US EPA

This final report summarizes a survey of state soil cleanup levels for dioxin and characterizes the science underlying these values. The objective of this project was to summarize existing state cleanup levels for dioxin in soil, together with their scientific bases where available. In May 2009, U.S. EPA Administrator Lisa P. Jackson issued EPA’s Science Plan for Activities Related to Dioxins in the Environment (https://www.epa.gov/dioxin/scienceplan). Included in the plan was a commitment by the Agency to prepare this report as a way to inform the development of interim preliminary remediation goals (PRG) for dioxin in soil that will be developed by EPA’s Office of Solid Waste and Emergency Response.

Information on soil dioxin cleanup levels was pursued for all 50 states, as well as DC, Puerto Rico, the Virgin Islands, and four Pacific islands. Nearly half have established cleanup levels, and another quarter have identified screening levels. A number of states have not identified generic concentrations, calling instead for site-specific determinations of cleanup levels to account for relevant conditions. The general cleanup levels established by states for unrestricted (residential) use span more than three orders of magnitude because of their different bases – including the cancer slope factor, target risk level, and exposure assumptions used as well as whether the value was derived for 2,3,7,8-tetrachlorodibenzo-p-dioxin or dioxin toxic equivalents. Most state cleanup levels are based on a 1985 EPA cancer slope factor of 150,000 (mg/kg d) ^-1 and fall at or below 120 ppt.

The purpose of this project was to summarize existing state cleanup levels for dioxin in soil, together with their scientific bases where available.

This is the final report.

U.S. EPA. Review Of State Soil Cleanup Levels For Dioxin (December 2009). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/156, 2009.