A fingerprint test has been developed to detect cocaine use that cannot be faked, scientists have announced.
Researchers led by the University of Surrey say the test is more hygienic, non-invasive and could lead to the introduction of portable drug tests for police within the next 10 years.
It is the first time a test has been developed to detect the ingestion of cocaine, rather than just touched.
Lead author Melanie Baile said: "When someone has taken cocaine, they excrete traces of benzoylecgonine and methylecgonine as they metabolise the drug, and these chemical indicators are present in fingerprint residue.
"For our part of the investigations, we sprayed a beam of solvent onto the fingerprint slide (a technique known as Desorption Electrospray Ionisation, or DESI) to determine if these substances were present. DESI has been used for a number of forensic applications, but no other studies have shown it to demonstrate drug use."
Published in the journal Analyst, the test used a technique called mass spectrometry to analyse the fingerprints of patients attending drug treatment services.
They tested participants fingerprints against saliva samples (the common method of detection) to see if the tests correlated. Findings showed a good match between the tests and the authors believe their findings provide "exciting opportunities" for the use of fingerprints as a new and secure method of drug detection.
Traditional testing methods for drug use have several limitations – blood tests require trained staff, urine tests have privacy concerns, while biological hazards mean samples must be stored and disposed of properly. They also need analysis off site.
Bailey said: "The beauty of this method is that, not only is it non-invasive and more hygienic than testing blood or saliva, it can't be faked. By the very nature of the test, the identity of the subject is captured within the fingerprint ridge detail itself.
"We are only bound by the size of the current technology. Companies are already working on miniaturised mass spectrometers, and in the future portable fingerprint drugs tests could be deployed. This will help to protect the public and indeed provide a much safer test for drug users."