Organized in accordance with EPA’s Guidelines for Ecological Risk Assessment (EPA, 1998), this framework is intended to assist EPA scientists in using the toxicity equivalence methodology in ecological risk assessments that involve dioxins and dioxin-like chemicals, as well as to inform EPA decision makers, other agencies and the public about this methodology.

While this framework touches on many aspects of ecological risk assessment, it is not intended to be a comprehensive guide to risk assessment involving dioxin-like chemicals. Rather, the framework provides an introduction to the toxicity equivalence methodology, offers considerations for how and when to apply it, and presents practical examples of its use.

Readers are referred elsewhere for details on topics such as:

• chemical analysis
• environmental fate and transport modeling
• development of stressor-response profiles for dioxin-like chemicals

• Framework for Application of the Toxicity Equivalence Methodology for Polychlorinated Dioxins, Furans, and Biphenyls in Ecological Risk Assessment (PDF)(92 pp, 1 MB, June 2008, 100-R-08-004)