Cannabis products are becoming increasingly potent and diverse, while drug gangs working together are creating new security risks on the continent, Europol warned on Thursday.
Estimated to rake in around 11.4 billion euros ($12.3 billion) annually, the cannabis trade is Europe's largest drug market, even overshadowing cocaine trafficking, Europol and the EU's drug monitoring agency said in a combined report.
"Latest estimates showed that some 22.6 million people (in the EU) between 15 and 64 have used cannabis in the last year," added Europol in a statement.
"Latest data reveal a significant increase in the potency of cannabis products," the Hague-based agency said, referring to the percentage of active ingredient THC in the drug.
The average potency of herbal cannabis in the EU rose by 57 percent from 2010 to 2021 while the average potency of cannabis resin increased by nearly 200 percent over the same period "raising additional health concerns for users."
Trafficking in cannabis has seen drug gangs often working together "providing services from production to distribution," Europol said.
Methods to smuggle cannabis have also diversified with traffickers using everything from drones and helicopters to unmanned semi-submersible vessels.
But illicit cannabis cultivation also had an environmental impact because of chemical pollution and "significant" water use, Europol said.
"For example, an indoor cannabis cultivation site of 500 plants would potentially consume between 1.6 million and 2 million litres of water per year," Europol said.
By comparison, an Olympic-sized swimming pool holds around 2.5 million litres of water.
"Much of the electricity used to cultivate cannabis indoors in the EU is stolen," Europol said.
Various European countries including the Czech Republic, Germany, Luxembourg, Malta and the Netherlands have been pushing for the legalisation of recreational marijuana.
For instance in the Netherlands from December a handful of cannabis cafes will take part in an experiment to sell their products supplied by government-approved growers.
Despite popular perception, cannabis remains illegal in the Netherlands but has been "tolerated" up to a certain amount since the 1970s.
"These changes highlight the need to invest in monitoring and evaluation to fully understand their impact on public health and safety," Europol said.