Identification of ah receptor agonists in soil of E-waste recycling sites from Taizhou area in China.

In recent years, increasing concern has surrounded the consequences of improper electric and electronic waste (e-waste) disposal. In order to mitigate or remediate the potentially severe toxic effects of e-waste recycling on the environment, organisms, and humans, many contaminated sites must first be well-characterized. In this study, soil samples were taken from Taizhou city, one of the largest e-waste disposal centers in China, which was involved in recycling for nearly 30 years. The extracts of the samples were assayed for aryl hydrocarbon receptor (AhR)-mediated ethoxyresorufin-O-deethylase (EROD) induction in the rat hepatoma cell line H4IIE. Some of the target AhR agonists, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs), were instrumentally analyzed as well. The cause-effect relationship and dose-response relationship between the chemical concentrations of AhR agonists and observed EROD activity were examined. The results showed that soil extracts could induce AhR activity significantly, and the chemically derived 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQcal) were perfectly correlated to bioassay-derived TCDD equivalents (TEQbio; R = 0.96, P < 0.001), which indicated that the known AhR agonists could account for the observed responses. Among different contributors, PCBs accounted for 87.2-98.2% and PCDD/Fs contributed 1.7-11.6% of TEQcal, while the contribution of PAHs could almost be neglected. Under these conditions, a quantitative dose-effect relationship between TEQ(PCB) and EROD activity could be evaluated, suggesting that the observed AhR effect was mainly caused by PCBs. Further source identification by congener profiles analysis showed that the crude dismantling of electric power devices and open burning of electric wires and printed circuit boards may be the main sources of these dioxin-like compounds. This study suggests that the combination of in vitro bioassay and chemical analysis is useful to screen, identify, and prioritize AhR agonists in soil from e-waste recycling areas.

[1]  Paul D. Jones,et al.  Development of toxic equivalency factors for PCB congeners and the assessment of TCDD and PCB mixtures in rainbow trout , 1995 .

[2]  Ming H Wong,et al.  Spatial distribution of polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in soil and combusted residue at Guiyu, an electronic waste recycling site in southeast China. , 2007, Environmental science & technology.

[3]  L. E. Johnston,et al.  Formation of polychlorinated dibenzofurans and dioxins during combustion, electrical equipment fires and PCB incineration. , 1985, Environmental health perspectives.

[4]  J. Giesy,et al.  Analysis of trace organic contaminants in sediment, pore water, and water samples from Onsan Bay, Korea: Instrumental analysis and in vitro gene expression assay , 2002, Environmental toxicology and chemistry.

[5]  Qinghua Zhang,et al.  Evidence for the transfer of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans from soil into biota. , 2006, The Science of the total environment.

[6]  H. Nakata,et al.  Bioaccumulation and toxic potencies of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in tidal flat and coastal ecosystems of the Ariake Sea, Japan. , 2003, Environmental science & technology.

[7]  Zijian Wang,et al.  Soil screening for identifying ecological risk stressors using a battery of in vitro cell bioassays. , 2006, Chemosphere.

[8]  Zijian Wang,et al.  EROD activities in a primary cell culture of grass carp (Ctenopharyngodon idellus) hepatocytes exposed to polychlorinated aromatic hydrocarbonas. , 2004, Ecotoxicology and environmental safety.

[9]  S. Tao,et al.  Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin. , 2004, The Science of the total environment.

[10]  Zijian Wang,et al.  Ecotoxicological and chemical characterization of selected treatment process effluents of municipal sewage treatment plant. , 2003, Ecotoxicology and environmental safety.

[11]  Min Qiao,et al.  Composition, sources, and potential toxicological significance of PAHs in the surface sediments of the Meiliang Bay, Taihu Lake, China. , 2006, Environment international.

[12]  D. Dixon,et al.  Ability of polycyclic aromatic hydrocarbons to induce 7-ethoxyresorufin-o-deethylase activity in a trout liver cell line. , 1999, Ecotoxicology and environmental safety.

[13]  H. Fiedler,et al.  PCDDs and PCDFs in soil and river sediment samples from a rural area in the United States of America , 1997 .

[14]  Yonglong Lu,et al.  A spatial temporal assessment of pollution from PCBs in China. , 2005, Chemosphere.

[15]  A. Kočan,et al.  Environmental contamination with polychlorinated biphenyls in the area of their former manufacture in Slovakia. , 2001, Chemosphere.

[16]  K. Jones,et al.  A congener-specific PCDD/F emissions inventory for the UK: do current estimates account for the measured atmospheric burden? , 2001, Chemosphere.

[17]  S. Safe.  Development validation and problems with the toxic equivalency factor approach for risk assessment of dioxins and related compounds. , 1998, Journal of animal science.

[18]  J. Giesy,et al.  Relative potencies of individual polycyclic aromatic hydrocarbons to induce dioxinlike and estrogenic responses in three cell lines , 2002, Environmental toxicology.

[19]  J. Giesy,et al.  Characterization and distribution of trace organic contaminants in sediment from Masan Bay, Korea. 2: In vitro gene expression assays , 1999 .

[20]  C. La Rocca,et al.  A study on PCB, PCDD/PCDF industrial contamination in a mixed urban-agricultural area significantly affecting the food chain and the human exposure. Part I: soil and feed. , 2007, Chemosphere.

[21]  K. Schramm,et al.  PCDD/Fs, PCBs, HCHs and HCB in sediments and soils of Ya-Er Lake area in China: Results on residual levels and correlation to the organic carbon and the particle size , 1997 .

[22]  Yingying Chen,et al.  Identification of Ah receptor agonists in sediment of Meiliang Bay, Taihu Lake, China. , 2006, Environmental science & technology.

[23]  T. Kashimoto,et al.  Levels of pcbs pcdds and pcdfs in soil samples from incineration sites for metal reclamation in taiwan , 1992 .

[24]  Ming H Wong,et al.  Trace metal contamination of sediments in an e-waste processing village in China. , 2007, Environmental pollution.

[25]  Gan‐Lin Zhang,et al.  Concentrations and possible sources of polychlorinated biphenyls in the soils of Hong Kong , 2007 .

[26]  K C Cheung,et al.  Distribution of polycyclic aromatic hydrocarbons in soils at Guiyu area of China, affected by recycling of electronic waste using primitive technologies. , 2006, Chemosphere.

[27]  Rolf Widmer,et al.  Global perspectives on e-waste , 2005 .

[28]  Qinghua Zhang,et al.  Polychlorinated dibenzo-p-dioxins/furans and polychlorinated biphenyls in sediments and aquatic organisms from the Taihu Lake, China. , 2005, Chemosphere.

[29]  Miroslav Machala,et al.  Cell bioassays for detection of aryl hydrocarbon (AhR) and estrogen receptor (ER) mediated activity in environmental samples , 2000, Environmental science and pollution research international.

[30]  M. M. Bradford.  A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. , 1976, Analytical biochemistry.

[31]  C. Tohyama,et al.  The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds. , 2006, Toxicological sciences : an official journal of the Society of Toxicology.

[32]  J. Giesy,et al.  Vertical Profiles of Dioxin-like and Estrogenic Activities Associated with a Sediment Core from Tokyo Bay, Japan , 2000 .