Concentrations of PCDD/PCDFs and PCBs in spent foundry sands. Chemosphere

Approximately 10 million tons of spent foundry sand (SFS) are generated in the United States each year, and their beneficial use in agricultural and horticultural applications is being considered. Other studies have demonstrated that trace elements are low enough in sands from iron, steel, and aluminum foundries to allow their beneficial use. Because data were not available on polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and polychlorinated biphenyls in SFSs, we analyzed representative spent sands from 10 foundries to assess the potential for these compounds to limit their use in soil-related applications. The total TEQ (toxicity equivalent) concentrations ranged from 0.01 to 3.13 ng TEQ kg?1, with an average concentration of 0.58 ng TEQ kg?1. These concentrations are within the range of natural background in soils

Risk characterization of spent foundry sands in soil-related applications

Spent molding sand is generated at about 2000 foundries in the U.S. when the sand can no longer be reclaimed within the foundry. Interest in beneficial use, rather than disposal of spent foundry sand (SFS), grew in recent years as the cost of landfilling increased and the potential benefit of using SFS in agriculture and horticulture became increasingly apparent. Thus, USDA-ARS researchers and the U.S. EPA's Office of Solid Waste, and researchers at The Ohio State University cooperated to conduct a risk assessment for beneficial use of SFS, and to develop guidance for such use. The available literature on SFS was reviewed and a program of sampling and comprehensive analysis of SFS was undertaken. The sample sets included foundries which cast iron, steel, or aluminum, and generated SFSs which contained low levels of potentially toxic trace elements and organic compounds. Data from these SFSs were evaluated using a pathway risk assessment approach, and it was concluded that most could be beneficially used due to high levels of copper and zinc commonly found in those sands. While most foundries use silica sand, it was also suggested that olivine sands not be beneficially used in soil-related applications, as they contain elevated levels of nickel which may present a phytotoxicity risk in acidic soils. Overall, however, the trace element concentrations in spent sands from iron, steel, and aluminum foundries were not unlike those found in U.S. soils. This guidance document recommends that SFSs with trace elements concentrations below the 95th percentile concentration of background U.S. soils can be safely applied to land or used in manufactured soils. Furthermore, none of the measured organic compounds were present at levels which would comprise excessive risk to humans or environmental receptors. The compounds present were largely biodegradable and mixing SFS in soils would promote natural biodegradation of these compounds

Risk characterization of spent foundry sands in soil-related applications

Spent molding sand is generated at about 2000 foundries in the U.S. when the sand can no longer be reclaimed within the foundry. Interest in beneficial use, rather than disposal of spent foundry sand (SFS), grew in recent years as the cost of landfilling increased and the potential benefit of using SFS in agriculture and horticulture became increasingly apparent. Thus, USDA-ARS researchers and the U.S. EPA's Office of Solid Waste, and researchers at The Ohio State University cooperated to conduct a risk assessment for beneficial use of SFS, and to develop guidance for such use. The available literature on SFS was reviewed and a program of sampling and comprehensive analysis of SFS was undertaken. The sample sets included foundries which cast iron, steel, or aluminum, and generated SFSs which contained low levels of potentially toxic trace elements and organic compounds. Data from these SFSs were evaluated using a pathway risk assessment approach, and it was concluded that most could be beneficially used due to high levels of copper and zinc commonly found in those sands. While most foundries use silica sand, it was also suggested that olivine sands not be beneficially used in soil-related applications, as they contain elevated levels of nickel which may present a phytotoxicity risk in acidic soils. Overall, however, the trace element concentrations in spent sands from iron, steel, and aluminum foundries were not unlike those found in U.S. soils. This guidance document recommends that SFSs with trace elements concentrations below the 95th percentile concentration of background U.S. soils can be safely applied to land or used in manufactured soils. Furthermore, none of the measured organic compounds were present at levels which would comprise excessive risk to humans or environmental receptors. The compounds present were largely biodegradable and mixing SFS in soils would promote natural biodegradation of these compounds