What is the maximum contaminant level (MCL) for arsenic in drinking water?

What is the maximum contaminant level (MCL) for arsenic in drinking water?

• A. 10 micrograms/L
• B. 5 micrograms/L
• C. 15 micrograms/L
• D. 25 micrograms/L

Answer: (A)

Arsenic is a toxic contaminant and a known carcinogen, so drinking water programs set a strict enforceable limit to protect public health. The maximum contaminant level for arsenic is ten micrograms per liter (which is the same as ten parts per billion). This standard was chosen to significantly reduce cancer risk compared with older, higher limits, and it is the limit used by EPA and implemented by states like Arizona through ADEQ. The units μg/L and ppb describe the same concentration, making it easy to compare results across tests and reports. So, ten micrograms per liter is the current official limit.

Arsenic is a toxic contaminant and a known carcinogen, so drinking water programs set a strict enforceable limit to protect public health. The maximum contaminant level for arsenic is ten micrograms per liter (which is the same as ten parts per billion). This standard was chosen to significantly reduce cancer risk compared with older, higher limits, and it is the limit used by EPA and implemented by states like Arizona through ADEQ. The units μg/L and ppb describe the same concentration, making it easy to compare results across tests and reports. So, ten micrograms per liter is the current official limit.