©Ouael Ben Salah via Unsplash
Wastewater doesn't lie. At the Nosedo wastewater treatment plant, on the southeastern outskirts of Milan, a faithful portrait of citizens' consumption habits (including food, tobacco and drugs) is drawn every year.
Since 2011, a typical week has been analyzed by the laboratory of the Mario Negri Institute for Pharmacological Research, which monitors six of the most widespread narcotics. The data are then integrated into the interactive European map of the 'Wastewater analysis and drugs' project, coordinated by the SAGE group in collaboration with the European Union Drugs Agency.
Cocaine: an upward trend, with a peak on Saturdays
Milan records 424 milligrams of cocaine per day per thousand inhabitants, a figure on the rise for the third year running. The trend is in line with that of other Western and Southern European metropolises, from Barcelona to Athens. Daily analysis reveals a clear peak at weekends, a pattern observed in 75% of the cities participating in the study.
Ketamine: mainly for recreational use
Ketamine is also on the rise, rising from 24.92 micrograms per day per thousand inhabitants in 2024 to 26.8 in 2025. The maximum concentration is recorded on Saturdays, a figure that rules out any link with hospital activity and indicates primarily non-therapeutic use. Milan, however, remains far from the levels observed in Belgium, Germany and the Netherlands.
MDMA up, cannabis down
MDMA continues the upward trend begun in the post-Covid period, with Amsterdam confirming its status as the European capital of this substance. Cannabis, on the other hand, shows a decline after years of relative stability, with consumption spread evenly throughout the week, with no peak at weekends. Data for amphetamine and methamphetamine remain stable and moderate, these substances being less widespread in Milan than in northern Europe.
Methodology
Samples are taken during 'normal' weeks, excluding exceptional events and periods of heavy rainfall - which would dilute concentrations in the water. Sara Castiglioni, head of the Environmental Epidemiological Indicators laboratory at the Mario Negri Institute, stresses that these data must be cross-referenced with medical, toxicological and clinical information. They also need to be supplemented by early warning systems for new substances, in order to obtain a truly exhaustive picture of the phenomenon.
Source: Mario Negri Institute
(©GreenMe.it 2026/Managing editor: Selma Keshkire - The Press Junction/Picture: Ouael Ben Salah via Unsplash)