A global downturn in the use of traditional drugs has been offset by a surge in the demand for "legal highs", rapidly changing the nature of the world's drug industry and threatening the power of individual countries to regulate it.
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While international markets for heroin, cocaine and cannabis either declined or remained stable over the past year, there has been a striking rise in new synthetic "designer drugs" that are not under international control, according to the UN World Drug Report 2011, which was published yesterday.
Opium production dropped by almost 40 per cent last year and the production of cocaine around the world has fallen by a sixth since 2007, according to the international body. However, the reduction in illicit drug-use can be partly explained by the "substitution" of illegal drugs for "unregulated" and "untested" stimulants, which experts warn could be just as dangerous to public health.
In Europe, which is described as one of the most "innovative" when it comes to new drugs, 110 new psychoactive substances were reported to the European Monitoring Centre for Drugs and Drug Addiction and Europol between 1997 and 2009. Last year, 41 new substances emerged – almost double the number recorded in 2009. Sixteen of these were first reported in the UK.
The most high profile has been mephedrone, or meow meow, which has been linked to a number of deaths, and was banned in the UK in April last year.
Other examples of "designer" drugs include Spice, a synthetic substance that emulates the effects of cannabis, and BZP, a chemical derivative often sold to mimic the effects of ecstasy.
Sandeep Chawla, director of policy and public affairs at the UN Drugs and Crime office, who supervised the report, said the majority of these drugs are "widely available" and "easily made" with a "little chemical know-how".
He said: "We are getting to a point where production of these drugs can take place next to the consumer, in his or her own kitchen or in their backyard. Recipes can be found on the internet and many of the so-called 'legal highs' can be made fairly simply.
"The report indicates there is no change in the fact that human beings have an appetite for psychoactive substances, the problem is the way in which they are now being produced completely changes the methods we have to control them. They are much too new and not tested, which means we don't know the effects they have."
The Government plans to bring in temporary banning orders for legal highs. A Home Office spokesman said: "We are committed to tackling new drugs and stopping them gaining a foothold in this country. That is why we have introduced proposals for a system of temporary bans on new psychoactive substances to protect the public while our independent experts assess the harms they pose."
Drug charities have warned that the speed at which new substances are emerging could present challenges for enforcement, education, prevention and health responses. They argue the effectiveness of a banning system would depend on the ability of customs officers to detect new consignments entering the country and on the strength of international cooperation.
The UN estimates that up to 6.2 per cent of the world's population used "illicit substances"at least once in 2009.
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