Ketamine use

UAntwerp scientists conduct sewage research at 26 different locations in Belgium

Ketamine use is on the rise in our country, scientists from the University of Antwerp conclude following a large-scale analysis of sewage samples. Compared with research from 2012, the values are up to 11 times higher.

Sewage can teach us a lot. For example, by analysing the excretion products in the water, scientists can map the spread of COVID-19 or drug use in society. The Toxicological Centre of the University of Antwerp is a pioneer in sewage water analysis. Professor Alexander van Nuijs and his colleagues have been conducting research projects since 2010.

In 2012, Van Nuijs used sewage analysis to conduct a small-scale study on the use of ketamine in Belgium at three locations. Legal ketamine is a fast-acting liquid anaesthetic that has been used in surgical procedures, amongst other things, since the 1960s. In the 1990s, it also emerged as a drug in the nightlife scene, in tablet and powder form. In the sewage study, ketamine was sometimes detected, but in very low quantities.

Large-scale study

In 2023, Natan Van Wichelen, PhD researcher at the Toxicological Centre at UAntwerp, conducted a much larger-scale study on ketamine. Between 2020 and 2023, he collected water samples in water treatment plants at 26 locations spread across Belgium. The study focused on large cities such as Antwerp and Brussels, but smaller towns and more rural municipalities were also included. Every day, a representative sample was analysed to see how much ketamine was present.

‘In Belgium, an increase in ketamine seizures and hospital admissions due to excessive ketamine use had been observed for some time. That’s why we investigated whether this trend was also visible in wastewater,’ says Van Wichelen. ‘The great advantage of wastewater is the fact that everyone participates in our research. This allows us to paint a good picture of the consumption of illegal substances, such as ketamine, which is more difficult to do through other methods.’

Not only at festivals

The figures confirmed the suspicions. ‘Compared to 2012, we now found the substance 7 to 11 times more in sewage. We didn’t expect such large increases. We haven't seen this kind of increase in use of an illicit drug in our research very often. We found large quantities of ketamine both in big cities and in more rural areas, so the use is widespread. The highest concentrations were found in cities and in regions close to the Dutch border. People often think that drugs are only used in big cities, but this kind of analysis reveals that ketamine is used all over Belgium.’

Ketamine is clearly used more at weekends than during the week: Saturday and Sunday consumption is 58% higher than on weekdays. Van Wichelen: ‘Ketamine is definitely a party drug, but it’s more than that. Consumption throughout the year is relatively stable. For some exotic drugs, we see huge peaks during holidays or festival periods and then they disappear again, but for ketamine it’s clear it’s used both in and outside the party environment.’

Dumping of ketamine in sewer network

The researchers are specifically looking for human metabolic excretion products in wastewater. Van Wichelen: ‘This assures us that what we measure was actually consumed by humans. In some samples we saw huge amounts of ketamine, but no large amounts of human metabolic excretion products. This is a typical example that pure ketamine was dumped in the wastewater on that day, without actually being consumed.’

The results of the study have been published in the renowned scientific journal Water Research (ScienceDirect).