Relationship between polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran, and dioxin-like polychlorinated biphenyl concentrations in vegetation and soil on residential properties

The University of Michigan Dioxin Exposure Study was undertaken to address concerns that the industrial discharge of dioxin like compounds in the Midland Michigan USA area had resulted in the contamination of soil and vegetation in the Tittabawassee River floodplain and downwind of the incinerator in the City of Midi Ind The study included the analysis of 597 vegetation samples predominantly grass and weeds from residential properties selected through a multistage probabilistic sample design in the Midland area and in Jackson and Calhoun Counties (Michigan) as a background comparison for 29 polychlorinated dibenzo p dioxins (PCDDs) polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) The mean toxic equivalent (TEQ) of the house primeter vegetation samples ranged from 4 2 to 377 pg/g The ratio of TEQs (vegetation to soil) was about 0 3 with a maximum of 3 5 Based on a calculation of the similarity of the congener patterns between the soil and the vegetation it appeared that the source of the contamination on the vegetation was the surrounding soil This conclusion was supported by linear regression analysis which showed that the largest contributor to the R-2 for the outcome variable of log 10 of the vegetation concentration was log 10 of the surrounding soil concentration Models of vegetation contamination usually focus on atmospheric deposition and partitioning The results obtained here suggest that the deposition of soil particles onto vegetation is a significant route of contamination for residential herbage Thus the inclusion of deposition of soil particles onto vegetation is critical to the accurate modeling of contamination residential herbage in communities impacted by historic industrial discharges of persistent organic compounds Environ Toxicol Chem 2010 29 2660-2668 (C) 2010 SETAC