Wastewater reveals Danes’ consumption of narcotics

A new report from the Institute of Forensic Medicine at Aarhus University provides, for the first time, a detailed insight into the consumption of narcotics such as cocaine, opioids, and alcohol by Danes – measured directly in wastewater. The study was conducted on behalf of the National Board of Health and is part of the government initiative “Youth without opioids.”

The report, titled “National mapping of narcotics in wastewater from Danish cities,” is based on measurements from treatment plants in Copenhagen, Aarhus, Odense, Aalborg, Esbjerg, and Næstved. These cities collectively represent about 20 percent of the Danish population.

Several results have surprised the researchers behind the report. Particularly notable is the significant variation in opioid consumption between the six cities.

“I am surprised by the relatively large differences we observe in the consumption of the opioids tramadol and oxycodone between the cities. We see the highest amounts in Aalborg, Esbjerg, and Næstved. The differences, which are also reflected in sales data, may be due to variations in prescription practices and demographics,” says Christian Lindholst, associate professor and institute director at the Institute of Forensic Medicine.

Furthermore, the wastewater analysis shows that the total consumption of prescription opioids in cities is lower than the amount sold on prescription, which according to researchers, may indicate overprescription compared to actual consumption.

Another notable observation is the consumption patterns of different substances. While cocaine, MDMA, and alcohol have a significantly higher intake on weekends, the consumption of amphetamines remains stable throughout the week.

“It is surprising that amphetamine and methamphetamine do not have the same consumption pattern as the ‘party drugs’ cocaine, MDMA, and alcohol. The consumption of amphetamines remains stable throughout the week,” says Lindholst.

He adds: “We know that many take amphetamines – in the form of lisdexamfetamine – in connection with the treatment of attention disorders, but a large part of amphetamine intake comes from illegally imported amphetamines. I would have expected a higher intake on weekends.”

In contrast to traditional surveys, wastewater analyses provide a more accurate picture of actual consumption in the population. Christian Lindholst is pleasantly surprised by the quality of the analysis.

“After all, we are dealing with the collection of untreated wastewater. This bodes well for the future use of wastewater data for surveillance purposes,” he says.

Among the key findings from the study, conducted in collaboration with local wastewater companies and with support from the Statens Serum Institut, are that the excretion of cocaine, MDMA, and alcohol is 2-3 times higher on weekends, and Copenhagen ranks highest in the consumption of cocaine, MDMA, and methamphetamine. The study also shows that amphetamine consumption is highest in Esbjerg and remains stable throughout the week. Additionally, the study reveals that the substance fentanyl could not be detected, which is due to consumption being below the detection threshold.

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