Degradability of creatinine under sewer conditions affects its potential to be used as biomarker in sewage epidemiology

Identification of protein biomarkers in wastewater linked to the incidence of COVID-19

Wastewater-based epidemiological (WBE) surveillance is a viable disease surveillance technique capable of monitoring the spread of infectious disease agents in sewershed communities. In addition to detecting viral genomes in wastewater, WBE surveillance can identify other endogenous biomarkers that are significantly elevated and excreted in the saliva, urine, and/or stool of infected individuals. Human protein biomarkers allow the realization of real-time WBE surveillance using highly sensitive biosensors. In this study, we analyzed endogenous protein biomarkers present in wastewater influent through liquid chromatography-tandem mass spectrophotometry and scaffold data-independent acquisition to identify candidate target protein biomarkers for WBE surveillance of SARS-CoV-2. We found that out of the 1382 proteins observed in the wastewater samples, 44 were human proteins associated with infectious diseases. These included immune response substances such as immunoglobulins, cytokine-chemokines, and complements, as well as proteins belonging to antimicrobial and antiviral groups. A significant correlation was observed between the intensity of human infectious disease-related protein biomarkers in wastewater and COVID-19 case numbers. Real-time WBE surveillance using biosensors targeting immune response proteins, such as antibodies or immunoglobulins, in wastewater holds promise for expediting the implementation of relevant policies for the effective prevention of infectious diseases in the near future.

Current state and future perspectives on de facto population markers for normalization in wastewater-based epidemiology: A systematic literature review

Wastewater-based epidemiology (WBE) and wastewater surveillance have become a valuable complementary data source to collect information on community-wide exposure through the measurement of human biomarkers in influent wastewater (IWW). In WBE, normalization of data with the de facto population that corresponds to a wastewater sample is crucial for a correct interpretation of spatio-temporal trends in exposure and consumption patterns. However, knowledge gaps remain in identifying and validating suitable de facto population biomarkers (PBs) for refinement of WBE back-estimations. WBE studies that apply de facto PBs (including hydrochemical parameters, utility consumption data sources, endo- and exogenous chemicals, biological biomarkers and signalling records) for relative trend analysis and absolute population size estimation were systematically reviewed from three databases (PubMed, Web of Science, SCOPUS) according to the PRISMA guidelines. We included in this review 81 publications that accounted for daily variations in population sizes by applying de facto population normalization. To date, a wide range of PBs have been proposed for de facto population normalization, complicating the comparability of normalized measurements across WBE studies. Additionally, the validation of potential PBs is complicated by the absence of an ideal external validator, magnifying the overall uncertainty for population normalization in WBE. Therefore, this review proposes a conceptual tier-based cross-validation approach for identifying and validating de facto PBs to guide their integration for i) relative trend analysis, and ii) absolute population size estimation. Furthermore, this review also provides a detailed evaluation of the uncertainty observed when comparing different de jure and de facto population estimation approaches. This study shows that their percentual differences can range up to ±200 %, with some exceptions showing even larger variations. This review underscores the need for collaboration among WBE researchers to further streamline the application of de facto population normalization and to evaluate the robustness of different PBs in different socio-demographic communities.

Wastewater-based surveillance as a tool for public health action: SARS-CoV-2 and beyond

Wastewater-based surveillance (WBS) has undergone dramatic advancement in the context of the coronavirus disease 2019 (COVID-19) pandemic. The power and potential of this platform technology were rapidly realized when it became evident that not only did WBS-measured SARS-CoV-2 RNA correlate strongly with COVID-19 clinical disease within monitored populations but also, in fact, it functioned as a leading indicator. Teams from across the globe rapidly innovated novel approaches by which wastewater could be collected from diverse sewersheds ranging from wastewater treatment plants (enabling community-level surveillance) to more granular locations including individual neighborhoods and high-risk buildings such as long-term care facilities (LTCF). Efficient processes enabled SARS-CoV-2 RNA extraction and concentration from the highly dilute wastewater matrix. Molecular and genomic tools to identify, quantify, and characterize SARS-CoV-2 and its various variants were adapted from clinical programs and applied to these mixed environmental systems. Novel data-sharing tools allowed this information to be mobilized and made immediately available to public health and government decision-makers and even the public, enabling evidence-informed decision-making based on local disease dynamics. WBS has since been recognized as a tool of transformative potential, providing near-real-time cost-effective, objective, comprehensive, and inclusive data on the changing prevalence of measured analytes across space and time in populations. However, as a consequence of rapid innovation from hundreds of teams simultaneously, tremendous heterogeneity currently exists in the SARS-CoV-2 WBS literature. This manuscript provides a state-of-the-art review of WBS as established with SARS-CoV-2 and details the current work underway expanding its scope to other infectious disease targets.

