In vitro bioassay determination of dioxin-like and estrogenic activity in sediment and water from Ulsan Bay and its vicinity, Korea

Extracts of sediment and water samples collected from Ulsan Bay, Korea, wer e screened for their ability to induce dioxin-like and estrogenic gene expr ession in vitro. Each sample was tested as raw extract (RE) and fractionate d extract (FE). Based on the initial screening of RE, 23 of 31 sediment sam ples showed significant dioxin-like activity in H4IIE-luc bioassay, whereas most sediment samples did not elicit estrogenic response in MVLN bioassay. Most of the activities associated with FE samples revealed that mid-polar (F2) and most polar (F3) fractions were responsible for the significant rep orter gene expression in H4IIE-luc bioassay. The results suggest that compl ex interactions may have depressed the activities of the known arylhydrocar bon receptor (AhR) agonists present in Fl samples. The F2 samples were the most active fraction. All F2 samples except one induced significant dioxin- like activity, and over half of the F2 samples induced significant estrogen ic activity. Ten of the F2 samples produced magnitudes of response in H4IIE -luc bioassay similar to those induced by a 2,3,7,8-tetrachlorodibenzo-p-di oxin standard. Sediment associated with F2 samples was estimated to contain 24.9-826 pg TCDD-EQ/g DW. Based on a qualitative mass balance analysis, po lycyclic aromatic hydrocarbons (PAHs) appeared to account for both the estr ogenic and dioxin-like responses observed. Over half of the F3 samples were either cytotoxic or caused morphological changes in both H4IIE-luc and MVL N cells. Known concentrations of alkylphenols and bisphenol A were not grea t enough to account for both the estrogenic response and cytotoxicity obser ved for F3 samples. Despite the apparent toxic or stressful effects, most o f F3 samples induced significant dioxin-like activity in vitro, adding to a growing body of evidence that suggests the presence of unidentified, relat ively polar, AhR agonists in sediment from some areas.