EPA developed this document to provide EPA regions, states, and tribes with a consolidated reference of toxicity values. The document provides information on toxicity values, EPA guidance on selecting toxicity values, and other efforts for selecting toxicity values at hazardous waste and cleanup sites. Appendices A through D provide guidance on calculating risk-based screening levels. Although developed primarily for typical UST sites, users may find it helpful when addressing petroleum contamination at non-UST sites.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.