Cocaine contamination of banknotes: a review.

Background: The analysis of drug traces on banknotes with different validated techniques can provide important information about the types of substances that are used in a geographical region. The aim of our review was to investigate banknotes' contamination by cocaine, by its metabolite, but also by other drugs.

Methods: A systematic literature search (English written literature) was conducted in MEDLINE, and Scopus, collecting studies from 1974 till 2017. The Key search terms included: 'banknote AND drug'; 'banknote AND cocaine'.

Results: The literature search yielded 88 publications; 9 were included in our review. In six studies that showed banknotes' positivity to cocaine, the percentage ranged from 2.5% to 100%. The concentration of cocaine ranged from 0.09 ng/note to 889 µg/note. Benzoylecgonine was indentified only in three studies with a range from 0.71 to 130 ng/note. Other indentified drugs were: amphetamine derivatives, opiates, benzodiazepines.

Conclusions: Circulating banknotes could be used to indicate substances used in a population, and those recently introduced in a geographical macro-area. The identification of very high amounts of cocaine can provide important information for the identification of banknotes used in illegal trafficking.