What is a primary health concern about nitrates in drinking water?

The primary health concern regarding nitrates in drinking water is linked to their potential to cause methemoglobinemia, commonly referred to as "blue baby syndrome," in infants. Nitrates in the body can be converted to nitrites, which inhibit the ability of hemoglobin to carry oxygen in the blood. This is particularly dangerous for infants, whose bodies are less capable of handling the elevated levels of nitrites, leading to a decreased oxygen availability. As a result, they may exhibit symptoms such as cyanosis, which gives the skin a bluish tint due to inadequate oxygenation.

While the other options present valid health concerns related to nitrates in water, they do not carry the same level of immediate risk for the most vulnerable population. Acute respiratory problems, kidney damage in adults, and bacterial growth are important considerations but are not as critical as the effects of nitrates on infant health. Nitrate exposure and its impact on young children is particularly concerning because it can lead to severe health complications that may require medical intervention.