Which illness is caused by exposure to excessive nitrates?

Which illness is caused by exposure to excessive nitrates?

• A. Cyanosis
• B. Hypoxia
• C. Methemoglobinemia
• D. Anemia

Answer: (C)

Exposure to excess nitrates can oxidize hemoglobin from the ferrous (Fe2+) to the ferric (Fe3+) state, forming methemoglobin. Methemoglobin binds oxygen poorly, so even when oxygen is present, the blood cannot deliver it effectively to tissues, leading to tissue hypoxia and a blue tint (cyanosis). The illness caused by this nitrate-related change is methemoglobinemia. This differs from general cyanosis, which is a symptom of low oxygen that can arise from many causes; hypoxia describes the state of insufficient oxygen delivery, not a specific toxin-induced disorder; and anemia refers to a reduced red blood cell mass or hemoglobin, not directly caused by nitrate exposure.

Exposure to excess nitrates can oxidize hemoglobin from the ferrous (Fe2+) to the ferric (Fe3+) state, forming methemoglobin. Methemoglobin binds oxygen poorly, so even when oxygen is present, the blood cannot deliver it effectively to tissues, leading to tissue hypoxia and a blue tint (cyanosis). The illness caused by this nitrate-related change is methemoglobinemia. This differs from general cyanosis, which is a symptom of low oxygen that can arise from many causes; hypoxia describes the state of insufficient oxygen delivery, not a specific toxin-induced disorder; and anemia refers to a reduced red blood cell mass or hemoglobin, not directly caused by nitrate exposure.