Understanding common population markers for SARS-CoV-2 RNA normalization in wastewater - A review

Wastewater monitoring and epidemiology have seen renewed interest during the recent COVID-19 pandemic. As a result, there is an increasing need to normalize wastewater-derived viral loads in local populations. Chemical tracers, both exogenous and endogenous compounds, have proven to be more stable and reliable for normalization than biological indicators. However, differing instrumentation and extraction methods can make it difficult to compare results. This review examines current extraction and quantification methods for ten common population indicators: creatinine, coprostanol, nicotine, cotinine, sucralose, acesulfame, androstenedione 5-hydroindoleacetic acid (5-HIAA), caffeine, and 1,7-dimethyluric acid. Some wastewater parameters such as ammonia, total nitrogen, total phosphorus, and daily flowrate were also evaluated. The analytical methods included direct injection, dilute and shoot, liquid/liquid, and solid phase extraction (SPE). Creatine, acesulfame, nicotine, 5-HIAA and androstenedione have been analysed by direct injection into LC-MS; however, most authors prefer to include SPE steps to avoid matrix effects. Both LC-MS and GC-MS have been successfully used to quantify coprostanol in wastewater, and the other selected indicators have been quantified successfully with LC-MS. Acidification to stabilize the sample before freezing to maintain the integrity of samples has been reported to be beneficial. However, there are arguments both for and against working at acidic pHs. Wastewater parameters mentioned earlier are quick and easy to quantify, but the data does not always represent the human population effectively. A preference for population indicators originating solely from humans is apparent. This review summarises methods employed for chemical indicators in wastewater, provides a basis for choosing an appropriate extraction and analysis method, and highlights the utility of accurate chemical tracer data for wastewater-based epidemiology.

Surveillance of SARS-CoV-2 in nine neighborhood sewersheds in Detroit Tri-County area, United States: Assessing per capita SARS-CoV-2 estimations and COVID-19 incidence

Wastewater-based epidemiology (WBE) has been suggested as a useful tool to predict the emergence and investigate the extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, we screened appropriate population biomarkers for wastewater SARS-CoV-2 normalization and compared the normalized SARS-CoV-2 values across locations with different demographic characteristics in southeastern Michigan. Wastewater samples were collected between December 2020 and October 2021 from nine neighborhood sewersheds in the Detroit Tri-County area. Using reverse transcriptase droplet digital polymerase chain reaction (RT-ddPCR), concentrations of N1 and N2 genes in the studied sites were quantified, with N1 values ranging from 1.92 × 10² genomic copies/L to 6.87 × 10³ gc/L and N2 values ranging from 1.91 × 10² gc/L to 6.45 × 10³ gc/L. The strongest correlations were observed with between cumulative COVID-19 cases per capita (referred as COVID-19 incidences thereafter), and SARS-CoV-2 concentrations normalized by total Kjeldahl nitrogen (TKN), creatinine, 5-hydroxyindoleacetic acid (5-HIAA) and xanthine when correlating the per capita SARS-CoV-2 and COVID-19 incidences. When SARS-CoV-2 concentrations in wastewater were normalized and compared with COVID-19 incidences, the differences between neighborhoods of varying demographics were reduced as compared to differences observed when comparing non-normalized SARS-CoV-2 with COVID-19 cases. This indicates when studying the disease burden in communities of different demographics, accurate per capita estimation is of great importance. The study suggests that monitoring selected water quality parameters or biomarkers, along with RNA concentrations in wastewater, will allow adequate data normalization for spatial comparisons, especially in areas where detailed sanitary sewage flows and contributing populations in the catchment areas are not available. This opens the possibility of using WBE to assess community infections in rural areas or the developing world where the contributing population of a sample could be unknown.

Biomarkers selection for population normalization in SARS-CoV-2 wastewater-based epidemiology

Wastewater-based epidemiology (WBE) has been one of the most cost-effective approaches to track the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) levels in the communities since the coronavirus disease 2019 (COVID-19) outbreak in 2020. Normalizing SARS-CoV-2 concentrations by the population biomarkers in wastewater is critical for interpreting the viral loads, comparing the epidemiological trends among the sewersheds, and identifying the vulnerable communities. In this study, five population biomarkers, pepper mild mottle virus (PMMoV), creatinine (CRE), 5-hydroxyindoleacetic acid (5-HIAA), caffeine (CAF) and its metabolite paraxanthine (PARA) were investigated and validated for their utility in normalizing the SARS-CoV-2 loads through two normalizing approaches using the data from 64 wastewater treatment plants (WWTPs) in Missouri. Their utility in assessing the real-time population contributing to the wastewater was also evaluated. The best performing candidate was further tested for its capacity for improving correlation between normalized SARS-CoV-2 loads and the clinical cases reported in the City of Columbia, Missouri, a university town with a constantly fluctuating population. Our results showed that, except CRE, the direct and indirect normalization approaches using biomarkers allow accounting for the changes in wastewater dilution and differences in relative human waste input over time regardless flow volume and population of the given WWTP. Among selected biomarkers, PARA is the most reliable population biomarker in determining the SARS-CoV-2 load per capita due to its high accuracy, low variability, and high temporal consistency to reflect the change in population dynamics and dilution in wastewater. It also demonstrated its excellent utility for real-time assessment of the population contributing to the wastewater. In addition, the viral loads normalized by the PARA-estimated population significantly improved the correlation (rho=0.5878, p < 0.05) between SARS-CoV-2 load per capita and case numbers per capita. This chemical biomarker complements the current normalization scheme recommended by CDC and helps us understand the size, distribution, and dynamics of local populations for forecasting the prevalence of SARS-CoV2 within each sewershed.

