Cocaine on your fingerprints

This new drug test is pointless. CNBC:

"New drug test can detect cocaine in a fingerprint in seconds"

A team of researchers has developed a simple paper-based test that can in a matter of seconds detect whether a person has recently been using cocaine.
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The test was 99 percent effective.
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The test could potentially be used in any of the usual situations where drug tests are needed, such as workplaces, legal situations, hospitals and treatment centers.

Well, of course the test is going to be 99 percent effective. Who doesn't have traces of cocaine on their finger tips? If you handle currency, you likely have traceable amounts of cocaine on your finger tips. More on that in a second.

And the test doesn't show, nor does it prove, that the person is using, or has used, cocaine. The only thing the paper-based test proves is that there are traces of cocaine on fingertips.

From CNN:

... 90 percent of paper money circulating in U.S. cities contains traces of cocaine.
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...not all bills are involved in drug use; they can get contaminated inside currency-counting machines at the bank.

"When the machine gets contaminated, it transfers the cocaine to the other bank notes," said [Yuegang Zuo, professor of chemistry and biochemistry at the University of Massachusetts Dartmouth].
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Cocaine binds to the green dye in money, he said.
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[ Adam Negrusz, an associate professor of forensic sciences at the University of Illinois at Chicago], said,  "Many of those bills, over 90 percent, are contaminated with cocaine. There is cocaine dust around the machines. These bank tellers breathe in cocaine. Cocaine gets into system, and you can test positive for cocaine."

This new "simple, paper-based test" raise a litany of legal issues and questions on the invasion of personal privacy (think blood sample taken without consent ). It also widens the already-open doorway on the abusive tactics of asset forfeiture  and property seizure  of people suspected, but not convicted, of any offense.

Additional reading:
The Incarceration of Daniel Chong
Drug-sniffing dogs and false alerts
Reasons for a false-positive cocaine test 
A false-positive tale of terror