HARTFORD, Conn. -- Most people have heard the phrase "dirty money," but probably aren't aware of just how dirty cash is.

Channel 3 gathered cash from several Connecticut locations: a grocery store, a coffee shop and gas station -- and had the bills -- ones, fives, a 10 and 20 -- tested for cocaine.

Dr. Fred Smith at the University of New Haven has made his career out of drug testing and used a basic method to test the bills for cocaine.

Smith rubbed the bills with a detection stick, which looks much like a pregnancy test. If the stick shows one line, it means no drugs were detected, two lines means that there are at least 50 nanograms of cocaine.

Smith said a nanogram is about the size of a pinhead if the pinhead were split into a million pieces.

Four out of the nine bills tested by Channel 3 came pack positive for cocaine. The tests reinforce other experts' findings, including a Dartmouth study from last year.

"The drug likes to stick to the fibers in money, and passes easily from bill to bill," Smith said. "It's virtually impossible to get high from the amount that's on the bills."

Still, Smith said even one nanogram can show up on a hair drug test.

He said cocaine can be found on more than just cash.

"We're probably touching objects contaminated with cocaine every day without knowing it," Smith said.

One of Smith's graduate students tested shopping cart handles, ATM machines and gas pumps, and said most of them did show traces of the drug.

Experts said the findings point to the prevalence of cocaine abuse today.

"It makes you think that drugs have taken over the whole culture," said Karen Kearns, of Middletown.

Smith said that drugs such as meth and some opiates are also commonly found on money because they stick easily to the paper.