Which of the following MCLs is the highest permissible level for drinking water?

The maximum contaminant level (MCL) for a substance reflects the highest permissible concentration allowed in drinking water to protect public health. In this context, the MCL for nitrate is set at a level that is designed to prevent health issues, particularly methemoglobinemia, or "blue baby syndrome," which primarily affects infants and can decrease the oxygen-carrying capacity of blood.

Nitrate can enter the water supply from agricultural runoff, sewage, and industrial waste, making its regulation vital for ensuring safe drinking water. In comparison to the MCLs for bromate, total trihalomethanes, and nitrite, the MCL for nitrate is generally higher. This is due to the higher concentrations commonly encountered in various water sources and the acceptable risk levels established by health authorities. It’s important to note that each of these contaminants has distinct health risks and regulatory thresholds, but in this scenario, the MCL for nitrate is the highest, which underscores its prevalence and the monitored risk associated with its presence in drinking water.