Chances are, you're carrying cocaine in your wallet. Trace amounts of it, anyway. A new Spanish study finds that paper money around the world is often contaminated with cocaine, LiveScience reports. Though concentrations vary by year and city, US bills had an average of up to 28.8 micrograms of cocaine on them—with some bills topping 1,300 micrograms. In Europe, Spain’s money is the most contaminated, with an average of 155 micrograms. By contrast, it's virtually nonexistent in Ireland.
"These findings should not be surprising, because cocaine and other drugs are traded using cash, which is handled by the same fingers that directly touch the drugs or wrappings," wrote the study’s authors, from the University of Valencia in Spain.