Evaluating the environmental impact of artificial sweeteners: a study of their distributions, photodegradation and toxicities

Acesulfame potassium triggers inflammatory bowel disease via the inhibition of focal adhesion pathway

Acesulfame potassium (ACK) was generally regarded as innocuous and extensively ingested. Nevertheless, ACK has recently gained attention as a burgeoning pollutant that has the potential to induce a range of health hazards, particularly to the digestive system. Herein, we uncover that ACK initiates inflammatory bowel disease (IBD) in mice and zebrafish, as indicated by the aggregation of macrophages in the intestine and the inhibition of intestinal mucus secretion. Transcriptome analysis of mice and zebrafish guts revealed that exposure to ACK typically impacts the cell cycle, focal adhesion, and PI3K-Akt signaling pathways. Using pharmacological approaches, we demonstrate that the PI3K-Akt signaling pathway and the generation of reactive oxygen species (ROS) triggered by cell division are not significant factors in the initiation of IBD caused by ACK. Remarkably, inhibition of the focal adhesion pathway is responsible for the IBD onset induced by ACK. Our results indicate the detrimental impacts and possible underlying mechanisms of ACK on the gastrointestinal system and provide insights for making informed choices about everyday dietary habits.

Acesulfame and other artificial sweeteners in a wastewater treatment plant in Alberta, Canada: Occurrence, degradation, and emission

Acesulfame (ACE), sucralose (SUC), cyclamate (CYC), and saccharin (SAC) are widely used artificial sweeteners that undergo negligible metabolism in the human body, and thus ubiquitously exist in wastewater treatment plants (WWTPs). Due to their persistence in WWTPs, ACE and SUC are found in natural waters globally. Wastewater samples were collected from the primary influent, primary effluent, secondary effluent, and final effluent of a WWTP in Alberta, Canada between August 2022 and February 2023, and the artificial sweeteners concentrations were measured by LC-MS/MS. Using wastewater-based epidemiology, the daily per capita consumption of ACE in the studied wastewater treatment plant catchment was estimated to be the highest in the world. Similar to other studies, the removal efficiency in WWTP was high for SAC and CYC, but low or even negative for SUC. However, ACE removal remained surprisingly high (>96%), even in the cold Canadian winter months. This result may indicate a further adaptation of microorganisms capable of biodegrading ACE in WWTP. The estimated per capita discharge into the environment of ACE, CYC, and SAC is low in Alberta due to the prevalent utilization of secondary treatment throughout the province, but is 17.4-18.8 times higher in Canada, since only 70.3% of total discharged wastewater in Canada undergoes secondary treatment.

Sucralose (C12H19Cl3O8) impact on microbial activity in estuarine and freshwater marsh soils

As the general population's diet has shifted to reflect current weight-loss trends, there has been an increase in zero-calorie artificial sweetener usage. Sucralose (C12H19Cl3O8), commonly known as Splenda® in the USA, is a primary example of these sweeteners. In recent years, sucralose has been identified as an environmental contaminant that cannot easily be broken down via bacterial decomposition. This study focuses on the impact of sucralose presence on microbial communities in brackish and freshwater systems. Microbial respiration and fluorescence were measured as indicators of microbial activity in sucralose-dosed samples taken from both freshwater and estuarine marsh environments. Results showed a significant difference between microbial concentration and respiration when dosed with varying levels of sucralose. Diatom respiration implied a negative correlation of community abundance with sucralose concentration. The freshwater cyanobacterial respiration increased in the presence of sucralose, implying a positive correlation of community abundance with sucralose concentration. This was in direct contrast to its brackish water counterpart. However, further investigation is necessary to confirm any potential utility of these communities in the breakdown of sucralose in the marsh environment.

Acesulfame degradation by thermally activated persulfate: Kinetics, transformation products and estimated toxicity

The existence of the artificial sweetener acesulfame (ACE) in quantities of significance can negatively impact water quality, and its consumption has been associated with deleterious health effects. The present investigation explores the efficacy of heat-activated sodium persulfate (SPS) for eliminating ACE. The complete degradation of 0.50 mg L-1 of ACE was achieved within 45 min under a reaction temperature of 50 °C and 100 mg L-1 of SPS. The impact of thermal decomposition on ACE at a temperature of 60 °C was negligible. This study considers several factors, such as the SPS and ACE loading, the reaction temperature, the initial pH, and the water matrix of the reactor. The results indicate that the method's efficiency is positively correlated with higher initial concentrations of SPS, whereas it is inversely associated with the initial concentration of ACE. Furthermore, higher reaction temperatures and acidic initial pH levels promote the degradation of acesulfame. At the same time, certain constituents of the water matrix, such as humic acid, chlorides, and bicarbonates, can hinder the degradation process. Additionally, the data from LC-QToF-MS analysis of the samples were used to investigate transformation through suspect and non-target screening approaches. Overall, ACE's eight transformation products (TPs) were detected, and a potential ACE decomposition pathway was proposed. The concentration of TPs followed a volcano curve, decreasing in long treatment times. The ecotoxicity of ACE and its identified TPs was predicted using the ECOSAR software. The majority of TPs exhibited not harmful values.

Vertical distribution and risk assessment of pharmaceuticals and other micropollutants in southern North Sea coastal waters

Pharmaceutical compounds are micropollutants of emerging concern, as well as other classes of chemicals such as UV filters and artificial sweeteners. They enter marine environments via wastewater treatment plants, aquaculture runoff, hospital effluents, and shipping activities. While many studies have investigated the presence and distribution of these pollutants in numerous coastal areas, our study is the first to focus on their occurrence, spatial distribution, and vertical distribution in the sea surface microlayer (SML) and the near-surface layer of marine environments. We analyzed 62 pharmaceutical compounds, one UV filter, and six artificial sweeteners from the SML to the corresponding underlying water (0 cm, 20 cm, 50 cm, 100 cm, and 150 cm) at four stations in the southern North Sea. One station is the enclosed Jade Bay, one is the Weser estuary at Bremerhaven, and the other two stations (NS_7 and NS_8) are in the open German Bight. Jade Bay receives pollutants from surrounding wastewater treatment plants, while the Weser estuary receives pollutants from cities like Bremerhaven, which has dense populations and industrial activities. Concentrations of pharmaceutical compounds were higher in the upper water layers (from the SML to 20 cm). Eleven pharmaceutical compounds (caffeine, carbamazepine, gemfibrozil, ibuprofen, metoprolol, salicylic acid, clarithromycin, novobiocin, clindamycin, trimethoprim, and tylosin) were detected in >95 % of our samples. One UV filter (benzophenone-4) was found in 83 % and three artificial sweeteners (acesulfame, saccharin, and sucralose) in 100 % of all our samples. All artificial sweeteners posed high risks to the freshwater invertebrate Daphnia magna. Understanding the spatial and vertical distribution of pharmaceuticals and other micropollutants in marine environments may be essential in assessing their dispersal and detection in other aquatic environments.

Advances in identifying and managing emerging contaminants in aquatic ecosystems: Analytical approaches, toxicity assessment, transformation pathways, environmental fate, and remediation strategies

Emerging contaminants (ECs) are increasingly recognized as threats to human health and ecosystems. This review evaluates advanced analytical methods, particularly mass spectrometry, for detecting ECs and understanding their toxicity, transformation pathways, and environmental distribution. Our findings underscore the reliability of current techniques and the potential of upcoming methods. The adverse effects of ECs on aquatic life necessitate both in vitro and in vivo toxicity assessments. Evaluating the distribution and degradation of ECs reveals that they undergo physical, chemical, and biological transformations. Remediation strategies such as advanced oxidation, adsorption, and membrane bioreactors effectively treat EC-contaminated waters, with combinations of these techniques showing the highest efficacy. To minimize the impact of ECs, a proactive approach involving monitoring, regulations, and public education is vital. Future research should prioritize the refining of detection methods and formulation of robust policies for EC management.