Pesticide exposure in New Zealand school-aged children: Urinary concentrations of biomarkers and assessment of determinants

This study aimed to assess pesticide exposure and its determinants in children aged 5-14 years. Urine samples (n = 953) were collected from 501 participating children living in urban areas (participant n = 300), rural areas but not on a farm (n = 76), and living on a farm (n = 125). The majority provided two samples, one in the high and one in the low spraying season. Information on diet, lifestyle, and demographic factors was collected by questionnaire. Urine was analysed for 20 pesticide biomarkers by GC-MS/MS and LC-MS/MS. Nine analytes were detected in > 80% of samples, including six organophosphate insecticide metabolites (DMP, DMTP, DEP, DETP, TCPy, PNP), two pyrethroid insecticide metabolites (3-PBA, trans-DCCA), and one herbicide (2,4-D). The highest concentration was measured for TCPy (median 13 μg/g creatinine), a metabolite of chlorpyrifos and triclopyr, followed by DMP (11 μg/g) and DMTP (3.7 μg/g). Urine metabolite levels were generally similar or low compared to those reported for other countries, while relatively high for TCPy and pyrethroid metabolites. Living on a farm was associated with higher TCPy levels during the high spray season. Living in rural areas, dog ownership and in-home pest control were associated with higher levels of pyrethroid metabolites. Urinary concentrations of several pesticide metabolites were higher during the low spraying season, possibly due to consumption of imported fruits and vegetables. Organic fruit consumption was not associated with lower urine concentrations, but consumption of organic food other than fruit or vegetables was associated with lower concentrations of TCPy in the high spray season. In conclusion, compared to other countries such as the U.S., New Zealand children had relatively high exposures to chlorpyrifos/triclopyr and pyrethroids. Factors associated with exposure included age, season, area of residence, diet, in-home pest control, and pets.

Enhanced decay of coronaviruses in sewers with domestic wastewater

Recent outbreaks caused by coronaviruses and their supposed potential fecal-oral transmission highlight the need for understanding the survival of infectious coronavirus in domestic sewers. To date, the survivability and decay of coronaviruses were predominately studied using small volumes of wastewater (normally 5-30 mL) in vials (in-vial tests). However, real sewers are more complicated than bulk wastewater (wastewater matrix only), in particular the presence of sewer biofilms and different operational conditions. This study investigated the decay of infectious human coronavirus 229E (HCoV-229E) and feline infectious peritonitis virus (FIPV), two typical surrogate coronaviruses, in laboratory-scale reactors mimicking the gravity (GS, gravity-driven sewers) and rising main sewers (RM, pressurized sewers) with and without sewer biofilms. The in-sewer decay of both coronaviruses was greatly enhanced in comparison to those reported in bulk wastewater through in-vial tests. 99% of HCoV-229E and FIPV decayed within 2 h under either GS or RM conditions with biofilms, in contrast to 6-10 h without biofilms. There is limited difference in the decay of HCoV and FIPV in reactors operated as RM or GS, with the T₉₀ and T₉₉ difference of 7-10 min and 14-20 min, respectively. The decay of both coronaviruses in sewer biofilm reactors can be simulated by biphasic first-order kinetic models, with the first-order rate constant 2-4 times higher during the first phase than the second phase. The decay of infectious HCoV and FIPV was significantly faster in the reactors with sewer biofilms than in the reactors without biofilms, suggesting an enhanced decay of these surrogate viruses due to the presence of biofilms and related processes. The mechanism of biofilms in virus adsorption and potential inactivation remains unclear and requires future investigations. The results indicate that the survivability of infectious coronaviruses detected using bulk wastewater overestimated the infectivity risk of coronavirus during wastewater transportations in sewers or the downstream treatment.

Biomarkers Selection for Population Normalization in SARS-CoV-2 Wastewater-based Epidemiology

Wastewater-based epidemiology (WBE) has been one of the most cost-effective approaches to track the SARS-CoV-2 levels in the communities since the COVID-19 outbreak in 2020. Normalizing SARS-CoV-2 concentrations by the population biomarkers in wastewater can be critical for interpreting the viral loads, comparing the epidemiological trends among the sewersheds, and identifying the vulnerable communities. In this study, five population biomarkers, pepper mild mottle virus (pMMoV), creatinine (CRE), 5-hydroxyindoleacetic acid (5-HIAA), caffeine (CAF) and its metabolite paraxanthine (PARA) were investigated for their utility in normalizing the SARS-CoV-2 loads through developed direct and indirect approaches. Their utility in assessing the real-time population contributing to the wastewater was also evaluated. The best performed candidate was further tested for its capacity for improving correlation between normalized SARS-CoV-2 loads and the clinical cases reported in the City of Columbia, Missouri, a university town with a constantly fluctuated population. Our results showed that, except CRE, the direct and indirect normalization approaches using biomarkers allow accounting for the changes in wastewater dilution and differences in relative human waste input over time regardless flow volume and population at any given WWTP. Among selected biomarkers, PARA is the most reliable population biomarker in determining the SARS-CoV-2 load per capita due to its high accuracy, low variability, and high temporal consistency to reflect the change in population dynamics and dilution in wastewater. It also demonstrated its excellent utility for real-time assessment of the population contributing to the wastewater. In addition, the viral loads normalized by the PARA-estimated population significantly improved the correlation ( rho =0.5878, p <0.05) between SARS-CoV-2 load per capita and case numbers per capita. This chemical biomarker offers an excellent alternative to the currently CDC-recommended pMMoV genetic biomarker to help us understand the size, distribution, and dynamics of local populations for forecasting the prevalence of SARS-CoV2 within each sewershed.

HIGHLIGHT bullet points

The paraxanthine (PARA), the metabolite of the caffeine, is a more reliable population biomarker in SARS-CoV-2 wastewater-based epidemiology studies than the currently recommended pMMoV genetic marker.SARS-CoV-2 load per capita could be directly normalized using the regression functions derived from correlation between paraxanthine and population without flowrate and population data.Normalizing SARS-CoV-2 levels with the chemical marker PARA significantly improved the correlation between viral loads per capita and case numbers per capita.The chemical marker PARA demonstrated its excellent utility for real-time assessment of the population contributing to the wastewater.

