Change in the chemical content of untreated wastewater of Athens, Greece under COVID-19 pandemic

Environmental concentration of the quaternary ammonium disinfectant benzalkonium chloride strongly induces resistance gene profiles in fish

Disinfectants are non-antibiotic biocides that have been used extensively in daily life, particularly since the onset of the COVID-19 pandemic. However, their effect on drug resistance has not received sufficient attention. Here, marine medaka were subjected to an environmental concentration (10 μg/L) of benzalkonium chloride (BAC), sulfamethazine (SMZ), and their combination, aiming to elucidate their contributions to antibiotic resistance. Overall, 10 μg/L BAC exhibited a stronger induction potential for multiple antibiotic resistance genes (ARGs) relative to a similar level of SMZ. Specifically, tetracycline resistance genes were readily induced, regardless of exposure to BAC, SMZ, or their combination. BAC exhibited a more pronounced induction of ARGs than SMZ and showed a stronger potential to stimulate multidrug resistance. SMZ and BAC induced distinct virulence factors. Bacteria increased pathogenicity primarily through biofilm formation and enhanced community sensing under SMZ exposure, whereas iron acquisition and the production of reactive oxygen species appeared to be the main mechanisms by which bacteria evaded host defenses under BAC exposure. A greater number of ARGs demonstrated a significant positive correlation with virulence factors following BAC exposure compared to both the SMZ exposure group and the co-exposure group, which further confirmed the strong ability of BAC to induce multidrug resistance. In summary, owing to the typically unregulated and low-dose use of disinfectants in daily life and their pseudo-persistence in the environment, their potential to induce resistance may exceed that of antibiotics. Therefore, increased attention and preventive measures are required to address their resistance-inducing effects.

Decentralized sewage treatment and energy recovery in high-rise buildings using anaerobic baffle reactor coupled with plant biofilter reactor: A focus on surfactant and phenol removal

The emergence of phenols and surfactants in domestic wastewater, largely attributed to changing Water, Sanitation, and Hygiene (WASH) practices, presents treatment challenges for conventional centralized systems. This study evaluates the performance of an integrated Anaerobic Baffled Reactor (ABR) and Plant Biofilter Reactor (PBFR) system for decentralized wastewater treatment and biogas recovery, focusing on its applicability in high-rise infrastructures. Real domestic wastewater, containing ammonia (55 mg/L), soluble chemical oxygen demand (s-COD, 580 mg/L), phenols (16 mg/L), and surfactants (17 mg/L), was treated under varying hydraulic retention times (HRTs) of 1, 2, and 3 days. At an HRT of 2 days, the system achieved up to 76 % ammonia removal, while phenol and surfactant removal reached 52 % and 85 % at 3 days HRT. COD removal exceeded 60 % across all HRTs. Principal Component Analysis (PCA) was employed to statistically interpret treatment performance. Mass spectrometry identified degradation by-products of phenols and surfactants, and their influence on biogas generation was assessed. Gas chromatography analysis indicated a high-quality biogas yield (CH₄ > 70 %, CO₂ ∼ 20 %). Adding dextrose significantly enhanced gas production by stimulating microbial metabolism compared to fructose and sucrose. However, high influent concentrations of phenols and surfactants exhibited inhibitory effects on microbial activity, emphasizing the need for controlled organic loading. MTT-based cytotoxicity assays confirmed the treated effluent's non-toxic nature. These findings demonstrate the technical feasibility of integrated ABR-PBFR systems for treating complex wastewater streams while enabling energy recovery. The study provides a scalable and sustainable framework for decentralized wastewater management in urban high-rise settings, supporting circular economy and sustainable water management objectives.

Smart Dust for Chemical Mapping

This review article explores the transformative potential of smart dust systems by examining how existing chemical sensing technologies can be adapted and advanced to realize their full capabilities. Smart dust, characterized by submillimeter-scale autonomous sensing platforms, offers unparalleled opportunities for real-time, spatiotemporal chemical mapping across diverse environments. This article introduces the technological advancements underpinning these systems, critically evaluates current limitations, and outlines new avenues for development. Key challenges, including multi-compound detection, system control, environmental impact, and cost, are discussed alongside potential solutions. By leveraging innovations in miniaturization, wireless communication, AI-driven data analysis, and sustainable materials, this review highlights the promise of smart dust to address critical challenges in environmental monitoring, healthcare, agriculture, and defense sectors. Through this lens, the article provides a strategic roadmap for advancing smart dust from concept to practical application, emphasizing its role in transforming the understanding and management of complex chemical systems.

Subchronic exposure to nonylphenol ethoxylate (NPE) induces cardiotoxicity and oxidative stress in American bullfrog tadpoles: a mechanistic approach

Tropical regions, particularly those with high levels of endemism such as South America, harbor a diverse array of amphibian species. However, these regions often lack specific regulations governing the release of emerging contaminants, including the surfactant nonylphenol ethoxylate (NPE), into water bodies, which can have devastating consequences for these sensitive ecosystems. This study evaluated the sublethal effects of 16-day subchronic exposure to NPE at an environmentally relevant concentration of 30 µg/L on American bullfrog (Lithobates catesbeianus) tadpoles using multiple endpoints, including biometric parameters, antioxidant responses, oxidative stress biomarkers, heart rate, and myocardial contractility. Our results revealed that exposure to NPE elicited a range of harmful effects on tadpoles, including significant reductions in hepatic and ventricular mass, disruptions in antioxidant defenses leading to oxidative stress-mediated damage in cardiac, hepatic, and muscular tissues, and changes in heart function such as negative inotropism and lusitropism, and tachycardia. These sublethal effects could have significant ecological impacts, affecting not only immediate survival but also compromising overall fitness through the reallocation of energy reserves.

Factors affecting mass inflow of quaternary ammonium compounds into Japanese sewage treatment plants

Quaternary ammonium compounds (QACs), ecotoxic organic chemicals linked to multidrug resistance, are being used increasingly, for example to prevent the transmission of infections such as covid-19, in households, hospitals, and industry. To understand the locations, fluctuations, and fractions of QACs entering sewers, we monitored 14 QACs (benzalkonium chloride [BAC]-C8, C10, C12, C14, C16, and C18; dialkyldimethylammonium chloride [DDAC]-C8, C10, and C12; alkyltrimethylammonium chloride [ATAC]-C12, C16, and C18; benzethonium chloride; and cetylpyridinium chloride), and a disinfectant (chlorhexidine) in influent at four Japanese sewage treatment plants (STPs) five times throughout a year. Mass inflows were relatively stable throughout the year, indicating that the recent seasonal covid-19 epidemic did not greatly influence them. The differences in mass inflows among the STPs were normalized successfully by sewered residential population (most relative SDs were <30%), implying households to be the main source. Per-capita mass inflows accounted for 58%-73% of the per-capita consumption of BAC-C12 + C14 + C16, 28%-59% of that of DDAC-C10, 52%-70% of that of ATAC-C12, 86%-99% of that of ATAC-C16, and 64%-82% of that of ATAC-C18, indicating that a large proportion of their consumption entered sewers. The high contribution of ATAC-C16 agreed with its limited use in primary and secondary industries, little of whose wastewaters enter sewers, whereas the low contribution of DDAC-C10 is attributable to its substantial use in animal husbandry. Our first observation of fractions of QACs entering sewers will advance the management of environmental risks.

A critical review of wastewater-based epidemiology as a tool to evaluate the unintentional human exposure to potentially harmful chemicals

Wastewater-based epidemiology (WBE) is a powerful tool to gather epidemiological insights at the community level, providing objective data on population exposure to harmful substances. A considerable portion of the human exposure to these potentially harmful chemicals occurs unintentionally, unlike substances such as pharmaceuticals, illicit drugs, or alcohol. In this context, this comprehensive review analyzes WBE studies focused on classes of organic chemicals to which humans are unintentionally exposed, namely organophosphorus flame retardants, per- and polyfluoroalkyl substances (PFAS), benzotriazoles and benzothiazoles, phthalates and terephthalates, benzophenones, pesticides, bisphenols, and parabens. The review highlights some advantages of WBE for public health surveillance, e.g., non-invasive analysis, predictive capability, nearly real-time data, population-wide insights, no ethical approval, and unbiased sampling. It also discusses challenges and future research directions in WBE regarding exposure to harmful chemicals from various sources. The review emphasizes the critical role of wastewater sampling, sample preparation, quality control, and instrumental analysis in achieving accurate and reliable results. Furthermore, it examines the selection of human biomarkers for WBE studies and explores strategies to link WBE with human biomonitoring (HBM), which together enhance both the precision and effectiveness of exposure assessments.

Downstream effects of the pandemic? Spatiotemporal trends of quaternary ammonium compounds in suspended particulate matter of German rivers

During the SARS-CoV-2 pandemic, the preventive use of antimicrobials such as quaternary ammonium compounds (QACs) surged worldwide. As cationic and surface-active biocides, QACs are only partly removed during wastewater treatment and may cause adverse ecological effects in the downstream environment. To understand the environmental consequences of increased disinfectant use during the pandemic, we investigated spatiotemporal QAC concentration trends in the suspended particulate matter (SPM) of three diverse German rivers. Covering pooled annual SPM samples from 2006-2021 and monthly samples from 2018-2021 collected by the German Environmental Specimen Bank, 31 QACs were quantified by high performance liquid chromatography-mass spectrometry. ∑QAC concentrations in annual samples differed by more than tenfold between rivers in the order Saar (average 6.7 µg/g) > Rhine (0.9 µg/g) > Mulde (0.3 µg/g). The strongest potential pandemic imprint was however observed in the Mulde (+67 %) and Rhine (+22 %). Besides pandemic dynamics, also seasonal variation and mineral content of SPM tentatively affected QAC concentrations. Exceedance of predicted no-effect concentrations for sediment suggest ecotoxicological risks for long-chained QACs already before the pandemic. Our study thus highlights the importance of monitoring the environmental effects of antimicrobial use during pandemics and calls for an urgent minimization of non-essential applications.

