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

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 (r(2) = 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 that the DR-cell assay might be a promising method for the rapid and low-cost screening of dioxins in ambient air samples.