Debunking the “cocaine on 100% of Irish banknotes” story

BBC: Cocaine on ‘100% of Irish euros’:

One hundred percent of banknotes in the Republic of Ireland carry traces of cocaine, a new study has found.

Researchers used the latest forensic techniques that would detect even the tiniest fragments to study a batch of 45 used banknotes.

The scientists at Dublin’s City University said they were “surprised by their findings”.

Also at RTE, Irish Examiner,,, even at Kazakhstan’s KazInform.

This story is (of course) being played widely in the media as “OMG Ireland must use more coke than anywhere else” — in particular, in comparison with a previous study in the US:

The most recent survey carried out in the US showed 65% of dollar notes were contaminated with cocaine.

The DCU press-release has a few more details:

Using a technique involving chromatography/mass spectrometry, a sample of 45 bank notes were analysed to show the level of contamination by cocaine. …

62% of notes were contaminated with levels of cocaine at concentrations greater than 2 nanograms/note, with 5% of the notes showing levels greater than 100 times higher, indicating suspected direct use of the note in either drug dealing or drug inhalation. … The remainder of the notes which showed only ultra-trace quantities of cocaine was most probably the result of contact with other contaminated notes, which could have occurred within bank counting machines or from other contaminated surfaces.

However, looking at an abstract of what I think is the paper in question, Evaluation of monolithic and sub 2 µm particle packed columns for the rapid screening for illicit drugs — application to the determination of drug contamination on Irish euro banknotes, Jonathan Bones, Mirek Macka and Brett Paull, Analyst, 2007, DOI: 10.1039/b615669j, that says:

A study comparing recently available 100 × 3 mm id, 200 × 3 mm id monolithic reversed-phase columns with a 50 × 2.1 mm id, 1.8 µm particle packed reversed-phase columns was carried out to determine the most efficient approach … for the rapid screening of samples for 16 illicit drugs and associated metabolites. … Method performance data showed that the new LC-MS/MS method was significantly more sensitive than previous GC-MS/MS based methods for this application.

My emphasis. I’d guess that that means that comparing this result to banknote-analysis experiments carried out elsewhere using different methods is probably invalid — perhaps this method is more efficient at picking up ‘contact with other contaminated notes, which could have occurred within bank counting machines or from other contaminated surfaces’, as noted in the DCU release?

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  1. Posted January 11, 2007 at 17:57 | Permalink

    Surely, regardless of the testing method, 45 notes is a ludicrously small sample? There must be millions of notes in circulation after all.

    No-ones denying that Ireland is awash with coke, but I dont think this survey definitively proves anything.

  2. ben
    Posted January 11, 2007 at 18:30 | Permalink
  3. Posted January 11, 2007 at 18:44 | Permalink

    wow, Ben, good link ;)

    ‘In another study, more than 135 bills from seven U.S. cities were tested, and all but four were contaminated with traces of cocaine. These bills had been collected from restaurants, stores, and banks in cities from Milwaukee to Dallas.’

    that’s 97% right there…

    also, discussion of the counting-machine issue:

    ‘When a cocaine-contaminated bill is processed through a sorting or counting machine, traces of the drug are easily passed to other bills in the same batch. ATMs serve to spread tiny amounts of cocaine to nearly all the currency they distribute, as do the counting machines used in banks and casinos.

    In one 1985 study done by the U.S. Drug Enforcement Administration on the money machines in a U.S. Federal Reserve district bank, random samples of $50 and $100 bills revealed that a third to a half of all the currency tested bore traces of cocaine. Moreover, the machines themselves were often found to test positive, meaning that subsequent batches of cash fed through them would also pick up cocaine residue. […] It takes only one bill to contaminate hundreds or even thousands of others, so the number of bills that have actually come into direct contact with the drug trade is far smaller than we might first assume upon seeing that “four of five” claim marked as true.’

  4. David Malone
    Posted January 11, 2007 at 20:09 | Permalink

    Fun calculation. One page on the Irish Central Bank web site says they had issued 145 million Euro bank notes.

    145000000×0.62x(0.95+100*0.05)x0.000000002 = 1.07g

    So, that’s between 1 gram and 100 grams if you collect all the Euro bank notes that have been issued.

  5. Posted January 16, 2007 at 14:56 | Permalink

    Justin, I think you are blatantly and irresponsibly using the facts to get in the way of a good story. You know some people have to make a living writing this stuff?

  6. ben
    Posted January 16, 2007 at 20:34 | Permalink

    “Facts are meaningless, you can use facts to prove anything that’s remotely true” — H. Simpson.

  7. greg
    Posted January 16, 2007 at 23:21 | Permalink

    I think the whole issue could be sidestepped if we could just teach people to not stick things in their noses…

    […]”ATMs serve to spread tiny amounts of cocaine to nearly all the currency they distribute, as do the counting machines used in banks and casinos.” […]

    And just as I thought… those damned banks and casinos are behind the cocaine problem!

    OK, coming off my lunch induced high, years ago I had the job of generating stacks of charts showing production output of a major US semicoductor company that has since managed to find themselves in Dilbert comics and “The Dilbert Principle” multiple times, and run themselves into the ground. Those charts went to the heads of Moto… uh… the company and on to corporate headquarters. I was asked many times to change data points that seemed suspicious. Later I learned “suspicious” meant the data was at odds with the story some manager wanted to tell. I’d refuse to change it of course, because I’d rather be right than employed, but would eventually be told if I wouldn’t change the data then at least change the axis so the data would either look like it was in-range, or was outside the axis where it was clipped and not so embarassing.

    That’s when I decided statistics and charts were usually a persuasion tool used by politically-minded people as a way of selling their hooey instead of a way to accurately visualize data and reveal trends or problems or maybe even solutions out of the problems.

    Nowdays I distrust numbers tossed out casually because there’s almost always some missing critical info that would reveal how bogus the information is.

    Finally, my favorite quote that applies to statistics these days is, “I reject your reality and substitute my own!”, as commonly said on “MythBusters”.