For arsenic MCL in drinking water, typical concentration?

• A. 10 µg/L.
• B. 100 µg/L.
• C. 1 mg/L.
• D. 0.1 µg/L.

Answer: (A)

Arsenic in drinking water is limited by a maximum contaminant level to limit cancer risk from long-term exposure. The standard ten micrograms per liter (10 µg/L), which equals 10 parts per billion, is the regulatory limit used in many places because it provides health protection while remaining feasible for treatment and monitoring. Among the options, ten µg/L matches this typical MCL. The other values are either much higher, meaning less stringent protection, or much lower than what is commonly adopted as the regulatory limit, making them not representative of the typical drinking-water standard.