Characterization and distribution of trace organic contaminants in sediment from Masan Bay, Korea. 2. In vitro gene expression assays

Extracts of sediment collected from Masan Bay, Korea were fractionated usin g Florisil columns. Fractions were screened for their ability to induce est rogen- and dioxinlike gene expression in vitro using MVLN and H4llE-luc cel ls, respectively, both before and after acid treatment. Florisil fraction 1 (F1), which was shown to contain polychlorinated biphenyls, induced very l ittle response in either assay. The midpolarity Florisil fraction (F2) was the most active fraction. Twenty-seven of 28 F2 samples induced significant estrogenic activity, and all 28 samples induced significant dioxinlike act ivity. Twelve of the F2 samples produced magnitudes of response in the diox in-responsive H4IIE-luc cells similar to those induced by a 23,7,8-tetrachl orodibenzo-p-dioxin (TCDD) standard. Acid treatment did not markedly dimini sh the activity of F2 samples. These results suggested the presence of unid entified, acid stable, aryl hydrocarbon receptor (AhR) and estrogen recepto r (ER) agonists in F2. Twenty-three of the 28 most polar florisil fractions (F3) were either cytotoxic or caused morphological changes in estrogen-res ponsive MVLN cells, while over half of the F3 samples caused similar effect s in H4llE-luc cells. Empirical evidence suggested that acid labile compoun ds contributed to both the estrogenic and cytotoxic responses of the MVLN c ells. Mass balance suggested that known concentrations of alkylphenols and bisphenol A may account for a portion of the estrogenic response but were n ot great enough to account for the toxicity. Acid labile compounds also con tributed substantially to the dioxinlike activity of F3 samples. This adds to a growing body of evidence which suggests the presence of unidentified, relatively polar, aryl hydrocarbon receptor agonists in sediment from some areas.