Arsenic (elemental symbol As) continues to create a quandary for U.S. risk assessors. Controversy swirls around the Environmental Protection Agency (EPA)'s most recent toxicological assessment of lung and bladder cancer mortality used to set drinking water standards and risk-based action levels for soil cleanup throughout the nation (Toxicological Review of Inorganic Arsenic, EPA/635/R-10/001). It is an old and continuing saga. The U.S. Public Health Service first regulated arsenic in drinking water at 50 ppb in 1942. Following passage of the Safe Drinking Water Act in 1974, responsibility fell to EPA to protect the nation from arsenic exposure in drinking water. EPA used risk assessment guidelines developed in the early 1980s that are still in use today.
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