Which emerging micropollutants deserve more attention in wastewater in the post-COVID-19 pandemic period? Based on distribution, risk, and exposure analysis

Aggravated accumulation of emerging micropollutants (EMs) in aquatic environments, especially after COVID-19, raised significant attention throughout the world for safety concerns. This article reviews the sources and occurrence of 25 anti-COVID-19 related EMs in wastewater. It should be pointed out that the concentration of anti-COVID-19 related EMs, such as antivirals, plasticizers, antimicrobials, and psychotropic drugs in wastewater increased notably after the pandemic. Furthermore, the ecotoxicity, ecological, and health risks of typical EMs before and after COVID-19 were emphatically compared and analyzed. Based on the environmental health prioritization index method, the priority control sequence of typical EMs related to anti-COVID-19 was identified. Lopinavir (LPV), venlafaxine (VLX), di(2-ethylhexyl) phthalate (DEHP), benzalkonium chloride (BAC), triclocarban (TCC), di-n-butyl phthalate (DBP), citalopram (CIT), diisobutyl phthalate (DIBP), and triclosan (TCS) were identified as the top-priority control EMs in the post-pandemic period. Besides, some insights into the toxicity and risk assessment of EMs were also provided. This review provides direction for proper understanding and controlling the EMs pollution after COVID-19, and is of significance to evaluate objectively the environmental and health impacts induced by COVID-19.

Occurrence of emerging contaminants in three river basins impacted by wastewater treatment plant effluents: Spatio-seasonal patterns and environmental risk assessment

The concern on the fate and distribution of contaminants of emerging concern (CECs) is a burning topic due to their widespread occurrence and potential harmful effects. Particularly, antibiotics have received great attention due to their implications in antimicrobial resistance occurrence. The impact of wastewater treatment plants (WWTP) is remarkable, being one of the main pathways for the introduction of CECs into aquatic systems. The combination of novel analytical methodologies and risk assessment strategies is a promising tool to find out environmentally relevant compounds posing major concerns in freshwater ecosystems impacted by those wastewater effluents. Within this context, a multi-target approach was applied in three Spanish river basins affected by different WWTP treated effluents for spatio-temporal monitoring of their chemical status. Solid phase extraction followed by ultra-high-performance liquid chromatography were used for the quantification of a large panel of compounds (n = 270), including pharmaceuticals and other consumer products, pesticides and industrial chemicals. To this end, water samples were collected in four sampling campaigns at three locations in each basin: (i) upstream from the WWTPs; (ii) WWTP effluent discharge points (effluent outfall); and (iii) downstream from the WWTPs (500 m downriver from the effluent outfall). Likewise, 24-h composite effluent samples from each of the WWTPs were provided in all sampling periods. First the occurrence and distribution of these compounds were assessed. Diverse seasonal trends were observed depending on the group of emerging compounds, though COVID-19 outbreak affected variations of certain pharmaceuticals. Detection frequencies and concentrations in effluents generally exceeded those in river samples and concentrations measured upstream WWTPs were generally low or non-quantifiable. Finally, risks associated with maximum contamination levels were evaluated using two different approaches to account for antibiotic resistance selection as well. From all studied compounds, 89 evidenced environmental risk on at least one occasion in this study.

Fate of quaternary ammonium compounds upon the UV/monochloramine process: Kinetics, transformation pathways and the formation of N-nitroso-N-methyl-N-alkylamines

Quaternary ammonium compounds (QACs) are widely detected in the aquatic environment due to their extensive use in a wide array of antibacterial products during the pandemic. In the current study, UV/monochloramine (UV/NH2Cl) was used to degrade three typical QACs, namely benzalkonium compounds (BACs), dialkyl dimethyl ammonium compounds (DADMACs), and alkyl trimethyl ammonium compounds (ATMACs). This process achieved high efficiency in removing BACs from water samples. The transformation products of QACs treated with UV/NH2Cl were identified and characterized using a high-resolution mass spectrometer, and transformation pathways were proposed. The formation of N-nitroso-N-methyl-N-alkylamines (NMAs) and N-nitrosodimethylamine (NDMA) were observed during QAC degradation. The molar formation yield of NDMA from C12-BAC was 0.04 %, while yields of NMAs reached 1.05 %. The ecotoxicity of NMAs derived from QACs was predicted using ECOSAR software. The increased toxicity could be attributed to the formation of NMAs with longer alkyl chains; these NMAs, exhibited a one order of magnitude increase in toxicity compared to their parent QACs. This study provides evidence that QACs are the specific and significant precursors of NMAs. Greater attention should be given to NMA formation and its potential threat to the ecosystem, including humans.

Longitudinal study and predictive modelling of urinary pesticide metabolite concentrations in residents of Guangzhou, China

Continuous human biomonitoring and predictive modelling of urinary pesticide metabolites are critical for evaluating pesticide exposure trends and associated health risks. We conducted repeat cross-sectional surveys to determine the urinary concentrations of eight pesticide metabolites in the residents of Guangzhou, China, from 2018 to 2022. We longitudinally analyzed the changes in these metabolite concentrations over the years and assessed the potential non-carcinogenic risks by calculating the hazard quotient and hazard index. No significant differences were observed in the total urinary pesticide metabolite concentrations over the 5 years (9.16-12.99 μg/L). The urinary concentrations of 3,5,6-trichloro-2-pyridinol and 2,4-dichlorophenoxyacetic acid reached their lowest levels in 2020 (1.47 and 0.11 μg/L). Conversely, urinary para-nitrophenol concentrations exhibited an inverse trend, peaking in 2020 (6.16 μg/L). The composition profiles of urinary pesticide metabolites showed that para-nitrophenol consistently constituted the largest proportion each year. Males consistently showed higher median concentrations of total urinary pesticide metabolites and individual metabolites of 3,5,6-trichloro-2-pyridinol, trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and para-nitrophenol than females. The concentrations of cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid in adults' urine were significantly higher than those in minors' urine each year. The total pesticide metabolite concentrations in adults' urine were significantly higher than those in minors' urine in 2018 and 2020, whereas no significant differences were observed in other years. No significant differences in urinary pesticide metabolite concentrations were observed among different BMI groups. Results showed that 14.17% of the population had hazard index values above 1, indicating a higher risk of health hazards. Three predictive models were employed to predict urinary pesticide metabolite concentrations for 2023-2024, revealing an increasing trend in 3,5,6-trichloro-2-pyridinol concentrations while other metabolites are expected to decrease. The study showed the concentration of para-nitrophenol peaked in 2020 while 3,5,6-trichloro-2-pyridinol and 2,4-dichlorophenoxyacetic acid reached their lowest levels, suggests that the COVID-19 pandemic may have influenced pesticide exposure patterns.

Assessing daily patterns in stimulant use during the COVID-19 pandemic in Melbourne, Australia using wastewater analysis

During the COVID-19 pandemic, one of Australia's biggest cities, Melbourne, experienced three major isolation ("lockdown") periods in 2020 (160 days) and in 2021 (111 days) which makes it one of the most locked down cities world-wide. This study assessed how the pandemic affected temporal trends in methamphetamine, MDMA and cocaine consumption using wastewater-based epidemiology. Daily samples were collected for most of 2020 and 2021 (n = 660 days). Concentrations were measured using direct-injection LC-MS/MS and back-calculated to consumption estimates. Results indicate that methamphetamine use was increasing before the first lockdown and decreased after the end of the first lockdown in 2020. Methamphetamine trends appeared to have remained steady throughout the second lockdown period before increasing steeply after it ended. For most of 2020, cocaine use remained steady, with an increase after the second lockdown. MDMA use decreased after the start of the first lockdown and remained steady throughout most of 2020 and 2021. In comparison to 2020, trends in 2021 were less variable and stimulant use did not appear to be as associated with COVID-19 restrictions. Overall, this study was able to show the impact of lockdown periods and the related social restrictions on illicit stimulant use. ENVIRONMENTAL IMPLICATION: Illicit drugs are hazardous chemicals, of concern both to humans and the environment. While studies have been undertaken to understand their temporal trends, this work utilizes wastewater-based epidemiology and daily sampling to provide a comprehensive understanding of the impact of the COVID-19 pandemic on the use of methamphetamine, MDMA and cocaine on one of the most locked-down cities in the world. Understanding the consequences of this significant intervention on illicit drug use could provide valuable insights into its potential environmental impact.