Insight into the evolution of microbial communities and resistance genes induced by sucralose in partial nitrification system with triclosan pre-exposure

Sucralose (SUC), an artificial sweetener widely used in food, beverages and pharmaceuticals, is frequently detected in various environmental matrices. Triclosan (TCS) is commonly used as a disinfectant and often co-exists with SUC in sewage environments. This study investigated the effects of SUC (0.1-10 mg/L) on the transmission of intracellular and extracellular antibiotic resistance genes (ARGs) in the partial nitrification systems with and without TCS pre-exposure. The reactors operated for 150 days, and SUC did not affect ammonia oxidation performance, while TCS led to the maintenance of partial nitrification. The types and abundances of extracellular ARGs in sludge and free ARGs in water increased significantly after TCS pre-exposure when faced SUC stress, which might be caused by a decrease in α-Helix/(β-Sheet + Random coil). SUC was more easily to enrich ARGs in partial nitrification systems with TCS pre-exposure, exacerbating the risk of ARGs transmission. The microbial community showed stronger relationships to cope with the direct stress of SUC, and the functional bacteria (Thauera and Nitrosomonas) in TCS pre-exposure system might be potential hosts of ARGs. This study might provide insights for better understanding the fates of SUC in partial nitrification systems and the ecological risks in wastewater containing TCS and SUC. ENVIRONMENTAL IMPLICATION: Sucralose (SUC) is often detected in the environment and considered as an emerging contaminant due to its soaring consumption and environmental persistence. Triclosan (TCS) is an antibacterial agent that often co-exists with SUC in personal care products and sewage environments. During 150 d, two partial nitrification reactors with and without TCS pre-exposure were established to study the effects of SUC on nitrification performance, antibiotic resistance genes (ARGs) and microbial communities. This study showed the refractory nature of SUC, and SUC led to the transmission of extracellular ARGs in partial nitrification system with TCS pre-exposure, exacerbating the risk of ARGs dissemination.

Cardiotoxic and neurobehavioral effects of sucralose and acesulfame in Daphnia: Toward understanding ecological impacts of artificial sweeteners

Artificial sweeteners are widely used in food and pharmaceuticals, but their stability and persistence raise concerns about their impact on aquatic life. Although standard toxicity tests do not reveal lethal effects, recent studies suggest a potential neurotoxic mode of action. Using environmentally relevant concentrations, we assessed the effects of sucralose and acesulfame, common sugar substitutes, on Daphnia magna focusing on biochemical (acetylcholinesterase activity; AChE), physiological (heart rate), and behavioural (swimming) endpoints. We found dose-dependent increases in AChE and inhibitory effects on heart rate and behaviour for both substances. Moreover, acesulfame induced a biphasic response in AChE activity, inhibiting it at lower concentrations and stimulating at higher ones. For all endpoints, the EC50 values were lower for acesulfame than for sucralose. Additionally, the relationship between acetylcholinesterase and heart rate differed depending on the substance, suggesting possible differences in the mode of action between sucralose and acesulfame. All observed EC50 values were at μg/l levels, i.e., within the levels reported for wastewater, with adverse effects observed at as low as 0.1 μg acesulfame /l. Our findings emphasise the need to re-evaluate risk assessment thresholds for artificial sweeteners and provide evidence for the neurotoxic effects of artificial sweeteners in the environment, informing international regulatory standards.

Stability of aspartame in the soft drinks: Identification of the novel phototransformation products and their toxicity evaluation

Photolytic transformation of aspartame - a widely used artificial sweetener - under the simulated sunlight was studied for the first time. The experiments were conducted in pH range of 2.5 - 7.0 and in eight soft drinks available in the market. The highest degradation rate in the tested buffered solutions was observed under the neutral pH conditions. Irradiation of the soft drinks resulted in significantly (up to tenfold) faster degradation of aspartame, regardless of its initial concentration in the beverage. Such considerable acceleration of decomposition, not reported for aspartame so far, was ascribed to influence of the co-occurring ingredients, which can act as the photosensitizers. These findings indicate that some formulations may be particularly unfavorable in the context of aspartame photostability. Qualitative analysis of the studied processes revealed formation of six phototransformation products including three previously not described. In silico estimation of toxicity showed that some of the identified photoproducts, including the novel phenolic derivatives, may be more harmful than the parent compound. Taking into account relatively extensive formation of those products in the soft drinks, such finding may be particularly important from the food safety point of view.

Influence of sucralose, acesulfame-k, and their mixture on brain's fish: A study of behavior, oxidative damage, and acetylcholinesterase activity in Daniorerio

Sucralose (SUC) and acesulfame-k (ACE-K) are widely used artificial sweeteners worldwide; however, they are frequently detected in aquatic environments due to their low metabolism and inadequate removal during wastewater treatment. The harmful effects of these compounds on hydrobionts have yet to be fully understood, as data on their toxicity is limited and inconclusive. This research aimed to determine the impact of SUC (50, 75, 125 μg/L) and ACE-K (50, 75, 125 μg/L), individually and in combination, on fish's swimming behavior, acetylcholinesterase activity, and oxidative stress response after four months of exposure. Following exposure, adult Danio rerio displayed anxiety-like behavior, as evidenced by increased freezing time and decreased swimming activity. Additionally, analysis of fish brain tissue revealed a disruption of REDOX homeostasis, leading to oxidative stress, which may be responsible for the observed inhibition of AChE activity. The results indicated that ACE-K was more toxic than SUC, and the mixture of both compounds produced a more detrimental effect than when each compound was administered alone. These findings highlight the hazardous impacts of SUC and ACE-K on fish in environmentally relevant concentrations, suggesting that these compounds should be added to the priority pollutant list.

Levels, consumption, and variations of eight artificial sweeteners in the wastewater treatment plants of Dalian city, China

Artificial sweeteners (ASs) are emerging contaminants in the environment, primarily derived from wastewater treatment plant (WWTP) effluents. In this study, the influents and effluents of three WWTPs in the Dalian urban area, China, were analyzed for the distribution of 8 typical ASs to investigate their seasonal fluctuations in the WWTPs. The results showed that acesulfame (ACE), sucralose (SUC), cyclamate (CYC), and saccharin (SAC) were both detected in the influent and effluent water samples of WWTPs, with concentrations ranging from not detected (ND) to 14.02 μg·L-1. In addition, SUC was the most abundant ASs type, accounting for 40 %-49 % and 78 %-96 % of the total ASs in the influent and effluent water, respectively. The WWTPs revealed high removal efficiencies of CYC, SAC, and ACE, while the SUC removal efficiency was poor (26 % ± 36 %). The ACE and SUC concentrations were higher in spring and summer, and all ASs showed lower levels in winter, which may be caused by the high consumption of ice-cream in warmer months. The per capita ASs loads in the WWTPs were determined in this study based on the wastewater analysis results. The calculated per capita daily mas loads for individual ASs ranged from 0.45 g·d-1·1000p-1 (ACE) to 2.04 g·d-1·1000p-1 (SUC). In addition, the relationship between per capita ASs consumption and socioeconomic status showed no significant correlation.

Global development and future trends of artificial sweetener research based on bibliometrics

Artificial sweeteners have sparked a heated debate worldwide due to their ambiguous impacts on public and environmental health and food safety and quality. Many studies on artificial sweeteners have been conducted; however, none scientometric studies exist in the field. This study aimed to elaborate on the knowledge creation and development of the field of artificial sweeteners and predict the frontiers of knowledge based on bibliometrics. In particular, this study combined VOSviewer, CiteSpace, and Bibliometrix to visualize the mapping of knowledge production, covered 2389 relevant scientific publications (1945-2022), and systematically analyzed articles and reviews (n = 2101). Scientific publications on artificial sweeteners have been growing at an annual rate of 6.28% and globally attracting 7979 contributors. Susan J. Brown with total publications (TP) of 17, average citation per article (AC) of 36.59, and Hirsch (h)-index of 12 and Robert F. Margolskee (TP = 12; AC = 2046; h-index = 11) were the most influential scholars. This field was clustered into four groups: eco-environment and toxicology, physicochemical mechanisms, public health and risks, and nutrition metabolism. The publications about environmental issues, in particular, "surface water," were most intensive during the last five years (2018-2022). Artificial sweeteners are gaining importance in the monitoring and assessment of environmental and public health. Results of the dual-map overlay showed that the future research frontiers tilt toward molecular biology, immunology, veterinary and animal sciences, and medicine. Findings of this study are conducive to identifying knowledge gaps and future research directions for scholars.

