Stephen Safe

TL;DR: The estrogenic activity of environmental chemicals and phytoestrogens in competition binding assays with ERα or ERβ protein, and in a transient gene expression assay using cells in which an acute estrogenic response is created by cotransfecting cultures with recombinant human ERβ complementary DNA (cDNA) in the presence of an estrogen-dependent reporter plasmid are investigated.

TL;DR: Concern was expressed about direct application of the TEF/total toxic equivalency (TEQ) approach to abiotic matrices, such as soil, sediment, etc., for direct application in human risk assessment as the present TEF scheme and TEQ methodology are primarily intended for estimating exposure and risks via oral ingestion.

TL;DR: It was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties.

TL;DR: The most toxic halogenated aromatic is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and based on in vivo and in vitro studies the relative toxicities have been determined relative to TCDD (i.e., toxic equivalents).

TL;DR: Analysis of the results of laboratory animal and wildlife studies suggests that the predictive value of TEQs for PCBs may be both species- and response-dependent because both additive and nonadditive (antagonistic) interactions have been observed with PCB mixtures.