 The market for cannabis is the largest market for any illicit drug in Europe today, with about 74 million Europeans who have tried the drug at least once in their lifetime and 18 million who have used it in the last year. We estimate that about 2,000 tonnes of the drug is consumed every year in the European Union. You find cannabis in the male form and in the female form. The male form does not produce any drug of any quantity. This which surprises a lot of people is a cannabis plant which is in flower and this central section here is just full of female flowers. In a normal situation when males are there to pollinate a female flower, this group of inflorescences would divert a lot of energy to seed production and by keeping the males away the female plant just keeps on producing one cluster of flowers on top of another. The inflorescences grow. Those inflorescences are covered in sticky, microscopically small structures called trichomes and as I brush this female flower now I'm actually rupturing those little structures. My fingers are getting sticky because they're covered now in hashish cannabis resin. In western Europe, cannabis resin, mostly from Morocco, used to dominate the cannabis market. There are two main ways of producing resin. The process that takes place in Nepal and India is a traditional method where you literally just hand rub the flowers like this. What's rather more usual though is to dry this material and then thrash the material over sieves and these trichomes fall off and when you compress it the resin and essential oils leak out and bind the whole material together as a sticky mass which then dries to the solid which people recognise on the streets as hashish. There are many types that are circulating. The type that I have in my hands is afghan. This material has this characteristic that's very plastic. What does dominate the European market is what's called soap bar, low potency product and it's incredibly hard. This is made in Morocco in vast quantities. Things have changed enormously. Certainly in mainland Europe there is a trend for high potency resin. It's made by sieving high potency high THC cannabis plants. We now see a shift in the consumption of the two main cannabis products, herb and resin with more and more herbal cannabis being produced and consumed across Europe. People talk about herbal cannabis but it's important to actually differentiate two very different types, traditional herbal cannabis that's grown outdoors in a situation where there are both male and female cannabis plants. Because energy has gone into seed production the potency of that outer material has gone down. In more contrast to this seeded cannabis we have seedless cannabis, cinnamilla. This is modern cannabis, an all-female crop that's been grown in absence of males. It's much more potent and it's much more fragrant. Cultivation of cannabis is now widespread across Europe with plantations being discovered in all countries in a variety of settings both indoors and outdoors. Some growers cultivate the plant for their own consumption or to supply their friends. But commercial growers are now reported everywhere. They are often part of organized crime and they are driven by the prospect of financial gain. There is an increase in some countries in large-scale cultivation sites run by criminal organizations. Some of them tend now to run multiple small-scale plantations to mitigate the risks of being detected by the police but also of being robbed by competitors. We also see physical violence associated with illicit cannabis production. These are plants whose heritage is Colombia, Afghanistan, Mexico. These are much more southerly latitudes than the Northern Europe and only indoors can you recreate those bright light conditions. In an indoor growing condition you can grow the entire crop from start to harvest in 11 weeks and then repeat the whole process. The yield of the cannabis plant is basically linearly proportional to the amount of light that you pour down on top of it. So the typical location has many, many bright lights trying to recreate a semi-tropical outdoor summer. One interesting thing that's happened in the last few years is that people have developed so-called auto-flowering cannabis plants. This enables growers to be guaranteed that their plants will flower irrespective of what day length they put them into. It's possible to flower a cannabis in 24 hours light a day. So the plant receives literally twice as much light as it would do in the traditional 12 hours like 12 hours dark regime and yield and potency go up accordingly. There has always been a large variation in the potency of cannabis across Europe with highly potent material being reported on occasion. The active ingredients in the cannabis plant are what we call the cannabinoids and they are unique to the cannabis plant. Over 80 cannabinoids have been identified to date but two of them with opposite effects are the most well known. There is THC, tetrahydrocannabinoid and CBD cannabidiol. In a wild population of cannabis plants there would be plants which have high THC, almost pure CBD and there would be a population of plants that had both. THC is the drug that gets you high, CBD in fact is anti-psychotic, it does not get you high. What's happened over many generations, growers have kept the seeds of the type of plants that were giving them the biggest high and what they were in effect doing was selecting the pure THC type and the CBD genetics were disappearing as a result of that. One of the biggest public health concerns associated with high potency cannabis in recent years is that it is made increasingly from plants with a very low content in CBD and because of this we may see an increase in some forms of mental illness associated with cannabis use. In addition to high potency herbal cannabis we also observe increasingly high potency resins. These are made from high THC cannabis plants. This material is going to be at least twice the potency of traditional resin with some samples reaching up to 60% THC. This is not just used as a recreational product, it's also used for medicinal purposes. Crude cannabis as a plant material is actually provided through dispensaries to treat a range of symptoms of which possibly pain control is the main use. This is a crude product that's not been through clinical trials. If we move on to pharmaceutical materials, these fall into two groups, those which are based on synthetic THC. There's a product called Dronabinol or Marinol for the treatment of nausea associated with chemotherapy for cancer patients and also to treat the loss of appetite with those with AIDS. But we now have products which are based on plant extracts and one of them, Sativex is used for the treatment of symptoms associated with multiple sclerosis. The markets for cannabis products seem to be in flux at the moment. On the legal medical markets, we have seen the emergence of new pharmaceuticals. On the illegal market, there are innovations that increase the potency. For policymakers, a major challenge for the future will be to find appropriate responses to the health risks posed by the new resins and herbs available.