Limitations to the Dutch cannabis toleration policy: Assumptions underlying the reclassification of cannabis above 15% THC.

The Netherlands has seen an increase in Δ9-tetrahydrocannabinol (THC) concentrations from approximately 8% in the 1990s up to 20% in 2004. Increased cannabis potency may lead to higher THC-exposure and cannabis related harm. The Dutch government officially condones the sale of cannabis from so called 'coffee shops', and the Opium Act distinguishes cannabis as a Schedule II drug with 'acceptable risk' from other drugs with 'unacceptable risk' (Schedule I). Even in 1976, however, cannabis potency was taken into account by distinguishing hemp oil as a Schedule I drug. In 2011, an advisory committee recommended tightening up legislation, leading to a 2013 bill proposing the reclassification of high potency cannabis products with a THC content of 15% or more as a Schedule I drug. The purpose of this measure was twofold: to reduce public health risks and to reduce illegal cultivation and export of cannabis by increasing punishment. This paper focuses on the public health aspects and describes the (explicit and implicit) assumptions underlying this '15% THC measure', as well as to what extent these are supported by scientific research. Based on scientific literature and other sources of information, we conclude that the 15% measure can provide in theory a slight health benefit for specific groups of cannabis users (i.e., frequent users preferring strong cannabis, purchasing from coffee shops, using 'steady quantities' and not changing their smoking behaviour), but certainly not for all cannabis users. These gains should be weighed against the investment in enforcement and the risk of unintended (adverse) effects. Given the many assumptions and uncertainty about the nature and extent of the expected buying and smoking behaviour changes, the measure is a political choice and based on thin evidence.

The relationship of quality and price of the psychostimulants cocaine and amphetamine with health care outcomes.

A major component of the illicit drug market can be subcategorized as the psychostimulant drug market, with cocaine and amphetamine as popular constituents. In The Netherlands, an increase in both health care outcomes addiction treatment and hospital admissions was noted for both amphetamine and cocaine throughout a period of 17 years (1992-2008). Both cocaine price and quality showed a decrease in The Netherlands during the studied period. We used time-series regression analysis to investigate whether price or quality of the drugs were associated with health care outcomes. Drug seizures were also added to the time-series regressions in order to check for possible effects of drug availability and supply. Price and quality of cocaine were strongly associated with health care outcomes of addiction treatment and hospital admissions. Price of amphetamine also showed a decrease during these 17 years, but was associated with an increase in addiction treatment only. Other amphetamine market variables did not show any relationship with the health care outcomes. It could be stated that following basic market logics does not apply equally to all psychostimulants of abuse. Other factors might play a role, such as the addictiveness or desirability of a specific drug in question. This finding is supportive of the dynamics of the illicit psychostimulant market affecting actual use and thereby health care outcomes.