PERI's practice is to assign ownership of polluting facilities on the basis of the most recent available data because this information is of greatest utility to shareholders and other stakeholders regarding the party currently responsible for the plants that released the toxic substances. We believe that when a corporation takes control of particular polluting facilities, they also take responsibility for the past pollution created by those facilities... PERI hopes that improved environmental performance since US Steel Corporation's acquisition of these plants will reduce US Steel's Toxic Score, and PERI will publish new data as these become available from EPA [US Environmental Protection Agency].