Human wastewater tracking in tropical Hawaiian island streams using qualitative and quantitative assessments of combined fecal indicating bacteria and sucralose, an organic micropollutant of emerging concern

Prevalence of cesspools on tropical islands suggests that high concentrations of enteric bacteria in streams and coastal waters are an indicator of groundwater contamination by human wastewater. But enterococci bacteria may also be from homeothermic animals common to these watersheds or bacteria living in sediments. Sucralose, a manufactured chemical not destroyed in passage through the human gut, cesspools, septic systems, or wastewater treatment facilities, was used to test for the presence of human wastewater in streams on the island of Kauai, Hawaii. Effluent from six municipal wastewater treatment plants showed an average concentration of 39,167 ng/L of sucralose, roughly back-calculated to 9 ng/L per person, enough to present itself in cesspool effluent contaminated waters. Of 24 streams tested, 79% were positive for sucralose at least once in four sets of sampling. All streams tested positive for enterococci bacteria above established standards. Serial testing of the pair of indicators in the same location over time and applying the Multiplication Rule to the independent samples provide a probabilistic certainty level that the water is chronically polluted by human waste. When repeatedly paired with tests for enterococci, sucralose testing is a cost-effective means for assessing human health risk and for developing proper waste management programs that has been underutilized in under-developed tropical and island settings.

Untreated wastewater impact and environmental risk assessment of artificial sweeteners in river water and sediments of the Danube River Basin in Serbia

Artificial sweeteners are receiving increasing attention as newly recognized emerging contaminants that mainly reach the aquatic environment through the discharge of municipal wastewater containing large amount of these compounds. In this study, the impact of raw untreated wastewater discharges on the levels and the water/sediment distribution of artificial sweeteners in the Danube River and its largest tributaries in Serbia was evaluated, and a comprehensive assessment of environmental risks for freshwater and benthic organisms was performed. Acesulfame and sucralose were detected in all river water samples (100%), while saccharin (59%) and cyclamate (12%) were less frequently found, indicating long-term continuous sewage-derived pollution. Aspartame (100%) and neotame (60%) were the only artificial sweeteners recorded in the sediment samples due to their preference to sorb to particulate matter in the water/sediment system. In terms of ecotoxicological risk, a low risk for aquatic organisms was determined at the detected levels of saccharin in river water, while a high to medium risk was found for benthic biota at the concentrations of neotame and aspartame detected in sediments. The largest contribution to the pollution of the Danube River Basin with artificial sweeteners, and consequently the highest environmental risk, was determined in the two largest cities, the capital Belgrade and Novi Sad, which raises the issue of transboundary pollution.

Occurrence, distribution, and ecological risk assessment of artificial sweeteners in surface and ground waters of the middle and lower reaches of the Yellow River (Henan section, China)

As a new class of water contaminants, artificial sweeteners (ASs) have attracted much attention due to their environmental persistence and potential adverse effects to human and the environment. This study systematically investigated the occurrence and distribution of four commonly used ASs in the effluent of wastewater treatment plants (WWTPs), surface water and groundwater in the middle and lower reaches of the Yellow River (Henan section). Sucralose (SUC) was dominant in WWTP effluents and had the highest mass loading. Acesulfame (ACE), cyclamate (CYC), saccharin (SAC), and SUC were consistently detected in surface water at concentrations ranging from 1.364 ng/L (CYC) to 7786 ng/L (ACE). Spatial analysis showed that the pollution level of ASs in the trunk stream was lower than that in most tributaries. The total concentrations of ASs detected in surface water ranged between 308.7 and 10,498 ng/L, while in groundwater, the total concentration of ASs detected was between ND-4863 ng/L. ACE and SUC are the main pollutants in surface water and groundwater within this survey area. The risk assessment showed that the risks of the four target ASs to aquatic organisms were negligible (risk quotient (RQ) values < 0.1), and the maximum risk quotient of the mixtures (MRQ) values of all rivers were all much less than 0.1.

Protein fractionation and shotgun proteomics analysis of enriched bacterial cultures shed new light on the enzymatically catalyzed degradation of acesulfame

The removal of organic micropollutants in municipal wastewater treatment is an extensively studied field of research, but the underlying enzymatic processes have only been elucidated to a small extent so far. In order to shed more light on the enzymatic degradation of the artificial sweetener acesulfame (ACE) in this context, we enriched two bacterial taxa which were not yet described to be involved in the degradation of ACE, an unknown Chelatococcus species and Ensifer adhaerens, by incubating activated sludge in chemically defined media containing ACE as sole carbon source. Cell-free lysates were extracted, spiked with ACE and analyzed via target LC-MS/MS, demonstrating for the first time enzymatically catalyzed ACE degradation outside of living cells. Fractionation of the lysate via two-dimensional fast protein liquid chromatography (FPLC) succeeded in a partial separation of the enzymes catalyzing the initial transformation reaction of ACE from those catalyzing the further transformation pathway. Thereby, an accumulation of the intermediate transformation product acetoacetamide-n-sulfonic acid (ANSA) in the ACE-degrading fractions was achieved, providing first quantitative evidence that the cleavage of the sulfuric ester moiety of ACE is the initial transformation step. The metaproteome of the enrichments was analyzed in the FPLC fractions and in the unfractionated lysate, using shotgun proteomics via UHPLC-HRMS/MS and label-free quantification. The comparison of protein abundances in the FPLC fractions to the corresponding ACE degradation rates revealed a metallo-β-lactamase fold metallo-hydrolase as most probable candidate for the enzyme catalyzing the initial transformation from ACE to ANSA. This enzyme was by far the most abundant of all detected proteins and amounted to a relative protein abundance of 91% in the most active fraction after the second fractionation step. Moreover, the analysis of the unfractionated lysate resulted in a list of further proteins possibly involved in the transformation of ACE, most striking a highly abundant amidase likely catalyzing the further transformation of ANSA, and an ABC transporter substrate-binding protein that may be involved in the uptake of ACE into the cell.

Occurrence and removal of four artificial sweeteners in wastewater treatment plants of China

Artificial sweeteners discharged into aquatic environments have raised concern because of their ubiquitous occurrence and potential biological effect. And some of them, such as sucralose (SUC) and acesulfame (ACE), have been identified as emerging contaminants. Wastewater treatment plants (WWTPs) are considered as important sources and sinks of artificial sweeteners discharged into the environment. In this study, the occurrence and removal of four representative artificial sweeteners in 12 WWTPs located in different provinces of China were investigated. The results showed that artificial sweeteners were detected widely in the investigated WWTPs. The median concentrations of the four target artificial sweeteners were detected in influents at levels of 0.03-3.85 μg L^-1 and decreased in the order of SUC > ACE > aspartame (APM) > neotame (NTM). Additionally, the per capita mass loads of total artificial sweeteners in the WWTPs could be affected by the location of the WWTPs and were higher in southern cities than in northern cities. It was also found that there was a distinct linear correlation between the per capita mass load of ACE in influents and population density. During the treatment of WWTPs, the overall removal efficiency of artificial sweeteners ranged from -116% to 99.1%. Among the target artificial sweeteners, SUC and ACE might have potential risk to aquatic environments based on the calculation of the risk quotient. Thus, advanced treatment processes were carried to further remove SUC and ACE to reduce their long-term cumulative effect. Overall, UV/H₂O₂ and UV/PDS showed a better effect than granular activated carbon (GAC) adsorption in the removal of artificial sweeteners. The reaction constants of ACE by UV/H₂O₂ and UV/PDS were higher than those of SUC, which is related to molar extinction coefficients. Meanwhile, the adsorption ability of GAC adsorption for SUC was better than that of ACE, which is in correlation with the octanol-water partition coefficient. By comparison of removal efficiency, UV/PDS was considered as the most suitable advanced treatment process to remove ACE and SUC.

