Rapid bioassay for the determination of dioxins and dioxin-like PCDFs and PCBs in meat and animal feeds

Abstract

Over the past several years, the numerous contamination incidents have raised concerns over the presence of halogenated aromatic hydrocarbons, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and related chemicals in foods and feeds. Here we applied a sensitive recombinant mouse hepatoma cell (H1L1.1c2) bioassay for the determination of dioxins and dioxin-like polychlorinated dibenzofurans (PCDFs) and biphenyls (PCBs) in meat and animal feeds. These cells responded to TCDD-like chemicals with dose-dependent induction of firefly luciferase activity, and the minimal detection limit of TCDD in the cell was 16 fg. Induction equivalency factors determined for pure TCDD-like polychlorinated dibenzo-p-dioxins (PCDDs), PCDFs, and PCBs in the bioassay were well-correlated with the World Health Organization's toxic equivalency factors. To determine the applicability of the bioassay system to detect those compounds presence in meat and feed samples, cell bioassays for 17 TCDD-like PCDDs and PCDFs congeners-spiked lipid extracted from beef or animal feed were performed. Mean recoveries of TCDD-like chlorinated PCDDs and PCDFs congeners from spiked beef or feed fat ranged from 61.2 to 122.3%. Within-laboratory coefficients of variation for analysis as index of precision were lower than 5.2%, and the calculated limits of detection and quantitation were 0.33 and 1 pg toxicity equivalency quantity (TEQ)/0.5 g fat, respectively. Correlation between bioassay- and high-resolution gas chromatography-mass spectrometry (HR-GC-MS)-determined TEQs for 10 meat samples was 0.85, with 1.2 times higher in bioassay than HR-GC-MS. The correlation between bioassay- and HR-GC-MS-determined TEQs in 10 animal feed products was 0.81, with 2.1 times higher in bioassay than HR-GC-MS. Overall, these results demonstrated that the recombinant cell bioassay can be used for the rapid detection and quantitation of PCDDs and dioxin-like PCDFs and PCBs in meats and animal feeds.