Ecotoxicity and environmental fates of newly recognized contaminants-artificial sweeteners: A review

Taste traces: Capsaicin and sweeteners as anthropogenic markers in municipal wastewater

Dietary-derived substances possess significant potential as anthropogenic markers owing to the large consumption and different intake habit. To investigate and evaluate such markers, wastewater samples from 35 wastewater treatment plants across 29 Chinese cities were collected to analyze artificial sweeteners (acesulfame and cyclamate) and natural spicy compounds (capsaicin and dihydrocapsaicin). Acesulfame (mean: 14.6 μg/L), cyclamate (mean: 24.3 μg/L), and capsaicin (mean: 101 ng/L) can be further investigated as anthropogenic markers due to their high detection frequency at high concentrations. Spatial use patterns revealed that acesulfame (5.31 g/d/1000 inhabitants (inh)) and cyclamate (8.16 g/d/1000 inh) use in northern China notably surpassed that in southern China (1.79 g/d/1000 inh and 3.23 g/d/1000 inh, p < 0.05). Conversely, chili pepper use was significantly higher (p < 0.05) in southern China (6702 g/d/1000 inh) than in northern China (2751 g/d/1000 inh), signifying a preference for sweetness in the northern regions and a predilection for spiciness in the southern regions. The total annual use of acesulfame (1842 t), cyclamate (3110 t), and chili (18.4 million tonnes) in China was estimated by this study, which was close to the national statistical production. In addition, sweetener use was negatively associated with the elderly population ratio, suggesting that the elderly population might not consume sweet foods. This study reveals the dietary sources of anthropogenic markers, highlighting the need for further research on the environmental implications of such markers.

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.

Benchmarking the Persistence of Active Pharmaceutical Ingredients in River Systems

Assessing the persistence of organic micropollutants from field data has been notoriously laborious, requiring extensive data including emissions and chemical properties, and the application of detailed mass-balance models, which often contain parameters that are impossible to measure. To overcome some of these obstacles, we developed the concept of persistence benchmarking for large rivers that receive numerous emissions and provide enough residence time to observe the dissipation of compounds. We estimated the dissipation rate constants of 41 compounds (mostly active pharmaceutical ingredients) from five measurement campaigns in the Rhine and Danube rivers using concentration rate profiles with respect to carbamazepine. Dissipation rates clearly distinguished between known fast- and slow-degrading compounds, and campaign-specific boundary conditions had an influence on a minor subset of compounds only. Benchmarking provided reasonable estimates on summer total system half-lives in the Rhine compared to previous laboratory experiments and a mass-balance modeling study. Consequently, benchmarking can be a straightforward persistence assessment method of continuously emitted organic micropollutants in large river systems, especially when it is supported by field monitoring campaigns of proper analytical quality and spatial resolution.

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.

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 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.

Natural and low-caloric rebaudioside A as a substitute for dietary sugars: A comprehensive review

For health and safety concerns, traditional high-calorie sweeteners and artificial sweeteners are gradually replaced in food industries by natural and low-calorie sweeteners. As a natural and high-quality sugar substitute, steviol glycosides (SvGls) are continually scrutinized regarding their safety and application. Recently, the cultivation of organic stevia has been increasing in many parts of Europe and Asia, and it is obvious that there is a vast market for sugar substitutes in the future. Rebaudioside A, the main component of SvGls, is gradually accepted by consumers due to its safe, zero calories, clear, and sweet taste with no significant undesirable characteristics. Hence, it can be used in various foods or dietary supplements as a sweetener. In addition, rebaudioside A has been demonstrated to have many physiological functions, such as antihypertension, anti-diabetes, and anticaries. But so far, there are few comprehensive reviews of rebaudioside A. In this review article, we discuss the physicochemical properties, metabolic process, safety, regulatory, health benefits, and biosynthetic pathway of rebaudioside A and summarize the modification methods and state-of-the-art production and purification techniques of rebaudioside A. Furthermore, the current problems hindering the future production and application of rebaudioside A are analyzed, and suggestions are provided.

