Over 10% of people who don't use drugs have traces of cocaine and heroin on their fingertips

Drugs like cocaine are incredibly prevalent in some cultures.
So much so, they can end up on the hands of people who have never touched drugs before.
New research from the University of Surrey has found that over one in 10 people has traces of cocaine and heroin on their fingers.
The traces can come from bank notes, surfaces, and other people's hands.

Recreational drugs are everywhere. In large cities and small towns, people find ways to use drugs on a regular basis, despite laws prohibiting against it and law enforcement desperately trying to crack down on dealers.

Drugs like cocaine are so prolific in society that some research has shown that they can end up on the fingers of people who have never touched them.

A new study, published in the journal Clinical Chemistry, found that trace amounts of cocaine and heroin were present on the fingers of drug free volunteers.

The researchers from the University of Surrey recruited 50 people who had never touched drugs, and 15 people who said they had taken cocaine or heroin in the past 24 hours.

About 13% of people who didn't use drugs had tiny amounts of cocaine on their fingers, and about 1% contained a substance associated with heroin.

Rather than thinking the volunteers were lying about their drug use, the researchers tested whether it was possible to transfer drugs through the environment. Drug free volunteers were asked to shake hands with a drug users, which showed how the substances could be transferred that way.

By testing the drug users as well, the team were able to create a forensic fingerprint for the drugs. This meant they could distinguish between environmental contamination and genuine drug use. Also, while people who don't use drugs merely had traces on their skin, users secreted the substances and byproducts through their sweat.

In 2011, research from the Home Office found that 11% of banknotes were contaminated with cocaine. Other research has found that every bank note in the UK is contaminated with cocaine within the first few weeks of entering circulation.

"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 lecturer in forensic analysis at the university and one of the authors of the study. "Even so, we were surprised that it was detected in so many of our fingerprint samples."

Another author, Mahado Ismail, said it's clear that fingerprint testing is the future of drug testing.

"There are many factors that set fingerprint testing apart," he said. "It's non-invasive, easy to collect and you have the ability to identify the donor by using the sample. Our study will help to add another robust layer to fingerprint drug testing."