Preparing for COVID-2x: Urban Planning Needs to Regard Urological Wastewater as an Invaluable Communal Public Health Asset and Not as a Burden

Prior to the COVID-19 pandemic, the analysis of urological wastewater had been a matter of academic curiosity and community-wide big-picture studies looking at drug use or the presence of select viruses such as Hepatitis. The COVID-19 pandemic saw systematic testing of urological wastewater emerge as a significant early detection tool for the presence of SARS-CoV-2 in a community. Even though the pandemic still rages in all continents, it is time to consider the post-pandemic world. This paper posits that urban planners should treat urological wastewater as a communal public health asset and that future sewer design should allow for stratified multi-order sampling.

In-sewer stability of selected analgesics and their metabolites

Understanding the in-sewer stability of analgesic biomarkers is important for interpreting wastewater-based epidemiology (WBE) data to estimate community-wide analgesic drugs consumption. The in-sewer stability of a suite of 19 analgesics and their metabolites was assessed using lab-scale sewer reactors. Target biomarkers were spiked into wastewater circulating in simulated gravity, rising main and control (no biofilm) sewer reactors. In-sewer transformation was observed over a hydraulic retention time of 12 h. All investigated biomarkers were stable under control reactor conditions. In gravity sewer conditions, diclofenac, desmetramadol, ibuprofen carboxylic acid, ketoprofen, lidocaine and tapentadol were highly stable (0-20% transformation in 12 h). Valdecoxib, parecoxib, etoricoxib, indomethacin, naltrexone, naloxone, piroxicam, ketoprofen, lidocaine, tapentadol, oxymorphone, hydrocodone, meperidine, hydromorphone were considered as moderately stable biomarkers (20-50% transformation in 12 h). Celecoxib and sulindac were considered unstable biomarkers (>50% transformation in 12 h). Ketoprofen, lidocaine, tapentadol, meperidine, hydromorphone were transformed to 0-20% whereas diclofenac, desmetramadol, ibuprofen carboxylic acid, valdecoxib, parecoxib, etoricoxib, indomethacin, naltrexone, piroxicam were transformed up to 20-50% in 12 h in rising main reactor (RMR). These biomarkers were considered as highly stable and stable biomarkers in RMR, respectively. Sulindac, celecoxib, naloxone, oxymorphone and hydrocodone were transformed more than 50% in 12 h and considered as unstable biomarkers in RMR. This study provides the information for a better understanding of the in-sewer loss of the analgesics before using them in WBE biomarkers for estimating drug loads at the population level.

Biosensors for wastewater-based epidemiology for monitoring public health

Public health is attracting increasing attention due to the current global pandemic, and wastewater-based epidemiology (WBE) has emerged as a powerful tool for monitoring of public health by analysis of a variety of biomarkers (e.g., chemicals and pathogens) in wastewater. Rapid development of WBE requires rapid and on-site analytical tools for monitoring of sewage biomarkers to provide immediate decision and intervention. Biosensors have been demonstrated to be highly sensitive and selective tools for the analysis of sewage biomarkers due to their fast response, ease-to-use, low cost and the potential for field-testing. This paper presents biosensors as effective tools for wastewater analysis of potential biomarkers and monitoring of public health via WBE. In particular, we discuss the use of sewage sensors for rapid detection of a range of targets, including rapid monitoring of community-wide illicit drug consumption and pathogens for early warning of infectious diseases outbreaks. Finally, we provide a perspective on the future use of the biosensor technology for WBE to enable rapid on-site monitoring of sewage, which will provide nearly real-time data for public health assessment and effective intervention.

Transformation of phthalates and their metabolites in wastewater under different sewer conditions

There is an increasing demand to monitor the human exposure to phthalates, and a few studies have used phthalate metabolites in wastewater to estimate exposure to these chemicals in the population. However, it is suspected that the stability of phthalates and phthalate metabolites during sewer transport can influence the final estimates. In this study, we used laboratory sewer reactors to evaluate the in-sewer transformation of phthalates and their metabolites, and deconjugation of phthalate metabolites. We found concentrations of parent phthalates decreased quickly over time while the concentrations of phthalate metabolites increased significantly for most compounds, indicating that parent phthalate compounds are partly transformed into their metabolites in the sewer. Our assessment of the deconjugation of glucuronide-conjugated phthalate metabolites found that this process did not significantly affect the concentrations of phthalate metabolites in the wastewater, with the relative difference ranging from -16% to 7% between enzymatically treated samples and control group. Additionally, our results showed that phthalate metabolites could be subject to rapid degradation during the incubation process. Our findings suggested that the level of phthalate metabolites in sewage could be strongly influenced by the in-sewer transformation of the parent phthalates and of themselves, and could not be assumed as uniquely the results of urinary excretion after human exposure to parent phthalates.

