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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 anyone who’s seen the Johnny Depp movie Blow knows, bills are often contaminated when they are rolled up and used to snort cocaine. (According to the study, bills for $5, $10, $20 and $50 tended to have higher amounts of cocaine compared to $1 and $100 notes.) But, as the prevalence of drug-dusted dollars conveys, it isn’t just people snorting and selling cocaine who might have some residue in their wallets. Once a small amount of the substance is introduced, it can spread among bills as they intermix in cash registers, day to day transactions, and bank counting machines, meaning, if you live in a city, you’ve probably had a laced bill mingling with your money at some point. Yet, don’t worry, you’re not likely to face any legal trouble or fail any company drug tests as a result: the amounts of cocaine found on bills ranged from a minuscule .006 micrograms to 1,240 micrograms—an amount comparable in weight to about 50 grains of sand, according to the researchers.