Degradation and transformation of 17α-estradiol in water-sediment systems under controlled aerobic and anaerobic conditions

Proposal for a tiered regulatory framework for the aquatic risk assessment of pesticides in Brazil

Aquatic risk assessment is essential to guarantee the sustainable use of pesticides and the conservation of water resources near agricultural fields. This article discusses a proposal for a tiered regulatory framework for the aquatic risk assessment of pesticides in Brazil. The first step is problem formulation, which includes establishing general and specific protection goals. In the exposure assessment, the Estimated Environmental Concentrations in water should be calculated based on realistic worst-case assumptions regarding application rate and frequency, the entry into the edge-of-field water body, and fate in the water body, using scenario-dependent models suggested by the Brazilian Environmental Agency. These calculations can be refined by including Efate studies with variable exposures to reflect realistic environmental conditions accurately and include mitigation measures that impact the modeling. In the hazard assessment, ecotoxicological data for toxicity to fish, aquatic invertebrates, algae, and aquatic plants should be required for all pesticides based on standardized protocols and species. Tier 2 has several refinement options, including incorporating toxicity data from additional test species and effect modeling. In Tier 3, population- and community-level effects are evaluated using semi-field studies. Considering the case study in Brazil, Tier 1 demonstrated that, from the 12 pesticides that were assessed, seven (58%) failed based on the value of the Risk Quotient. In Tier 2, when exposure refinement options and mitigation measures such as buffer zones are considered, all seven pesticides, for which Tier 1 indicated risk, still failed the assessment. The risk for four of these seven pesticides could be refined by considering toxicity information from additional species. Refinement options and mitigation measures that could be applied to the agricultural scenario in Brazil were discussed. In conclusion, the proposed tiered risk assessment is a feasible way to evaluate whether a pesticide will pose an unacceptable risk to aquatic organisms. Integr Environ Assess Manag 2024;20:1514-1528. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Assessing the transformation products and fate of Oxytetracycline by simulated aerobic degradation tests

Oxytetracycline (OTC) is a widely used broad-spectrum antibiotic, whose presence in water and sediments was reported in various regions of the world. The effects of OTC and other tetracyclines on the environment have been intensively studied although many of their transformation products (TPs) formed in the environment and their impact have not been yet fully characterized. Abiotic and biotic degradation tests under aerobic conditions at two pH values were carried out using OTC in artificial water/sediment systems to assess the effect of these variables on the environmental fate of the pollutant. HPLC-MSn was employed to detect and identify the main degradation products and pathways. Several transformations involved in the process were identified including alcohol oxidation, decarbonylation and hydroxylation. Differences in TPs and kinetics were found among degradation conditions, remarking a faster degradation of both OTC and TPs in the presence of microorganisms and at lower pH values. In summary, a total of 44 TPs were detected and structures were proposed for 20 of them, none of them having been previously reported. Furthermore, OTC degradation generated 24 TPs which remained in either solution or sediment, although none of them displayed higher algae toxicity than OTC. These results might be useful for planning future remediation and monitoring strategies.

Microbial Degradation of Free and Halogenated Estrogens in River Water-Sediment Microcosms

Halogenated estrogens are formed during chlorine-based wastewater disinfection and have been detected in wastewater treatment plant effluent; however, very little is known about their susceptibility to biodegradation in natural waters. To better understand the biodegradation of free and halogenated estrogens in a large river under environmentally relevant conditions, we measured estrogen kinetics in aerobic microcosms containing water and sediment from the Willamette River (OR, USA) at two concentrations (50 and 1250 ng L^-1). Control microcosms were used to characterize losses due to sorption and other abiotic processes, and microbial dynamics were monitored using 16S rRNA gene sequencing and ATP. We found that estrogen biodegradation occurred on timescales of hours to days and that in river water spiked at 50 ng L^-1 half-lives were significantly shorter for 17β-estradiol (t_1/2,bio = 42 ± 3 h) compared to its monobromo (t_1/2,bio = 49 ± 5 h), dibromo (t_1/2,bio = 88 ± 12 h), and dichloro (t_1/2,bio = 98 ± 16 h) forms. Biodegradation was also faster in microcosms with high initial estrogen concentrations as well as those containing sediment. Free and halogenated estrone were important transformation products in both abiotic and biotic microcosms. Taken together, our findings suggest that biodegradation is a key process for removing free estrogens from surface waters but likely plays a much smaller role for the more highly photolabile halogenated forms.