Deciphering natural and anthropogenic nitrate and recharge sources in arid region groundwater

Recently, the subsoils of ephemeral stream (arroyos) floodplains in the northern Chihuahuan Desert were discovered to contain large naturally occurring NO₃^- reservoirs (floodplain: ~38,000 kg NO₃-N/ha; background: ~60 kg NO₃-N/ha). These reservoirs may be mobilized through land use change or natural stream channel migration which makes differentiating between anthropogenic and natural groundwater NO₃^- sources challenging. In this study, the fate and sources of NO₃^- were investigated in an area with multiple NO₃^- sources such as accidental sewer line releases and sewage lagoons as well as natural reservoirs of subsoil NO₃^-. To differentiate sources, this study used a large suite of geochemical tools including δ¹⁵N[NO₃], δ¹⁸O[NO₃], δ¹⁵N[N₂], δ¹³C[DIC], ¹⁴C, tritium (³H), dissolved gas concentrations, major ion chemistry, and contaminants of emerging concern (CEC) including artificial sweeteners. NO₃^- at sites with the highest concentrations (25 to 229 mg/L NO₃-N) were determined to be largely sourced from naturally occurring subsoil NO₃^- based on δ¹⁵N[NO₃] (<8 ‰) and mass ratios of Cl^-/Br^- (〈100) and NO₃^-/Cl^- (>1.5). Anthropogenic NO₃^- was deciphered using mass ratios of Cl^-/Br^- (>120) and NO₃^-/Cl^- (<1), δ¹⁵N[NO₃] (>8 ‰), and CEC detections. Nitrogen isotope analyses indicated that denitrification is fairly limited in the field area. CEC were detected at 67 % of sites including ³H dead sites (<1 pCi/L) with low percent modern carbon-14 (PMC; <30 %). Local supply wells are ³H dead with low PMC; as ³H does not re-equilibrate and ¹⁴C is very slow to re-equilibrate during recirculation through infrastructure, sites with low PMC, ³H < 1 pCi/L, and CEC detections were interpreted as locations with substantial anthropogenic groundwater recharge. Neotame was used to identify locations of very recent (<15 years before present) or ongoing wastewater influxes to the aquifer. This work shows the important influence of naturally occurring subsoil NO₃^- reservoirs on groundwater in arid regions and the major contribution of artificial recharge.

Daily Variability in Urinary Artificial Sweeteners and Its Association with Oxidative Stress Biomarkers

Urinary artificial sweeteners (ASs) have been proved to be useful biomarkers for assessing their dietary intakes; however, it is unclear how well a spot urine sample may represent a longer-term exposure. Therefore, a longitudinal study was designed and six ASs and two oxidative stress biomarkers, namely, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA), were determined. Acesulfame (ACE) and saccharin (SAC) were detected in most urines with concentration ranges of Collapse

Key Words

• artificial sweeteners
• exposure assessment
• human biomonitoring
• oxidative stress biomarkers
• variability

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MESH Headings

• Humans
• 8-Hydroxy-2'-Deoxyguanosine
• Biomarkers/urine
• Deoxyguanosine
• Longitudinal Studies
• Oxidative Stress
• Saccharin
• Sweetening Agents

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Grants Collapse

Affiliation(s)

Yumeng Shi MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Hongkai Zhu MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Fei Wang Tianjin Key Laboratory of Clean Energy and Pollution Control, School of Energy and Environmental Engineering, Hebei University of Technology, Tianjin 300401, China
Shucong Chen MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Ke Xu MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Lei Wang MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Hongwen Sun MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China

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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.

