}_2^{-}$).
These nitrites enter the bloodstream and oxidize the ferrous iron ($\text{Fe}^{2+}$) in active hemoglobin to its ferric state ($\text{Fe}^{3+}$), converting it into methemoglobin.
Unlike normal hemoglobin, methemoglobin cannot bind oxygen, leading to tissue hypoxia and clinical cyanosis.
This is famously known as "blue baby syndrome" because infants are highly susceptible due to their lower levels of methemoglobin reductase enzymes.

Step 3: Final Answer:
Methemoglobinemia disease is caused by Nitrate in ground water.