Next time you see someone sniffing a $20 dollar bill, that's probably why:
it would seem from a new analysis of 234 banknotes from 18 U.S. cities that found cocaine on 90 percent of the bills tested.
What might be more surprising is the fact that the percentage of contaminated bills seems to be rising; just two years ago, Zuo did a similar study that found cocaine on only 67 percent of banknotes in Massachusetts. "It is too early to draw a conclusion about why," Zuo says. "The economic downturn may partly contribute to the jump.
Levels of cocaine ranged from .006 micrograms to more than 1,240 micrograms—the equivalent of 50 grains of sand—on U.S. bills, and $5, $10 and $20 bills on average carried more contamination than $1 or $100 bills.