A form of high-grade white heroin is making a comeback on Britain's streets, the Serious Organised Crime Agency (Soca) warned today.
Heroin hydrochloride was widespread during the 1970s but was replaced by more well-known "brown" heroin.
Easy to snort and inject because it is water-soluble, white heroin's dangers were made clear in Quentin Tarantino's cult film Pulp Fiction, in which Uma Thurman's character snorts the powder, thinking it is cocaine, and then collapses.
Today Soca warned of a resurgence in the drug in the UK, manufactured and shipped in from Afghanistan.
Deputy director Steve Coates said there had been a few seizures of small amounts of white heroin in the past year but the return of the drug was noticeable.
He said: "We're not panicking but we have noticed the re-emergence of this white heroin which virtually disappeared in the '80s and '90s."
He said there had been seizures overseas in Afghanistan and Turkey, as well as a huge haul last year of £5.5 million worth of heroin, including white heroin, in straws sewn into the weave of Afghan rugs.
Mr Coates, who has been involved in investigating the heroin trade for more than 20 years, said law enforcement agencies had seen a "seismic change" in the supply to the UK.
He said: "I would estimate over 92% of heroin used in the UK and probably throughout Europe comes from Afghanistan.
"Back in the '70s heroin in the UK was mainly Chinese and south-east Asian.
"Heroin hydrochloride was popular. It's water-soluble which means it's easier to inject."
He said as Chinese involvement waned in the early 1980s, the gap in the market was filled by brown heroin from Afghanistan.
"In the early '90s, there was a seismic shift in heroin trafficking to the UK. Turkish-Kurdish groups really got involved," he said.
"When the Turkish criminals started to get involved we saw a real difference - multi-hundred kilo loads, principally from Turkey.
"They were extremely sophisticated consignments in vehicles, in secret compartments or metal trays."
Investigations culminated in the largest ever seizure in 1997 when authorities intercepted a haul of 890lb (404kg) imported in bathrobes from Turkey - a common route from Afghanistan.
In June 2003, 875lb (397kg) was seized in a joint Customs and Excise and National Crime Squad operation.
But Mr Coates said that, despite these successes, heroin hydrochloride posed a new threat.
Overseas seizures in Afghanistan and Turkey suggest large-scale producers have started to manufacture white heroin and export it to the UK.
Mr Coates said Soca is working with partners in the UK and Afghanistan and Turkey to stop the lethal drug reaching the UK.
Soca's aim is to warn police, drugs charities and users of the return of white heroin and its dangers, he said.
He added: "We've identified this as a potential threat.
"We're not over-egging it. We simply want to let partners know we've registered this and to keep it on the radar.
"There's been a definitive change in the market and we can see the way this has moved on. One of our duties is to publicise that."
Gary Sutton, head of drug services at drugs charity Release, echoed Mr Coates's view that the return of white heroin should not bring panic, but awareness.
He said: "I'm not surprised about its resurgence. All it takes is one or two half-decent chemists and you can make heroin.
"In Afghanistan they've got God knows how much opium and brown heroin so just to take it one step further and make heroin hydrochloride seems simple."
He said it was far easier to inject white heroin than brown heroin, as the ritual of "cooking" it was not necessary and it just needed to be mixed with water.
He said the Pulp Fiction scenario could be possible, and snorting white heroin carries a higher risk of overdose than smoking brown heroin.
Mr Sutton said today's users may be less aware than their predecessors.
"I think there's probably not the same level of knowledge. I get the feeling people don't have that same embedded knowledge about the culture, the history and where the drugs come from."
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