Evaluating chemicals of emerging concern in the Ganga River at the two major cities Prayagraj and Varanasi through validated analytical approaches

Evaluating environmental water quality means to assess and protect the environment against unfriendly impacts from various organic impurities emerging from industrial emissions and those released during harvesting. Potential risks related with release of polycyclic aromatic hydrocarbons (PAHs), pesticides and pharmaceuticals (PhAcs), and personal care products (PCPs) into the environment have turned into an increasingly serious issue in ecological safety. Monitoring helps in control of chemicals and ecological status compliance to safeguard specific water uses, for example, drinking water abstraction. A longitudinal review was carried out for 55 different persistent organic pollutants (POPs) for the Ganga River which passes through the urban areas of Prayagraj and Varanasi, India, through validated analytical approaches and measurement uncertainty (MU) estimation to assess their potential use for routine analysis. Furthermore, environmental risk assessment (ERA) carried out in the present study has revealed risk quotient (RQ) higher than 1 in a portion of the aquatic bodies. Using a conservative RQ strategy, POPs were assessed for having extensive risks under acute and chronic exposure, proposing that there is currently critical ecological risk identified with these compounds present in the Ganga River. In general, these outcomes demonstrate a significant contribution for focusing on measures and feasible techniques to minimize the unfavorable effects of contaminants on the aquatic environment.

Distribution, ecological fate, and risks of steroid estrogens in environmental matrices

Over the past two decades, steroidal estrogens (SEs) such as 17α-ethylestradiol (EE2), 17β-estradiol (E2),17α-estradiol (17α-E2), estriol (E3) and estrone (E1) have elicited worldwide attention due to their potentially harmful effects on human health and aquatic organisms even at low concentration ng/L. Natural steroidal estrogens exhibit greater endocrine disruption potency due to their high binding effect on nuclear estrogen receptors (ER). However, less has been explored regarding their associated environmental risks and fate. A comprehensive bibliometric study of the current research status of SEs was conducted using the Web of Science to assess the development trends and current knowledge of SEs in the last two decades, from 2001 to 2021 October. The number of publications has tremendously increased from 2003 to 2021. We summarized the contamination status and the associated ecological risks of SEs in different environmental compartments. The results revealed that SEs are ubiquitous in surface waters and natural SEs are most studied. We further carried out an in-depth evaluation and synthesis of major research hotspots and the dominant SEs in the matrices were E1, 17β-E2, 17α-E2, E3 and EE2. Nonetheless, investigations of SEs in soils, groundwater, and sediments remain scarce. This study elucidates SEs distribution, toxicological risks, ecological fate and mitigation measures, which will be beneficial for future monitoring, management, and risk assessment. Further studies are recommended to assess the toxicological risks of different SEs in complex environmental matrices to pursue a more precise and holistic quantitative estimation of estrogenic risk.

Occurrence and Fate of Steroid Estrogens in a Chinese Typical Concentrated Dairy Farm and Slurry Irrigated Soil

Animal husbandry is the second largest source of steroid estrogen (SE) pollutants in the environment, and it is significant to investigate the occurrence and fate of SEs discharged from concentrated animal feeding operations. In this research, with a Chinese typical concentrated dairy farm as the object, the concentrations of SEs (E1, 17α-E2, 17β-E2, E3, and E1-S3) in slurry, lagoon water, and slurry-irrigated soil samples in summer, autumn, and winter were determined. The total concentrations of SEs (mainly E1, 17α-E2, and 17β-E2) in slurry were very high in the range of 263.1-2475.08 ng·L^-1. In the lagoon water, the removal efficiencies of the aerobic tank could reach up to 89.53%, with significant fluctuation in different seasons. In the slurry-irrigated soil, the maximum concentrations of SEs in the topsoil and subsoil were 21.54 ng·g^-1 to 6.82 g·g^-1, respectively. Most of the SEs tended to transport downward and accumulate in the soil accompanied with the complex mutual conversion. Correlations and hierarchical clustering analysis showed a variety of intertransformation among SEs, and the concentrations of SEs were correlated with various physicochemical indexes, such as TN and NO₃^--N of the slurry, chemical oxygen demand of the lagoon water, and the heavy metals of soil. In addition, 17β-estradiol equivalency assessment and risk quotients indicated that the slurry irrigation and discharge of the lagoon water would cause potential estrogenic risks to the environment. Consequently, reasonable slurry irrigation and lagoon water discharge are essential to efficiently control SE pollution in the environment.