Are we using more sugar substitutes? Wastewater analysis reveals differences and rising trends in artificial sweetener usage in Swedish urban catchments

The market for artificial sweeteners as substitutes for conventional sugar (sucrose) is growing, despite potential health risks associated with their intake. Estimating population usage of artificial sweeteners is therefore crucial, and wastewater analysis can serve as a complement to existing methods. This study evaluated spatial and temporal usage of artificial sweeteners in five Swedish communities based on wastewater analysis. We further compared their levels measured in wastewater with the restrictions during the COVID-19 pandemic in Sweden and assessed health risks to the Swedish population. Influent wastewater samples (n = 194) collected in March 2019-February 2022 from communities in central and southern Sweden were analyzed for acesulfame, saccharin, and sucralose using liquid-chromatography coupled with tandem mass spectrometry. Spatial differences in loads for individual artificial sweetener were observed, with sucralose being higher in Kalmar (southern Sweden), and acesulfame and saccharin in Enköping and Östhammar (central Sweden). Based on sucrose equivalent doses, all communities showed a consistent prevalence pattern of sucralose > acesulfame > saccharin. Four communities with relatively short monitoring periods showed no apparent temporal changes in usage, but the four-year monitoring in Uppsala revealed a significant (p < 0.05) annual increase of ∼19 % for sucralose, ∼9 % for acesulfame and ∼8 % for saccharin. This trend showed no instant or delayed effects from COVID-19 restrictions, reflecting positively on the studied population which retained similar exposure to the artificial sweeteners despite potential pandemic stresses. Among the three artificial sweeteners, only acesulfame's levels were at the lower end of the health-related threshold for consumption of artificially sweetened beverages; yet, all were far below the acceptable daily intake, indicating no appreciable health risks. Our study provided valuable, pilot insights into the spatio-temporal usage of artificial sweeteners in Sweden and their associated health risks. This shows the usefulness of wastewater analysis for public health authorities wishing to assess future relevant interventions.

Recent advances in photocatalytic removal of antiviral drugs by Z-scheme and S-scheme heterojunction

The possible impact of antivirals on ecosystems and the emergence of antiviral resistance are the reasons for concern about their environmental release. Consequently, there has been a significant increase in curiosity regarding their presence in both organic and synthetic systems in recent years. The primary objective of this review is to address the void of information regarding the global presence of antiviral drugs in both wastewater and natural water sources. Photocatalytic degradation of pollutants is an eco-friendly, cost-effective method that effectively addresses environmental degradation. The development of efficient photocatalysts remains a significant issue in accelerating the degradation of pollutants, especially when employing solar light. Thus, the development of Z-scheme and S-scheme semiconductor heterojunctions has emerged as a viable method to improve light absorption and enhance the redox capability of photocatalysts. The principles of Z-scheme and S-scheme are reviewed extensively. The degradation route and occurrence of antiviral are discussed briefly. Finally, a short preview of the degradation of antiviral using Z-scheme and S-scheme is also highlighted.

Target and Nontarget Screening to Support Capacity Scaling for Substance Use Assessment through a Statewide Wastewater Surveillance Network in New York

Wastewater-based epidemiology (WBE) has been widely implemented around the world as a complementary tool to conventional surveillance techniques to inform and improve public health responses. Currently, wastewater surveillance programs in the U.S. are evaluating integrated approaches to address public health challenges across multiple domains, including substance abuse. In this work, we demonstrated the potential of online solid-phase extraction coupled with liquid chromatography-high-resolution mass spectrometry to support targeted quantification and nontargeted analysis of psychoactive and lifestyle substances as a step toward understanding the operational feasibility of a statewide wastewater surveillance program for substance use assessment in New York. Target screening confirmed 39 substances in influent samples collected from 10 wastewater treatment plants with varying sewershed characteristics and is anticipated to meet the throughput demands as the statewide program scales up to full capacity. Nontarget screening prioritized additional compounds for identification at three confidence levels, including psychoactive substances, such as opioid analgesics, phenethylamines, and cathinone derivatives. Consumption rates of 12 target substances detected in over 80% of wastewater samples were similar to those reported by previous U.S.-based WBE studies despite the uncertainty associated with back-calculations. For selected substances, the relative bias in consumption estimates was sensitive to variations in monitoring frequency, and factors beyond human excretion (e.g., as indicated by the parent-to-metabolite ratios) might also contribute to their prevalence at the sewershed scale. Overall, our study marks the initial phase of refining analytical workflows and data interpretation in preparation for the incorporation of substance use assessment into the statewide wastewater surveillance program in New York.

Workflow to facilitate the detection of new psychoactive substances and drugs of abuse in influent urban wastewater

The complexity around the dynamic markets for new psychoactive substances (NPS) forces researchers to develop and apply innovative analytical strategies to detect and identify them in influent urban wastewater. In this work a comprehensive suspect screening workflow following liquid chromatography - high resolution mass spectrometry analysis was established utilising the open-source InSpectra data processing platform and the HighResNPS library. In total, 278 urban influent wastewater samples from 47 sites in 16 countries were collected to investigate the presence of NPS and other drugs of abuse. A total of 50 compounds were detected in samples from at least one site. Most compounds found were prescription drugs such as gabapentin (detection frequency 79%), codeine (40%) and pregabalin (15%). However, cocaine was the most found illicit drug (83%), in all countries where samples were collected apart from the Republic of Korea and China. Eight NPS were also identified with this protocol: 3-methylmethcathinone 11%), eutylone (6%), etizolam (2%), 3-chloromethcathinone (4%), mitragynine (6%), phenibut (2%), 25I-NBOH (2%) and trimethoxyamphetamine (2%). The latter three have not previously been reported in municipal wastewater samples. The workflow employed allowed the prioritisation of features to be further investigated, reducing processing time and gaining in confidence in their identification.

Pharmaceutical and Recreational Drug Usage Patterns during and Post COVID-19 Determined by Wastewater-Based Epidemiology

Wastewater-based epidemiology (WBE) was applied to evaluate the consumption trends of pharmaceuticals (i.e., antibiotics, non-steroidal anti-inflammatory drugs, antiepileptics, antihypertensives, and others), as well as recreational drugs (caffeine, alcohol, and nicotine), in Latvia from December 2020 to July 2023. The time period covers both the COVID-19 pandemic and the post-pandemic periods; therefore, the impact of the implemented restrictions and the consequences of the illness in terms of the usage of pharmaceuticals thereon were investigated. Additionally, the seasonality and impact of the seasonal flu and other acute upper respiratory infections were studied. The results revealed that the pandemic impacted the consumption of alcohol, nicotine, and caffeine, as well as several pharmaceuticals, such as antihypertensives, antidepressants, psychiatric drugs, and the painkiller ibuprofen. The findings suggest that the imposed restrictions during the pandemic may have had a negative effect on the population's health and mental well-being. Distinct seasonal trends were discovered in the consumption patterns of caffeine and alcohol, where lower use was observed during the summer. The seasonal consumption trends of pharmaceuticals were discovered in the case of antibiotics, the antiasthmatic drug salbutamol, and the decongestant xylometazoline, where higher consumption occurred during colder seasons.

Sustainable biosurfactant production from secondary feedstock-recent advances, process optimization and perspectives

Biosurfactants have garnered increased attention lately due to their superiority of their properties over fossil-derived counterparts. While the cost of production remains a significant hurdle to surpass synthetic surfactants, biosurfactants have been anticipated to gain a larger market share in the coming decades. Among these, glycolipids, a type of low-molecular-weight biosurfactant, stand out for their efficacy in reducing surface and interfacial tension, which made them highly sought-after for various surfactant-related applications. Glycolipids are composed of hydrophilic carbohydrate moieties linked to hydrophobic fatty acid chains through ester bonds that mainly include rhamnolipids, trehalose lipids, sophorolipids, and mannosylerythritol lipids. This review highlights the current landscape of glycolipids and covers specific glycolipid productivity and the diverse range of products found in the global market. Applications such as bioremediation, food processing, petroleum refining, biomedical uses, and increasing agriculture output have been discussed. Additionally, the latest advancements in production cost reduction for glycolipid and the challenges of utilizing second-generation feedstocks for sustainable production are also thoroughly examined. Overall, this review proposes a balance between environmental advantages, economic viability, and societal benefits through the optimized integration of secondary feedstocks in biosurfactant production.

Effective disinfecting of negative pressure pipelines of DCUs reduces the risk of cross infection in dental care

Objectives

Microbial contamination of various accessory parts of the dental chair units (DCUs) is an essential source of cross infection, while the accessories of the crucial suction function are usually overlooked. In this study, we aim to find an effective disinfectant and a cost-effective method to remove bacterioplankton and bacterial biofilm deposited in the negative pressure suction pipelines to control cross infection during dental treatment.

Methods

Double-chain quaternary ammonium salt disinfectant (Orotol Plus®), 3% hydrogen peroxide solution plus multi-enzyme cleaning agent and chlorine disinfectant are used to clean and disinfect the negative pressure pipelines of DCUs. Microbiological examinations, air condition detection, corrosion tests and gene sequencing are performed.

Results

Little bacteria grow in the pipelines disinfected with double-chain quaternary ammonium salt disinfectants, destruction of biofilms in these pipelines appears, and multi-resistant bacteria cannot be detected. Minimal damage to metal sheets and fittings is caused by double-chain quaternary ammonium salt disinfectants.

Conclusion

Double-chain quaternary ammonium salt disinfectant has excellent bactericidal ability and anti-biofilm effect, and it is less corrosive to the fittings of the pipelines. Thus, the double-chain quaternary ammonium salt disinfectant is a potential novel disinfectant for negative pressure suction pipelines of DCUs to control cross infection during dental treatment.

Clinical significance

It is essential to add all these data to our dental practice to control cross infection with a broader landscape.

