Many environmental contaminants accumulate in soils. Understanding the concentrations and spatial distribution of these chemicals is critical to determining how they may contribute to human exposure via direct contact or uptake through the food chain. The purpose of this document is to report the results of a pilot survey of the levels of polychlorinated dibenzop- dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and mercury in rural soils of the United States. All samples were collected during 2003.This report provides a national-scale pilot survey of the levels of the following chemicals in rural/remote soils of the United States: chlorinated dibenzo-p-dioxins (CDDs), chlorinated dibenzofurans (CDFs), polychlorinated biphenyls (PCBs), and mercury. Soils can serve as long-term reservoirs for CDDs, CDFs, PCBs, and mercury, with releases to both terrestrial and aquatic systems (U.S. EPA, 2003, 1997; Brzuzy and Hites, 1996). Understanding their distribution in soil is important because they are taken up by plants and animals through soil pathways and bioaccumulate through the human food chain. The relative importance of soil as a potential source for these chemicals is increasing as their point source emissions are being reduced. The final reason for conducting this study is that relatively few soil surveys of these compounds have been conducted.

EPA/600/R-05/048F. April 2007.