The purity and potency of illegal drugs is Europe is on the rise, according to a new report by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA). In its annual analysis of European drug trends, the EMCDDA also found that heroin use was in decline, that London's sewers had the highest concentration of cocaine among all European capitals, and that two new psychoactive substances hit the market every week.

According to the report, more than 80 million adults — nearly a quarter of the EU's population — have tried an illicit substance at some point in their lives. Cannabis is Europe's most popular drug, followed by cocaine. According to the survey, 1 percent of European adults smoke cannabis "daily or almost daily." Illicit drugs are involved in 3.4 percent of all deaths of Europeans ages 15-39.

The EMCDDA found that 19.3 million Europeans ages 15-64 had used cannabis in 2014 — an estimated 5.7 percent of Europe's population — with consumption on the rise in several countries, including Denmark, Finland, Sweden, France, and Bulgaria. Just under a quarter of European school students ages 15-16 confessed to smoking the drug at least once, including nearly one in two Czech teens.

The survey also noted that cannabis is the most commonly seized drug in Europe, accounting for 80 percent of Europe's 1 million annual drug busts. According to the survey, Europeans are increasingly growing their own product, and the number of plants seized by authorities increased from 1.5 million in 2002 to 3.7 million in 2013.

Presenting the report in Lisbon on Thursday, EMCDDA director Wolfgang Götz highlighted the findings surrounding cannabis, and said that he did not expect Europe to legalize the drug any time soon. "I don't see a discussion coming up of the level as it is in the Americas," he said.

Another significant finding concerns the potency of cannabis — the THC content — which has risen dramatically over recent years. According to the report, the THC content for dried marijuana buds has doubled over the last five years, and also over the last 10 years for the "resin" form of the drug. European smokers may have market competition to thank for stronger weed, particularly in domestic production, where the report says "high-potency herbal products have taken an increasing market share in recent years."

The report also found that the number of people seeking treatment for cannabis use climbed from 45,000 in 2006 to 61,000 in 2013, with cannabis addiction the mostly reported reason for entering a drug rehabilitation facility among first-time patients. The demand for treatment from cocaine addiction, however, is in decline.

And yet cocaine — sniffed, snorted, injected, or smoked as crack cocaine — remains popular. According to the survey, the highest concentration of users is found in only a handful of countries, including Spain, Ireland, France, Denmark, and the UK, where 9.5 percent of adults claim they have used the illicit stimulant.

Analysis of wastewater from several European capitals showed that London's sewers have the EU's highest concentration of cocaine. Research found, however, that London fell behind cocaine-loving Amsterdam in this department during the weekend.

Cocaine residues in European wastewater.

Perhaps unsurprising is the conclusion that a large amount of Europe's cocaine is consumed in nightclubs, with 22 percent of "regular nightclub goers" — defined as attending clubs at least once every three months — claiming they had used cocaine at least once.

Heroin came out as the most common opioid in Europe, and also the most addictive. Research found that, while demand for the drug had plateaued, heroin-related issues still accounted for the lion's share of drug-related health and social costs in EU member states. Nonetheless, the data showed a decline in the demand for heroin-related treatment, and overall, Europe's' drug agency described heroin trends in the area as "relatively positive."

Still, the survey found that heroin injectors were most at risk from drug overdoses, and opioids were the cause of 66 percent of all fatal overdoses. Recent data also draws a parallel between increased heroin purity and the climb in fatal overdoses.

The most common form of heroin — brown heroin — arrives in Europe from Afghanistan, while the less common form — white heroin — has historically been produced in Southeast Asia. Most of the heroin imported into Europe travels along the "Balkan route" — from Afghanistan to the Balkans, via Turkey — but drug agencies have also noticed the development of the "southern route," which stretches from Iran and Pakistan via Africa or the Arab Peninsula. Increasingly, opium originating from Afghanistan is being transformed in European laboratories.

The EMCDDA noted a "resurgence" of MDMA following a production decline at the end of the last decade. According to the report, 12 million Europeans say they have tried amphetamines at some point in their life, while 12.3 have taken ecstasy.

The EMCDDA underscored the development of a deliberate "marketing" strategy for MDMA, and said that drug pushers are producing high-dose tablets in various shapes and adorned with different logos to make the product more attractive to consumers. Production of MDMA in Europe today appears to be concentrated around Belgium and the Netherlands.

Europe's drug users are also faced with a constant supply of new psychoactive substances, with a reported 101 new substances introduced onto the market in 2014. Made up mainly of synthetic cannabinoids, stimulants, hallucinogens, and opioids, a lot of these products are "legal highs" that are mostly consumed by young people.

French daily Le Figaro has noted that France tops the tables of recent users, with 8 percent of young French people having tried one of these substances in the last year. While some of the products can be bought on the streets, they are mostly procured online. The internet, the report says, is "an important driver" for this new market, and there are currently 651 websites selling legal highs.

According to the EMCDDA, "the growth of online and virtual drug markets poses major challenges to law enforcement and drug control policies." Referring to "deep web" platforms such as Evolution, Agora, or Silk Road, whose founder Ross Ulbricht was recently sentenced to life in prison, the agency recommended that existing drug regulation models "be adapted to perform in a global and virtual context."

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