Wastewater-based epidemiology for monitoring cocaine and cannabis: A review of methods and applications

Wastewater-based epidemiology (WBE) is an effective tool for monitoring public health, drug use, chemical exposure, and lifestyle habits. This review summarises and discusses analytical protocols for determining cannabis and cocaine biomarkers in wastewater. The WBE requirements for these biomarkers, including detectability, human urinary excretion, metabolic uniqueness, and stability, are thoroughly investigated. Various analytical methods that involve sample enrichment steps that increase the sensitivity and specificity of detecting 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) for cannabis and benzoylecgonine (BE) for cocaine using liquid chromatography-mass spectrometry (LC-MS/MS) are highlighted. Studies have also shown temporal and spatial variations, such as Reykjavik, Iceland (2017–2020) observed fluctuating cocaine consumption, peaking at 2,660 mg/day/1,000 inhabitants in April 2019 and declining to 1,020 mg/day/1,000 inhabitants by June 2020. These methods can be beneficial for replicating these studies in various regions. The lack of studies and the primary challenges and opportunities associated with WBE in developing nations are discussed. Future directions are proposed to improve data quality and expand the global application of WBE. This review aims to support the development of targeted public health interventions and policies tailored to diverse regional needs, ultimately promoting a more collaborative and effective global drug surveillance system. Towards Universal Drug Monitoring: Wastewater-Based Epidemiology for Cannabis and Cocaine Across Diverse Regions