Persulfate-based strategy for promoted acesulfame removal during sludge anaerobic fermentation: Combined chemical and biological effects

The acesulfame (ACE) degradation in waste activated sludge (WAS) via direct anaerobic fermentation is difficult and the efficient elimination techniques are imperative for the ultimate safe WAS disposal. Persulfate (PS)-based approach was developed to promote the ACE removal during WAS anaerobic fermentation. Results demonstrated the effectiveness of PS-based treatments on ACE degradation, and the ACE removal efficiency was respectively 48.2% and 96.2% in the PS and PS/Fe-treated reactors while it was only 6.0% in the control reactor. Mechanism explorations revealed that the active free radicals (i.e. OH• and SO₄^•-) generated in the PS-based reactors were the key oxidative species for the ACE degradation. However, such effects were interfered by the released soluble substrates (i.e. protein, carbohydrate and inorganic ions) during anaerobic fermentation by competing and/or quenching free radicals, which caused the deceleration of the ACE removal efficiency. Moreover, the PS-based treatment facilitated the enrichment of functional microorganisms (i.e. Phyllobacteriaceae and Bradyrhizobiaceae) and upregulated the critical genes (i.e. pncB and nadE) involved in the ACE degradation. Based on the density functional theory (DFT) and metabolic intermediates analysis, the hydroxylation and oxidative ring-opening were the two main proposed metabolic pathways for ACE degradation. Overall, the combined chemical and biological metabolism effects collectively contributed to the efficient ACE degradation, and it provided a novel and effective strategy for refractory pollutants removal during WAS anaerobic fermentation.

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.

Degradation of saccharin by UV/H2O2 and UV/PS processes: A comparative study

Artificial sweeteners have raised emerging concern due to their potential threats to human health, which were frequently detected in aquatic environment with median concentrations. Although current researches have widely reported that ultraviolet light-activated persulfate process (UV/PS) was superior to UV/H₂O₂ process for the degradation of refractory organic contaminants, UV/H₂O₂ process presented a more satisfactory saccharin (SAC) removal efficiency than UV/PS process, completely degraded 20 mg/L SAC within 45 min. Hence, quenching and probe experiments were employed to investigate the difference between hydroxyl radical (OH)- and sulfate radical (SO₄^-)-mediated oxidation mechanisms, which revealed the higher reactivity of OH (1.37-1.56 × 10⁹ M^-1 s^-1) toward SAC than SO₄^- (3.84-4.13 × 10⁸ M^-1 s^-1). A combination of density functional theory calculation and transformation products identification disclosed that OH preferred to attack the benzene ring of SAC via hydrogen atom transfer pathway, whereas SO₄^- oxidation was conducive to the cleavage of -C-NH₂ bond. Increasing oxidant concentration significantly accelerated SAC degradation in both processes, while UV/H₂O₂ process consumed lower electrical energy with respect to UV/PS process. Additionally, UV/H₂O₂ system presented excellent adaptability and stability under various water matrices parameters (e.g. pH, anions and humic acid). While both UV/H₂O₂ and UV/PS processes promoted the generation of disinfection by-products (DBPs) during subsequent chlorination, and prolonging pretreatment time posed positive effect on reducing the formation of DBPs. Overall, the results clearly demonstrate the high efficiency, economy and practicality of UV/H₂O₂ process in the remediation of SAC-contaminated water.

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.

Impact assessment of anthropogenic activities on the ecological systems in the Xiongan New Area in the North China Plain

The aim of this study is to assess the impact of anthropogenic activities on the ecological systems in the Xiongan New Area (XNA), China. Artificial sweeteners (ASs) were used as anthropogenic tracers to investigate how anthropogenic activities affect water, soil, and plant layers. For this purpose, the concentrations of 4 typical ASs, acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC) were measured in water, soil, and plant layers. Moreover, a tracer test was conducted in the critical zone observatory (CZO) in the southern part of the study area to investigate the migration path and time of anthropogenic activities on the ecological systems. Acesulfame, SUC, SAC, and CYC were widely detected in all of the sample types, and their average values were 0.22, 0.53, 0.06, and 0.08 µg/L in the water layer; 0.04, 0.18, 0.06, and 0.06 µg/kg in the soil layer; and 1.79, 0.11, 4.42, and 0.95 µg/kg in the plant layer, respectively. The tracer test showed that 1.1% to 1.8% of the impacts of the anthropogenic activities migrated from the surface to the shallow aquifer within 13 d, 6% to 19% migrated to the maize layer within 28 d, and 79% to 93% were adsorbed and biodegraded in the soil layer. Therefore, the scope and strength of the influence of the anthropogenic activities on the environmental media exhibit a decreasing sequence of maize > water > soil. This study not only quantitatively characterizes the impact of anthropogenic activities on the ecological environment but also presents the first comprehensive overview of the environmental fate of ASs in the critical zone of the XNA, China. Integr Environ Assess Manag 2021;17:866-876. © 2021 SETAC.

