Image: Flickr/Tax Credits

Urban legend has it that “all” of our paper currency is tainted with cocaine. These scientists decided to test whether this is true, and if so, how much of the drug is there. By testing over four thousand bills of various denominations gathered from 90 locations over more than a decade, they estimate that the “average” bill carries only 2.34 ng of cocaine (a tiny, tiny amount), but any given bill has ~15% chance of having more than 20 ng… which is still a tin