Seasonal occurrence, removal and mass loads of artificial sweeteners in the largest water reclamation plant in China

Artificial sweeteners (ASs) are of growing concern as an emerging contaminant. In the study, the seasonal occurrence, removal and mass load of six ASs in sewage, suspended particulate matter (SPM) and sludge were investigated throughout the treatment process of the largest water reclamation plant in China. The highest ASs concentrations in the influent (13.0 μg/L), effluent (2.22 μg/L), SPM (4.48 μg/g) and sludge (0.15 μg/g) were observed in the dry season, which were 1.24- to 5.0-fold higher than in the normal season and 1.06- to 37.5-fold higher than the flood season. Following treatment, ASs concentrations decreased by 24.3 %, 51.7 % and 5.1 % (on average) in primary, secondary and reclaimed processes, respectively. Among the investigated ASs, acesulfame (93.1 %) and cyclamate (98.4 %) were removed most efficiently, with removal occurring mainly in secondary processes, while sucralose exhibited the lowest removal efficiency (38.7 %). Seasonal characteristics affect the consumption of ASs, which subsequently changes the input and discharge ASs loads of STPs. The maximum mass load of ASs occurred in the dry season, ranging from 0.002 (neotame) to 1.33 mg/d/person (cyclamate), while the maximum emission load occurred in the flood season, ranging from 0.003 (neotame) to 0.83 mg/d/person (sucralose). The mass and emission load of ASs in Beijing is significantly lower than in European or the United States, due to Beijing having low per capita consumption of ASs (5.50 mg/d/person). The highest ASs risk in the receiving water occurred in the flood season due to the input of other pollution sources by rainfall runoff. Meanwhile, attention should be paid to the risk of receiving water close to the STP outlet in the dry seasons for the highest ASs concentration in the STP effluent in the season. The present study provides important guidance on controlling the input and reducing the emission of ASs in different seasons.

Priority screening of contaminant of emerging concern (CECs) in surface water from drinking water sources in the lower reaches of the Yangtze River based on exposure-activity ratios (EARs)

Surface water provides ecological services such as drinking water supply. However, contaminants of emerging concern (CECs) are rising concerns because they are ubiquitously detected in surface water and pose potential risks to the aquatic environment and human health. This study investigated the occurrence of 165 CECs in surface water from drinking water source areas along the lower reaches of the Yangtze River to prioritize the CECs and to estimate potential biological activity based on exposure-activity ratio (EAR). A total of 70 CECs were detected in the surface water at least once at the selected 17 sampling sites, and their concentrations ranged from 0.592 to 4650 ng/L. Twenty-four CECs were detected at each site, and these were mostly pharmaceutical and personal care products and pesticides. Sucralose, 1H-benzotriazole and carbendazim were the most common CECs with high median concentrations in the study area. Specifically, sucralose, an artificial sweetener, was presented at each site with the highest median concentration (3010 ng/L), which indicated that anthropogenic inputs are an important source of contaminants. Medroxyprogesterone and trenbolone were identified as the priority contaminants of interest, with maximum EAR_chemical values of 0.389 and 0.183, respectively. Among all the sites, the higher cumulative EAR_mixture value was found from Nantong City (0.765), which indicated that this site could have a relatively greater potential for biological effects, and these effects were mainly due to medroxyprogesterone and trenbolone. In regard to the bioactivity of all detected CECs, nuclear receptors showed the greatest potential bioactivity in this region, particularly androgen receptor-mediated bioactivity, which is most likely affected organisms residing in the source water area. These results suggest that the drinking water sources from the studied region are contaminated with CECs, and highlight the prioritization of future monitoring and research to protect source waters.

Young population consume twice as much artificial sweetener than the general population - A wastewater-based assessment in China

Understanding artificial sweetener consumption patterns and levels in different demographics is important for formulating public health policies on controlling sugar consumption. There is a considerable knowledge gap with respect to the pattern of artificial sweetener consumption in China. To narrow this gap, wastewater analysis was used to assess the temporal patterns of consumption of seven artificial sweeteners in an urban population and a university town in a megacity in South China over a one-year period. Daily influent wastewater samples were collected from an urban catchment and weekly samples collected from a university sub-catchment. Population normalized per capita consumption of the four detected artificial sweeteners (cyclamate, acesulfame, sucralose and saccharin) in the university catchment (1.0-5.9 mg d^-1 p^-1) was much higher than those in urban catchment (0.5-1.3 mg d^-1 p^-1), indicating younger population consume more artificial sweeteners than the general population. The daily consumption of artificial sweeteners was found to be stable throughout the week in the urban catchment. Time-series analysis showed that an average increase in temperature of 1 °C was associated with an increase consumption of 33 μg d^-1 p^-1 for acesulfame, 15 μg d^-1 p^-1 for sucralose and 14 μg d^-1 p^-1 for saccharin. This was the first study that objectively quantified the greater consumption of artificial sweeteners (proxy for consumption of artificially sweetened food and beverages) in a younger age group when compared to the general population, which could potentially pose a risk of health related diseases.

Acute exposure to environmentally relevant concentrations of sucralose disrupts embryonic development and leads to an oxidative stress response in Danio rerio

Sucralose (SUC) is the most consumed artificial sweetener worldwide, not metabolized by the human body, and barely eliminated from water in wastewater treatment plants. Although different studies have reported high concentrations of this sweetener in aquatic environments, limited to no information is known about the toxic effects this drug may produce over water organisms. Moreover, most of the current studies have used non-environmentally relevant concentrations of SUC for these effects. Herein, we aimed to evaluate the harmful effects that environmentally relevant concentrations of SUC may induce in the early life stages of Danio rerio. According to our results, SUC altered the embryonic development of D. rerio, producing several malformations that led to their death. The major malformations were scoliosis, pericardial edema, yolk deformation, and tail malformation. However, embryos also got craniofacial malformations, eye absence, fin absence, dwarfism, delay of the hatching process, and hypopigmentation. SUC also generated an oxidative stress response in the embryos characterized by an increase in the levels of lipid peroxidation, hydroperoxides, and carbonyl proteins. To overcome this oxidative stress response, we observed a significant increase in the levels of antioxidant enzymes superoxide dismutase and catalase. Moreover, a significant boost in the expression of antioxidant defense-related genes, Nuclear respiratory factor 1a (Nrf1a) and Nuclear respiratory factor 2a (Nrf2a), was also observed at all concentrations. Concerning apoptosis-related genes, we observed the expression of Caspase 3 (CASP3) and Caspase 9 (CASP9) was increased in a concentration-dependent manner. Overall, we conclude environmentally relevant concentrations of SUC are harmful to the early life stages of fish as they produce malformations, oxidative stress, and increased gene expression of apoptosis-related genes on embryos.

5-Keto-D-Fructose, a Natural Diketone and Potential Sugar Substitute, Significantly Reduces the Viability of Prokaryotic and Eukaryotic Cells

5-Keto-D-fructose (5-KF) is a natural diketone occurring in micromolar concentrations in honey, white wine, and vinegar. The oxidation of D-fructose to 5-KF is catalyzed by the membrane-bound fructose dehydrogenase complex found in several acetic acid bacteria. Since 5-KF has a sweetening power comparable to fructose and is presumably calorie-free, there is great interest in making the diketone commercially available as a new sugar substitute. Based on a genetically modified variant of the acetic acid bacterium Gluconobacter oxydans 621H, an efficient process for the microbial production of 5-KF was recently developed. However, data on the toxicology of the compound are completely lacking to date. Therefore, this study aimed to investigate the effect of 5-KF on the viability of prokaryotic and eukaryotic cells. It was found that the compound significantly inhibited the growth of the gram-positive and gram-negative model organisms Bacillus subtilis and Escherichia coli in a concentration-dependent manner. Furthermore, cell viability assays confirmed severe cytotoxicity of 5-KF toward the colon cancer cell line HT-29. Since these effects already occurred at concentrations of 5 mM, the use of 5-KF in the food sector should be avoided. The studies performed revealed that in the presence of amines, 5-KF promoted a strong Maillard reaction. The inherent reactivity of 5-KF as well as the Maillard products formed could be the trigger for the observed inhibition of prokaryotic and eukaryotic cells.

Line ferries and cargo ships for the monitoring of marine contaminants of emerging concern: Application along a Europe-Arctic transect

Contaminants of emerging concern (CEC) are a focus in marine protection. Several CECs are released with wastewater effluents to coastal environments and their offshore occurrence has been recently documented. Routine monitoring is key for implementing marine protection acts, however infrastructural, financial, and technical limitations hinder this task along broad spatial transects. Here we show the efficacy of a new infrastructure enabling unmanned sampling of surface water from ships of opportunity in providing reliable and cost-effective routine monitoring of CECs along a Europe-Arctic transect. The distribution and long-range transport of several pharmaceuticals and personal care products, artificial food additives, and stimulants were assessed. Validation of operations through strict procedural and analytical quality criteria is presented. A framework to estimate a compound-specific spatial range (SR) index of marine long-range transport based on monitoring results and information on source spatial distribution, is introduced. Estimated SR values ranged 50-350 km depending on compound, yielding a ranking of long-range transport potential which reflected expectations based on degradation half-lives. SR values were used to calculate prior maps of detection probability that can be used to plan future routine monitoring in the region.

