More than one in 10 people who have never used class A drugs may have traces of cocaine or heroin on their fingertips, forensic scientists say. The scientists believe the participants became contaminated from banknotes, tables and other surfaces, as reported in the journal Clinical Chemistry.

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More than one in 10 people who have never used class A drugs may have traces of cocaine or heroin on their fingertips, forensic scientists say. The scientists believe the participants became contaminated from banknotes, tables and other surfaces, as reported in the journal Clinical Chemistry.