Wastewater doesn’t lie. From the Nosedo purifier, in the south-eastern outskirts of Milan, a faithful photograph emerges every year of the consumption habits of citizens, food, smoking, including drugs. Since 2011, a sample week has been analyzed by the laboratory of the Mario Negri Pharmacological Research Institute, which monitors six of the most widespread narcotic substances. The data then flows into the project’s interactive European map Wastewater analysis and drugscoordinated by the SAGE group in collaboration with the European Union Drugs Agency.
Cocaine: growing trend, peaking on Saturdays
Milan records 424 milligrams of cocaine per day per thousand inhabitants, a figure increasing for the third consecutive year. The trend aligns with that of other metropolises in Western and Southern Europe, from Barcelona to Athens. The daily analysis shows a sharp peak on the weekend, a pattern found in 75% of the cities participating in the study.
Ketamine: mainly recreational use
Ketamine also shows growth, going from 24.92 micrograms per day per thousand inhabitants in 2024 to 26.8 in 2025. The maximum concentration is recorded on Saturdays, given that it excludes a link with hospital activity and indicates mainly non-therapeutic consumption. However, Milan remains far from the levels of Belgium, Germany and the Netherlands.
MDMA up, cannabis down
MDMA continues the rise that began in the post-Covid period – with Amsterdam confirming itself as the European capital of the substance. Cannabis, on the contrary, shows a decline after years of substantial stability, with consumption distributed evenly throughout the week, without peaks on the weekend. The data on amphetamine and methamphetamine, less widespread in Milan than in Northern Europe, are stable and contained.
The methodology
The samplings are carried out in “normal” weeks, far from extraordinary events and periods of heavy rain – which would dilute the concentrations in the water. Sara Castiglioni, head of the Mario Negri Environmental Epidemiological Indicators laboratory, underlines how these data must be integrated with medical, toxicological and clinical information, as well as with early warning systems on new substances, to obtain a truly complete picture of the phenomenon.
