A study by one of Ireland's leading universities has found that every bank note tested in a sample of notes in circulation was contaminated with cocaine.
The project at Dublin City University's National Centre for Sensor Research used notes sourced at a bank branch in north Co Dublin.
Some drugs groups have said they are not surprised by the findings.
€5, €10, €20 and €50 used notes were withdrawn from a bank in north Dublin to be tested for the study. All 45 notes tested positive for cocaine traces, and three had traces of heroin.
It is a large sample and, though not a quantitative measure, it does give an indication of the degree to which drugs are being used, according to Professor Brett Paull of DCU.
A similar study in the United States showed 65% of dollar notes were contaminated with the drug.
Notes are commonly rolled up and used to snort cocaine. They can also be contaminated as a result of transfer during drug dealing or the counting process in banks.
Anti-drugs group Aisling International says it is not surprised by the findings. Director Maria Byrne says the drug use problem must be addressed urgently and effectively.
