British scientists at Bath University have determined that over the past 50 years, marijuana sold worldwide has become stronger by 14%. The team came to this conclusion by analyzing 80 thousand hemp samples purchased from 1970 to 2017.
Specialists have studied samples from the USA, UK, France, Italy, New Zealand, Netherlands and Denmark. The strength of the effect of grass they determined by the concentration of tetrahydrocannabinol (THC), the most active substance of marijuana, which has a psychotropic effect. As it turned out, the effect increased not only from cannabis, but also from its resin (hashish) by 24%.
However, the concentration of cannabidiol (CBD), a non-psychoactive substance used for medical purposes, has remained at the same level as before.
The trend can be explained by the fact that the range of cannabis has recently expanded. For example, marijuana sensymilla – mature but unfertilized inflorescences of female cannabis plants, whose fruits contain much more THC than the adult plant, which was in the process of a hippie at the Woodstock festival – has become more commonly used.
According to scientists, such “hardening” of marijuana is dangerous: their past research has shown that regular use of cannabis with high concentrations of THC can cause addiction and mental disorders.
“As the effects of cannabis increased, so did the number of patients who see doctors because of addiction problems,” said Tom Freeman, lead author of the study. – Europeans are now more likely to seek treatment for drug addiction because of grass than because of heroin or cocaine.