Evaluating the stability of prescription drugs in municipal wastewater and sewers based on wastewater-based epidemiology

Wastewater-based epidemiology (WBE) is considered as an effective tool for monitoring drug consumption, which is often obtained by back-calculation using the influent concentration and other parameters of wastewater treatment plants. Lack of information on the transformation of drugs in municipal wastewater and sewers may lead to inaccurate consumption estimation. Fourteen prescription drugs in four major categories of diseases (cardiovascular, diabetes, depression, and asthma) were selected to study their adsorption and biodegradation in wastewater and biofilm sewers under different temperatures, pH and biofilms conditions. The result demonstrated that the decay percentage of drugs in wastewater is increased with temperature. Within 72 h, eleven of these 14 drugs, such as metformin, metoprolol, bezafibrate, etc., have decay percentages below 20% in wastewater, which are considered as stable drugs; and the decay percentages of the other three, monluster, paroxetine, and sertraline, are greater than 20%, which are the most unstable drugs. In lab-scale aerobic and anaerobic sewers, the decay percentages of metformin, glipizide, metoprolol, gemfibrozil, and atorvastatin are less than 20% within 24 h. The decay percentages of venlafaxine, citalopram, fluoxetine, salmeterol, and salbutamol within 24 h are 20%-60% and paroxetine and sertraline are close to or even exceed 80% within 6 h. Biodegradation of drugs in sewers with aerobic or anaerobic biofilms is higher than that in wastewater systems without biofilms. The results showed that when the per capita consumption of drugs is estimated by using the WBE method, the stability of drugs in wastewater and different types of sewers will significantly affect their residual concentrations.

Wastewater-based estimation of the prevalence of gout in Australia

Allopurinol, a first-line gout treatment drug in Australia, was assessed as a wastewater-based epidemiology biomarker of gout via quantification of the urinary metabolite, oxypurinol in wastewater. The in-sewer stability of oxypurinol was examined using laboratory-scale sewer reactors. Wastewater from 75 wastewater treatment plants across Australia, covering approximately 52% (12.2 million) of the country's population, was collected on the 2016 census day. Oxypurinol was quantified in the wastewater samples and population-weighted mass loads calculated. Pearson and Spearman rank-order correlations were applied to investigate any link between allopurinol, other selected wastewater biomarkers, and socio-economic indicators. Oxypurinol was shown to be stable in sewer conditions and suitable as a WBE biomarker. Oxypurinol was detected in all wastewater samples. The estimated consumption of allopurinol ranged from 1.9 to 32 g/day/1000 people equating to 4.8 to 80 DDD/day/1000 people. The prevalence of gout across all tested sewer catchments was between 0.5% to 8%, with a median of 2.9% nationally. No significant positive correlation was observed between allopurinol consumption and alcohol consumption, mean age of catchment population, remoteness or higher socioeconomic status. There was a significant positive correlation with selective analgesic drug use. Wastewater analysis can be used to study gout prevalence and can provide additional insights on population level risk factors when triangulated with other biomarkers.

Considerations for assessing stability of wastewater-based epidemiology biomarkers using biofilm-free and sewer reactor tests

Wastewater-based epidemiology is an increasingly popular method for analysing drugs or metabolites excreted by populations. The in-sewer transformation of biomarkers is important but often receives little consideration in published studies. Many studies publish stability under biofilm-free conditions only, which do not represent actual sewer conditions. This study aims to fill a gap in the field by comparing the wastewater stability of 33 licit drug and pharmaceutical biomarkers in biofilm-free (BFF) conditions to stability in sewer biofilm reactors. All but one biomarker was stable under BFF conditions, whereas most transformed in sewer biofilm reactors. Sewer reactor results tended to overestimate the degradation in pilot and actual sewers, whereas BFF stability had no clear relationship to stability in pilot and actual sewers. Our results provide additional basis for more informed interpretation of biofilm-free and sewer reactor stability results for past and future WBE studies.

Evaluating the stability of three oxidative stress biomarkers under sewer conditions and potential impact for use in wastewater-based epidemiology

Wastewater contains a wealth of information about the population who contribute to it including biological and chemical markers of human activity and exposures. F₂-isoprostanes have been proposed as oxidative stress biomarkers that can be measured in wastewater to provide a measure of oxidative stress at the population level. While an association between tobacco use and their level in wastewater has been demonstrated, an in-sewer stability assessment has not been conducted to support their use as oxidative stress biomarkers for wastewater-based epidemiology studies. In this study we investigated the stability of 8-iso-prostaglandin F_2α (PGF_2α), its metabolite dinor-11β-Prostaglandin F_2α (dnPGF_2α) and Prostaglandin E₂ (PGE₂) (representative of other classes of prostaglandins) in laboratory-scale sewer reactors simulating real sewers. PGF_2α, dnPGF_2α and PGE₂ were all found to be sufficiently stable under typical sewer conditions therefore satisfying the stability requirement of wastewater-based epidemiology population health biomarkers.

Evaluating the in-sewer stability of three potential population biomarkers for application in wastewater-based epidemiology

Endogenous chemicals specific to human metabolism have been suggested to be good candidates for markers of population size in wastewater-based epidemiology (WBE). So far, creatinine is the only endogenous chemical to be assessed against the criteria of in-sewer stability. This study thus aimed to evaluate the fate of three other endogenous compounds, 5-hydroxy indole acetic acid (5-HIAA), cortisol and androstenedione, under different sewer conditions using laboratory-scale sewer reactors. The results showed that while all compounds were stable in wastewater only (i.e. without biofilm), cortisol and androstenedione degraded quickly in sewers with the presence of sewer biofilms. The degradation followed first-order kinetics similar to that of creatinine. In contrast, 5-HIAA was relatively stable in sewer reactors. This study also recognised the impact of wastewater pH on the detectability of 5-HIAA using a LC-MS/MS direct injection method. In samples acidified to pH 2, the method did not allow routine detection/quantification of 5-HIAA whereas in non-acidified samples the method was sufficiently sensitive for routine quantification of 5-HIAA. The stability of 5-HIAA in sewers and the possibility to measure it using a simple and rapid analytical method corroborate that 5-HIAA may be a suitable biomarker for estimation of population size in WBE.