Dual-high-frequency from single-piezoelectric crystal for ACE degradation by hybrid advanced oxidation UV-sonochemistry process

This study investigates the combination of two waves emitted from a single-piezoelectric crystal by use of a dual-frequency generator in a sonochemical reactor. The dual-frequency configurations analyzed were the double-modulated fundamental frequency (376-376 kHz), resonant and second harmonic, termed 376D, 376R and 376H respectively. The effect of the phase shift (Φ) and the percentage of modulation between added waves were described by the total acoustic power distribution (P_t) measured inside the sonoreactor. Moreover, optimal angle alignment and modulation between dual-frequency waves for 376D, 376R and 376H cases were selected in order to evaluate the ultrasonic synergy by sonochemical reactivity in production of H₂O₂, in degradation rate of a model emerging pollutant ACE, and in the TOC and biodegradability evolution in the treated effluent. Phase shift and percentage of modulation had strong effect on the resulted waveform and on the sonochemical efficiency for all, harmonic and non-harmonic, dual-frequency combinations created. In the 376D case, the best reinforcement conditions are founded at 0° and 360°. In the 376H the maximum power distribution presents a 90° period. Shift phase does not determines any cyclic pattern in the total power distribution for the 376R case. The highest H₂O₂ production rate was observed for the 376H case followed for 376D and 376R configurations with 1.61, 1.12 and 0.58 μM/min by angle alignment in 105, 0 and 110° respectively. The highest initial degradation rate of ACE was observed for the 376D case followed for 376H and 376R with 0.56, 0.42 and 0.33 μM/min at 100% modulation. Reduced mineralization was observed in all dual-frequency configurations (8.54% for 376D and approximately 4.5% for 376R and 3756H modes). Contrasting results are observed regard to biodegradability ratio following the next sequence 376D < 376H≈376R with 0.9, 2.30 and 2.33 respectively. Relevant intensification in hydroxyl radicals production is observed by the UV-US system increasing up three folds the ACE removal and mineralization and two folds higher biodegradability of effluent in particular for 376R and 376H cases at optimal operation condition of dual-frequency signal.

Acesulfame aerobic biodegradation by enriched consortia and Chelatococcus spp.: Kinetics, transformation products, and genomic characterization

The artificial sweetener Acesulfame (ACE) has been frequently detected in wastewater treatment plants (WWTPs) and is regarded as an emerging pollutant due to its low biodegradability. However, recent observations of ACE biodegradation in WWTPs have stimulated interest in the ACE-degrading bacteria and mineralization pathways. In this study, next-generation sequencing methods, Illumina and Nanopore sequencing, were combined to explore the ACE-degrading communities enriched from the activated sludge of six municipal wastewater treatment plants. Metagenomic investigations indicated that all enrichments were similarly dominated by the phyla Proteobacteria and Planctomycetes. Notably, at the species level, four metagenome-assembled genomes (MAGs) were shared by six enriched communities with considerable abundances, indicating that they may be responsible for ACE biodegradation in the enrichments. Besides, two ACE-degrading pure strains, affiliated to the genus Chelatococcus, were isolated from the enrichment. The genomic analysis showed that these two isolates were the new species that were genetically distinct from their relatives. Two type strains, Chelatococcus asaccharovorans DSM 6462 and Chelatococcus composti DSM 101465, could not degrade ACE, implying that the ACE-degrading capability was not shared among the different species in the genus Chelatococcus. The results of the degradation experiment showed that the two isolates could use ACE as the sole carbon source and mineralize ~90% of the total organic carbon. Three biotransformation products (TP96, TP180B, and TP182B) were demonstrated by UPLC-QTOF-MS. The results of this study provide valuable insights into ACE biodegradation and its biotransformation products.

Artificial sweeteners in end-use biosolids in Australia

Artificial sweeteners are contaminants of emerging concern that can enter the aquatic and terrestrial environments via wastewater effluent discharge and the environmental application of biosolids. The release of artificial sweeteners from the use of biosolids in Australia was assessed. The concentration of seven artificial sweeteners was quantified in biosolids samples collected from 71 wastewater treatment plants (WWTPs) across Australia during Census 2016. Sucralose, saccharin, acesulfame, aspartame and cyclamate were detected in biosolids samples at median concentrations ranging from 0.18 ng/g (dry weight) (range: <LOQ-34 ng/g) for cyclamate to 220 ng/g (range: <LOQ -3,670 ng/g) for sucralose, while neotame and neohesperidin dihydrochalcone were not detected. The relationship between the concentration of artificial sweeteners in biosolids and moisture content was assessed with the concentration of artificial sweeteners decreasing as dewatering time increased in a biosolids drying hall. The geometric means (± standard deviation) for per capita loads of individual artificial sweeteners ranged from 8.7 (1.6, 48) µg year^-1 person^-1 for cyclamate to 4,000 (1,000, 15,000) µg year^-1 person^-1 for sucralose with 223 kg of artificial sweeteners released to terrestrial environment from biosolids end-use annually in Australia. Due to the low loads of artificial sweeteners in biosolids compared with wastewater effluent, risks associated with artificial sweeteners in biosolids are likely limited.

Tracking the fate of artificial sweeteners within the coastal waters of Shenzhen city, China: From wastewater treatment plants to sea

Artificial sweeteners (ASs), as a new emerging pollutant, the fate from wastewater treatment plants (WWTPs) to sea is growing concerned. In this study, the distribution and polluted loading of six typical ASs were analyzed based on the measurement in influent, primary effluent, secondary effluent, tertiary effluent, suspended particulate matter (SPM), and sludge from four WWTPs and receiving waters near the coast of Shenzhen city, China. Elevated levels of ASs were detected in WWTPs located near a highly populated area (about 14,000 people km^-2). Sucralose was predominant in all water samples (0.1-22.2 μg L^-1), and had a 1.6-704.0 times higher concentration than the means of other ASs detected. Aspartame were mainly distributed in SPM and sludge, and the fractions in offshore water exceeded 45%. Acesulfame, sucralose, cyclamate and saccharin could be effectively removed by secondary biochemical treatment. The average daily loading (4.2 g d^-1 1000people^-1) and discharge loading (0.4 g d^-1 1000people^-1) of sucralose in WWTPs was higher than those of the other ASs. Dissolved organic carbon and UV₂₅₄ can affect the fate of ASs, and SPM mainly affects the distributions of aspartame and neotame. As a potential sewage indicator, neotame deserves further attention.

Removal of low-calorie sweeteners at five Brazilian wastewater treatment plants and their occurrence in surface water

The consumption of low-calorie sweeteners (LCSs) such as acesulfame (ACE), sucralose (SUC), saccharin (SAC), cyclamate (CYC), aspartame (ASP), neotame (NEO), and stevioside (STV) is increasing worldwide to meet the demand for reduced-calorie foods and beverages. However, there are no consumption data available in Brazil, as well as their concentration in sewage and removal on wastewater treatment plants (WWTPs). In the present study, ACE, SUC, SAC, CYC, ASP, NEO, and STV were assessed at five WWTPs located in the metropolitan region of Campinas (São Paulo State, Brazil), in operation with different treatment processes. Surface water was also analyzed. Analyses were carried out by on-line solid-phase extraction ultra-high performance liquid chromatography-tandem mass spectrometry. The major points are the following: LCS concentrations in the influents ranged from 0.25 to 189 μg L^-1 and followed the order CYC > ACE > SAC > SUC. NEO, ASP, and STV were not detected at any sampling site. Sweetener concentrations in the WWTP outputs differed mainly due to the different treatment setups employed. CYC and SAC were completely removed by biodegradation-based processes, while ACE removal was favored by the anaerobic-anoxic-aerobic process. SUC presented the highest concentration in the treated sewage, even at the WWTP operating with ultrafiltration membranes and therefore could be a marker compound for evaluation of the efficiency of removal of contaminants in WWTPs. Risk quotient estimation, using the PNEC and MEC values, indicated that the levels of the LCS reported here were harmless to the biota. The consumption of ACE, CYC, SAC, and SUC was estimated to be 2634 t year^-1.

