The estimation of cannabis consumption through wastewater analysis

Making waves: Wastewater-based surveillance of cannabis use

Monitoring cannabis consumption holds great interest due to the increasing trend towards its legalization for both medicinal and recreational purposes, despite the potential risks and harms involved. Wastewater-based surveillance (WBS) offers a valuable tool for assessing shifts and patterns in drug consumption and to evaluate law enforcement strategies and harm reduction programs. However, WBS-derived cannabis use estimates have been linked to greater uncertainties compared to other drugs, in part due to the many different routes of administration and a substantial excretion of metabolites in faecal matter. Therefore, the usual approach for estimating consumed amounts and scaling consumption compared to other problem drugs requires a rethink. This viewpoint highlights the progress made in this area and describes the current existing barriers related to in-sewer and in-sample behaviour (e.g., adsorption/desorption mechanisms), analytical procedures used (e.g., sample preparation), and pharmacokinetic aspects (e.g., administration route) linked to cannabis biomarkers in influent wastewater. These need to be addressed to improve the estimation of cannabis use and reflect spatial and temporal trends in the same way as for other drugs. Until then, we recommend being cautious when interpreting wastewater-based cannabis consumption estimates.

Occurrence of Z-drugs, benzodiazepines, and ketamine in wastewater in the United States and Mexico during the Covid-19 pandemic

Z-drugs, benzodiazepines and ketamine are classes of psychotropic drugs prescribed for treating anxiety, sleep disorders and depression with known side effects including an elevated risk of addiction and substance misuse. These drugs have a strong potential for misuse, which has escalated over the years and was hypothesized here to have been exacerbated during the COVID-19 pandemic. Wastewater-based epidemiology (WBE) constitutes a fast, easy, and relatively inexpensive approach to epidemiological surveys for understanding the incidence and frequency of uses of these drugs. In this study, we analyzed wastewater (n = 376) from 50 cities across the United States and Mexico from July to October 2020 to estimate drug use rates during a pandemic event. Both time and flow proportional composite and grab samples of untreated municipal wastewater were analyzed using solid-phase extraction followed by liquid chromatography-tandem mass spectrometry to determine loadings of alprazolam, clonazepam, diazepam, ketamine, lorazepam, nordiazepam, temazepam, zolpidem, and zaleplon in raw wastewater. Simultaneously, prescription data of the aforementioned drugs were extracted from the Medicaid database from 2019 to 2021. Results showed high detection frequencies of ketamine (90 %), lorazepam (87 %), clonazepam (76 %) and temazepam (73 %) across both Mexico and United States and comparatively lower detection frequencies for zaleplon (22 %), zolpidem (9 %), nordiazepam (<1 %), diazepam (<1 %), and alprazolam (<1 %) during the pandemic. Average mass consumption rates, estimated using WBE and reported in units of mg/day/1000 persons, ranged between 62 (temazepam) and 1100 (clonazepam) in the United States. Results obtained from the Medicaid database also showed a significant change (p < 0.05) in the prescription volume between the first quarter of 2019 (before the pandemic) and the first quarter of 2021 (pandemic event) for alprazolam, clonazepam and lorazepam. Study results include the first detections of zaleplon and zolpidem in wastewater from North America.

Detection of Eight Cannabinoids and One Tracer in Wastewater and River Water by SPE-UPLC–ESI-MS/MS

The consumption of illicit drugs represents a global social and economic problem. Using suitable analytical methods, monitoring, and detection of different illegal drugs residues and their metabolites in wastewater samples can help combat this problem. Our article defines a method to develop, validate, and practically applicate a rapid and robust analytical process for the evaluation of six naturally occurring cannabinoids (CBG, CBD, CBDV, CBN, THC, THCV), two cannabinoids in acidic form (CBDA, THCA-A), and the major cannabis-related human metabolite (THC-COOH). After SPE offline enrichment, we used a UPLC–ESI-MS/MS system, which permitted the determination of several by-products. Studied matrices were samples of different origins: (i) effluent water from a wastewater treatment plant in the Porto urban area; (ii) environmental water from Febros River, the last left-bank tributary of the Douro River. The multi-residue approach was substantiated and successfully employed to analyze the water samples collected in the above locations. The rapid and precise quantification of nine different cannabinoids in different water samples occurred within nine minutes at the ng L−1 level. The appearance of dozens of ng L−1 of some cannabis secondary metabolites, such as CBD, CBDA, CBN, THCA-A, indicates this plant species’ widespread usage among the general population in the considered area.

Partitioning of phytocannabinoids between faeces and water - Implications for wastewater-based epidemiology

Evaluating consumption estimates for lipophilic drugs in wastewater has proven to be a challenge. A common feature for these compounds is that they are excreted in faeces and in conjugated form in urine. Limited research with no obvious experimental evidence has been conducted to investigate the degree to which faecal-bound chemical markers contribute towards mass loads in wastewater. Cannabis chemical markers, known as phytocannabinoids, have been suggested in literature to fall into this category. In this study, cannabis users (n = 9) and non-cannabis users (n = 5) were recruited and provided faecal and urine samples after using the substance. The common chemical markers of cannabis consumption, 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH), 11-hydroxy-Δ⁹-tetrahydrocannabinol (THC-OH), Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD), were investigated. An extraction method was developed for the cannabis chemical markers in faecal matter and urine and analysis was performed by liquid chromatography-mass spectrometry. Participant samples were used to establish adsorption and desorption dissolution kinetics models and to assess the equilibrium between faeces and water for these compounds. Equilibration between phases were found to be fast (<5 min). THC-COOH, which is the primary metabolite used in wastewater studies, partitioned ~40% in water while the less polar metabolite and CBD remained largely associated with the particulate fraction. Faecal loads of both cannabis users and non-users affected the total measured amounts of cannabinoids in the aqueous phase. The implications for wastewater monitoring of lipophilic substances are discussed.

