What is the maximum contaminant level of arsenic set by the Arsenic Rule?

The maximum contaminant level (MCL) of arsenic established by the Arsenic Rule is 10 micrograms per liter (µg/L), which is equivalent to 10 parts per billion (ppb). This standard was put in place to protect public health because arsenic is a carcinogen and can cause various health issues over long-term exposure, including skin lesions, developmental effects, cardiovascular disease, neurotoxicity, and diabetes.

The Arsenic Rule is part of the Safe Drinking Water Act and aims to minimize the health risks associated with arsenic in drinking water supplies. The choice of 10 µg/L reflects a balance between public health protection and the feasibility of achieving this level in water treatment processes.