Drug dealers and users handling cash have tainted the nation's supply of dollar bills with microscopic amounts of cocaine. A test of 24 bills collected at random in Orange County, both crisp and tattered and ranging in denomination from $1 to $100, found minute amounts of cocaine had accumulated on each, the Orange County Register reported. The newspaper said the Toxicology Testing Service Inc. in Miami, which performed the tests, has found that cocaine-contaminated currency is prevalent throughout the country. "At least 10 out of 11 bills anywhere we tested had cocaine," technician Terry Hall said. Steven Fike, a technician at the U.S. Customs lab in San Francisco, said cocaine residue appears on at least 70% of the bills he tests, an increase from 10% to 15% three years ago. Cocaine most commonly accumulates on $20 bills, which rarely contain more than 75 to 100 micrograms, Fike said, adding that a user would have to lick 10,000 $20 bills to receive any effect.