Retrospective spatiotemporal study of antidepressants in Slovenian wastewaters

This study utilizes wastewater-based epidemiology (WBE) to evaluate spatiotemporal changes in the consumption of antidepressants before and during the COVID-19 pandemic in Slovenia. Composite 24-h influent wastewater samples (n = 210) were collected from six wastewater treatment plants between summer 2019 and spring 2021. The samples were extracted using 96-well solid-phase extraction and analysed by liquid chromatography-tandem mass spectrometry. The measured concentrations of target antidepressant biomarkers were then converted to population-normalised mass loads (PNMLs), taking into account flow rate and catchment population. Ten biomarkers, including amitriptyline, bupropion, bupropion-OH, citalopram, norcitalopram, normirtazapine, venlafaxine, O-desmethylvenlafaxine, trazodone, and moclobemide, were above the lower limit of quantification and were included in the spatiotemporal temporal assessment. The highest PNMLs were detected for O-desmethylvenlafaxine (mean ± SD: 82.1 ± 21.2 mg/day/1000 inhabitants) and venlafaxine (38.0 ± 10.6 mg/day/1000 inhabitants), followed by citalopram (27.0 ± 10.7 mg/day/1000 inhabitants). In addition, the mean metabolite/parent compound ratios were comparable with other WBE studies indicating consumption rather than direct disposal. Overall, the results indicated significant spatiotemporal variations depending on the location, and the PNMLs of most biomarkers increased during the first wave of the COVID-19 pandemic (spring of 2020). However, no clear spatial patterns were revealed related to the pandemic.

Comprehensive profiling and semi-quantification of exogenous chemicals in human urine using HRMS-based strategies

Chemicals infiltrate our daily experiences through multiple exposure pathways. Human biomonitoring (HBM) is routinely used to comprehensively understand these chemical interactions. Historically, HBM depended on targeted screening methods limited to a relatively small set of chemicals with triple quadrupole instruments typically. However, recent advances in high-resolution mass spectrometry (HRMS) have facilitated the use of broad-scope target, suspect, and non-target strategies, enhancing chemical exposome characterization within acceptable detection limits. Despite these advancements, establishing robust and efficient sample treatment protocols is still essential for trustworthy broad-range chemical analysis. This study sought to validate a methodology leveraging HRMS-based strategies for accurate profiling of exogenous chemicals and related metabolites in urine samples. We evaluated five extraction protocols, each encompassing various chemical classes, such as pharmaceuticals, plastic additives, personal care products, and pesticides, in terms of their extraction recoveries, linearity, matrix effect, sensitivity, and reproducibility. The most effective protocol was extensively validated and subsequently applied to 10 real human urine samples using wide-scope target analysis encompassing over 2000 chemicals. We successfully identified and semi-quantified a total of 36 chemicals using an ionization efficiency-based model, affirming the methodology's robust performance. Notably, our results dismissed the need for a deconjugation step, a typically labor-intensive and time-consuming process.

Risks of benzalkonium chlorides as emerging contaminants in the environment and possible control strategies from the perspective of ecopharmacovigilance

An unprecedented increase in the use of disinfection products triggered by the coronavirus disease 2019 (COVID-19) pandemic is resulting in aggravating environmental loads of disinfectants as emerging contaminants, which has been considered a cause for worldwide secondary disasters. This review analyzed the literature published in the last decade about occurrence, bioaccumulation, and possible environmental risks of benzalkonium chlorides (BKCs) as emerging contaminants. Results indicated that BKCs globally occurred in municipal wastewater, surface water, groundwater, reclaimed water, sludge, sediment, soil, roof runoff, and residential dust samples across 13 countries. The maximum residual levels of 30 mg/L and 421 μg/g were reported in water and solid environmental samples, respectively. Emerging evidences suggested possible bioaccumulation of BKCs in plants, even perhaps humans. Environmentally relevant concentrations of BKCs exert potential adverse impacts on aquatic and terrestrial species, including genotoxicity, respiratory toxicity, behavioural effects and neurotoxicity, endocrine disruption and reproductive impairment, phytotoxicity, etc. Given the intrinsic biocidal and preservative properties of disinfectants, the inductive effects of residual BKCs in environment in terms of resistance and imbalance of microorganisms have been paid special attention. Considering the similarities of disinfectants to pharmaceuticals, from the perspective of ecopharmacovigilance (EPV), a well-established strategy for pharmaceutical emerging contaminants, we use the control of BKC pollution as a case, and provide some recommendations for employing the EPV measures to manage environmental risks posed by disinfectant emerging contaminants.

Changes in prevalence and sociodemographic correlates of tobacco and nicotine use in Finland during the COVID-19 pandemic

BACKGROUND

The impact of the coronavirus disease 2019 (COVID-19) pandemic on tobacco and nicotine use remains debated. We examined whether the prevalence of tobacco and nicotine use and nicotine-replacement therapy (NRT) changed during the COVID-19 pandemic and whether changes differed by sociodemographic groups.

METHODS

Repeated cross-sectional study of three national surveys in Finland (2018, 2019 and 2020; n = 58 526 adults aged 20 and over). Outcomes were daily and occasional smoking, smokeless tobacco (snus) use, e-cigarettes use, total tobacco or nicotine use and NRT use. We examined changes for each outcome by sex, age, educational tertiles, marital status, mother tongue and social participation.

RESULTS

Daily smoking decreased among males by 1.15 percentage points (pp) [95% confidence interval (CI) -2.10 to -0.20] between 2018 and 2020 and 0.86 pp among females (95% CI -1.58 to -0.15). Daily snus use remained stable in both sexes. Daily e-cigarette use was below 1% and remained stable. We found weak evidence of a reduction in total tobacco or nicotine use between 2018 and 2020 (males -1.18 pp, 95% CI -2.68 to 0.32 and females -0.8 pp, 95% CI -1.81 to 0.22). NRT use remained stable. Snus and NRT use decreased among 60- to 74-year-olds but remained stable in other age groups. We did not find evidence of interactions by subgroup for other outcomes.

CONCLUSIONS

Daily smoking decreased in Finland between 2018 and 2020, but other forms of tobacco use did not experience a reduction. The COVID-19 pandemic does not seem to have altered the sustained reduction of smoking in Finland, although substantial sociodemographic differences persist.

Low concentration quaternary ammonium compounds promoted antibiotic resistance gene transfer via plasmid conjugation

During the pandemic of COVID-19, the amounts of quaternary ammonium compounds (QACs) used to inactivate the virus in public facilities, hospitals and households increased, which raised concerns about the evolution and transmission of antimicrobial resistance (AMR). Although QACs may play an important role in the propagation of antibiotic resistance gene (ARGs), the potential contribution and mechanism remains unclear. Here, the results showed that benzyl dodecyl dimethyl ammonium chloride (DDBAC) and didecyl dimethyl ammonium chloride (DDAC) significantly promoted plasmid RP4-mediated ARGs transfer within and across genera at environmental relevant concentrations (0.0004-0.4 mg/L). Low concentrations of QACs did not contribute to the permeability of the cell plasma membrane, but significantly increased the permeability of the cell outer membrane due to the decrease in content of lipopolysaccharides. QACs altered the composition and content of extracellular polymeric substances (EPS) and were positively correlated with the conjugation frequency. Furthermore, transcriptional expression levels of genes encode for mating pairing formation (trbB), DNA replication and translocation (trfA), and global regulators (korA, korB, trbA) are regulated by QACs. And we demonstrate for the first time that QACs decreased the concentration of extracellular AI-2 signals, which was verified to be involved in regulating conjugative transfer genes (trbB, trfA). Collectively, our findings underscore the risk of increased disinfectant concentrations of QACs on the ARGs transfer and provide new mechanisms of plasmid conjugation.

Do the lockdown-imposed changes in a wastewater treatment plant catchment's socio-demographics impact longitudinal temporal trends in psychoactive pharmaceutical use?

Wastewater-based epidemiology (WBE) includes the analysis of human metabolic biomarkers of xenobiotics in influent wastewater. WBE complements existing drug utilization approaches and provides objective, spatio-temporal information on the consumption of pharmaceuticals in the general population. This approach was applied to 24-h composite influent wastewater samples from Leuven, Belgium. Daily samples were analysed from September 2019 to December 2019 (n = 76), and on three days of the week (Monday, Wednesday, Saturday) from January 2020 to April 2022 (n = 367). Sample analysis consisted of 96-well solid-phase extraction and liquid chromatography coupled to tandem mass spectrometry. Measured concentrations of 21 biomarkers for antidepressant and opioid use were converted to population-normalized mass loads (PNML) by considering the flow rate and catchment population. To capture population movements, mobile phone data was used. Amitriptyline, hydroxy-bupropion, norcitalopram, citalopram, normirtazapine, trazodone, O-desmethylvenlafaxine, codeine, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), methadone, morphine, O-desmethyltramadol, and tramadol were included in the temporal assessment since concentrations were above the lower limit of quantification. The PNML of most biomarkers increased (with 3-119 %) throughout the sampling period. The population disruption during the COVID-19 pandemic led to a major change in the socio-demographics of the catchment area, resulting in temporal differences in the PNML of the different biomarkers. As such, higher PNML were observed during the different lockdown phases, which were characterized by the outflow of university students and a decreasing commuting in and out the catchment area. The effects of the fluctuating socio-demographics of the catchment population were further evidenced by the different week-weekend pattern of PNMLs over the course of the sampling campaign. Mean parent/metabolite ratios (i.e., citalopram/norcitalopram, tramadol/O-desmethyltramadol, venlafaxine/O-desmethylvenlafaxine, and methadone/EDDP) remained relatively stable throughout the entire sampling campaign (RSD% below 25 % for all ratios, except for methadone/EDDP) and therefore were not affected by this population change.

