DIOXINLIKE COMPONENTS IN INCINERATOR FLY-ASH - A COMPARISON BETWEEN CHEMICAL-ANALYSIS DATA AND RESULTS FROM A CELL-CULTURE BIOASSAY

Potent polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibe nzofurans (PCDFs), and dioxinlike polychlorinated biphenyls (PCBs) are among the most relevant toxic emissions from incinerators. Induction of cytochrome P450 1A1-catalyzed 7-ethoxyresonifin O-deethylase (EROD) activity in mammalian cell culture (EROD bioassay) is thought to be a selective and sensitive parameter used for the quantification of diox inlike compounds. Fly ash extracts from municipal waste incinerators ( MWI), a crematorium, wood combustors, and a noble metal recycling faci lity sere analyzed in the EROD bioassay using rat hepatocytes in prima ry culture. Fractions containing 2,3,7,8-substituted PCDDs/PCDFs, diox inlike PCBs, and 16 major polycyclic aromatic hydrocarbons (PAHs) were isolated from the extract and analyzed by gas chromatography-mass spe ctrometry (GC-MS) and by the EROD bioassay. It was found that with MWI samples the bioassay of the extract resulted in a two- to five-fold h igher estimate of TCDD equivalents (TEQ) than the chemical analysis of PCDDs/PCDFs and PCBs, However, the outcome of both methods was signif icantly correlated, making thr bioassay useful as a tough estimate for the sum of potent PCDDs/PCDFs and dioxinlike PCBs in extracts from MW I fly ash samples and in a fly ash sample from a crematorium. In noble metal recycling facility and wood combustor samples, higher amounts o f PAHs were found. contributing to more pronounced differences between the results of both methods, The remaining unexplained inducing poten cy in ny ash samples probably results from additional dioxinlike compo nents including certain PAHs not analyzed in this study. The hypothesi s that emissions from MWI of hitherto unidentified dioxinlike compound s are higher by orders of magnitude than emissions of potent PCDDs/PCD Fs and dioxinlike PCBs could not be confirmed. We found no indication for a marked synergistic interaction of dioxinlike fly ash components in the bioassay.