Identification of new eligible indicator organisms for combined sewer overflow via 16S rRNA gene amplicon sequencing in Kanda River, Tokyo

Fecal indicator bacteria (FIB) are commonly used to evaluate the pollution impact of combined sewer overflows (CSOs) in urban rivers. Although water quality assessment with FIB has a long tradition, recent studies demonstrated that FIB have a low correlation with pathogens and therefore are not accurate enough for the assessment of potential human hazards in water. Consequently, new eligible and more specific indicators have to be identified, which was done in this study via sequencing of genetic markers from total community DNA. To identify potential microbiome-based indicators, microbial communities in samples from an urban river in Tokyo under different climatic conditions (dry and rainy) were compared with the influent and effluent of three domestic wastewater treatment plants (WWTPs) by analyzing 16 S rRNA gene amplicon libraries. In the first part of this study, physicochemical parameters and FIB quantification with selective culture techniques facilitated the identification of samples contaminated with CSO, sewage, or both. This allowed the grouping of samples into CSO-contaminated and non-contaminated samples, an essential step prior to the microbiome comparison between samples. Increased turbidity, ammonia concentrations, and E. coli [up to (9.37 ± 0.95) × 10² CFU/mL after 11.5 mm of rainfall] were observed in CSO-contaminated river samples. Comparison of dry weather (including WWTP samples) and rainy weather samples showed a reduction in microbial diversity in CSO-contaminated samples. Furthermore, the results of this study suggest Bacteroides spp. as a novel indicator of sewage pollution in surface waters.

Environmental Impact of the Presence, Distribution, and Use of Artificial Sweeteners as Emerging Sources of Pollution

Artificial sweeteners are posing a new threat to the environment. The water ecosystem is the primary recipient of these emerging contaminants. Once ingested, sufficient amount of these artificial sweeteners escape unchanged from the human body and are added to the environment. However, some are added in the form of their breakdown products through excretion. Artificial sweeteners are resistant to wastewater treatment processes and are therefore continuously introduced into the water environments. However, the environmental behavior, fate, and long-term ecotoxicological contributions of artificial sweeteners in our water resources still remain largely unknown. Some artificial sweeteners like saccharin are used as a food additive in animal feeds. It also forms the degradation product of the sulfonylurea herbicides. All artificial sweeteners enter into the wastewater treatment plants from the industries and households. From the effluents, they finally reside into the receiving environmental bodies including wastewaters, groundwaters, and surface waters. The global production of these sweeteners is several hundred tons annually and is continuously being added into the environment.

Emission and Mass Load of Artificial Sweeteners from a Pig Farm to Its Surrounding Environment: Contribution of Airborne Pathway and Biomonitoring Potential

An investigation was conducted by determining artificial sweeteners (ASs) in 80 samples from various environmental matrices, including dry deposition, rainfall, soil, leaf, and bark samples around a pig farm in Tianjin, China. Saccharin, cyclamate, and acesulfame were predominant in dry deposition and rainfall samples. Spatially, the distribution of ASs showed a consistent trend of farm center > downwind sites > upwind sites > reference site. The annual total mass loads of saccharin (70%), cyclamate (25%), and acesulfame (5%) via dry deposition and precipitation within a 5 km radius of the pig farm were estimated at 3.9 and 6.2 kg in the average-case and worst-case scenarios, respectively, accounting for 12-18% of the overall emission, indicating that pig farms are a significant source of ASs to the atmosphere and to the vicinal environment via dry and wet deposition. The distribution trends of ASs in tree bark and leaves were similar and tree bark performed better in passively biomonitoring the AS contamination. Overall, pig farms were predicted to release 65-114, 22-38, 2.0-3.5, and 0.6-1.1 tons by feed application in China, Europe, Latin America, and North America, respectively, to the vicinal environment via dry deposition and precipitation.

Degradation of acesulfame in UV/monochloramine process: Kinetics, transformation pathways and toxicity assessment

UV/monochloramine (UV/NH₂Cl) is an emerging advanced oxidation process that can generate various reactive species like reactive chlorine species (RCS) and hydroxyl radicals for micropollutant removal. This study investigated the potential toxicity of transformation products resulting from UV/NH₂Cl treatment of acesulfame (ACE), as an example of micropollutant, found in worldwide aquatic environment. Compared with UV photolysis and chloramination, the UV/NH₂Cl process more effectively degraded ACE. The transformation products of ACE treated with the UV/NH₂Cl process were identified and characterized with high resolution mass spectrometry. The formation of chlorinated-TPs indicated the role of RCS in UV/NH₂Cl transformation even though UV photolysis was predominantly responsible for the ACE degradation. The Vibrio fischeri bioluminescence inhibition assay revealed a higher toxicity of TPs derived from UV/NH₂Cl than from UV photolysis. The increased toxicity could be attributed to most of the generated chlorinated-TPs (Cl-TPs), in particular those halo-alcohols. The ECOSAR program predicts that halo-alcohol TPs are more toxic than their non-chlorinated analogues and other Cl-TPs. This study provides insight into the important role of reactive species in the micropollutants' transformation of UV/NH₂Cl process. It further provides information relevant to the potential risk when applying the process for micropollutant removal in water treatment.

Removal of Diclofenac in Wastewater Using Biosorption and Advanced Oxidation Techniques: Comparative Results

Wastewater treatment is a topic of primary interest with regard to the environment. Diclofenac is a common analgesic drug often detected in wastewater and surface water. In this paper, three commonly available agrifood waste types (artichoke agrowaste, olive-mill residues, and citrus waste) were reused as sorbents of diclofenac present in aqueous effluents. Citrus-waste biomass for a dose of 2 g·L−1 allowed for removing 99.7% of diclofenac present in the initial sample, with a sorption capacity of 9 mg of adsorbed diclofenac for each gram of used biomass. The respective values obtained for olive-mill residues and artichoke agrowaste were around 4.15 mg·g−1. Advanced oxidation processes with UV/H2O2 and UV/HOCl were shown to be effective treatments for the elimination of diclofenac. A significant reduction in chemical oxygen demand (COD; 40–48%) was also achieved with these oxidation treatments. Despite the lesser effectiveness of the sorption process, it should be considered that the reuse and valorization of these lignocellulosic agrifood residues would facilitate the fostering of a circular economy.

National wastewater reconnaissance of artificial sweetener consumption and emission in Australia

Artificial sweeteners are used as sugar substitutes in our daily lives yet consumption and release patterns are currently unknown in Australia. The spatial distribution of artificial sweetener consumption and WWTP effluent emission in Australia was estimated by wastewater analysis. Wastewater influent and effluent samples were collected from 69 WWTPs across Australia during the week of the 2016 Australian census. Mean population-weighted per capita loads for individual artificial sweeteners (cyclamate, aspartame, acesulfame, sucralose, saccharin) ranged from 0.12 ± 0.14 mg d^-1p^-1 for aspartame to 6.9 ± 2.8 mg d^-1p^-1 for acesulfame with 1004 kg of these artificial sweeteners being consumed daily in Australia. Significant removal of aspartame (100%), cyclamate (92 ± 18%) and saccharin (88 ± 21%) was observed during wastewater treatment. The average per capita release to the environment for individual artificial sweeteners (cyclamate, acesulfame, sucralose, saccharin) ranged from 230 ± 780 mg d^-1 1000p^-1 (cyclamate) to 3800 ± 1400 mg d^-1 1000p^-1 (sucralose). The daily release of artificial sweeteners from Australian WWTPs was estimated to be 142 kg suggesting that 14% of the artificial sweeteners consumed in Australia are released into the environment. To the best of our knowledge, this is the first wastewater study to estimate the occurrence and population-normalized artificial sweetener consumption and emission in Australia.

Variable persistence of artificial sweeteners during wastewater treatment: Implications for future use as tracers

For more than a decade the artificial sweeteners acesulfame (ACE) and sucralose (SUC) have been applied as tracers of the input of wastewater to environmental waters. Recently concerns have been raised that degradation of ACE during treatment may hinder or restrict its use as a wastewater tracer. In this study the value of ACE and SUC as tracers was reassessed based on samples of wastewater at 12 municipal wastewater treatment (MWWT) plants and from 7 septic systems and associated septic plumes in groundwater. The results indicated stability of SUC during MWWT at most plants, and variable removal of both sweeteners during some MWWT and in the septic wastewater systems. However, the residual concentrations of ACE and SUC in municipal effluent and in septic plumes indicate that both sweeteners remain valuable wastewater tracers. The mass ratio SUC/ACE was found to be a useful parameter for examining the relative persistence of these sweeteners.