Identification and characterization of quaternary ammonium compounds in Flemish indoor dust by ion-mobility high-resolution mass spectrometry

Quaternary ammonium compounds (QACs) are a class of surfactants commonly used in disinfecting and cleaning products. Their use has substantially increased during the COVID-19 pandemic leading to increasing human exposure. QACs have been associated with hypersensitivity reactions and an increased risk of asthma. This study introduces the first identification, characterization and semi-quantification of QACs in European indoor dust using ion-mobility high-resolution mass spectrometry (IM-HRMS), including the acquisition of collision cross section values (^DTCCS_N2) for targeted and suspect QACs. A total of 46 indoor dust samples collected in Belgium were analyzed using target and suspect screening. Targeted QACs (n = 21) were detected with detection frequencies ranging between 4.2 and 100 %, while 15 QACs showed detection frequencies > 90 %. Semi-quantified concentrations of individual QACs showed a maximum of 32.23 µg/g with a median ∑QAC concentration of 13.05 µg/g and allowed the calculation of Estimated Daily Intakes for adults and toddlers. Most abundant QACs matched the patterns reported in indoor dust collected in the United States. Suspect screening allowed the identification of 17 additional QACs. A dialkyl dimethyl ammonium compound with mixed chain lengths (C16:C18) was characterized as a major QAC homologue with a maximum semi-quantified concentration of 24.90 µg/g. The high detection frequencies and structural variabilities observed call for more European studies on potential human exposure to these compounds. For all targeted QACs, drift tube IM-HRMS derived collision cross section values (^DTCCS_N2) are reported. Reference ^DTCCS_N2 values allowed the characterization of CCS-m/z trendlines for each of the targeted QAC classes. Experimental CCS-m/z ratios of suspect QACs were compared with the CCS-m/z trendlines. The alignment between the two datasets served as an additional confirmation of the assigned suspect QACs. The use of the 4bit multiplexing acquisition mode with consecutive high-resolution demultiplexing confirmed the presence of isomers for two of the suspect QACs.

Microplastics and other emerging contaminants in the environment after COVID-19 pandemic: The need of global reconnaissance studies

Evidence of the increase of emerging contaminants in the environment due to the COVID-19 pandemic, such as personal protective equipment (PPE), disinfectants, pharmaceuticals, etc., has enlarged. Here we explain the variety of pathways of these emerging contaminants to enter the environment, including wastewater treatment plants, improper disposal of PPE, and runoff from surfaces treated with disinfectants. We also discuss the current state-of-art of the toxicological implications of these emerging contaminants. Initial research suggests that they may have harmful effects on aquatic organisms and human health. Future directions are suggested as further research is needed to fully understand the impacts of these contaminants on the environment and humans, as well as to develop effective approaches to mitigate their potential negative effects.

Target and suspect screening of (new) psychoactive substances in South Korean wastewater by LC-HRMS

New psychoactive substances (NPS) are a type of abused drug designed to mimic the effects of the currently known illicit drugs, whose structures are constantly changing to escape surveillance. The quick identification of NPS use in the community therefore demands immediate action. This study aimed to develop a target and suspect screening method using LC-HRMS to identify NPS in wastewater samples. An in-house database of 95 traditional and NPS was built using the reference standards, and an analytical method was developed. Wastewater samples were collected from 29 wastewater treatment plants (WWTP) across South Korea, representing 50 % of the total population. The psychoactive substances in waste water samples were screened using in-house database and developed analytical methods. A total of 14 substances were detected in the target analysis, including three NPS (N-methyl-2-AI, 25E-NBOMe, and 25D-NBOMe) and 11 traditional psychoactive substances and their metabolites (zolpidem phenyl-4-COOH, ephedrine, ritalinic acid, tramadol, phenmetrazine, phendimetrazine, phentermine, methamphetamine, codeine, morphine, and ketamine). Out of these, N-methyl-2-AI, zolpidem phenyl-4-COOH, ephedrine, ritalinic acid, tramadol, phenmetrazine, and phendimetrazine were detected with a detection frequency of over 50 %. Primarily, N-methyl-2-Al was detected in all the wastewater samples. Additionally, four NPSs (amphetamine-N-propyl, benzydamine, isoethcathinone, methoxyphenamine) were tentatively identified at level 2b in a suspect screening analysis. This is the most comprehensive study to investigate NPS using target and suspect analysis methods at the national level. This study raises a need for continuous monitoring of NPS in South Korea.

Environmental concentrations of surfactants as a trigger for climax of horizonal gene transfer of antibiotic resistance

Ubiquitous antibiotic resistance genes (ARGs) is a significant global human health concern. Surfactants have been extensively used worldwide, and the consumption of surfactants containing hygiene, cleaning agents and disinfectants was multiplied during COVID-19 pandemic, which have caused significantly increased pollution of surfactants in aquatic environment. Whether such ever-increasing surfactant concentration boost dissemination risk of ARGs still remains unknown. Here the effects of three typical surfactants such as sodium dodecyl sulfate, cetyltrimethylammonium bromide and benzalkonium chloride on the transformation of pUC19 plasmid (2686 bp)-borne ARGs to recipient bacteria E. coli DH5ɑ were investigated. It was found that these surfactants at environmental concentrations facilitated horizonal gene transfer (HGT) via transformation. The transformation triggering concentrations for the three surfactants were 0.25-0.34 mg/L with a maximum increased transformation frequency of 13.51-22.93-fold. The mechanisms involved in activated HGT of ARGs via transformation triggered by surfactants could be mainly attributed to the increased production of reactive oxygen species, which further enhanced cell membrane permeability. These findings provide new sights for understanding of ARG propagation and also imply that the drastic rise of surfactant concentration in aquatic environment may significantly increase the dissemination risk of antibiotic resistance.

Antiviral drugs in wastewater are on the rise as emerging contaminants: A comprehensive review of spatiotemporal characteristics, removal technologies and environmental risks

Antiviral drugs (ATVs) are widely used to treat illnesses caused by viruses. Particularly, ATVs were consumed in such large quantities during the pandemic that high concentrations were detected in wastewater and aquatic environment. Since ATVs are not fully absorbed by the human or animal body, this results in large amounts of them being discharged into the sewage through urine or feces. Most ATVs can be degraded by microbes at wastewater treatment plants (WWTPs), while some ATVs either require deep treatment to reduce concentration and toxicity. Parent and metabolites residing in effluent posed a varying degree of risk when entering the aquatic environment, while increasing the potential of natural reservoirs for environmentally acquired antiviral drug resistance potential. There is a rising research on the behavior of ATVs in the environment has surged since the pandemic. In the context of multiple viral diseases worldwide, especially during the current COVID-19 pandemic, a comprehensive assessment of the occurrence, removal, and risk of ATVs is urgently needed. This review aims to discuss the fate of ATVs in WWTPs from various regions in the world with wastewater as the main analyzing object. The ultimate goal is to focus on ATVs with high ecological impact and regulate their use or develop advanced treatment technologies to mitigate the risk to the environment.

Quaternary Ammonium Compounds: A Chemical Class of Emerging Concern

Quaternary ammonium compounds (QACs), a large class of chemicals that includes high production volume substances, have been used for decades as antimicrobials, preservatives, and antistatic agents and for other functions in cleaning, disinfecting, personal care products, and durable consumer goods. QAC use has accelerated in response to the COVID-19 pandemic and the banning of 19 antimicrobials from several personal care products by the US Food and Drug Administration in 2016. Studies conducted before and after the onset of the pandemic indicate increased human exposure to QACs. Environmental releases of these chemicals have also increased. Emerging information on adverse environmental and human health impacts of QACs is motivating a reconsideration of the risks and benefits across the life cycle of their production, use, and disposal. This work presents a critical review of the literature and scientific perspective developed by a multidisciplinary, multi-institutional team of authors from academia, governmental, and nonprofit organizations. The review evaluates currently available information on the ecological and human health profile of QACs and identifies multiple areas of potential concern. Adverse ecological effects include acute and chronic toxicity to susceptible aquatic organisms, with concentrations of some QACs approaching levels of concern. Suspected or known adverse health outcomes include dermal and respiratory effects, developmental and reproductive toxicity, disruption of metabolic function such as lipid homeostasis, and impairment of mitochondrial function. QACs' role in antimicrobial resistance has also been demonstrated. In the US regulatory system, how a QAC is managed depends on how it is used, for example in pesticides or personal care products. This can result in the same QACs receiving different degrees of scrutiny depending on the use and the agency regulating it. Further, the US Environmental Protection Agency's current method of grouping QACs based on structure, first proposed in 1988, is insufficient to address the wide range of QAC chemistries, potential toxicities, and exposure scenarios. Consequently, exposures to common mixtures of QACs and from multiple sources remain largely unassessed. Some restrictions on the use of QACs have been implemented in the US and elsewhere, primarily focused on personal care products. Assessing the risks posed by QACs is hampered by their vast structural diversity and a lack of quantitative data on exposure and toxicity for the majority of these compounds. This review identifies important data gaps and provides research and policy recommendations for preserving the utility of QAC chemistries while also seeking to limit adverse environmental and human health effects.

