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15 years’ research into drugs in sewage water

In 2023, for the fourteenth year in a row, researchers measured drugs in sewage water with the objective of detecting geographical differences and temporal trends in drug use of urban populations in Europe. KWR has contributed to this research from the outset through the SCORE network. The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) in Lisbon publishes the measurement results. Sewage is a ‘mirror of society’. In this mirror administrators see how drug use in their city is developing. Thanks to the long-running research, they can discover trends over time as well as compare their different situations with each other.

In Amsterdam, Utrecht and the Eindhoven region, residues of various drugs have since 2010 been measured in sewage water annually over a period of one week. The figures below show the average use of the active substance for cocaine, amphetamine (speed) and MDMA (XTC), expressed in milligrams per 1000 inhabitants per day.

Trends in the Netherlands over 2010-2023

Cocaine

It is apparent that the consumption of cocaine has increased, particularly since 2016 (with a slight decline in Amsterdam during the corona pandemic).

Cocaïnegebruik Adam, Utr, Ehoven 2010-2023

Cocaine use is determined by measuring the metabolite benzoylecgonine, a substance that is formed in the human body. The chart shows, by city, the average amount of the active substance used per day per 1000 inhabitants. This allows for comparisons between cities of different sizes.

MDMA (XTC)

Starting in 2016, XTC use in the Eindhoven region, and to a lesser extent in Utrecht, slightly decreased; while its use in Amsterdam showed some variation but no clear trend.

 

Amphetamine

Amphetamine use is somewhat more variable. In Amsterdam it remained about the same. In Utrecht its use increased, but there are no data for 2023. For the Eindhoven region there are not sufficient data to establish a trend. Suspected waste residues from amphetamine production in the samples make measurements of use impossible.

 

2023 Results

In March 2023, the sewage water in Amsterdam, Utrecht, the Eindhoven region, Leeuwarden and Rotterdam were analysed over a period of one week for the presence of residues of: cocaine, amphetamine (speed), MDMA (XTC), THC (the active substance in cannabis products) and methamphetamine (crystal meth).

The charts below show the average use of the active substance per city, expressed in milligrams per 1000 inhabitants per day. The drug use in the cities concerned usually differs, but only to a certain extent. Often this difference is less than a factor of two. This indicates that drug use not only occurs in our country’s largest cities, but also in provincial capitals, as well as in the small municipalities that we studied.

Cocaine

Cocaine consumption is somewhat higher in the cities of Amsterdam, Rotterdam and Leeuwarden than in Utrecht and the Eindhoven region.

Cocaine use is determined by measuring the metabolite benzoylecgonine, a substance that is formed in the human body. The chart shows, by city, the average amount of the active substance consumed per day per 1000 inhabitants. This allows for comparisons between cities of different sizes.

Amphetamine (speed)

The use of amphetamine (speed) is higher in Leeuwarden and Rotterdam than in Amsterdam. Amphetamine use in Utrecht and the Eindhoven region could not be determined because the discharged residues from the production of these drugs distorted the measurements.

Amphetamine use is determined by measuring amphetamine residues in the sewage water. The chart shows, by city, the average use of the active substance, expressed in milligrams per 1000 inhabitants per day. This allows for comparisons between cities of different sizes.

MDMA (xtc)

The use of MDMA (XTC) is higher in Rotterdam and Amsterdam than in Utrecht and Leeuwarden. For the Eindhoven region, the use could not be determined because the discharged residues from the production of these drugs distorted the measurements.

XTC use is determined by measuring MDMA residues in the sewage water. The chart shows, by city, the average use of the active substance, expressed in milligrams per 1000 inhabitants per day. This allows for comparisons between cities of different sizes.

THC (cannabis)

The consumption of cannabis (THC is the active substance in cannabis products) is somewhat higher in the cities of Amsterdam, Rotterdam and Leeuwarden than in Utrecht and the Eindhoven region.

THC use is determined by measuring the metabolite THC carboxylic acid, a substance formed in the human body. The THC chart shows, by city, the average use of the active substance, expressed in milligrams per 1000 inhabitants per day. This allows for comparisons between cities of different sizes.

Methamphetamine

The use of methamphetamine is low in all cities, but, in relative terms, it is the highest in Amsterdam, followed by the Eindhoven region and Leeuwarden.

 

Collaboration with the Water Authorities

KWR is very pleased with the collaboration with the Water Authorities, which have always proven to be very open and ready to cooperate. It is not the task of the managers of the regional wastewater treatment plants (WWTPs) to detect narcotic substances. Moreover, the WWTPs are not designed to remove residues of pharmaceuticals or narcotic substances from wastewater. Some drugs, such as amphetamine and cocaine are very effectively removed during treatment. Other substances, such as MDMA (XTC), as well as valium, are not, or hardly, removed. The concentrations of drugs in surface water are usually low (up to a few tens of nanograms per litre) as a result of the usually very strong dilution.

What sewage surveillance will KWR do in 2024?

The regular monitoring of drugs in sewage water can provide insight into the differences in drug use between cities and trends over time.

KWR’s ambition is not only to record drug use in the five big cities included in the EMCDDA report numbers, but also in other cities and in smaller municipalities in the Netherlands, and, ultimately, even in all of the Netherlands. In 2024, we will also investigate the sewage water in various large Dutch cities and smaller municipalities in order to map drug use in country. For the first time or, for a number of municipalities, for the second time.

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