"When it comes to which country's currency contains the most cocaine the United States is No. 1 worldwide, while Spanish notes take the top spot in Europe, a new study finds.

The findings, detailed in the latest issue of the journal Trends in Analytical Chemistry, reflect the popularity of the illicit drug, the researchers say.

"These findings should not be surprising, because cocaine and other drugs are traded using cash, which is handled by the same fingers that directly touch the drugs or wrappings," chemists Sergio Armenta and Miguel de la Guardia from the University of Valencia in Spain write. "Moreover, many cocaine users use a wrapped banknote to sniff this drug, so inducing direct cocaine contamination of the banknotes." "

http://news.xinhuanet.com/english/2008-08/06/content_8991009.htm