Background Risk from Regional Mean Inorganic Concentrations from Southeastern Soils. T. H. Wood and S. W. Duda, RUST Environment and Infrastructure, Inc., 15 Brendan Way, Greenville, SC 29615
Limited background data for inorganic constituents in soil is frequently a problem in baseline risk assessments and can contribute significant uncertainty to the estimated site-related risk and hazard. A literature review was conducted to develop a compilation of background inorganic concentrations for soils found in the southeast. Mean soil concentrations were calculated for distinct soil types where n>3. Soil types and studies not meeting this criterion were grouped in a generic, geographic context prior to determination of regional mean concentrations. Distributions of background concentrations were developed where data were sufficient. Using the method for remedial goal development suggested by EPA Region IV (i.e. the ratio method), soil-specific background risk and hazard for residential and industrial land use scenarios were calculated using the standardized exposure factors employed in the EPA Region III Risk-Based Concentration Table. The significance for risk characterization was discussed. Calculated background risk and hazard for each soil type/element combination were compiled in tabular format. The resulting table and compilation of background distributions are very useful tools for interpreting risk assessment results where background data are nonexistent, sparse, or suspect.