What is the maximum contaminant level for nitrates in drinking water?

The maximum contaminant level for nitrates in drinking water is established at 10 mg/l, which is based on health guidelines to protect public health. Nitrates can come from various sources, including agricultural runoff, septic systems, and wastewater discharges, and elevated levels can pose significant health risks, particularly to infants. Nitrates can interfere with the ability of blood to carry oxygen, leading to a condition known as methemoglobinemia or "blue baby syndrome" in young children.

Setting the maximum limit at 10 mg/l reflects the balance between providing access to water while protecting against these potential health risks. This limit is enforced by regulatory agencies to ensure safe drinking water standards. Lower values, such as those proposed in the other options, do not align with the established safety levels for drinking water contaminants, which is why they are not the correct choice.