Hard drugs have become part of our everyday society – so much so that a significant percentage of people who have never used nevertheless have trace amounts on their very fingerprints, according to a new study.

Thirteen percent of those who had never used Class A drugs in the United Kingdom showed trace amounts of cocaine or a heroin metabolite on their prints, according to the paper in the journal Clinical Chemistry.

By far the more common trace chemical was cocaine – which is likely from currency in common circulation, or from the occasional handshake, said the researchers.

“Believe it or not, cocaine is a very common environmental contaminant – it is well known that it is present on many bank notes,” said Melanie Bailey, a forensic analyst at the University of Surrey, and one of the authors. “Even so, we were surprised that it was detected in so many of our fingerprint samples.”

The unwashed hands of 50 people who had never used the drugs, and 15 regulars who had used cocaine or heroin in the previous 24 hours were tested.

The researchers say they were able to determine a cut-off level to discriminate the non-users’ trace amounts from those of users.

“By establishing a threshold for significant on a fingerprint test, we can give those tested the peace of mind of knowing that whatever the result of the test may be, it was not affected by their everyday activities or shaking hands with someone that had taken drugs.”

The researchers, who were partly funded by the Cambridge-based commercial venture called Intelligent Fingerprinting, which markets a dactyloscopic drug test, contend in a press release that “it’s clear that fingerprint testing is the future of drug testing.”

The same day of the publication of the research paper, Intelligent Fingerprinting announced its international release of its commercial test, which would involve confirmation testing at a Cambridgeshire laboratory using liquid chromatography mass spectrometry.