Arsenic in Arizona's Water Supply

To reduce the risk of cancer from this chronic exposure to arsenic, the EPA changed the allowable limit for drinking water from 50 ppb to 10 ppb in January of 2006. This is projected to reduce the risk of cancer and other illnesses from arsenic by around 80%. The exact benefit cannot be defined because other sources of arsenic such as food or air are contributors to the health risk.  View document.