| Dioxinlike Components in Incinerator Fly Ash: A Comparison between Chemical Analysis Data and Results from a Cell Culture Bioassay Markus Till,
1
Peter Behnisch,
2
Hanspaul Hagenmaier,
2
Karl Walter Bock,
1
and Dieter Schrenk
3
1
Institute of Toxicology; and
2
Institute of Organic Chemistry, University of Tübingen, Tübingen, Germany
3
Food Chemistry/ Environmental Toxicology, University of Kaiserslautern, Kaiserslautern, Germany
Abstract
Potent polychlorinated dibenzo-p-dioxins (PCDDs) , polychlorinated dibenzofurans (PCDFs) , and dioxinlike polychlorinated biphenyls (PCBs) are among the most relevant toxic emissions from incinerators. Induction of cytochrome P450 1A1-catalyzed 7-ethoxyresorufin O-deethylase (EROD) activity in mammalian cell culture (EROD bioassay) is thought to be a selective and sensitive parameter used for the quantification of dioxinlike compounds. Fly ash extracts from municipal waste incinerators (MWI) , a crematorium, wood combustors, and a noble metal recycling facility were analyzed in the EROD bioassay using rat hepatocytes in primary culture. Fractions containing 2,3,7,8-substituted PCDDs/PCDFs, dioxinlike PCBs, and 16 major polycyclic aromatic hydrocarbons (PAHs) were isolated from the extract and analyzed by gas chromatography-mass spectrometry (GC-MS) and by the EROD bioassay. It was found that with MWI samples the bioassay of the extract resulted in a two- to fivefold higher estimate of TCDD equivalents (TEQ) than the chemical analysis of PCDDs/PCDFs and PCBs. However, the outcome of both methods was significantly correlated, making the bioassay useful as a rough estimate for the sum of potent PCDDs/PCDFs and dioxinlike PCBs in extracts from MWI fly ash samples and in a fly ash sample from a crematorium. In noble metal recycling facility and wood combustor samples, higher amounts of PAHs were found, contributing to more pronounced differences between the results of both methods. The remaining unexplained inducing potency in fly ash samples probably results from additional dioxinlike components including certain PAHs not analyzed in this study. The hypothesis that emissions from MWI of hitherto unidentified dioxinlike compounds are higher by orders of magnitude than emissions of potent PCDDs/PCDFs and dioxinlike PCBs could not be confirmed. We found no indication for a marked synergistic interaction of dioxinlike fly ash components in the bioassay. Key words : bioassay, dioxin, EROD, fly ash, incineration, PAH, PCB. Environ Health Perspect 105:1326-1332 (1997) .
Address correspondence to D. Schrenk, Food Chemistry/Environmental Toxicology, University of Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern, Germany. The authors are grateful to Silvia Vetter for expert technical assistance. This study was supported by a grant from the Projekt Umwelt und Gesundheit of the State of Baden-Württemberg. The animals used for hepatocyte donation received care and treatment in accordance with the German Animal Protection Act (Tierschutzgesetz) . Received 28 May 1997 ; accepted 13 August 1997.
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