News you can use - drug detection

A bit of interesting news from England's University of Surrey

One in 10 people have traces of cocaine or heroin on their fingerprints
Scientists have found that drugs are now so prevalent that 13 per cent of those taking part in a test were found to have traces of class A drugs on their fingerprints - despite never using them.

But, it is possible to differentiate:

Researchers tested fingerprints from the unwashed hands of the drug-free volunteers and, despite having no history of drug use, still found traces of class A drugs. Around 13 per cent of fingerprints were found to contain cocaine and one per cent contained a metabolite of heroin. By setting a "cut-off" level, researchers were able to distinguish between fingerprints that had environmental contaminants from those produced after genuine drug use - even after people washed their hands.

The study is here: Noninvasive Detection of Cocaine and Heroin Use with Single Fingerprints: Determination of an Environmental Cutoff