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.