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, 11H-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.
Endocrine-disrupting potential was evaluated during the
sewage
treatment process using in vitro bioassays. Aryl hydrocarbon receptor
(AhR)-, androgen receptor (AR)-, glucocorticoid receptor (GR)-, and
estrogen receptor (ER)-mediated activities were assessed over five
steps of the treatment process. Bioassays of organic extracts showed
that AhR, AR, and GR potencies tended to decrease through the sewage
treatment process, whereas ER potencies did not significantly decrease.
Bioassays on reverse-phase high-performance liquid chromatography
fractions showed that F5 (log K
OW 2.5–3.0)
had great ER potencies. Full-scan screening of these fractions detected
two novel ER agonists, arenobufagin and loratadine, which are used
pharmaceuticals. These compounds accounted for 3.3–25% of the
total ER potencies and 4% of the ER potencies in the final effluent.
The well-known ER agonists, estrone and 17β-estradiol, accounted
for 60 and 17% of the ER potencies in F5 of the influent and primary
treatment, respectively. Fourier transform ion cyclotron resonance
mass spectrometry analysis showed that various molecules were generated
during the treatment process, especially CHO and CHOS (C: carbon,
H: hydrogen, O: oxygen, and S: sulfur). This study documented that
widely used pharmaceuticals are introduced into the aquatic environments
without being removed during the sewage treatment process.
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