Images that show how fingerprints can be used to reveal whether you are a smoker, an avid coffee drinker, or even a hard drug user, have been revealed by UK scientists.

They were produced using a novel forensic technique that could in future be used on fingerprints collected at a crime scene. If the prints in question are not on file, this would still give police a powerful way to shrink their pool of suspects, by identifying their lifestyle habits.

The technique was developed by a team of forensics experts at the University of East Anglia (UEA) in Norwich, and King's College in London, both in the UK.

It exploits the fact that the breakdown products - metabolites - of substances people consume are deposited in sweat found in pores in their fingerprint ridges. To detect these metabolites they use gold nanoparticles.

Washing no defence

The researchers, led by David Russell at UEA, claimed in 2006 that fingerprints could be used in this way (see Fingerprints reveal lifestyle habits. Now they have shown that it works in practice, even shortly after someone has washed their hands.

The team designed a system capable of detecting cotinine, a metabolite of nicotine. This metabolite was chosen because simple contact with a cigarette or tobacco is not enough to produce it.

To detect cotinine, a fingerprint is simply dabbed with a solution containing gold nanoparticles with attached antibodies that bind to the metabolite.

Then a second antibody that binds to the cotinine antibodies and is marked with a fluorescent dye is applied. If the owner of the print is a smoker, shining light on it will reveal a florescent glow along its ridge patterns.

Besides extending the test to antibodies capable of detecting alcohol and illicit drugs, Russell thinks the technique could be used to detect performance-enhancing drug use in sport.

Journal reference: Angewandte Chemie International Edition (vol 46, p 4100)