From CNN.com:
Research presented this weekend reinforced previous findings that 90 percent of paper money circulating in U.S. cities contains traces of cocaine. Scientists say the amount of cocaine found on bills is not enough to cause health risks.
"When I was a young kid, my mom told me the dirtiest thing in the world is money," said the researcher, Yuegang Zuo, professor of chemistry and biochemistry at the University of Massachusetts Dartmouth. "Mom is always right."
Money can be contaminated with cocaine during drug deals or if a user snorts with a bill. But not all bills are involved in drug use; they can get contaminated inside currency-counting machines at the bank.
"When the machine gets contaminated, it transfers the cocaine to the other bank notes," Zuo said. These bills have fewer remnants of cocaine. Some of the dollars in his experiment had .006 micrograms, which is several thousands of times smaller than a single grain of sand.
Zuo hopes to compile the data from his research to form a drug use map, saying it could provide insights about regional cocaine use.
In his study, the rate of drug-contaminated money varied geographically from urban to less populated areas. A hundred percent of the sample bills collected from major cities such as Miami, Florida; Boston, Massachusetts; and Detroit, Michigan, tested positive for cocaine, but samples collected from smaller cities such as Salt Lake City, Utah; Niagara Falls, New York;and Dearborn, Michigan, had 87 to 67 percent.
Compared with currency from Brazil, Canada, China and Japan, U.S. bills had the highest percentage of cocaine, with 90 percent of 234 bank notes contaminated. Canada followed with 85 percent and Brazil with 80 percent. China and Japan had the lowest, with 20 and 12 percent respectively.
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