Drug Markets

Since the 1990s, the Ministry of Health enabled the testing of illicit drugs for drug users to prevent serious health hazards associated with unexpected dangerous substances. This illicit drug testing system is called the Drugs Information and Monitoring System (DIMS); DIMS is a national network of testing facilities that furthermore aims at gaining an insight into the market of controlled substances. DIMS is embedded within the Trimbos Institute and is funded by the Ministry of Health (VWS). DIMS also runs the THC monitor (by analyzing cannabis samples purchased in randomly selected coffee shops on a yearly basis), and since 2012, DIMS also hosts the Monitor New Drugs, which focuses specifically on New Psychoactive Substances. 

More about DIMS

THC monitor

Many of the cannabis products sold in coffee shops originate from Dutch-grown marijuana, known in Dutch as 'nederwiet'. On behalf of the Ministry of Health, Welfare, and Sport, the THC Monitor investigates the potency of cannabis products sold in coffee shops in the Netherlands.

Report THC monitor 2016-2017 (in Dutch)

For more information, please contact Sander Rigter

Monitor of New Drugs

The Monitor of New Drugs (MND) assesses the presence of new (mostly unregulated) psychoactive substances in the DIMS system, along with data from the National Forensic Institute and the Customs Laboratory. The MND reports directly to the Ministry of Health, Welfare, and Sport, as well as to the Office of the Coordination, Assessment and Monitoring of New Drugs.

For more information, please contact Daan van der Gouwe

Monitor Drug-related Incidents

The Monitor Drug-related Incidents collects information on presentations with drug-related acute toxicities at four medical services and in eight regions of the Netherlands to provide an indicative base for monitoring.

Report Monitor Drug-related Incidents 2016 (in Dutch)

For more information, please contact Esther Croes.

Other monitoring studies

Red Alert

When substances are found in drugs that pose an acute danger to public health, for example contaminated XTC pills or pills with an extremely high dose of MDMA, a Red Alert procedure is started. In case of a Red Alert, health authorities and the media are informed. The public is informed via news items, posters and flyers at parties. The goal of a Red Alert is to inform as many people as possible and keep the number of incidents as small as possible.

For more informatie, please contact Daan van der Gouwe

Esther  Croes

Esther Croes


PhD. Medical doctor and genetic and clinical epidemiologist. International project leader and co-worker in a wide range of projects. Main focus of her work is on the somatic consequences of substance use: tobacco control, drug-related emergencies and viral hepatitis.

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Daan van der Gouwe

Daan van der Gouwe

Drugs researcher

Drugs researcher who monitors the Dutch market in illicit drugs. He also monitors New Psychoactive Substances, has expertise in (international) policy evaluations and is involved in the CADAP program. He is one of the leading spokespersons for Trimbos when it comes to drug-related issues.

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Raymond Niesink

Toxicoloog/Senior wetenschappelijk Medewerker

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Sander  Rigter

Sander Rigter

Projectmedewerker A

Researcher at the Drugs Information and Monitoring System (DIMS). Expertise in analyzing drug samples, their effects and drug policy. He has a vast national and international network in this field. Sander also coordinates a yearly monitor of the content of cannabis sold in Dutch coffee shops.

More about Sander