Which of the following is an acceptable MCL for nitrite?

The correct maximum contaminant level (MCL) for nitrite in drinking water is set at 1 mg/L. This standard is established to protect public health, particularly to prevent methemoglobinemia, commonly referred to as "blue baby syndrome," which can occur when infants are exposed to elevated levels of nitrites in their drinking water. The 1 mg/L limit is seen as a threshold that balances the need for safe drinking water while recognizing that nitrite can enter water supplies through various sources, including agricultural runoff or wastewater discharge.

The other options for nitrite MCLs exceed the established health guidelines. Standards are put in place based on extensive research and health studies, and exceeding these levels could pose risks to vulnerable populations, particularly infants. Therefore, understanding and adhering to the 1 mg/L MCL for nitrite ensures that water treatment facilities can effectively safeguard public health.