Fate and behavior of progestogens in activated sludge treatment: Kinetics and transformation products.

Previous studies have shown the high ecotoxicological potential of progestogens (PGs) on the reproductive system of aquatic organisms. Yet the ubiquitous presence of several PGs in wastewater treatment plant (WWTP) effluents indicates an incomplete removal during treatment. To investigate the fate and behavior of PGs during biological wastewater treatment, nine commonly used PGs were incubated in aerobic lab-scale degradation experiments with activated sludge taken from a municipal WWTP. The degradation kinetics revealed a fast removal after 48 h for most of the compounds. Cyproterone acetate and dienogest were the most recalcitrant of the analyzed steroids with half-lives of 8.65 h and 4.55 h, respectively. Thus, only moderate removals of these PGs can be predicted in full-scale WWTPs. Moreover, numerous transformation products (TPs) were detected via high-resolution mass spectrometry. Hydrogenation or dehydrogenation of ring A and non-selective hydroxylations of 17α-hydroxyprogesterone derivatives (medroxyprogesterone acetate, chlormadinone acetate, cyproterone acetate) as well as for 19-nortestosterone derivatives (dienogest, norethisterone acetate, etonogestrel) were observed as major transformation reactions. Seven of the identified TPs were confirmed by reference standards. The biodegradation of cyproterone acetate revealed an almost quantitative transformation to 3α‑hydroxy cyproterone acetate which is reported to be genotoxic. In a comparative evaluation of the TPs formed and the steroid structure, it was observed that molecular structure played a role in the inhibition of several transformation reactions, explaining the increased recalcitrance of these compounds. In addition, aromatization of the steroid ring A was identified for the 19-nortestosterone derivatives leading to the formation of estrogen-like TPs. For instance, the degradation of norethisterone acetate led to the formation of 17α-ethinylestradiol, a well-known and very potent synthetic estrogen. The evidence of the conversion of progestogenic to estrogenic compounds and the formation of potentially hazardous TPs indicates the need of a more comprehensive environmental risk assessment for synthetic steroids. Two of the newly identified TPs (3α-hydroxy cyproterone acetate and ∆9,11-dehydro-17α-cyanomethyl estradiol) were detected in WWTP effluents for the first time. Copyright © 2020. Published by Elsevier Ltd.

Citation

Alexander Weizel, Michael P Schlüsener, Georg Dierkes, Arne Wick, Thomas A Ternes. Fate and behavior of progestogens in activated sludge treatment: Kinetics and transformation products. Water research. 2021 Jan 01;188:116515

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PMID: 33125988

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