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A toxic equivalency factor scale for polychlorinated dibenzofurans

January 1, 1994

The ethoxyresorufin O-deethylase (EROD) induction of 20 polychiorinated dibenzofurans (PCDFs) was examined in the H4IIE rat hepatoma cell bioassay. The selection of the compounds tested was based on a multivariate chemical characterization laying the groundwork for covering the whole chemical series of PCDFs. The EROD induction potency was found to vary in ED50 values from 25 to 100,000,000 pg/mg, i.e., nearly seven orders of magnitude. The response of the bioassay was calibrated against the 2,3,7,8-tetrachlorodibenzo-p-dioxin, enabling the corresponding toxic equivalency factors (TEFs) to be calculated. In order to establish a quantitative structure-activity relationship (QSAR) for the TEF values, 37 physicochemical descriptor variables were used to chemically characterize the 87 tetra- to octachlorinated PCDFs. Using partial least-squares modeling on a training set of 10 congeners, a QSAR model with sound predictive power was obtained. The QSAR model was validated with a validation set of additional 10 congeners. The predicted TEFs indicate that a large number of congeners are potent EROD inducers.

Citation Information

Publication Year 1994
Title A toxic equivalency factor scale for polychlorinated dibenzofurans
DOI 10.1093/toxsci/22.2.277
Authors M. Tysklind, D. Tillitt, L. Eriksson, K. Lundgren, C. Rappe
Publication Type Article
Publication Subtype Journal Article
Series Title Toxicological Sciences
Series Number
Index ID 70177034
Record Source USGS Publications Warehouse
USGS Organization Columbia Environmental Research Center