Comprehensive micropollutant characterization of wastewater during Covid-19 crisis in 2020: Suspect screening and environmental risk prioritization strategy

Micropollutants monitoring in wastewater can serve as a picture of what is consuming society and how it can impact the aquatic environment. In this work, a suspect screening approach was used to detect the known and unknown contaminants in wastewater samples collected from two wastewater treatment plants (WWTPs) located in the Basque Country (Crispijana in Alava, and Galindo in Vizcaya) during two weekly sampling campaigns, which included the months from April to July 2020, part of the confinement period caused by COVID-19. To that aim, high-resolution mass spectrometry was used to collect full-scan data-dependent tandem mass spectra from the water samples using a suspect database containing >40,000 chemical substances. The presence of > 80 contaminants was confirmed (level 1) and quantified in both WWTP samples, while at least 47 compounds were tentatively identified (2a). Among the contaminants of concern, an increase in the occurrence of some compounds used for COVID-19 disease treatment, such as lopinavir and hydroxychloroquine, was observed during the lockdown. A prioritization strategy for environmental risk assessment was carried out considering only the compounds quantified in the effluents of Crispijana and Galindo WWTPs. The compounds were scored based on the removal efficiency, estimated persistency, bioconcentration factor, mobility, toxicity potential and frequency of detection in the samples. With this approach, 33 compounds (e.g. amantadine, clozapine or lopinavir) were found to be considered key contaminants in the analyzed samples based on their concentration, occurrence and potential toxicity. Additionally, antimicrobial (RQ-AR) and antiviral (EDRP) risk of certain compounds was evaluated, where ciprofloxacin and fluconazole represented medium risk for antibiotic resistance (1 > RQ-AR > 0.1) in the aquatic ecosystems. Regarding mixture toxicity, the computed sum of toxic unit values of the different effluents (> 1) suggest that interactions between the compounds need to be considered for future environmental risk assessments.

Three years of wastewater surveillance for new psychoactive substances from 16 countries

The proliferation of new psychoactive substances (NPS) over recent years has made their surveillance complex. The analysis of raw municipal influent wastewater can allow a broader insight into community consumption patterns of NPS. This study examines data from an international wastewater surveillance program that collected and analysed influent wastewater samples from up to 47 sites in 16 countries between 2019 and 2022. Influent wastewater samples were collected over the New Year period and analysed using validated liquid chromatography - mass spectrometry methods. Over the three years, a total of 18 NPS were found in at least one site. Synthetic cathinones were the most found class followed by phenethylamines and designer benzodiazepines. Furthermore, two ketamine analogues, one plant based NPS (mitragynine) and methiopropamine were also quantified across the three years. This work demonstrates that NPS are used across different continents and countries with the use of some more evident in particular regions. For example, mitragynine has highest mass loads in sites in the United States, while eutylone and 3-methylmethcathinone increased considerably in New Zealand and in several European countries, respectively. Moreover, 2F-deschloroketamine, an analogue of ketamine, has emerged more recently and could be quantified in several sites, including one in China, where it is considered as one of the drugs of most concern. Finally, some NPS were detected in specific regions during the initial sampling campaigns and spread to additional sites by the third campaign. Hence, wastewater surveillance can provide an insight into temporal and spatial trends of NPS use.

Wastewater surveillance of SARS-CoV-2 and chemical markers in campus dormitories in an evolving COVID - 19 pandemic

In this study, we report the implementation of a comprehensive wastewater surveillance testing program at a university campus in Singapore to identify Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infected individuals and the usage of pharmaceuticals and personal care products (PPCPs) as well as other emerging contaminants (ECs). This unique co-monitoring program simultaneously measured SARS-CoV-2 with chemical markers/contaminants as the COVID-19 situation evolved from pandemic to endemic stages, following a nationwide mass vaccination drive. SARS-CoV-2 RNA concentrations in wastewater from campus dormitories were measured using real-time reverse transcription-polymerase chain reaction (RT-qPCR) and corroborated with the number of symptomatic COVID-19 cases confirmed with the antigen rapid test (ART). Consistent results were observed where the concentrations of SARS-CoV-2 RNA detected in wastewater increased proportionately with the number of COVID-19 infected individuals residing on campus. Similarly, a wide range of ECs, including disinfectants and antibiotics, were detected through sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) techniques to establish PPCPs consumption patterns during various stages of the COVID-19 pandemic in Singapore. Statistical correlation of SARS-CoV-2 RNA was observed with few ECs belonging to disinfectants, PCPs and antibiotics. A high concentration of disinfectants and subsequent positive correlation with the number of reported cases on the university campus indicates that disinfectants could serve as a chemical marker during such unprecedented times.

Quaternary ammonium compounds of emerging concern: Classification, occurrence, fate, toxicity and antimicrobial resistance

Amplified hygiene and precautionary measures are of utmost importance to control the spread of COVID-19 and future infection; however, these changes in practice are projected to trigger a rise in the purchase, utilisation and hence, discharge of many disinfectants into the environment. While alcohol-based, hydrogen peroxide-based, and chlorine-based compounds have been used widely, quaternary ammonium compounds (QACs) based disinfectants are of significant concern due to their overuse during this pandemic. This review presents the classification of disinfectants and their mechanism of action, focusing on QACs. Most importantly, the occurrence, fate, toxicity and antimicrobial resistance due to QACs are covered in this paper. Here we collated evidence from multiple studies and found rising trends of concern, including an increase in the mass load of QACs at a wastewater treatment plant (WWTP) by 331% compared to before the COVID-19 pandemic, as well as an increases in the concentration of 62% in residential dust, resulting in high concentrations of QACs in human blood and breast milk and suggesting that these could be potential sources of persistent QACs in infants. In addition to increased toxicity to human and aquatic life, increased use of QACs and accelerated use of antibiotics and antimicrobials during the COVID-19 pandemic could multiply the threat to antimicrobial resistance.

Study of Cationic Surfactants Raw Materials for COVID-19 Disinfecting Formulations by Potentiometric Surfactant Sensor

The behavior of a new 1,3-dioctadecyl-1H-imidazol-3-ium tetraphenylborate (DODI-TPB) surfactant sensor was studied in single and complex mixtures of technical grade QACs-benzalkonium chloride (BAC), N,N-didecyl-N,N-dimethylammonium chloride (DDAC), and N,N-dioctyl-N,N-dimethylammonium chloride (DOAC) usually used in COVID-19 disinfecting agents formulations. The results obtained with the new DODI-TPB sensor were in good agreement with data measured by a 1,3-dihexadecyl-1H-benzo[d]imidazol-3-ium-tetraphenylborate (DMI-TPB) surfactant sensor, as well as two-phase titration used as a reference method. The quantitative titrations of a two-component mixture of the cationic homologs (a) DDAC and DOAC; and (b) BAC and DOAC showed that the new DODI-TPB surfactant sensor can clearly distinguish two separate mixture components in a single potentiometric titration curve with two characteristic inflexion points. The consumption of SDS (used as a titrant) in the end-point 1 (EP 1) corresponded to the content of DDAC (or BAC), whereas the consumption in the end-point 2 (EP 2) corresponded to the total content of both cationic surfactants in the mixture. DOAC content in both mixtures can be calculated from the difference of the titrant used to achieve EP1 and EP2. The addition of nonionic surfactants resulted in the signal change decrease from 333.2 mV (1:0; no nonionic surfactant added) to 243.0 mV (1:10, w/w). The sensor was successfully tested in ten two-component COVID-19 disinfecting formulations.

Spatiotemporal trends and impact of Covid-19 lockdown on eight sewage contaminants in Brisbane, Australia, from 2012 to 2020

This study aims to investigate the spatiotemporal trends and impact of COVID-19 lockdowns to the profile of physiochemical parameters in the influent of wastewater treatment plants (WWTPs) around Brisbane, Australia. One 24-hr composite influent sample was collected from 10 WWTPs and analyzed for a range of physiochemical parameters per week (i.e., chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), ammonia, volatile suspended solid (VSS)) and per month (i.e., Ni and Cr) from 2012 to 2020, including the period of COVID-19 lockdowns in the region. The catchments studied were urban, with a mix of domestic and industrial activities contributing towards the contaminant profile. Statistical analysis identified that industrial and commercial land use, as well as population size had a large impact to the parameter loads and profile. Per capita mass loads of Cr in one catchment were 100 times higher than in others from one industrial point source. TP demonstrated a potential monotonic decrease over time due to practical reduction policies that have been implemented for phosphorous content in household detergents, except for one catchment where trade waste from food manufacturing industries contributed to an overall increase of 6.9%/year TP. The COVID-19 lockdown (March-April 2020) posed different impact on different catchments, either decrease (7-61%) or increase (2-40%) of most parameter loads (e.g., COD, TOC, TN, TP, VSS, Ammonia), which was likely driven by catchment characteristics (i.e., the proportion of residential, commercial, and industrial land uses). This study enhances our understanding of spatiotemporal trend of contaminants in the catchments for further effective source control.

Extending the Protection Ability and Life Cycle of Medical Masks through the Washing Process

The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances-surfactants-in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability.

