Nitrate exposure in drinking water is associated with which health effect?

• A. Gastroenteritis
• B. Methemoglobinemia
• C. Neurological effects
• D. Kidney failure

Answer: (B)

Nitrate exposure in drinking water is linked to methemoglobinemia, especially in infants. Nitrates themselves aren’t the direct toxin; they can be reduced to nitrite by bacteria in the mouth and gut. Nitrite then oxidizes hemoglobin in red blood cells to methemoglobin, which can’t carry oxygen effectively. This impairs oxygen delivery to tissues and can lead to cyanosis, rapid breathing, fatigue, and poor feeding, with infants under six months being most at risk due to immature enzyme systems and higher gut bacterial activity that promote this conversion. If significant, it’s a medical concern that requires removing the source of nitrate and, in some cases, specific treatment.

Gastroenteritis involves infection or irritation of the digestive tract and presents with diarrhea and vomiting, not the oxygen-transport problem caused by methemoglobinemia. Neurological effects and kidney failure aren’t the typical health effects associated with nitrate exposure in drinking water.