A method and its application to determine the amount of cannabinoids in sewage sludge and biosolids

Xenobiotic cannabinoids (phyto and synthetic) are highly lipophilic compounds and have been shown to accumulate within the particulate fraction of wastewater. Limited research has been conducted to investigate the occurrence of cannabinoids in sewage sludge and/or biosolids. The analysis of excreted cannabinoids from sewage sludge or biosolids can provide information about community health, as well as potentially long-term environmental impacts. In this study, a liquid-liquid extraction method was developed for the extraction and detection method for 50 cannabinoids by liquid chromatography-mass spectrometry, including the cannabis urinary biomarker 11-nor-9-carboxy-Δ⁹-tetrahydrocannabinol (THC-COOH), Δ⁹-tetrahydrocannabinol (THC), cannabidiol (CBD), and a variety of different generation synthetic cannabinoids and their respective metabolites. Method validation assessed criteria including linearity, selectivity, recovery, and matrix effects. The method was applied to samples collected from a conventional activated sludge reactor treatment facility from various stages of the treatment process. Three cannabinoids were abundant in primary sludge including THC, THC-COOH, and CBD, where THC was the most ubiquitous with concentrations up to 3200 μg kg^-1. Only THC and THC-COOH were detectable in aged biosolids. The detection of some cannabinoids in biosolids demonstrated that these compounds are stable throughout the treatment process.

Analysis of 39 drugs and metabolites, including 8 glucuronide conjugates, in an upstream wastewater network via HPLC-MS/MS

Pharmaceutical compounds ingested by humans are metabolized and excreted in urine and feces. These metabolites can be quantified in wastewater networks using wastewater-based epidemiology (WBE) methods. Standard WBE methods focus on samples collected at wastewater treatment plants (WWTPs). However, these methods do not capture more labile classes of metabolites such as glucuronide conjugates, products of the major phase II metabolic pathway for drug elimination. By shifting sample collection more upstream, these unambiguous markers of human exposure are captured before hydrolysis in the wastewater network. In this paper, we present an HPLC-MS/MS method that quantifies 8 glucuronide conjugates in addition to 31 parent and other metabolites of prescription and synthetic opioids, overdose treatment drugs, illicit drugs, and population markers. Calibration curves for all analytes are linear (r2 > 0.98), except THC (r2 = 0.97), and in the targeted range (0.1-1,000 ng mL-1) with lower limits of quantification (S/N = 9) ranging from 0.098 to 48.75 ng mL-1. This method is fast with an injection-to-injection time of 7.5 min. We demonstrate the application of the method to five wastewater samples collected from a manhole in a city in eastern Massachusetts. Collected wastewater samples were filtered and extracted via solid-phase extraction (SPE). The SPE cartridges are eluted and concentrated in the laboratory via nitrogen-drying. The method and case study presented here demonstrate the potential and application of expanding WBE to monitoring labile metabolites in upstream wastewater networks.

The embodiment of wastewater data for the estimation of illicit drug consumption in Spain

Data obtained from wastewater analysis can provide rapid and complementary insights in illicit drug consumption at community level. Within Europe, Spain is an important country of transit of both cocaine and cannabis. The quantity of seized drugs and prevalence of their use rank Spain at the top of Europe. Hence, the implementation of a wastewater monitoring program at national level would help to get better understanding of spatial differences and trends in use of illicit drugs. In this study, a national wastewater campaign was performed for the first time to get more insight on the consumption of illicit drugs within Spain. The 13 Spanish cities monitored cover approximately 6 million inhabitants (12.8% of the Spanish population). Untreated wastewater samples were analyzed for urinary biomarkers of amphetamine, methamphetamine, MDMA, cocaine, and cannabis. In addition, weekend samples were monitored for 17 new psychoactive substances. Cannabis and cocaine are the most consumed drugs in Spain, but geographical variations showed, for instance, comparatively higher levels of methamphetamine in Barcelona and amphetamine in Bilbao, with about 1-fold higher consumption of these two substances in such metropolitan areas. For amphetamine, an enantiomeric profiling was performed in order to assure the results were due to consumption and not to illegal dumping of production residues. Furthermore, different correction factors for the excretion of cannabis were used to compare consumption estimations. All wastewater results were compared with previously reported data, national seizure data and general population survey data, were a reasonable agreement was found. Daily and yearly drug consumption were extrapolated to the entire Spanish population with due precautions because of the uncertainty associated. These data was further used to estimate the retail drug market, where for instance cocaine illicit consumption alone was calculated to contribute to 0.2-0.5% of the Spanish gross domestic product (ca. 3000-6000 million Euro/year).