WASHINGTON, Aug. 17 (UPI) -- Cocaine is present in up to 90 percent of paper money in the United States and it may be related to the economic downturn, U.S. researchers said.
Study leader Yuegang Zuo of the University of Massachusetts in Dartmouth tested banknotes from more than 30 cities in five countries and found the United States and Canada had the highest contamination rates, with an average of between 85 percent and 90 percent. China and Japan had the lowest, between 12 percent and 20 percent contamination, Zuo said.
Zuo said a similar study two years ago found 67 percent of U.S. bills contained traces of cocaine.
"I'm not sure why we've seen this apparent increase, but it could be related to the economic downturn, with stressed people turning to cocaine," Zuo said in a statement. "Such studies are useful, because the data can help law enforcement agencies and forensic specialists identify patterns of drug use in a community."
Paper money can become contaminated with cocaine during drug deals and snorting cocaine through rolled bills. Contamination spreads to other money while in currency-counting machines.
The finding was presented at the 238th National Meeting of the American Chemical Society in Washington.