Removal of Pharmaceuticals and Illicit Drugs from Wastewater Due to Ferric Dosing in Sewers

Ferric (Fe³⁺) salt dosing is an efficient sulfide control strategy in the sewer network, with potential for multiple benefits including phosphorus removal in the biological reactors and sulfide emission control in the anaerobic digesters of wastewater treatment plant (WWTP). This paper extends the knowledge on the benefit of iron dosing by exploring its impact on the fate of organic micropollutants (MPs) in the wastewater using sewer reactors simulating a rising main sewer pipe. The sulfide produced by the sewer biofilms reacted with Fe³⁺ forming black colored iron sulfide (FeS). Among the selected MPs, morphine, methadone, and atenolol had >90% initial rapid removal within 5 min of ferric dosing in the sewer reactor. The ultimate removal after 6 h of retention time in the reactor reached 93-97%. Other compounds, ketamine, codeine, carbamazepine, and acesulfame had 30-70% concentration decrease. The ultimate removal varied between 35 and 70% depending on the biodegradability of those MPs. In contrast, paracetamol had no initial removal. The rapid removal of MPs was likely due to adsorption to the FeS surface, which is further confirmed by batch tests with different FeS concentrations. The results showed a direct relationship between the removal of MPs and FeS concentration. The transformation kinetics of these compounds in the reactor without Fe³⁺ dosing is in good agreement with biodegradation associated with the sewer biofilms in the reactor. This study revealed a significant additional benefit of dosing ferric salts in sewers, that is, the removal of MPs before the sewage enters the WWTP.

Wastewater analysis for nicotine, cocaine, amphetamines, opioids and cannabis in New York City

According to current surveys and overdoses data, there is a drug crisis in the USA. Wastewater-based epidemiology (WBE) is an evolving discipline that analyses wastewater samples to detect drugs and metabolites to estimate drug consumption in a certain community. This study demonstrates how drug relative presence could be tracked by testing wastewater, providing real-time results, in different boroughs in New York City throughout 1 year. We developed and fully validated two analytical methods, one for 21 drugs and metabolites, including nicotine, cocaine, amphetamines, opioids and cannabis markers; and another for the normalization factor creatinine. Both methods were performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using positive electrospray ionization, achieving a limit of quantification of 5–10 ng/L for drugs and metabolites, and 0.01 mg/L for creatinine. These methods were applied to 48 one-time grab wastewater samples collected from six wastewater treatment plants in New York City (Manhattan, The Bronx, Queens and Brooklyn), eight different times throughout 2016, before and after major holidays, including Memorial Day, 4th of July, Labour Day and New Year’s. In this study, the drug group normalized concentrations present in the wastewater samples, in decreasing order, were cocaine, nicotine, opioids, cannabis and amphetamines. When looking at individual compounds, the one with the highest normalized concentration was benzoylecgonine (BE), followed by cotinine, morphine and 11-nor-9-carboxy-tetrahydrocannabinol (THCCOOH). To estimate community use, these concentrations were multiplied by the corresponding correction factor, and the most present were THCCOOH, followed by BE, cotinine and morphine. When comparing the treatment plants by drug group (nicotine, cocaine, amphetamines, opioids and cannabis), samples collected from The Bronx had the highest normalized concentrations for nicotine, cocaine and opioids; The Bronx and Manhattan for cannabis; and Manhattan and Queens for amphetamines. In most of the cases, no effect due to holiday was observed. This study provides the first snapshot of drug use in New York City and how that changes between key calendar dates employing wastewater analysis.

Can water quality indicators and biomarkers be used to estimate real-time population?

The precise population estimation, short-term or real-time, is crucial to social and civil management, such as public resource distribution, education budgets, health care, and public safety. In this paper, we reviewed the methods for estimation of real-time population. For real-time population estimation, especially for a certain wastewater treatment plant catchment, many water quality indicators and biomarkers were selected as potential markers and their stability, consumption coefficient, and uncertainty were assessed. The conventional water quality indicators, such as wastewater discharge volume, chemical oxygen demand, biochemical oxygen demand, ammonia nitrogen, and total phosphorus, were used to calculate the serving population within a WWTP catchment. These parameters are all affected by the behavior, living habits and health conditions of people in different regions. Among them, wastewater discharge volume and ammonia might be more suitable for population estimation than the other parameters which may be influenced by additional industrial discharge. Moreover, acesulfame could be used to estimate the general population, while caffeine, tobacco, and carbamazepine could be applied as biomarkers for a specific population. Furthermore, the per capita loading differ should be considered and measured independently. To reduce the uncertainty of population, comprehensive model with multi-parameters should be developed and applicability should be checked.

Population histamine burden assessed using wastewater-based epidemiology: The association of 1,4‑methylimidazole acetic acid and fexofenadine

Systematic sampling and analysis of wastewater has become an important tool for monitoring consumption of drugs and other substances, and has been proposed as a method to evaluate aspects of population health using endogenous biomarkers. 1,4‑methylimidazoleacetic acid (MIAA) is an endogenous biomarker and metabolite of histamine turnover. Its urinary excretion is elevated in conditions such as mastocytosis, hay fever, hives, food allergies and anaphylaxis. The aim of this study was to develop and apply methods for MIAA in wastewater and compare its occurrence with antihistamine use in wastewater. Consecutive daily samples were collected from seven catchments serving populations from 3000 to 2 million and covering rural and urban communities during the 2016 Census in Australia. MIAA and the antihistamines (ranitidine, fexofenadine, cetirizine) were quantified consistently. Per capita excretion of MIAA (mg/d/capita) estimated from the WW concentrations were consistent with findings from previous clinical studies. We found significant positive correlations between loads of MIAA and fexofenadine (R² = 0.68, p < 0.0001) and cetirizine (R² = 0.25, p = 0.03) across the various catchments. Sewer reactor experiments on the degradation of MIAA and the antihistamines found that fexofenadine is stable for at least 24 h while MIAA, ranitidine and cetirizine are subject to degradation, and this should be considered in interpretations. To the best of our knowledge, this study is the first wastewater study to introduce and monitor an endogenous metabolite of histamine, and the first study to monitor and relate proxies of disease and treatment of disease.

