What is an issue with high concentrations of nitrates in drinking water?

High concentrations of nitrates in drinking water can lead to methemoglobinemia, commonly known as "blue baby syndrome." This condition primarily affects infants and is characterized by a reduced ability of the blood to carry oxygen. Nitrates, when consumed in large amounts, can be converted in the body to nitrites, which interfere with the normal function of hemoglobin—the molecule responsible for transporting oxygen in the blood. In infants, this can lead to serious health issues, including difficulty breathing and a change in skin color.

Understanding this effect is crucial, especially in communities that rely on well water or where nitrogen fertilizers are heavily used in agriculture, as these practices can lead to elevated nitrate levels in local water supplies. The other options relate to different health effects or aspects of water quality but do not specifically address the primary concern associated with high nitrate levels in drinking water like methemoglobinemia does.