Natural estrogens in surface waters of a catchment with intensive livestock farming in Switzerland

Natural estrogens such as 17α-estradiol (E2α), 17β-estradiol (E2β), estrone (E1), and estriol (E3), released to surface waters from both urban and agricultural sources, are endocrine disrupting for fish. Here, we assess the prevalence of livestock farming derived natural estrogens in tributaries and ponds in the agriculturally dominated catchment of Lake Baldegg, Switzerland. Passive samplers were deployed in the main tributary and daily time-proportional water samples were collected in five tributaries for 30 days at the beginning of the vegetation period. Furthermore, we took grab samples of 12 ponds in the catchment. Aqueous samples were liquid-liquid extracted, derivatized, and analysed with LC-MS/MS and stream water samples additionally with ERα-CALUX, a bioassay for assessing total estrogenic activity. Natural estrogens were regularly detected, with mean concentrations ranging from below the limit of detection to 0.55 ng L^-1 for E2β and E1, respectively, and passive sampling and bioassay results largely confirmed these findings. Monte Carlo simulated mean natural estrogen concentrations underestimated measured ones by a factor of three to 11. An agricultural area's hydrological contribution and connectivity to surface waters seemed to be more important for the development of estrogen concentrations in streams than livestock densities in a catchment or the actual loads of slurry applied. Pond water occasionally contained natural estrogens in concentrations up to 8.6 ng L^-1 for E2α. The environmental quality standards of the European Union (0.4 ng L^-1 for E2β and 3.6 ng L^-1 for E1) were never exceeded for longer than a day in tributaries, but E1 reached critical concentrations for aquatic organisms in ponds.

Spatio-temporal distribution and transformation of 17α- and 17β-estradiol in sterilized soil: A column experiment

The environmental behaviors of steroid estrogens (SEs) associated with land irrigation and application are of critical concern worldwide. Understanding the spatio-temporal distribution and transformation process of these estrogenic compounds in soil is greatly significant. In this study, laboratory soil column experiments were conducted to investigate and explore the migration and abiotic transformation of 17α-estradiol (17α-E2) and 17β-estradiol (17β-E2) over spatial and time scales. Results indicated that the migration tendency of 17α-E2 and 17β-E2 was similar. Discrepancies in transport for different SEs groups might be due to the competitive sorption and isomeric transformation in the binary-solute system. 17α-E2 and 17β-E2 can also undergo the abiotic transformation during soil column transport. The soil with naturally abundant mineral substances (e.g., iron and manganese oxides) indicated that E2 isomers tended to mineral-promoted racemization, oxidation, reduction, and radical coupling reactions. Some possible transformation products (e.g., SE₂₃₉, E2₃₇₈, and SE dimer₄₇₆) were identified and proposed in soil samples. Compared to the single compound tests, the estimated 17β-estradiol equivalency (EEQ) values of E2 mixture were higher during SEs migration process.

Occurrence, sorption, and transformation of free and conjugated natural steroid estrogens in the environment

Natural steroid estrogens (NSEs), including free estrogens (FEs) and conjugated estrogens (CEs), are of emerging concern globally among public and scientific community due to their recognized adverse effects on human and wildlife endocrine systems in recent years. In this review, the properties, occurrence, sorption process, and transformation pathways of NSEs are clarified in the environment. The work comprehensively summarizes the occurrence of both free and conjugated estrogens in different natural and built environments (e.g., river, WWTPs, CAFOs, soil, and sediment). The sorption process of NSEs can be impacted by organic compounds, colloids, composition of clay minerals, specific surface area (SSA), cation exchange capacity (CEC), and pH value. The degradation and transformation of free and conjugated estrogens in the environment primarily involves oxidation, reduction, deconjugation, and esterification reactions. Elaboration about the major, subordinate, and minor transformation pathways of both biotic and abiotic processes among NSEs is highlighted. The moiety types and binding sites also would affect deconjugation degree and preferential transformation pathways of CEs. Notably, some intermediate products of NSEs still remain estrogenic potency during transformation process; the elimination of total estrogenic activity needs to be addressed in further studies. The in-depth researches regarding the behavior of both free and conjugated estrogens are further required to tackle their contamination problem in the ecosystem. Graphical abstract ᅟ.