Concentrations of organophosphate flame retardants and plasticizers in urine from young children in Queensland, Australia and associations with environmental and behavioural factors

In recent years, the production and usage volumes of organophosphate flame retardants (OPFRs) has increased substantially. Certain OPFRs are suspected reproductive toxins, carcinogenic, and neurotoxic. Insufficient information is available on human exposure pathways to these chemicals, particularly in Australia. We aim to assess the association between OPFR concentrations in the urine of children to environmental and behavioural risk factors. Concentrations of eight OPFRs and eleven metabolites were measured in the urine of 51 children, aged 3-29 months, in Southeast Queensland, Australia and compared to their behavioural and environmental risk factor data obtained by an online questionnaire. Of the 11 OPFR metabolites analysed, 55% were frequently detected in the majority (> 80%) of samples. The most frequently detected metabolite was bis(1,3-dichloroisopropyl) phosphate (BDCIPP) (detected in 100% of samples), followed by 1-hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP) (96%), diphenyl phosphate (DPHP) (94%) and bis(1-chloroisopropyl) phosphate (BCIPP) (86%). In multivariable modelling, age was positively associated with concentrations of bis(2-butoxyethyl) phosphate (BBOEP) and negatively associated with concentrations of BCIPP and BCIPHIPP. Other non-age related factors, including vacuuming frequency, hand-washing frequency and presence and number of some electrical appliances in the home were also associated with concentrations of OPFR metabolites.

Monitoring wastewater for assessing community health: Sewage Chemical-Information Mining (SCIM)

Timely assessment of the aggregate health of small-area human populations is essential for guiding the optimal investment of resources needed for preventing, avoiding, controlling, or mitigating human exposure risks, as well as for maintaining or promoting health. Seeking those interventions yielding the greatest benefit with respect to the allocation of resources is critical for making progress toward community sustainability, reducing health disparities, promoting social justice, and maintaining or improving collective health and well-being. More informative, faster, and less-costly approaches are needed for guiding investigation of cause-effect linkages involving communities and stressors originating from both the built and natural environments. One such emerging approach involves the continuous monitoring of sewage for chemicals that serve as indicators of the collective status of human health (or stress/disease) or any other facet relevant to gauging time-trends in community-wide health. This nascent approach can be referred to as Sewage Chemical-Information Mining (SCIM) and involves the monitoring of sewage for the information that resides in the form of natural and anthropogenic chemicals that enter sewers as a result of the everyday actions, activities, and behaviors of humans. Of particular interest is a specific embodiment of SCIM that would entail the targeted monitoring of a broad suite of endogenous biomarkers of key physiologic processes (as opposed to xenobiotics or their metabolites). This application is termed BioSCIM-an approach roughly analogous to a hypothetical community-wide collective clinical urinalysis, or to a hypothetical en masse human biomonitoring program. BioSCIM would be used for gauging the status or time-trends in community-wide health on a continuous basis. This paper presents an update on the progress made with the development of the BioSCIM concept in the period of time since its original publication in 2012, as well as the next steps required for its continued development.

Potential impact of the sewer system on the applicability of alcohol and tobacco biomarkers in wastewater-based epidemiology

Understanding the actual consumption of alcohol and tobacco in the population is important for forming public health policy. For this purpose, wastewater-based epidemiology has been applied as a complementary method to estimate the overall alcohol and tobacco consumption in different communities. However, the stability of their consumption biomarkers - ethyl sulfate, ethyl glucuronide, cotinine, and trans-3'-hydroxycotinine - in the sewer system has not yet been assessed. This study aimed to conduct such assessment using sewer reactors mimicking conditions of rising main, gravity sewer, and wastewater alone, over a 12-hour period. The results show that cotinine and trans-3'-hydroxycotinine are relatively stable under all sewer conditions while ethyl sulfate was only stable in wastewater alone and gradually degraded in rising main and gravity sewer conditions. Ethyl glucuronide quickly degraded in all reactors. These findings suggest that cotinine and trans-3'-hydroxycotinine are good biomarkers to estimate tobacco consumption; ethyl sulfate may be used as a biomarker to estimate alcohol consumption, but its in-sewer loss should be accounted for in the calculation of consumption estimates. Ethyl glucuronide, and probably most of glucuronide compounds, are not suitable biomarkers to be used in wastewater-based epidemiology due to their in-sewer instability.

