EPA. 2001. Supplemental Guidance to RAGS: Region 4 Bulletins, Ecological Risk Assessment. Originally published: EPA Region IV. 1995. Ecological Risk Assessment Bulletin No. 2: Ecological Screening Values. U.S. Environmental Protection Agency Region 4, Waste Management Division, Atlanta, GA. Website version last updated 30 November 2001: http://www.epa.gov/region4/waste/ots/epatab4.pdf.