Application of a Bioassay Using DR-EcoScreen Cells to the Determination of Dioxins in Ambient Air: A Comparative Study with HRGC-HRMS Analysis

Abstract

There is a strong need for the development of relatively rapid and low-cost bioassays for the determination of dioxins (polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls) in environmental and food samples. In this study, we applied a bioassay system using highly sensitive DR-EcoScreen cells (DR-cell assay) to the determination of low levels of dioxins in ambient air samples. The dioxins from 80 ambient air samples were extracted, purified by cleanup procedure, and applied to both DR-cell assay and high-resolution gas chromatography/high-resolution mass spectrometry (HRGC-HRMS) analysis. Interestingly, the toxic equivalents (TEQ) values obtained from the DR-cell assay were closely correlated with those from the HRGC-HRMS analysis (r2 = 0.957). Although the cell-based TEQ values were relatively (3.66-fold) higher than the TEQ values from the HRGC-HRMS analysis, this discrepancy was thought to be due to the difference between the toxic equivalency factor (TEF) and the relative potency (DR-REP) determined for individual dioxins. Therefore, we multiplied the TEQ values from the DR-cell assay by a conversion coefficient (0.273, the reciprocal of 3.66) and could approximate the values from the HRGC-HRMS analysis. These results clearly suggest at the DR-cell assay might be a promising method for the rapid and low-cost screening of dioxins in ambient air samples.

Simple and rapid determination of PCDD/Fs in flue gases from various waste incinerators in China using DR-EcoScreen cells

“…Interestingly, although the BEQ values were 4.10 to 6.07-fold higher than the I-TEQ values, we found good linear relationships between the two methods for four types of samples. This tendency was similar to the results of our previous study using 80 ambient air samples obtained in Japan (Anezaki et al, 2009), for which the BEQ values were 3.66-fold higher than the I-TEQ values, although the two sets of data were closely correlated (r 2 = 0.957). In previous study, the discrepancy between the BEQ and I-TEQ values was thought to be due to differences between the WHO-TEF values and relative potency of the AhR agonistic activity estimated using the DR-cell assay (DR-REP) values (Anezaki et al, 2009).…”

“…This result was also supported by other studies (Iino et al, 2003;Zhang et al, 2011). On the other hand, the DR-REP values for 7 PCDDs were lower than their I-TEF, except for 1,2,3,4,7,8-HxCDD, whereas the DR-REP values for the 10 PCDFs were higher than their I-TEF values, except for OCDF (Anezaki et al, 2009). This implies that the BEQ values obtained from the DR-cell assay could cause an underestimation and overestimation of PCDDs and PCDFs, respectively, compared to the I-TEQ values from the HRGC-HRMS using the I-TEF values.…”

“…In both sets of samples, the contribution of PCDFs to the total I-TEQ was higher than those of PCDDs. 2,3,4,7,in particular,was found to contribute approximately 40% to the total I-TEQ and to be main contributor, whose DR-REP value was 2.8-fold higher than its I-TEF value (Anezaki et al, 2009). This result was also supported by other studies (Iino et al, 2003;Zhang et al, 2011).…”

“…Thus, the DR-cell assay is compatible with high-throughput automation and can reduce the overall workload in a laboratory. Most recently, based on a comparative study with HRGC-HRMS analysis, it has been reported that the DR-cell assay was helpful in determining low levels of PCDD/Fs and dioxin-like polychlorinated biphenyls (PCBs) in ambient air samples (Anezaki et al, 2009) as well as in fish and seafood samples (Kojima et al, 2011).…”

Application of the EROD-H4IIE bioassay for the determination of dioxins in pork in comparison to high resolution gas chromatography coupled to high resolution mass spectrometry

“…This analytical technique requires investment in infrastructure and equipment at a considerable cost as well as highly trained technicians to detect individual congeners of PCDD/Fs and DL PCBs (Valdovinos 2009, Babin et al 2010. Therefore, a number of screening assays has been developed, such as the 7-ethoxyresorufin-O-deethylase (EROD)-bioassay, the aryl hydrocarbon hydroxylase (AHH) bioassay, the enzyme immunoassay (EIA), the chemical-activated luciferase gene expression (CALUX), the gel retardation of AhR DNA binding (GRAB) assay, the recAhr DELFIA assay kit, the Ah receptor (AhR) (or filtration) assay with radiolabeled dioxins, the Ah-immunoassay (AhIA) (Behnisch et al 2001), the chemical-activated fluorescent expression (CAFLUX) (Zhao et al 2010) and DR-EcoScreen® bioassay (Anezaki et al 2009, Kojima et al 2010. A viable alternative is to use in vitro bioassay cell line H4IIE rat hepatoma as screening method in pork production, considering that Schoffer et al (2011) determined the equivalence between the results of the bioassay of meat from broiler chickens with HRGC/HRMS, showing that the first one provides very accurate estimates (R 2 =0.885), and is therefore considered a useful technique for biomonitoring, as a screening method, in broiler chicken production and can be extended to other animal production systems.…”