Vast numbers of xenobiotics are known still to be present in treated municipal wastewater treatment plant (WWTP) effluents. Some of these possess endocrine-disrupting potency and pose risks for exposed aquatic animals. We searched for 17 potential environmental contaminants having affinity to the progesterone receptor. Relative potency values of these progesterone receptor-active chemicals were obtained. On the basis of relative potencies and measured environmental concentrations, the contribution of progestins to measured progestagenic activities was evaluated. Wastewaters (influent and effluent) and surrounding surface waters (upstream and downstream) at six municipal WWTPs were screened using instrumental chemical analysis and in vitro reporter gene bioassay. We showed the presence of target compounds and (anti-)progestagenic activities in municipal wastewater and surface water. Nine and seven progestins were identified in influent and effluent wastewaters, respectively. Only two compounds, progesterone and medroxyprogesterone were found in surface waters. Progestagenic agonistic activities in influents were partially masked by strong anti-progestagenic activities that were detected in all influents and ranged from 2.63 to 83 ng/L of mifepristone equivalents (EQs). Progestagenic activities were detected in all effluents and ranged from 0.06 to 0.47 ng/L of reference compound ORG 2058 EQs (a synthetic progestin equivalents), thus indicating incomplete removal of progestins during wastewater treatment processing. This activity poses a continuing risk for the aquatic environment. By contrast, anti-progestagenic activities showed better removal efficiency in WWTPs compared to progestagenic agonistic activities. Anti-progestagenic activities were found in only three of six effluents and ranged from 0.26 to 2.1 ng/L mifepristone EQs. We explained most of the progestagenic activity in municipal WWTP effluents by the presence of synthetic progestins and progesterone, which contributed 65-96% of such activity in samples where no antagonistic activity was found. The progestins medroxyprogesterone acetate, megestrol acetate and progesterone contributed most to the progestagenic activity detected in municipal effluents. Anti-progestagenic activities were found in some municipal effluents, but no causative agents were revealed because two analysed selective progesterone receptor modulators (SPRMs) with anti-progestagenic activities, mifepristone and ulipristal acetate, were not present in the effluents.

University of South Bohemia in České Budějovice Faculty of Fisheries and Protection of Waters South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses Zátiší 728 2 389 25 Vodňany Czech Republic

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