A toxic equivalency factor scale for polychlorinated dibenzofurans

Toxicological Sciences
By: , and 



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.

Publication type Article
Publication Subtype Journal Article
Title A toxic equivalency factor scale for polychlorinated dibenzofurans
Series title Toxicological Sciences
DOI 10.1093/toxsci/22.2.277
Volume 22
Issue 2
Year Published 1994
Language English
Publisher Oxford Journals
Contributing office(s) Columbia Environmental Research Center
Description 9 p.
First page 277
Last page 285
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