Performance of ultraviolet/persulfate process in degrading artificial sweetener acesulfame

The degradation of the artificial sweetener acesulfame (ACE) was investigated using an ultraviolet (UV)₃₆₅-activated peroxydisulfate (PDS) process. The results demonstrated that the ACE reaction rate with the UV/PDS process followed pseudo first-order kinetics (R² > 0.9) under various conditions. A high dosage of PDS, alkaline condition, and the existence of NO₃^- and Cl^- enhanced ACE degradation; however, a high dosage of ACE, the existence of HCO₃^-, humic acid, and fulvic acid, and a real water matrix did not facilitate the degradation of ACE. Four types of transformation products were detected in the degradation of ACE by UV/PDS, and the primary degradation pathways were oxidation, hydroxyl substitution, hydrolysis, and hydration. The hydroxyl radicals played a predominant role (71.31%) in the degradation of ACE by the UV/PDS process, followed by sulfate radicals (14.57%) and UV photolysis (8.83%). Both the degradation and mineralization rates of ACE using the UV/PDS process had significant advantages over that of the UV/H₂O₂ process regarding ACE degradation, indicating that the UV/PDS process is more promising for treating water containing ACE.

A Review of the Environmental Fate and Effects of Acesulfame-Potassium

The use of low and no calorie sweeteners (LNCSs) has increased substantially the past several decades. Their high solubility in water, low absorption to soils, and reliable analytical methods facilitate their detection in wastewater and surface waters. Low and no calorie sweeteners are widely used in food and beverage products around the world, have been approved as food additives, and are considered safe for human consumption by the United States Food and Drug Administration (USFDA) and other regulatory authorities. Concerns have been raised, however, regarding their growing presence and potential aquatic toxicity. Recent studies have provided new empirical environmental monitoring, environmental fate, and ecotoxicity on acesulfame potassium (ACE-K). Acesulfame potassium is an important high-production LNCS, widely detected in the environment and generally reported to be environmentally persistent. Acesulfame-potassium was selected for this environmental fate and effects review to determine its comparative risk to aquatic organisms. The biodegradation of ACE-K is predicted to be low, based on available quantitative structure-activity relationship (QSAR) models, and this has been confirmed by several investigations, mostly published prior to 2014. More recently, there appears to be an interesting paradigm shift with several reports of the enhanced ability of wastewater treatment plants to biodegrade ACE-K. Some studies report that ACE-K can be photodegraded into potentially toxic breakdown products, whereas other data indicate that this may not be the case. A robust set of acute and chronic ecotoxicity studies in fish, invertebrates, and freshwater plants provided critical data on ACE-K's aquatic toxicity. Acesulfame-potassium concentrations in wastewater and surface water are generally in the lower parts per billion (ppb) range, whereas concentrations in sludge and groundwater are much lower (parts per trillion [ppt]). This preliminary environmental risk assessment establishes that ACE-K has high margins of safety (MOSs) and presents a negligible risk to the aquatic environment based on a collation of extensive ACE-K environmental monitoring, conservative predicted environmental concentration (PEC) and predicted no-effect concentration (PNEC) estimates, and prudent probabilistic exposure modeling. Integr Environ Assess Manag 2020;16:421-437. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Under the radar - Exceptionally high environmental concentrations of the high production volume chemical sulfamic acid in the urban water cycle

Elevated concentrations of sulfamate, the anion of sulfamic acid, were found in surface waters and finished drinking water in Germany with concentrations up to 580 μg/L and 140 μg/L, respectively. Wastewater treatment plant (WWTP) effluent was identified as the dominant source of sulfamate in the urban water cycle, as sulfamate concentrations correlated positively (0.77 > r < 0.99) with concentrations of the wastewater tracer carbamazepine in samples from different waterbodies. Ozonation and activated sludge experiments proved that sulfamate can be formed from chemical and biological degradation of various precursors. Molar sulfamate yields were highly compound-specific and ranged from 2% to 56%. However, the transformation of precursors to sulfamate in WWTPs and wastewater-impacted waterbodies was found to be quantitatively irrelevant, since concentrations of sulfamate in these compartments are already high, presumably due to its primary use as an acidic cleaning agent. Sulfamate concentrations in the influent and effluent of studied WWTPs ranged from 520 μg/L to 1900 μg/L and from 490 μg/L to 1600 μg/L, respectively. Laboratory batch experiments were performed to assess the recalcitrance of sulfamate for chemical oxidation. In combination with the results from sampling conducted at full-scale waterworks, it was shown that common drinking water treatment techniques, including ozonation and filtration with activated carbon, are not capable to remove sulfamate. The results of biodegradation tests and from the analysis of samples taken at four bank filtration sites indicate that sulfamate is attenuated in the sediment/water interface of aquatic systems and during aquifer passage under aerobic and anaerobic conditions. Sulfamate concentrations decreased by between 62% and 99% during aquifer passage at the bank filtration sites. Considering the few data on short term ecotoxicity, about 30% of the presented sulfamate levels in ground and surface water samples did exceed the predicted no-effect concentration (PNEC) of sulfamate, and thus effects of sulfamate on the aquatic ecosystem of wastewater-impacted waterbodies in Germany cannot be excluded so far. Toxicological estimations suggest that no risk to human health is expected by concentrations of sulfamate typically encountered in tap water.

Artificial Sweeteners in Pig Feed: A Worldwide Survey and Case Study in Pig Farms in Tianjin, China

Some artificial sweeteners (ASs) are used in pig feeds, although little is known on this regard. An investigation was conducted by determining seven common ASs in pig feed, manure, wastewater, compost, and soil from 16 pig farms in Tianjin, China. Saccharin (SAC) was predominant in feed (1.41-326 mg/kg) and manure samples (1.06-401 mg/kg). The annual mass loads of ASs in pig feeds were estimated at 5.69-119, 4.92-149, and 1.29-35 kg per 10³ piglets, hogs, and sows, respectively. The annual emission of ASs via biowaste (i.e., manure) was estimated at 3.58-85.2, 0.04-26.2, and 0.08-9.97 kg per 10³ capita for the three dominant ASs, i.e., SAC, neotame (NEO), and cyclamate (CYC). On a global scale, SAC was also widely detected at concentrations of 0.01-326 mg/kg in pig feed from China, Switzerland, Japan, Chile, and the United States, suggesting the worldwide use of ASs in pig feed. NEO and CYC were found in 41% and 30% of the feed samples, respectively, at concentrations of 0.05-70 mg/kg, whereas other ASs were barely found with rather lower concentrations. The annual mass loads of ASs consumed via pig feed consumption were estimated at 2400 tons worldwide. Thus, pig farming is an important source of ASs to the environment.

Zebrafish neuro-behavioral profiles altered by acesulfame (ACE) within the range of "no observed effect concentrations (NOECs)"

Recently, artificial sweeteners have received widespread attention as the emerging environmental pollutants, among which, acesulfame (ACE) is ubiquitously present and extremely persistent in the ecosystem. Although the environmental behavior of ACE has already been well studied, its chronic eco-toxicological effects on aquatic organisms are rarely reported. Thus, more researches should be performed to determine the concentration which exerted the observable toxicological effect. Herein, we examined neuro-behavioral effects of ACE at 1, 10 and 100 mg/L on adult zebrafish via performing the behavioral test batteries including light/dark preference test, novel tank diving test, novel object exploration test, social preference test and colour-enhanced CPP test. In addition, in order to fully phenotype the behavioral alteration induced by ACE, we applied the techniques deriving from behavioral phenomics to analyze and interpret the big data from a large number of behavioral variables. Furthermore, the alterations of neurotransmitter in brain were also assayed to confirm the behavioral results. We found that ACE within the concentration range of No Observed Effect Concentrations (NOECs) had remarkably altered the neuro-behavioral profiles: altered the preference for light/dark, reduced the exploration ability of zebrafish in the novel tank and novel object exploration test, affected the group preference of zebrafish, changed the colour preference, learning and memory ability of zebrafish and disturbed the quantitative patterns of neurotransmitter in brain. As a result, this research can offer a reference for readjusting the NOECs of ACE and assessing neurotoxicity of artificial sweeteners.

