title: Contribution of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) to the toxic equivalency of dioxin-like compounds in archived biosolids from the U.S. EPA's 2001 national sewage sludge survey.
abstract: The World Health Organization recently proposed the inclusion of brominated congeners in addition to chlorinated congeners when computing the toxic equivalency (TEQ) of dioxin-like compounds (DLCs) in assessments of human health risks. In the present study, 12 polybrominated dibenzo-p-dioxins and furans (PBDD/Fs) were analyzed by gas chromatography/high resolution mass spectrometry in the composited, archived biosolids that were collected in 32 U.S. states and the District of Columbia from 94 wastewater treatment plants by the United States Environmental Protection Agency in its 2001 national sewage sludge survey. Two PBDDs and five PBDFs were detected in the biosolids composites at varying frequencies (40-100%) with a total mean concentration of 10,000 ng/kg dry weight (range: 630-42,800), of which 1,2,3,4,6,7,8-hepta-BDF constituted about 95% by mass. Relative to commercial polybrominated diphenyl ether (PBDE) formulations, the ratio of PBDD/Fs to PBDEs in biosolids was 55-times higher (∼ 0.002% vs ∼ 0.11%), which indicates potential PBDE transformation or possibly additional sources of PBDD/Fs in the environment. The TEQ contribution of PBDD/Fs was estimated at 162 ng/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (range: 15-672), which is equivalent to 75% (range: 12-96%) of the total TEQ in biosolids. The TEQ of DLCs released annually to U.S. soils as a result of the land application of biosolids was estimated at 720 g (range: 530-1600 g). Among all known DLCs determined in biosolids, brominated analogs contributed 370% more TEQ than did chlorinated congeners, which indicates the need to include brominated DLCs in the exposure and risk assessment of land-applied biosolids.
authors.affiliation: Center for Environmental Security, The Biodesign Institute, Security and Defense Systems Initiative, Arizona State University , 781 East Terrace Mall, Tempe, Arizona 85287-5904, United States.
authors.forename: Arjun K
authors.initials: AK
authors.lastname: Venkatesan
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
mesh_terms: D001572:Benzofurans / Q000633:toxicity*; D003625:Data Collection; D004147:Dioxins / Q000633:toxicity*; D055768:Halogenated Diphenyl Ethers / Q000633:toxicity; D012722:Sewage / Q000737:chemistry*; D014481:United States; D014484:United States Environmental Protection Agency
chemical_list: D001572:Benzofurans; D004147:Dioxins; D055768:Halogenated Diphenyl Ethers; D012722:Sewage; C023614:dibenzofuran; C020887:dibenzo(1,4)dioxin