Traces of cocaine were found on every euro banknote tested in a recent Irish study.

Credit: iStockphoto

Related articles

• Mathematically mapping music
• Substances in grapefruit juice that interact dangerously with some drugs identified
• Frog fossil spawns 10 million-year-old bone marrow discovery
• Mobile phones reveal maths of human movement
• A briefcase-sized bomb detector

DUBLIN: Traces of cocaine were found on every banknote tested in an Irish study of drug contamination of currency.

Every one of the 45 banknotes in the randomly-selected sample tested positive for trace quantities of cocaine, according to a paper published in the British Royal Society of Chemistry's journal, The Analyst.

"The 100 per cent rate uncovered in this project was surprising," said the researchers, because "the most recent survey carried out in the U.S. showed 65 per cent of dollar notes were contaminated with cocaine.

"Although not a quantitative measure, the presence of illicit substances on banknotes in general circulation provides an indication of the degree to which substances are being used by the community."

The research was carried out by Jonathan Bones and Brett Paull, at Dublin City University's National Centre for Sensor Research. "This is the largest sample of notes ever used in an experiment of this kind in Ireland", Bones said.

Traces of heroin were also detected on three of the notes.

The scientists used a process involving chromatography and mass spectrometry, techniques that enabled them to separate out and identify all substances, including illicit drugs, on the five, 10, 20 and 50 euro notes in the sample. According to the researchers, the cotton structure of the notes absorbs chemical residues, making them relatively easy to analyse.

The study found 62 per cent of the notes were contaminated with cocaine at concentrations greater than two nanograms (two billionths of a gram) per note, with five per cent of the notes showing levels more than 100 times higher. The researchers suspect that these high levels indicate direct use of the note in either drug dealing or drug inhalation.

The residues in the remainder of the notes, which showed only "ultra-trace quantities of cocaine", were most probably the result of contact with other contaminated notes, the researchers said. The contact could have occurred within bank counting machines or from other contaminated surfaces.

The highest amounts of cocaine residues were found on 20 and 50 euro banknotes, with small traces present on the five and 10 euro notes.