Removal of artificial sweeteners using UV/persulfate: Radical-based degradation kinetic model in wastewater, pathways and toxicity

Artificial sweeteners (ASs) have been frequently detected in aquatic environment and are of emerging concern due to their environmental persistence, acesulfame (ACE) and sucralose (SUC) are two ASs that are difficult to remove. The ultraviolet/persulfate (UV/PS) advanced oxidation process has been proven to remove ASs in real wastewater effectively. In this study, radical-based degradation kinetic model, pathways and toxicity evaluation of ASs by UV/PS process were explored. ACE and SUC were effectively removed by UV/PS process, and UV photolysis, hydroxyl radicals (HO^∙) and sulfate radicals (SO₄^∙-) contributes the degradation of ASs. A kinetic prediction model for ASs degradation was established based on the second-order rate constants with HO^∙ and SO₄^∙-, and the steady state concentrations of HO^∙ and SO₄^∙- were calculated through the degradations of two reference compounds. The kinetic model could predict the degradation process of ASs in five real wastewaters effluents. Furthermore, two models based on the kinetic and the water matrices parameters for ASs degradation in wastewater were compared. Finally, the tentative pathways of ASs degradations by UV/PS were proposed. Also, toxicity evaluation showed that ASs after UV/PS treatment enhanced the toxicity on C. carpio liver, and prolongation of treatment time and recovery in fresh water can reduce the toxicity on C. carpio.

Transformations of organic micropollutants undergoing permanganate/bisulfite treatment: Kinetics, pathways and toxicity

Permanganate/bisulfite (PM/BS) is a relatively new advanced oxidation process that can degrade organic micropollutants at extraordinary high rates. In this study, the degradability of PM/BS process towards different representative types of compounds was studied by investigating the kinetics, reaction site specificity and transformation chemistry. Acesulfame (ACE) and carbamazepine (CBZ) were two typical compounds containing olefinic moieties. Sucralose (SUC) was selected as a reference compound, and it is without aromatic and olefinic moieties. The kinetics results indicated that ACE and CBZ were effectively degraded while SUC was not. Preferred reaction sites of Mn³⁺ species was elucidated by identification of the ACE-transformation products (TPs) and CBZ-TPs with UHPLC-QTOF-MS. Seventeen ACE-TPs including two new compounds and eleven CBZ-TPs produced during the PM/BS process were identified and characterized. Transformation pathways revealed that cleavage of olefinic double bonds was the main reaction mechanism. Chemical structures containing electron-donating groups preferentially reacted with electrophilic Mn³⁺ species during the process. In addition, transformation products of ACE and CBZ during PM/BS process did not induce higher toxicity. This study provides a preliminary interpretation on the selectivity of PM/BS process according to the micropollutants' chemical structures, which hope to shed light on the future development of PM/BS treatment.

Rapid removal of acesulfame potassium by acid-activated ferrate(VI) under mild alkaline conditions

Acesulfame potassium (ACE) is a widely used artificial sweetener that has consistently been detected in wastewater and surface waters. The high-valent iron-based green oxidant known as ferrate(VI) (potassium ferrate(VI); Fe(VI)) had low reactivity with ACE (i.e. 4 h (or 240 min) contact time removed only ∼ 67% ACE) at a molar ratio of 6.0 ([Fe(VI)]:[ACE]). Comparatively, it took 60 s (or 1 min) to remove ∼94% ACE when HCl (786 μM) was added to a mixture of Fe(VI)-ACE at the same molar ratio of 6.0 (or acid-activated Fe(VI)). Significantly, the final pH (i.e. 7.6-8.1) was similar for Fe(VI) and acid-activated Fe(VI). An empirical model using response surface methodology was developed that could describe reasonably well the removal efficiency of ACE. Inorganic constituents of wastewater (Cl^-, Na⁺, Ca²⁺, and Mg²⁺) had no significant effect on the oxidation of ACE by acid-activated Fe(VI). The degradation efficiency of ACE decreased in the presence of 10 mg/L of natural organic matter (NOM) but remained unchanged at 5 mg NOM/L. Sulfamic acid as the oxidized product of ACE was identified by liquid chromatography high resolution mass spectrometry method. Reaction pathways include ring opening of ACE through hydrolytic transformation. Acid-activated Fe(VI) has advantage of rapid removal of ACE under mild alkaline conditions of wastewater treatment plants compared to other oxidation processes such as chlorination, ozonation, and light-based processes.

Combined effects of artificial sweetener acesulfame on the uptake of Cd in rice (Oryza sativa L.)

Organic pollutants are widely detected in surface water, groundwater and irrigation sewage in farmland soil, some of which can form complexes with heavy metal ions as ligands in the environment. Acesulfame (ACE), one of the most popular artificial sweeteners, has been found in wastewater sometimes at tens of microgram per liter. However, the combined effects of heavy metals and ACE are still unclear. In the present study, the effects of ACE on cadmium (Cd) absorption and translocation in rice seedlings (Oryza sativa L.) under different exposure conditions were investigated using hydroponic experiments. Under the combined exposure treatments of ACE and Cd, absorption of Cd and ACE in rice significantly decreased when compared with the single exposure treatments, while the alleviation of oxidative damage in rice was also found. Under the sequential exposure treatments of Cd and ACE, the post-exposed ACE activated the pre-absorbed Cd in plant, and accelerated the release of Cd to the environment as well as its translocation from the roots to shoots. In addition, compared with the single Cd exposure, the accumulated ACE can alleviate the oxidative damage in rice shoots induced by Cd, although the Cd concentrations in shoots changed little. In summary, the combined pollution of artificial sweetener ACE was beneficial to relieve the toxicological damage and ecological risk caused by Cd.

Review on the determination and distribution patterns of a widespread contaminant artificial sweetener in the environment

The accurate determination of widespread artificial sweeteners (ASs) and the information of their distributions in environments are of significance to investigate the environmental behaviors. This paper firstly reviews the typical analytic methodologies for ASs and the main influencing factors during the analytic processes. Solid-phase extraction (SPE) with LC-ESI-MS is currently the leading-edge method. However, the efficiency and accuracy for ASs analysis in environmental samples are also dependent on the SPE cartridges, buffers and pH, matrix effects, and sample stability. A basic procedure for ASs determination in different environmental samples is proposed. The current occurrences of ASs in environments are then evaluated. The ASs, especially the acesulfame and sucralose, are widely detected in various environmental medium. The concentrations of investigated ASs are generally in the order of wastewater treatment plants (WWTPs) influent > WWTPs effluent > surface water > groundwater > drinking water; and atmosphere > soil. The ASs levels in the environment exhibit significant differences among different regions. Further analysis indicates that the phenomenon is highly correlated with the consumption patterns and the removal efficiency of WWTPs in a specific country.

Photo-Fenton treatment of saccharin in a solar pilot compound parabolic collector: Use of olive mill wastewater as iron chelating agent, preliminary results

The aim of this work was to investigate the treatment of the artificial sweetener saccharin (SAC) in a solar compound parabolic collector pilot plant by means of the photo-Fenton process at pH 2.8. Olive mill wastewater (OMW) was used as iron chelating agent to avoid acidification of water at pH 2.8. For comparative purposes, Ethylenediamine-N, N-disuccinic acid (EDDS), a well-studied iron chelator, was also employed at circumneutral pH. Degradation products formed along treatment were identified by LC-QTOF-MS analysis. Their degradation was associated with toxicity removal, evaluated by monitoring changes in the bioluminescence of Vibrio fischeri bacteria. Results showed that conventional photo-Fenton at pH 2.8 could easily degrade SAC and its intermediates yielding k, apparent reaction rate constant, in the range of 0.64-0.82 L kJ^-1, as well as, eliminate effluent's chronic toxicity. Both OMW and EDDS formed iron-complexes able to catalyse H₂O₂ decomposition and generate HO. OMW yielded lower SAC oxidation rates (k = 0.05-0.1 L kJ^-1) than EDDS (k = 2.21-7.88 L kJ^-1) possibly due to its higher TOC contribution. However, the degradation rates were improved (k = 0.13 L kJ^-1) by increasing OMW dilution in the reactant mixture. All in all, encouraging results were obtained by using OMW as iron chelating agent, thus rendering this approach promising towards the increase of process sustainability.