Newly Identified AhR-Active Compounds in the Sediments of an Industrial Area Using Effect-Directed Analysis

Effect-directed analysis was used to identify previously unidentified aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area of Ulsan Bay, Korea. The specific objectives were to (i) investigate potent fractions of sediment extracts using the H4IIE- luc bioassay, (ii) determine the concentrations of known AhR agonists (polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs)), (iii) identify previously unreported AhR agonists in fractions by use of GC-QTOFMS, and (iv) evaluate contributions of individual compounds to overall AhR-mediated potencies, found primarily in fractions containing aromatics with log K ow 5–8. Greater concentrations of PAHs and SOs were also found in those fractions. On the basis of GC-QTOFMS and GC-MSD analyses, 16 candidates for AhR agonists were identified in extracts of sediments. Of these, seven compounds, including 1-methylchrysene, benzo[ j ]fluoranthene, 3-methylchrysene, 5-methylbenz[ a ]anthracene, 11 H -benzo[ b ]fluorene, benzo[ b ]naphtho[2,3- d ]furan, and benzo[ b ]naphtho[2,1- d ]thiophene, exhibited significant AhR activity. Relative potency values of newly identified AhR agonists were found to be greater than or comparable to that of benzo[ a ]pyrene (BaP). The potency balance analysis showed that newly identified AhR agonists explained 0.07–16% of bioassay-derived BaP-EQs. These chemicals were widely distributed in industrial sediments; thus, it is of immediate importance to conduct studies on sources and potential effects of those chemicals.