Sucralose Affects Thyroid Hormone Signaling in American Bullfrog [Rana (Lithobates) catesbeiana] Tadpoles

Nonnutritive sweeteners used in food and beverage products are widespread, persistent aquatic pollutants. Despite this, their impact on aquatic organisms, particularly vertebrates, is not well-studied. Recent findings in rodents suggest sucralose, a chlorinated disaccharide, alters thyroid hormone (TH) metabolism. Because amphibian tadpole metamorphosis is TH-dependent, we hypothesized sucralose may alter signaling for this postembryonic developmental process. The present study used the American bullfrog, Rana (Lithobates) catesbeiana, as a sensitive, environmentally relevant model for testing TH disruption in the absence and presence of thyroxine (T₄), a hormone that induces metamorphosis. Premetamorphic R. catesbeiana tadpoles were immersed in 1-, 15-, and 32-mg/L sucralose solutions ± 5 nM (3.9 µg/L) thyroxine (T₄) for 48 h. RNA transcripts encoding thyroid hormone receptors alpha and beta (thra and thrb) and TH-induced basic region leucine zipper protein (thibz) were analyzed in four tissues: back skin, liver, olfactory epithelium, and tail fin, using reverse transcription quantitative real-time PCR (RT-qPCR). We found that sucralose altered the expression of fundamental TH-response genes involved in anuran metamorphosis in a tissue- and TH-status dependent manner. As organochlorines induce xenobiotic metabolism, we isolated and characterized three novel R. catesbeiana gene transcripts involved in xenobiotic metabolism: pregnane X receptor (nr1i2), constitutive androstane receptor (nr1i3), and cytochrome p450 3a4 (cyp3a4). We analyzed their expression using RT-qPCR and found evidence of their modulation by sucralose. To our knowledge, these data are the first to show xenobiotic and thyroid-disrupting activities in amphibians and further investigations into cumulative effects of environmental sucralose exposure are warranted.

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.

Aqueous degradation of artificial sweeteners saccharin and neotame by metal organic framework material

The artificial sweeteners (ASs) saccharin (SAC) and neotame (NEO) are widely used across the globe and are considered as emerging contaminants in surface, ground, and drinking waters. To degrade SAC and NEO, the metal organic framework material Co-based bio-MOF-11 was prepared by hydrothermal reaction and used with peroxymonosulfate (PMS) activator. The effects of the initial concentration of SAC and NEO, bio-MOF-11-Co dosage, PMS concentration, initial pH, temperature, and competitive anions were determined. The results revealed that bio-MOF-11-Co effectively catalyzed the degradation of SAC and NEO and possessed good stability and recycling efficiency. The degradation reaction was effective from pH 3.6-9.8 and followed quasi-first-order kinetics with degradation rate constants of 0.001-0.013 min^-1 for SAC and 0.03-0.52 min^-1 for NEO. Increased temperature was conducive to the degradation of both artificial sweeteners. The presence of Cl^- inhibited the degradation of SAC and NEO, while the presence of CO₃^2- promoted their degradation. Electron paramagnetic resonance (EPR) and free radical quenching demonstrated that the primary free radicals were sulfate radicals ( [Formula: see text] ) and hydroxyl radicals (HO). The change of cobalt oxidation state and electron transfer in bio-MOF-11-Co mainly induces the production of [Formula: see text] . A plausible mechanism for degradation is [Formula: see text] and HO attack on CS bonds, NS bonds, and benzene rings.

