title: Detection of retinoic acid receptor agonistic activity and identification of causative compounds in municipal wastewater treatment plants in Japan.
abstract: Retinoic acid (RA) receptor (RAR) agonists are potential toxicants that can cause teratogenesis in vertebrates. To determine the occurrence of RAR agonists in municipal wastewater treatment plants (WWTPs), we examined the RARα agonistic activities of influent and effluent samples from several municipal WWTPs in Osaka, Japan, using a yeast two-hybrid assay. Significant RARα agonistic activity was detected in all the influent samples investigated, suggesting that municipal wastewater consistently contains RAR agonists. Fractionations using high-performance liquid chromatography, directed by the bioassay, found several bioactive peaks from influent samples. The RAR agonists, all-trans RA (atRA), 13-cis RA (13cRA), 4-oxo-atRA, and 4-oxo-13cRA, possibly arising from human urine, were identified by liquid chromatography ion trap time-of-flight mass spectrometry. Quantification of the identified compounds in municipal WWTPs confirmed that they were responsible for the majority of RARα agonistic activity in WWTP influents, and also revealed they were readily removed from wastewater by activated sludge treatment. Simultaneous measurement of the RARα agonistic activity revealed that although total activity typically declined concomitant with the reduction of the four identified compounds, it remained high after the decline of RAs and 4-oxo-RAs in one WWTP, suggesting the occurrence of unidentified RAR agonists during the activated sludge treatment.
authors.affiliation: Division of Sustainable Energy and Environmental Engineering, Osaka University, Suita, Osaka, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Sawada
authors.forename: Daisuke
authors.initials: D
authors.lastname: Inoue
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Wada
authors.forename: Kazunari
authors.initials: K
authors.lastname: Sei
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Michihiko
authors.initials: M
authors.lastname: Ike
mesh_terms: D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007564:Japan; D018168:Receptors, Retinoic Acid / Q000819:agonists*; D000072482:Retinoic Acid Receptor alpha; D012722:Sewage; D014212:Tretinoin / Q000032:analysis / Q000737:chemistry / Q000633:toxicity; D020798:Two-Hybrid System Techniques; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*
chemical_list: C000607071:RARA protein, human; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D012722:Sewage; D014874:Water Pollutants, Chemical; D014212:Tretinoin