Evaluation of in-sewer transformation of selected illicit drugs and pharmaceutical biomarkers

Wastewater-based epidemiology (WBE) is considered to be a useful tool for monitoring chemical consumption in the population. However, the lack of information on potential transformation of biomarkers in the sewer system can compromise the accuracy of the consumption estimation. The present study contributes to addressing this issue by investigating the in-sewer stability of biomarkers from a number of commonly used drugs using laboratory sewer reactors that can mimic different sewer conditions. A stable and an unstable chemical (carbamazepine and caffeine) were also used as benchmarking chemicals to reflect the chemical degradation potential in different sewer conditions. The results suggested that ketamine and norketamine were unstable in gravity and rising main sewers, ketamine was unstable in bulk liquid while norketamine was stable under the same condition. Similarly, mephedrone and methylone were unstable in sewer conditions with considerable deviation. Significant loss of buprenorphine, methadone, oxycodone and codeine was observed in the rising main sewer. Morphine and codeine glucuronide were found to be deconjugated from their glucuronides quickly in the presence of biofilms. This study indicates that it is important to evaluate the stability of biomarkers in the sewer system before using them in WBE for estimating consumption/exposure to reduce uncertainties.

Impact of in-Sewer Degradation of Pharmaceutical and Personal Care Products (PPCPs) Population Markers on a Population Model

A key uncertainty of wastewater-based epidemiology is the size of the population which contributed to a given wastewater sample. We previously developed and validated a Bayesian inference model to estimate population size based on 14 population markers which: (1) are easily measured and (2) have mass loads which correlate with population size. However, the potential uncertainty of the model prediction due to in-sewer degradation of these markers was not evaluated. In this study, we addressed this gap by testing their stability under sewer conditions and assessed whether degradation impacts the model estimates. Five markers, which formed the core of our model, were stable in the sewers while the others were not. Our evaluation showed that the presence of unstable population markers in the model did not decrease the precision of the population estimates providing that stable markers such as acesulfame remained in the model. However, to achieve the minimum uncertainty in population estimates, we propose that the core markers to be included in population models for other sites should meet two additional criteria: (3) negligible degradation in wastewater to ensure the stability of chemicals during collection; and (4) < 10% in-sewer degradation could occur during the mean residence time of the sewer network.

Estimating population size in wastewater-based epidemiology. Valencia metropolitan area as a case study

Wastewater can provide a wealth of epidemiologic data on common drugs consumed and on health and nutritional problems based on the biomarkers excreted into community sewage systems. One of the biggest uncertainties of these studies is the estimation of the number of inhabitants served by the treatment plants. Twelve human urine biomarkers -5-hydroxyindoleacetic acid (5-HIAA), acesulfame, atenolol, caffeine, carbamazepine, codeine, cotinine, creatinine, hydrochlorothiazide (HCTZ), naproxen, salicylic acid (SA) and hydroxycotinine (OHCOT)- were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to estimate population size. The results reveal that populations calculated from cotinine, 5-HIAA and caffeine are commonly in agreement with those calculated by the hydrochemical parameters. Creatinine is too unstable to be applicable. HCTZ, naproxen, codeine, OHCOT and carbamazepine, under or overestimate the population compared to the hydrochemical population estimates but showed constant results through the weekdays. The consumption of cannabis, cocaine, heroin and bufotenine in Valencia was estimated for a week using different population calculations.

Emerging contaminants (pharmaceuticals, personal care products, a food additive and pesticides) in waters of Sydney estuary, Australia

The current investigation of marine water from 30 sites adjacent to stormwater outlets across the entire Sydney estuary is the first such research in Australia. The number of analytes detected were: 8/59 pharmaceutical compounds (codeine, paracetamol, tramadol, venlafaxine, propranolol, fluoxetine, iopromide and carbamazepine), 7/38 of the pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), 3,4-dichloroaniline, carbaryl, diuron, 2-methyl-4-chlorophenoxyacetic acid (MCPA), mecoprop and simazine) and 0/3 of the personal care products (PCPs) analysed. An artificial sweetener (acesulfame) was detected, however none of the nine antibiotics analysed were identified. Sewage water is not discharged to this estuary, except infrequently as overflow during high-precipitation events. The presence of acesulfame (a recognised marker of domestic wastewater) and pharmaceuticals in water from all parts of the estuary after a dry period, suggests sewage water is leaking into the stormwater system in this catchment. The pesticides are applied to the environment and were discharged via stormwater to the estuary.

Wastewater analysis to monitor use of caffeine and nicotine and evaluation of their metabolites as biomarkers for population size assessment

The use of caffeine, nicotine and some major metabolites was investigated by wastewater analysis in 13 sewage treatment plants (STPs) across Italy, and their suitability was tested as qualitative and quantitative biomarkers for assessing population size and dynamics. A specific analytical method based on mass spectrometry was developed and validated in raw urban wastewater, and included two caffeine metabolites, 1-methylxanthine and 7-methylxanthine, never reported in wastewater before. All these compounds were found widely at the μg/L level. Mass loads, calculated by multiplying concentrations by the wastewater daily flow rate and normalized to the population served by each plant, were used to compare the profiles from different cities. Some regional differences were observed in the mass loads, especially for nicotine metabolites, which were significantly higher in the south than in the center and north of Italy, reflecting smoking prevalences from population surveys. There were no significant weekly trends, although the mean mass loads of caffeine and its metabolites were slightly lower during the weekend. Most caffeine and nicotine metabolites fulfilled the requirements for an ideal biomarker for the assessment of population size, i.e. being easily detectable in wastewater, stable in sewage and during sampling, and reflecting human metabolism. Nicotine metabolites were tested as quantitative biomarkers to estimate population size and the results agreed well with census data. Caffeine and its metabolites were confirmed as good qualitative biomarkers, but additional information is needed on the caffeine metabolism in relation to the multiple sources of its main metabolites. This exploratory study opens the way to the routine use of nicotine metabolites for estimating population size and dynamics.