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 tiny amount, but it’s there! Um… yay?!
The quantitation of cocaine on U.S. currency: survey and significance of the levels of contamination.
“It has long been suspected that the illicit distribution of cocaine in the United States has led to a large-scale contamination of the currency supply. To investigate the extent of contamination, 418 currency samples (4174 bills) were collected from 90 locations around the United States from 1993 to 2009. The extent of their cocaine contamination was quantitated via gas chromatography/mass spectrometry or liquid chromatography/mass spectrometry. The level of cocaine contamination was determined to average 2.34 ng/bill across all denominations ($1, $5, $10, $20, $50, and $100). Levels of cocaine contamination on currency submitted to the Federal Bureau of Investigation Laboratory in criminal cases over the 1993-2001 timeframe had significantly higher contamination than currency in general circulation. A mathematical model was developed based on the background survey that indicates the likelihood of drawing a bill in specific concentration ranges. For example, there is a 0.8349 likelihood that random bill will have contamination less than 20 ng.”