BBC Future
The Real Risk

Highs and lows of illegal drugs

About the author

David Spiegelhalter is Winton Professor of the Public Understanding of Risk at the University of Cambridge, UK. His professional background is in medical statistics. He is a frequent contributor to the media, and has been an advisor on risk issues as diverse as breast implants, volcanic ash, clinical trials, surgical mortality, and the inquiry into mass murderer Harold Shipman. He is a Fellow of the Royal Society and was awarded an OBE in 2006. You can see more of David’s explorations of risk at the Understanding Uncertainty website, or follow him on Twitter at @undunc

Risks of illegal drug use

(Copyright: Science Photo Library)

Our resident statistician David Spiegelhalter sifts through the data to discover how much is being swallowed, smoked, snorted or injected.

People have taken mood-altering substances in various forms since time began. Remains of opium poppy husks have been found in Neolithic settlements in Europe; natives of South America have long chewed coca leaves as a mild stimulant or to suppress pain; almost everything faintly edible has been fermented to make alcohol.

Drug production went from cottage to factory industry from the late 1820s onwards, with Heinrich Merck’s commercialization of morphine, an extract from opium. This laid the foundation for the pharmaceutical company that still bears his name, Merck. Heroin, also known as diamorphine, was first derived from morphine in St Mary’s Medical School in London in 1874, but rediscovered by the Bayer pharmaceutical company in 1897, and marketed as a non-additive painkiller and cough medicine.   

Meanwhile, cocaine was extracted from coca leaves and found widespread usage: one product available for children in the late 1800s claimed Cocaine toothache drops. Instantaneous cure!  Sigmund Freud was one of many cocaine enthusiasts, as was Sherlock Holmes, much to Dr Watson’s frequent disgust.

User behaviour

From the early 20th century onwards, increasing pressure based on addictive properties of opiates and cocaine saw criminalisation for misuse. Among the many implications and consequences of such measures, it makes it tricky for us statisticians nowadays to find out how much is being swallowed, smoked, snorted or injected.

The 2011 world drug report by the UN Office on Drugs and Crime (UNODC) illustrates this difficulty; the report estimates that between 149 million and 271 million people aged 15-64 years had used an illicit drug at least once in 2009. That’s between 3.3 and 6.1% of the global population. Around 125-203 million were cannabis users (2.8-4.5% of the global population), between 14 and 56 million people (0.3-1.3%) used an amphetamine-style stimulant, 14-21 million (0.3-0.5%) used cocaine, and 12-21 million were opioid users.

The best data on drug use come from developed countries in Europe, North America and Australasia. For instance, the British Crime Survey (BCS) guarantees anonymity when it asks about use of illegal drugs. Responses scaled up to the adult (16 to 59) population of England and Wales show around one in three are estimated to have used illegal drugs in their lifetime, with around 9% using them in the past year. Men are about twice as likely to be users than women, and an unsurprising relationship found between nightclub and pub visits and illicit drug use. I could have told them that for free.

I could also tell them for free that these drugs can certainly be dangerous in the wrong hands: Manchester general practitioner Harold Shipman injected over 200 of his patients with lethal doses of diamorphine (heroin) in his murderous career, before he was finally caught in 1998 due to a clumsy forgery of a will.  And there are numerous famous deaths due to drug overdoses, whether deliberate or not, from Janis Joplin to the Singing Nun.

Death threat

But working out exactly how many people die due to misuse of illegal drugs is difficult: generally a mention on the death certificate means the death is considered as drug-related, even if not solely due to the drug.

Taking the England and Wales figures as an example, there were 1,784 deaths in 2010 from misuse of illegal drugs, without alcohol specifically mentioned, down a bit from preceding years, but double that in 1993. The peak decade is for men in their 30s with 544 deaths in a year, that’s about one for every 680 men in this age band.   Almost exactly half the total deaths (791) were due to heroin or morphine.  Cocaine was associated with 144 deaths, amphetamine 56, while those involving ecstasy (MDMA) fell to only eight after averaging around 50 a year from 2001 to 2008.

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