Temporal monitoring of stimulants during the COVID-19 pandemic in Belgium through the analysis of influent wastewater

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.

Reporting population size in wastewater-based epidemiology: A scoping review

Knowledge of the number of people present in a catchment is fundamental for the assessment of spatio-temporal trends in wastewater-based epidemiology (WBE). Accurately estimating the number of people connected to wastewater catchments is challenging however, because populations are dynamic. Methods used to estimate population size can significantly influence the calculation and interpretation of population-normalised wastewater data (PNWD). This paper systematically reviews the reporting of population data in 339 WBE studies. Studies were evaluated based on their reporting of population size, the source of population data, the population calculation methods, and the uncertainties in population estimates. Most papers reported population size (96 %) and the source of population data (60 %). Fewer studies reported the uncertainties in their population data (50 %) and the methods used to calculate these estimates (28 %). This is relevant because different methods have unique strengths and limitations which can affect the accuracy of PNWD. Only 64 studies (19 %) reported all four components of population data. The reporting of population data has remained consistent in the past decade. Based on the findings, we recommend generalised reporting criteria for population data in WBE. As WBE is further mainstreamed and applied, the clear and comprehensive reporting of population data will only become increasingly important.

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.

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.

Assessment of restriction measures implemented during COVID pandemics on community lifestyle choices via wastewater-based epidemiology

SARS-CoV-2 pandemic affected lifestyle habits, and the mental health and wellbeing of people around the world. In this manuscript, two towns (Paulton and Radstock) and two cities (Bath and Bristol) in Southwest England (> 1 million people) were monitored for two years using Wastewater-Based Epidemiology to assess impacts of COVID (including management measures such as lockdowns and movement restrictions) on community lifestyle choices: illicit drugs, legal stimulants, abused pharmaceuticals and pain pharma usage. Results were triangulated with key dates captured during the pandemic (national lockdowns, restrictions and social distancing measures, etc.). This highlighted a reduction in cocaine intake (as benzoylecgonine) (community average: -36 %) during the first lockdown and an increase in illicit drugs usage after the 3rd national lockdown (community averages for amphetamine: +8 %, cocaine/benzoylecgonine: +39 %, ketamine:+70 %) when restrictions were removed, and social interaction and recreational activities increased. There was a reduction in the intake of caffeine (as 1,7-dimethylxanthine) (community average:-39 %) after 3rd national lockdown coinciding with pubs reopening while nicotine intake (via cotinine) remained stable indicating lack of impact of COVID on smoking habits. Pain pharma often used in pain management resulting from injuries linked with sport activities (naproxen and diclofenac) showed decrease in usage due to lockdown restrictions in physical exercise and access to gyms/sport facilities.

Restrictive measures and substance use reporting: New evidence from the COVID-19 pandemic

BACKGROUND

Since the beginning of the COVID-19 pandemic, several studies have been conducted on the impact of lockdown and containment measures on various aspects of individual and social behaviour, including substance use. The increasing body of literature investigating this phenomenon emphasizes the need for additional studies at the local level. We investigate changes in reported illicit drug consumption following changes in public measures limiting individual mobility in the province of Bergamo, one of the regions that faced the most severe consequences in terms of number of cases and death toll in the early stages of the pandemic.

METHODS

The empirical analysis is based on a unique dataset covering all people recorded by police forces as drug users between January 2019 and December 2021 in the province of Bergamo. Data relate to reports for illicit drug consumption and not criminal activities.

RESULTS

Estimates show that, during periods when individual mobility was severely limited, the probability of reported cannabis consumption decreased by 8-9%, while that of reported cocaine use increased by 6-12%. No significant changes emerge in the reported consumption of heroin or polysubstance. Furthermore, while reported cannabis use returned to pre-pandemic levels once the restrictive measures were eased, the increased likelihood of reported cocaine use appears to have been more long-lasting. These findings are robust to alternative estimation strategies and different model specifications. Our study also reveals significant gender, age and housing status disparities in reported drug use.

CONCLUSION

We provide a novel and distinctive perspective on the topic by using previously unexploited administrative data sources. We show that the relationship between restrictions and reported drug use varies by type of substance. Our methodology and findings can support the design of targeted policies for better resource allocation and improved public health outcomes.

Using wastewater-based epidemiology to evaluate the relative scale of use of opioids

Wastewater analysis (WWA) has been used as a tool to monitor population drug use, both pharmaceutical and illicit, for over 15 years. Policymakers, law enforcement and treatment services may use WWA-derived data to seek an objective understanding of the extent of drug use in specific areas. Therefore, wastewater data should best be reported in a meaningful form to allow those that are not experts in the field to compare the scale within and between drug classes. Excreted drug loads quantified in wastewater describe the mass of drug present in the sewer. Normalisation for wastewater flow and population is standard practice and critical for comparing drug loads between different catchments and indicates a transition to an epidemiological approach (wastewater-based epidemiology (WBE)). A further consideration is necessary to accurately compare the measured level of one drug to another. The standard dose of a drug taken to elicit a therapeutic effect will vary, with some compounds requiring microgram amounts, while others are administered in the gram range. When WBE data is expressed with units representing excreted or consumed loads without considering dose amounts, the scale of drug use when comparing multiple compounds becomes distorted. To demonstrate the utility and significance of including known excretion rates, potency and typical dose amounts into back-calculations of the measured drug load, this paper compares the levels of 5 prescribed (codeine, morphine, oxycodone, fentanyl and methadone) and 1 illicit (heroin) opioid from South Australian wastewater. The data is presented at each stage of the back-calculation starting with the total mass load measured, to consumed amounts factoring in excretion rates and finally the number of doses the load equates to. This is the first paper to describe the levels of 6 opioids measured in wastewater over a 4-year period in South Australia that demonstrate the relative scale of use.

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.