Organic contaminants in Ganga basin: from the Green Revolution to the emerging concerns of modern India

The Ganga basin includes some of the most densely populated areas in the world, in a region characterized by extremely high demographic and economic growth rates. Although anthropogenic pressure in this area is increasing, the pollution status of the Ganga is still poorly studied and understood. In the light of this, we have carried out a systematic literature review of the sources, levels and spatiotemporal distribution of organic pollutants in surface water and sediment of the Ganga basin, including for the first time emerging contaminants (ECs). We have identified 61 publications over the past thirty years, with data on a total of 271 organic compounds, including pesticides, industrial chemicals, and by-products, artificial sweeteners, pharmaceuticals, and personal care products (PPCPs).

The most studied organic contaminants are pesticides, whereas knowledge of industrial compounds and PPCPs, among which some of the major ECs, is highly fragmentary. Most studies focus on the main channel of the Ganga, the Yamuna, the Gomti, and the deltaic region, while most of the Ganga's major tributaries, and the entire southern part of the catchment, have not been investigated. Hotspots of contamination coincide with major urban agglomerations, including Delhi, Kolkata, Kanpur, Varanasi, and Patna. Pesticides levels have decreased at most of the sites over recent decades, while potentially harmful concentrations of polychlorinated biphenyls (PCBs), organotin compounds (OTCs), and some PPCPs have been detected in the last ten years. Considering the limited geographical coverage of sampling and number of analyzed compounds, this review highlights the need for a more careful selection of locations, compounds and environmental matrices, prioritizing PPCPs and catchment-scale, source-to-sink studies.

Trends in artificial sweetener consumption: A 7-year wastewater-based epidemiology study in Queensland, Australia

A 7-year temporal trend study of artificial sweetener consumption was performed by determining per capital mass loads in 293 influent wastewater samples collected from a wastewater treatment plant in Australia between 2012 and 2018. Population-weighted per capita mass loads of the four detected artificial sweeteners ranged from 2.4 ± 0.8 mg d^-1 p^-1 for saccharin to 7.8 ± 2.0 mg d^-1 p^-1 for acesulfame over the study period. Negligible intra-week fluctuations were observed, however the consumption of acesulfame was seen to be significantly influenced by season with the highest consumption in summer. The consumption of sucralose and saccharin significantly increased with an annual increase rate of 10% and 6.0%. Cyclamate consumption declined over the same period with average annual decrease rate of 11%, which agrees with data from market surveys. Sucrose equivalence of total artificial sweeteners consumption showed an increase between 2012 and 2016, then decreased in 2018. This is the first long-term trend study of artificial sweetener consumption by wastewater analysis and highlights the feasibility to quantitatively measure artificial sweeter consumption over time.

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.

Biodegradability assessment of food additives using OECD 301F respirometric test

The ready biodegradability of twenty food additives, belonging to the classes of artificial sweeteners, natural sweeteners, preservatives and colorings, was investigated using activated sludge as inoculum and OECD 301F respirometric test. According to the results, saccharin, aspartame, sodium cyclamate, xylitol, erythritol, maltitol, potassium sorbate, benzoic acid and sodium ascorbate are characterized as readily biodegradable compounds, partial biodegradation (<60% during the test) was noticed for steviol, inulin, alitame, curcumin, ponceau 4R and tartrazine, while no biodegradation was observed for the other five compounds. The duration of lag phase before the start of biodegradation varied between the target compounds, while their ultimate biodegradation half-life values ranged between 0.7 ± 0.1 days (benzoic acid) and 24.6 ± 1.0 days (curcumin). The expected removal of target compounds due to ultimate biodegradation mechanism was estimated for a biological wastewater treatment system operated at a retention time of one day and percentages higher than 40% were calculated for sodium cyclamate, potassium sorbate and benzoic acid. Higher removal percentages are expected in full-scale Sewage Treatment Plants (STPs) due to the contribution of other mechanisms such as sorption to suspended solids, (bio)transformation and co-metabolic phenomena. Further biodegradation experiments should be conducted under different experimental conditions for the food additives that did not fulfill the requirements of the applied protocol. Future studies should also focus on the occurrence and fate of food colorants and natural sweeteners in full-scale STPs.

