A wastewater-based approach to monitor shifting trends in illicit drugs consumption in Switzerland
Background: In January 2021, with the support of public health authorities, Switzerland launched a wastewater-based monitoring project called DroMedARio, aimed at providing a global status report on national trends in the consumption of illicit drugs, also covering pharmaceuticals, alcohol and tobacco (not further discussed). Recently, two issues have been of particular concern to public health and law enforcement stakeholders in the illicit drugs field. On the one hand, the outbreak of crack cocaine consumption, which frequently occurs in open, communal areas, has led to street disturbances, including violent behaviour, drug transactions in public spaces as well as public drunkenness. On the other hand, the surge in popularity of ketamine has raised alarms, as this high-toxicity product induces in its users a state of severe disassociation from their body and serious bladder issues, potentially leading to long-term bladder damage. Objective and timely data was therefore needed to assess the severity and extent of the problem.
Methods: The 4-year long ongoing DroMedARio project explores the spatial and temporal dimensions of consumption trends thanks to a large-scale and high-frequency stratified sampling strategy. 24-hour composite samples are collected every 13 days from 10 wastewater treatments plants of Swiss cities with diverse socio-demographics, covering about 2 million people (23% of the Swiss population). This sums up to 28 samples per year, with each day of the week equally represented. Samples undergo solid-phase extraction and ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis, to qualify and quantify 14 illicit drugs parent substances or urinary metabolites.
Results: Currently more than halfway through the project, the data collected has highlighted interesting spatial differences between cities and linguistic regions, such as a clear Swiss German preference for synthetic stimulants. Moreover, objective data on crack cocaine and ketamine allowed different patterns of use to be identified and the severity of the situation to be better assessed. Ketamine use was most prevalent in big cities and during the weekend, indicative of a recreational use, unlike crack cocaine. A global increase in cocaine wastewater loads has been noticed as well, in agreement with the current European trend. Finally, increased harm due to a rise in co-consumption of cocaine and alcohol during the weekend was additionally identified.
Conclusion: By leveraging the insights obtained from a project such as DroMedARio, relevant stakeholders can proactively tailor interventions, allocate resources efficiently and adapt their policy to the current local situation. This approach facilitates a more effective and targeted response, ultimately contributing to the overarching goal of mitigating the impact of illicit drug consumption on both public health and community well-being.
