A major health risk associated with elevated levels of nitrates in drinking water is?

Elevated levels of nitrates in drinking water are particularly concerning because they can lead to a condition known as "blue baby syndrome" or methemoglobinemia. This condition primarily affects infants, as their digestive systems convert nitrates into nitrites, which can interfere with the ability of blood to carry oxygen. The resulting low oxygen levels cause a bluish discoloration of the skin, particularly around the lips and extremities, which is where the term "blue baby syndrome" comes from.

Understanding this health risk underscores the importance of monitoring and managing nitrate levels in water sources, especially in areas where agricultural practices may contribute to nitrate contamination. The other potential health issues listed, while serious, are not directly associated with nitrates in the same way that blue baby syndrome is. Thus, focusing on the specific risks posed by nitrate exposure highlights why blue baby syndrome is recognized as a major health risk in this context.