Up To 80% of All US Bills Contain Trace Amounts of Cocaine

In one 1985 study done by the U.S. Drug Enforcement Administration on the money machines in a U.S. Federal Reserve district bank, random samples of $50 and $100 bills revealed that a third to a half of all the currency tested bore traces of cocaine. Moreover, the machines themselves were often found to test positive, meaning that subsequent batches of cash fed through them would also pick up cocaine residue. Expert evidence given before a federal appeals court in 1995 showed that three out of four bills randomly examined in the Los Angeles area bore traces of the drug.

In a 1997 study conducted at the Argonne National Laboratory, nearly four out of five one-dollar bills in Chicago suburbs were found to bear discernable traces of cocaine. In another study, more than 135 bills from seven U.S. cities were tested, and all but four were contaminated with traces of cocaine. These bills had been collected from restaurants, stores, and banks in cities from Milwaukee to Dallas.

http://www.smartmoneydaily.com/news/whats-in-your-wallet-probably-cocaine.aspx