Occurrence, Distribution and Ecological Risk of Bisphenol Analogues in the Surface Water from a Water Diversion Project in Nanjing, China

Due to the widespread use of bisphenol analogues (BPs) as alternatives to bisphenol A (BPA), considerable attention for health risk has been shown in aquatic ecosystems. The occurrence and distribution of six BPs were researched in a soluble phase (<10^-3 μm), colloidal phase (10^-3 μm to 1 µm), and suspended particulate matter (SPM >1 µm) in a water diversion project of Nanjing, China. Except for bisphenol Z, all BPs were detected in two or three phases, where the total concentrations of detected BPs were 161-613 ng/L, 5.19-77.2 ng/L, and 47.5-353 ng/g for the soluble phase, colloidal phase, and SPM, respectively. Among the detected compounds, BPA is still the dominant BPs in the soluble and colloidal phases, which is followed by bisphenol-S , while bisphenol-AF was the major contaminant in SPM, followed by BPA. The mean contribution proportions of colloids were 1-2 orders of magnitude higher than SPM, which suggests that colloids have a clear impact on regulating BPs' environmental behaviors. In terms of spatial distribution, the water diversion project could reduce the pollution levels of BPs, which might further affect the ecological security of the Yangtze River.

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.

Evaluation of the artificial sweetener sucralose as a sanitary wastewater tracer in Narragansett Bay, Rhode Island, USA

Narragansett Bay is an urban estuary that historically has been impacted by long-term discharge of sanitary wastewater (WW) effluents. High-density water sampling was conducted in Narragansett Bay, RI, USA, in an effort to understand the distribution and behavior of sucralose, an artificial sweetener that has shown utility as a sanitary wastewater tracer. Water samples were collected at sixty-seven sites and analyzed for sucralose, whose performance was compared to other tracers present in wastewater effluents. Concentrations of sucralose were much higher than the other tracers measured, carbamazepine and caffeine, ranging from 18 to 3180 ng/L and corresponded well with salinity (r² = 0.88), demonstrating conservative behavior throughout the Bay. Mapped interpolation data using an empirical bayesian kriging model clearly show the spatial trends of WW and how estuarine processes influence dilution and dispersion throughout the Bay. These findings provide further evidence of the efficacy of sucralose as a wastewater tracer in large urban estuaries where continuous high-volume discharge of WW occur.

Genomic resolution of bacterial populations in saccharin and cyclamate degradation

The benefits of extensive artificial sweeteners use come at a cost of their ubiquitous occurrence in the aquatic environment. Biodegradation is crucial for the removal of artificial sweeteners in the environment, yet comprehensive characterizations of the degradation consortia that degrade these compounds have not been initiated. Here, we performed metagenomic analysis of microbial communities fulfilling complete mineralization of two typical artificial sweeteners, i.e. saccharin and cyclamate. Genome-resolved metagenomics enabled the recovery and metabolic characterization of total 23 population genomes from 8 phyla in the two consortia, most of which represented novel species. The saccharin-degrading consortia was notably dominated by a betaproteobacterial genome from the family Rhodocyclaceae, accounting for 15.5% of total sequences. For the cyclamate enrichment, 28.1% of the total sequences were assigned to three similarly abundant Alphaproteobacteria population genomes belonging to the family Sphingomonadaceae and Methylobacteriaceae. The metabolic potential of these population genomes were examined to potentially identify the roles of these populations in biodegradation of artificial sweeteners, and focusing on the energy and nutrient metabolisms.