Cocaine, heroin found on fingerprints of non-users in England

March 23 (UPI) -- Thirteen percent of non-Class A drug users had traces or cocaine and 1 percent contained heroin on their fingerprints, according to a study conducted in England.

Researchers at the University of Surrey tested the fingerprints of 50 drug-free volunteers and 15 drug users. Their findings were published Thursday Clinical Chemistry.

"Believe it or not, cocaine is a very common environmental contaminant -- it is well known that it is present on many bank notes," Dr. Melanie Bailey, lecturer in forensic analysis at the University of Surrey, said in a press release. "Even so, we were surprised that it was detected in so many of our fingerprint samples."

Although the substances were found on drug-free participants, researchers are hoping their new technique could be used in drug testing instead of other tests, including urine and saliva.

"By establishing a threshold for significance on a fingerprint test, we can give those tested the piece-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," Bailey said.

With a cut-off point for their measurements, researchers were able to distinguish between "normal" environmental contamination and the amount resulting from actual drug use.

Researchers tested fingerprints from unwashed hands of the drug-free volunteers. Around 13 percent of fingerprints contained cocaine and 1 per cent had a metabolite of heroin.

Also tested were washed hands of drug users who said they took cocaine or heroin in the previous 24 hours. Traces were found on 87.5 percent for cocaine users and 100 percents for heroin ones.

The researchers also checked whether drug residue could be transferred via a handshake by asking study participants who had not been exposed to drugs to shake the hands of drug users.

Although cocaine and heroin was transferred by shaking hands with a drug user, researchers established the cut-off level allowed them distinguish between drug use and secondary transfer.

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

The work was funded partly by Intelligent Fingerprinting, a company that has developed a portable fingerprint-based drug screening system that analyzes sweat from a fingerprint.

Intelligent Fingerprinting's CEO, Dr. Jerry Walker, said the study "helps to establish a quantifiable high threshold for environmental drug traces."