WASHINGTON (AP) — The Environmental Protection Agency added 12 hazardous waste sites to the list of the most-contaminated places in the United States on Friday, clearing the way for major cleanups to rid the sites of dangerous toxins.

Arsenic, lead and mercury were among a long list of toxins found at the sites — mostly former factories, chemical plants and contaminated water plumes. Investigators also found elements like benzene, copper and chromium, plus harmful chemicals associated with pesticides and industrial solvents.