"In the Netherlands, harm reduction activities are implemented through outreach work, low-threshold facilities and centres for ‘social addiction care’, the main goal of which is to establish and maintain contact with difficult-to-reach drug users.

"The Netherlands Opium Act is the basis for the current drug legislation. It defines drug trafficking, cultivation and production and dealing in and possession of drugs as criminal acts. The Act and its amendments confirm the distinction between Schedule I drugs (e.g. heroin, cocaine, MDMA/ecstasy, amphetamines) and Schedule II drugs (e.g. cannabis, hallucinogenic mushrooms).

"Since 1976, it has been a basic principle of Dutch drug policy to pursue the separation of the markets for ‘soft’ and ‘hard’ drugs. The Opium Act Directive states that the ‘Dutch drugs policy aims to discourage and reduce drug use, certainly in so far as it causes damage to health and to society, and to prevent and reduce the damage associated with drug use, drug production and the drugs trade’ (Stc 2011-11134). The 1995 white paper ‘Drug policy: continuity and change’ sets out comprehensively the principles of the Dutch illicit drugs policy.

"Studies reporting estimates of high-risk drug use can help to identify the extent of the more entrenched drug use problems, while data on first-time entrants to specialised drug treatment centres, when considered alongside other indicators, can inform an understanding of the nature of and trends in high-risk drug use.

"Data on the use of illicit substances among students aged 15-16 are reported in the European School Survey Project on Alcohol and Other Drugs (ESPAD). This survey has been carried out regularly in the Netherlands since 1999 and the most recent data are from 2015. The ESPAD studies indicate a decreasing trend in lifetime cannabis use among school-age children over the period 1999-2015. Nevertheless, in 2015, lifetime use of cannabis among students in the Netherlands was notably higher than the ESPAD average (based on data from 35 countries).

"Cannabis is the most common illicit substance used by the Dutch adult general population aged 15-64 years, followed at a distance by MDMA/ecstasy and cocaine. The gender gap regarding cannabis use remains: last year prevalence of cannabis use among young adults was approximately twice as high among males as among females. The use of all illicit drugs is concentrated among young adults aged 15-34 years.

(Syringe Exchange Data And Trends For The Netherlands, 2012)
"• In Amsterdam, figures are available since 1990. After a steady increase until 1993 (1,082,880 syringes were exchanged in that year), the number of exchanged syringes declined and slightly fluctuates below 200,000 syringes per year since 2007 (146,000 in 2012) (source: M. Buster, GGD Amsterdam).

(High-Potency Cannabis and Titration of Dosage Among Experienced Users) "Although experienced young adult cannabis users with a preference for stronger joints titrated their THC exposure to some extent by inhaling less smoke, in general more potent cannabis was used in higher dosages leading to a higher THC exposure compared to users preferring lower potency cannabis.

(High-Potency Cannabis and Potential For Developing Dependence) "This study among 98 experienced cannabis smokers is the first naturalistic study to examine whether users of cannabis with high THC concentration titrate the psychoactive effects by using lower doses and/or by reduced inhalation, and whether cannabis smoking behaviour (topography) predicts cannabis dependence severity independently of total THC exposure.

(Smoking Behavior and Potential for Developing Dependence on Cannabis) "Differences in cannabis smoking behaviour may also represent different risks for cannabis dependence independently of total THC exposure. Similar to cigarette smokers [16,21–24], cannabis smokers typically gradually decrease the puff volume and puff duration during the course of one joint, whereas puff velocity and interpuff interval gradually increase [20].