Time has an interesting article about how most US money contains traces of cocaine:
A study that tested paper money from 30 big cities in five countries—including the U.S., Brazil, Canada, China and Japan—found that big metropolitan areas in both Canada and the U.S. have an alarmingly high presence of cocaine on their currency, with traces of the narcotic on 85-90% of bills. Brazil, coming in just behind the North American nations, had contamination on 80% of paper money. On the other end of the spectrum, in China and Japan, cocaine was present on a much lower 12-20% of banknotes.
The findings, presented Sunday at a meeting of the American Chemical Society in Washington, D.C., suggest that the prevalence of cocaine-laced bills in U.S. cities has jumped about 20% since just two years ago. University of Massachusetts chemistry professor Yuegang Zuo, the lead author on the current study, conducted a similar analysis in 2007 which found that 67% of U.S. banknotes had some traces of cocaine. The study authors speculate that the increase of residue on bills is likely in step with an increase in cocaine consumption—already as much as a $70 billion annual industry in the U.S., according to the researchers. An estimated 6 million Americans use cocaine each year, consuming somewhere between 259-447 tons of the stuff.
As news goes, the dollar bill-coke connection isn’t new–Snopes breaks down how it works.