Although the potency of cannabis has increased in almost all European countries between 2006 and 2016, substantial differences persist between countries, with important consequences for public health. Possible explanations for variations in the cannabis market across Europe include tastes (demand side) and differences in price
due to repression (supply side).
One of the characteristics of the illicit drug market is the unexplained variability in product characteristics between countries. For example, the markets balance at a surprisingly different purity. As we have seen recently with the Madrid resin.
For hard drugs the purity index is important against the risk of overdose
According to Dr. Tom Freeman an active member of the British Association of Psychopharmacology no study provides insight into what determines the purity at which a market equilibrates, but purity may be important for overdose risks. In the case of cannabis there is no overdose ....
Freeman bring new observations to this puzzle of variable balances on national markets. They present data on the potency of cannabis [measured by the percentage of tetrahydrocannabinol (THC)] in 21 European countries during the period 2006-16.
Leaving aside the Netherlands, with their near-legal cannabis market and steadfast potency of 15%, the 2016 range is around 3-15%, while in 2006 it was about 0,5-10%. Similar trends can be seen for cannabis resin. There are few signs of convergence or harmonization between markets.
What could explain these persistent differences in the potency of cannabis?
Three assumptions: one on the demand side and two on the supply side.
Divergent national preferences : For various reasons, alcohol markets have shown persistent differences in the shares of alcohol consumption represented by wine, spirits and beer. Although there are signs of some convergence in Europe, at least in part due to more uniform tax and regulatory policies, cross-national differences in these shares remain significant.
In some countries, consumers prefer a higher potency, or at least have become accustomed to strong cannabis. During the last 10 years, the ranking of countries has undergone changes
marked. For example, Croatia went from the penultimate lowest potency (in THC) in 2006 to the sixth in 2016. France still number one. Although variation in taste certainly plays a role, it is not compatible with consumption preferences.
Variation in law enforcement : the potency of cannabis is a consequence of the way it is produced. Growing indoors, which is often associated with more potent cannabis, reduces the risk of detection. Thus, more intense enforcement or harsher sentences following a conviction may favor smaller growing areas and greater potency. High potency may therefore be the result of more intense enforcement or more severe penalties.
Variation in the cost of internal productions : Prices for indoor crops, especially labor, energy and land, vary by country. Where labor is expensive and land and electricity are cheap, growers may choose to grow cannabis at low power. Thus, regardless of the application of the law, variations in power may reflect economic differences between countries.
There is no doubt that other studies can cite other factors that plausibly influence the average potency of cannabis. As with purity in the cocaine and heroin markets, the power of cannabis is a producer's decision, which partly reflects the taste of the customer. Variation in potency is probably important for public health, as Freeman et al point out, because user titration is imperfect; those who consume very high potency cannabis may consume more THC. Thus, it would be useful to study the matter.