Widespread occurrence of quaternary alkylammonium disinfectants in soils of Hesse, Germany

Quaternary alkylammonium compounds (QAACs) are cationic organic compounds with amphiphilic properties that are widely used as surfactants and disinfectants in industry, households and agriculture. Several studies suggest that QAACs co-select for antibiotic resistant microorganisms and thus may contribute to the spread of antibiotic resistance in the environment. Data on QAAC occurrence in soil are scarce and limited to soils that are prone to direct exposure to QAACs. Therefore, we conducted a comprehensive study on the occurrence of QAACs in soils of Hesse, a federal state in Germany, covering an area of 21,115 km². Sixty-five soil samples that comprised different land uses (arable, grassland, forest, vineyard) and area types (rural, agglomeration) were analysed for concentrations of alkyltrimethylammonium (ATMACs, with alkyl chain lengths C8-C16), benzylalkyldimethylammonium (BACs, C8-C18) and dialkyldimethylammonium compounds (DADMACs, C8-C18) via HPLC-MS/MS after ultrasonic-assisted extraction with acidified acetonitrile. QAACs were detected in 97 % of the soil samples irrespective of land use and area type. The most abundant QAAC homologues were DADMACs > BACs > ATMACs. The highest total QAAC concentrations were detected in alluvial soils influenced by the deposition of suspended particles during flood events, with DADMAC-C16 and -C18 as the dominant homologues. The high abundance of long-chain DADMACs suggests that legacy pollution and accumulation govern QAAC concentrations in soils. The presence of QAACs in forest soils points to a potential input via atmospheric deposition. Our work highlights the widespread occurrence of QAACs in soils of Hesse and the need for more research on their entry paths and fate in the soil ecosystem.

Wide-Scope Target and Suspect Screening of Antibiotics in Effluent Wastewater from Wastewater Treatment Plants in Europe

The occurrence of antibiotics in the environment could result in the development of antibiotic-resistant bacteria, which could result in a public health crisis. The occurrence of 676 antibiotics and the main transformation products (TPs) was investigated in the 48 wastewater treatment plants (WWTPs) from 11 countries (Germany, Romania, Serbia, Croatia, Slovenia, Hungary, Slovakia, Czechia, Austria, Cyprus, and Greece) by target and suspect screening. Target screening involved the investigation of antibiotics with reference standards (40 antibiotics). Suspect screening covered 676 antibiotics retrieved from the NORMAN Substance Database (antibiotic list on NORMAN network). Forty-seven antibiotics were detected in effluent wastewater samples: thirty-two by target screening and fifteen additional ones by suspect screening. An ecotoxicological risk assessment was performed based on occurrence data and predicted no effect concentration (PNEC), which involved the derivation of frequency of appearance (FoA), frequency of PNEC exceedance (FoE), and extent of PNEC exceedance (EoE). Azithromycin, erythromycin, clarithromycin, ofloxacin, and ciprofloxacin were prioritized as the calculated risk score was above 1. The median of antibiotics' load to freshwater ecosystems was 0.59 g/day/WWTP. The detection of antibiotics across countries indicates the presence of antibiotics in the ecosystems of Europe, which may trigger unwanted responses from the ecosystem, including antibiotic resistance.

Wastewater-based monitoring of illicit drugs in Cyprus by UPLC-MS/MS: The impact of the COVID-19 pandemic

The outbreak and spread of COVID-19 impacted through various ways the lives of millions of humans globally. In this work, wastewater-based epidemiology (WBE) was applied to investigate the effect of the actions taken by the Republic of Cyprus to confine COVID-19 on the use of illicit stimulant drugs. Daily influent samples were collected from the six main wastewater treatment plants (WWTPs) of the country i) before lockdown (3-9 April 2019), ii) during lockdown (21-27 April 2020), iii) during the post-lockdown period (14-20 July 2020), and, iv) during each season of the following year (20-26 April 2021, 19-25 July 2021, 11-17 October 2021, 25 December 2021-2 January 2022), and analyzed for amphetamine, methamphetamine, MDMA and cocaine. In most areas, amphetamine and methamphetamine use was not affected during the confinement period, but as availability of the substances decreased with time, a drop in their use was observed when most restriction measures were eased (up to 9- and 22-fold decrease, respectively). The limitations on social interactions and events during the quarantine period seem to have led to the reduction of MDMA and cocaine and driven a sharp decrease of their use in most areas studied (up to 11 and 6 times lower, respectively). However, the re-opening of activities led to a pronounced consumption increase, reaching maximum daily values of 800 and 2691 mg/1000 inhabitants/day, respectively. In 2021, drug use was re-established to lower levels. The examination of weekly patterns during this year revealed higher weekend use of methamphetamine, MDMA and cocaine. Our results suggest that both the implementation and the easing of COVID-19 related measures affected the availability and the use of drugs. This study also provides the first insight on the consumption of illicit drugs in the Republic of Cyprus during pre-, post- and pandemic times and demonstrates the importance of WBE.

Multiclass target analysis of contaminants of emerging concern including transformation products, soil bioavailability assessment and retrospective screening as tools to evaluate risks associated with reclaimed water reuse

The occurrence of 200 multiclass contaminants of emerging concern (CECs) encompassing 168 medicinal products and transformation products (TPs), 5 artificial sweeteners, 12 industrial chemicals, and 15 other compounds was investigated in influent and effluent wastewater samples collected during 7 consecutive days from 5 wastewater treatment plants (WWTPs) located in Cyprus. The methodology included a generic solid-phase extraction protocol using mixed-bed cartridges followed by Ultra-High Performance Liquid Chromatography coupled with Quadrupole-Time of Flight Mass Spectrometry (UHPLC-QTOF-MS) analysis. A total of 63 CECs were detected at least in one sample, with 52 and 55 out of the 200 compounds detected in influents and effluents, respectively. Ten (10) out of the 24 families of parent compounds and associated TPs were found in the wastewater samples (influent or effluent). 1-H-benzotriazole, carbamazepine, citalopram, lamotrigine, sucralose, tramadol, and venlafaxine (>80 % frequency of appearance in effluents) were assessed with respect to their bioavailability in soil as part of different scenarios of irrigation with reclaimed water following a qualitative approach. A high score of 12 (high probability) was predicted for 2 scenarios, a low score of 3 (rare occasions) for 2 scenarios, while the rest 28 scenarios had scores 5-8 (unlikely or limited possibility) and 9-11 (possibly). Retrospective screening was performed with the use of a target database of 2466 compounds and led to the detection of 158 additional compounds (medicinal products (65), medicinal products TPs (15), illicit drugs (7), illicit drugs TPs (3), industrial chemicals (11), plant protection products (25), plant protection products TPs (10), and various other compounds (22). This work aspires to showcase how the presence of CECs in wastewater could be investigated and assessed at WWTP level, including an expert-based methodology for assessing the soil bioavailability of CECs, with the aim to develop sustainable practices and enhance reclaimed water reuse.

Evaluating the impact of COVID-19 countermeasures on alcohol consumption through wastewater-based epidemiology: A case study in Belgium

Wastewater-based epidemiology (WBE) is a complementary approach to monitor alcohol consumption in the general population. This method measures concentrations of xenobiotic biomarkers (e.g., ethyl sulphate) in influent wastewater (IWW) and converts these to population-normalized mass loads (PNML, in g/day/1000 inhabitants) by multiplying with the flow rate and dividing by the catchment population. The aims of this case study were to: (i) investigate temporal trends in alcohol use during the COVID-19 pandemic; and (ii) measure the effect of policy measures on alcohol consumption. Daily 24-h composite IWW samples (n = 735) were collected in the wastewater treatment plant of the university city of Leuven (Belgium) starting from September 2019 to September 2021. This is the first study that investigates alcohol use through WBE for a continuous period of two years on a daily basis. Mobile phone data was used to accurately capture population fluxes in the catchment area. Data was evaluated using a time series based statistical framework to graphically and quantitatively assess temporal differences in the measured PNML. Different WBE studies observed temporal changes in alcohol use during the COVID-19 pandemic. In this study, the PNML of ethyl sulphate decreased during the first lockdown phase, potentially indicating that less alcohol was consumed at the Leuven area during home confinement. Contrastingly, alcohol use increased after the re-opening of the catering industry. Additionally, a decrease in alcohol use was observed during the exam periods at the University of Leuven and an increase during the holiday periods. The present study shows the potential of WBE to rapidly assess the impact of some policy measures on alcohol consumption in Belgium. This study also indicates that WBE could be employed as a complementary data source to fill in some of the current knowledge gaps linked to lifestyle behavior.

The 1,3-Dioctadecyl-1H-imidazol-3-ium Based Potentiometric Surfactant Sensor for Detecting Cationic Surfactants in Commercial Products

A low-cost and fast potentiometric surfactant sensor for cationic surfactants, based on the new ion-pair 1,3-dioctadecyl-1H-imidazol-3-ium-tetraphenylborate (DODI-TPB), is presented. The new cationic surfactant DODI-Br was synthesized and characterized by NMR, LC-MS, and elemental analysis, and was used for synthesis of the DODI-TPB ionophore. The DODI-TPB surfactant sensor was obtained by implementation of the ionophore in PVC. The sensor showed excellent response characteristics with near-Nernstian slopes to the cationic surfactants DMIC, CPC, CTAB, and Hyamine 1622. The highest voltage responses were obtained for DMIC and CPC (58.7 mV/decade of activity). DMIC had the lowest detection limit (0.9 × 10^-6 M) and the broadest useful linear concentration range (1.8 × 10^-6 to 1.0 × 10^-4 M). An interference study showed remarkable stability. Potentiometric titration curves for the titration of cationic surfactants (DMIC, CPC, CTAB, and Hyamine 1622), with DDS and TPB used as titrants, showed sigmoidal curves with well-defined inflexion points and a broad signal change. The standard addition method was successfully applied with recovery rates from 98.9 to 101.2 at two concentrations. The amount of cationic surfactant found in disinfectants and antiseptics was in good agreement with the referent two-phase titration method and the surfactant sensor on the market. This new surfactant sensor represents a low-cost alternative to existing methods for cationic surfactant detection.

