These industries polluted the site with polychlorinated biphenyls (PCBs), mercury, lead, dioxins, and cancer-causing polycyclic aromatic hydrocarbons (cPAHs). Large amounts of contaminants are still present at the site and remediation efforts are ongoing. Due to the complexity and size of the site, the cleanup is being managed in three parts, referred to as Operable Units by the U.S. Environmental Protection Agency (EPA): Operable Unit 1 - the estuary and salt marsh; Operable Unit 2 - the cell buildings area and groundwater; and, Operable Unit 3 - the upland soils and sediments where industrial activities took place. Each of these Operable Units has its own documents and schedule of remediation activities.