Nationwide investigation on the use of new psychoactive substances in Italy through urban wastewater analysis

New psychoactive substances (NPS) emerged in the mid-2000s as a legal alternative to established illicit drugs. Despite the high individual and public harm associated to NPS, little is known about their real extent of use. New strategies are required to deal with the challenging monitoring of NPS, affected by the high number of substances available in the market, their rapid change and level of innovation, and their easy distribution mainly through the web. In this study, a wastewater-based epidemiology (WBE) approach was applied for a nationwide monitoring of the use of eight categories of NPS in the population, including fentanyl analogues. Sixty-two biomarkers of NPS were selected following an established criterion, that included the most frequently and recently reported. A selective analytical method based on solid-phase extraction and liquid chromatography-tandem mass spectrometry was developed and validated for NPS analysis in wastewater. Composite wastewater samples (24 h) were collected in 33 Italian cities in October-November 2020 and analyzed according the validated method. Results highlighted the use of ten NPS, mainly synthetic cathinones and tryptamines, all over Italy. Methcathinone was found in all the cities and the highest mass loads corresponded to 3-methylmethcathinone with values up to 3.8 mg/day/1000 inhabitants. Low levels of fentanyl (found in 9 cities) and its main metabolite norfentanyl (11) were found whereas no fentanyl analogues were identified. As far as we know, this is the first time that the use of fentanyl and its analogues was investigated in Italy by wastewater analysis. WBE is a useful tool to rapidly evaluate emerging trends of NPS use, complementing common indicators (i.e. population surveys, seizures) and helping to establish measures for public health protection.

Antiviral drugs against influenza: Treatment methods, environmental risk assessment and analytical determination

Over the past few years, antiviral drugs against influenza are considered emerging contaminants since they cause environmental toxicity even at low concentrations. They have been found in environmental matrices all around the world, showing that conventional treatment methods fail to remove them from water and wastewater. In addition, the metabolites and transformation products of these drugs can be more persistent than original in the environment. Several techniques to degrade/remove antiviral drugs against influenza have been investigated to prevent this contamination. In this study, the characteristics of antiviral drugs against influenza, their measurement by analytical methods, and their removal in both water and wastewater treatment plants (WWTPs) were presented. Different treatment methods, such as traditional procedures (biological processes, filtration, coagulation, flocculation, and sedimentation), advanced oxidation processes (AOPs), adsorption and combined methods, were assessed. Ecotoxicological effects of both the antiviral drug and its metabolites as well as the transformation products formed as a result of treatment were evaluated. In addition, future perspectives for improving the removal of antiviral drugs against influenza, their metabolites and transformation products were further discussed. The research indicated that the main tested techniques in this study were ozonation, photolysis and photocatalysis. Combined methods, particularly those that use renewable energy and waste materials, appear to be the optimum approach for the treatment of effluents containing antiviral drugs against influenza. In light of high concentrations or probable antiviral resistance, this comprehensive assessment suggests that antiviral drug monitoring is required, and some of those substances may cause toxicological effects.

Use of illicit drugs, alcohol and tobacco in Spain and Portugal during the COVID-19 crisis in 2020 as measured by wastewater-based epidemiology

The COVID-19 pandemic spread rapidly worldwide in the year 2020, which was initially restrained by drastic mobility restrictions. In this work, we investigated the use of illicit drugs (amphetamine, methamphetamine, ecstasy, cocaine and cannabis), and licit substances of abuse (alcohol and tobacco) during the earlier months (March-July 2020) of the pandemic restrictions in four Spanish (Bilbao and its metropolitan area, Vitoria-Gasteiz, Castellón and Santiago de Compostela) and two Portuguese (Porto and Vila do Conde) locations by wastewater-based epidemiology (WBE). The results show that no methamphetamine was detected in any of the locations monitored, while amphetamine use was only detectable in the two locations from the Basque Country (Bilbao and its metropolitan area and Vitoria-Gasteiz), with high estimated average usage rates (700-930 mg day-1 1000 inhabitant-1). The remaining substances were detected in all the investigated catchment areas. In general, no remarkable changes were found in population normalized loads compared to former years, except for cocaine (i.e. its main metabolite, benzoylecgonine). For this drug, a notable decrease in use was discernible in Castellón, while its usage in Porto and Santiago de Compostela seemed to continue in a rising trend, already initiated in former years. Furthermore, two events of ecstasy (3,4-methylenedioxymethamphetamine, MDMA) dumping in the sewage network were confirmed by enantiomeric analysis, one in Santiago de Compostela just prior the lockdown and the second one in the Bilbao and its metropolitan area in July after relieving the more stringent measures. The latter could also be associated with a police intervention. The comparison of WBE with (web) survey data, which do not provide information at a local level, points towards contradictory conclusions for some of the substances, thereby highlighting the need for stable WBE networks capable of near real-time monitoring drug use.

Target and suspect screening of 4777 per- and polyfluoroalkyl substances (PFAS) in river water, wastewater, groundwater and biota samples in the Danube River Basin

Per- and polyfluoroalkyl substances (PFAS) are under regulatory scrutiny since some of them are persistent, bioaccumulative, and toxic. The occurrence of 4777 PFAS was investigated in the Danube River Basin (DRB; 11 countries) using target and suspect screening. Target screening involved investigation of PFAS with 56 commercially available reference standards. Suspect screening covered 4777 PFAS retrieved from the NORMAN Substance Database, including all individual PFAS lists submitted to the NORMAN Suspect List Exchange Database. Mass spectrometry fragmentation patterns and retention time index predictions of the studied PFAS were established for their screening by liquid chromatography - high resolution mass spectrometry using NORMAN Digital Sample Freezing Platform (DSFP). In total, 82 PFAS were detected in the studied 95 samples of river water, wastewater, groundwater, biota and sediments. Suspect screening detected 72 PFAS that were missed by target screening. Predicted no effect concentrations (PNECs) were derived for each PFAS via a quantitative structure-toxicity relationship (QSTR)-based approach and used for assessment of their environmental risk. Risk characterization revealed 18 PFAS of environmental concern in at least one matrix. The presence of PFAS in all studied environmental compartments across the DRB indicates a potentially large-scale migration of PFAS in Europe, which might require their further systematic regulatory monitoring.

Molecular mechanism of antibiotic resistance induced by mono- and twin-chained quaternary ammonium compounds

The usage of quaternary ammonium compounds (QACs) as disinfectants has increased dramatically since the outbreak of COVID-19 pandemic, leading to potentially accelerated emergence of antibiotic resistance. Long-term exposure to subinhibitory level QACs can lead to multidrug resistance, but the contribution of mutagenesis to resistance evolution is obscure. In this study, we subcultured E. coli K-12 under subinhibitory (0.25 × and 0.5 × Minimum Inhibitory Concentration, MIC) or inhibitory (1 × and 2 × MIC) concentrations of benzalkonium chloride (BAC, mono-chained) or didecyldimethylammonium chloride (DDAC, twin-chained) for 60 days. The sensitivity of QAC-adapted cells to five typical antibiotics decreased significantly, and in particular, the MIC of rifampicin increased by 85 times. E. coli adapted faster to BAC but developed 20-167% higher antibiotic resistance with 56% more mutations under DDAC exposure. The broader mutations induced by QACs, including negative regulators (acrR, marR, soxR, and crp), outer membrane proteins and transporters (mipA and sbmA), and RNA polymerase (rpoB and rpoC), potentially contributed to the high multi-drug resistance. After QACs stresses were removed, the phenotypic resistance induced by subinhibitory concentrations of QACs was reversible, whereas that induced by inhibitory concentrations of QACs was irreversible. The different patterns and molecular mechanism of antibiotic resistance induced by BAC and DDAC is informative to estimating the risks of broader QACs present at varied concentrations in the environment.

Qualitative fingerprinting of psychoactive pharmaceuticals, illicit drugs, and related human metabolites in wastewater: A year-long study from Riga, Latvia

The COVID-19 pandemic has become an unprecedented public health emergency causing immense societal and socio-economic consequences. Multiple studies have outlined that interventions to curb the spread of the virus are likely to have an effect on substance use patterns. In this study, we explored the presence of psychoactive pharmaceuticals, illicit drugs and related human metabolites in 24-h composite wastewater samples that were collected weekly in 2021 from the central WWTP of Riga, Latvia. The analysis was performed via suspect screening approach using three separate high-resolution mass spectrometry (HRMS) workflows, which relied on reversed-phase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC) and direct infusion HRMS. In total, 39 out of 149 substances were detected throughout the sampling period. These include pharmaceuticals (mainly antiepileptics, antidepressants and antipsychotics), illicit drugs (e.g., MDMA, MDEA, cocaine, etc.) and new psychoactive substances (alpha-PVP). The results were evaluated in relation to COVID-19 incidence rate and the severity of containment and closure policies. For some compounds we observed temporal changes that may be potentially linked to the state of the pandemic. For instance, higher detection rates were observed for several illicit drugs during periods, when restrictions on public events were relaxed. Meanwhile, some psychoactive pharmaceuticals and drugs used to treat upper respiratory tract infections displayed increased prevalence in weeks when the national COVID-19 incidence rates were higher. However, without baseline reference data from previous years, it is difficult to discern how much of the relationships seen are linked to pandemic progression and seasonal variability.