Substance Users Get Creative to Fool Drug Tests

A cat-and-mouse game goes on every day in the American workplace. The mice in this game are drug-using workers or job applicants, and the cats are the hard-pressed drug abuse specialists trying to keep them out of factories, offices, and hospitals and off the highways.

As chemists and pathologists develop more sophisticated tools to test for the presence of drugs of abuse in users, the users seek new ways to outwit them. Naturally, much information on how to beat the tests—some true, some not—is available over the Internet, along with devices and materials intended to deceive the folks back in the lab.

Perhaps 70 percent of large U.S. companies now test for drugs, said Robert Kirkpatrick, M.D., an associate professor of family medicine at the University of Tennessee in Memphis and medical director for workers' compensation at the Tennessee Department of Labor and Workforce Development. He spoke at the university's combined psychiatry/family medicine educational program in June.

Perhaps 20 million Americans are tested for drugs each year, said Kirkpatrick. The bad news is that mice only roll downhill. “Companies that don't drug test get all the users,” he said.

Many companies take their cue from the U.S. Department of Transportation (DOT), which tests truck drivers and other transportation workers for five drugs: marijuana (THC), amphetamine, opiates, phencyclidine, and cocaine. DOT does not test for benzodiazepines, barbiturates, or hydrocodone, but other employers may test for those and other drugs.

“DOT only tests for those five drugs because [DOT officials] decided that these are the most important and because they don't have the capacity to test more,” said Kirkpatrick. “If you want tests for other drugs, you have to ask for them.”

Physicians treating workers' compensation patients should always ask about pending drug or alcohol tests. Regulations vary from state to state, but under worker's compensation laws in Tennessee, for instance, insurance companies won't pay for treatment if the tests are positive, he said. “The exception is that the provider gets paid for any care given before the results are available,” said Kirkpatrick.

To fool the testers, drug users try delay, dilution, adulteration, and substitution.

Just waiting two to four days—if rules permit or if the subject can finagle a delay—may reduce detectable levels of four of the five drugs on the DOT list. Cannabinoids, however, are lipid soluble and so remain in body fat, resulting in detectable levels for at least a month. Pudgy users are at greater risk for longer times than their skinny, faster-metabolizing comrades, said Kirkpatrick. THC is also incorporated in the hair, which can also be tested, although with a technically more difficult process than urine tests.

He doesn't worry about cocaine users' ability to outwit drug testers, however. “They do the drug every day and can't quit long enough to pass,” he said.

Dilution lures other worried test takers.

Drinking lots of water will lower the concentration of drugs or metabolites in urine below threshold levels. However, it will also lower the specific gravity and creatinine levels, raising the suspicions of lab technicians and invalidating the test.

Some users try to disguise the presence of drugs in their urine by adding common household chemicals like salt, vinegar, bleach, lemon juice, Drano, or Visine eye drops to the specimen cup, said Amitava Dasgupta, Ph.D., a professor of pathology and laboratory medicine at the University of Texas at Houston Medical School, who spoke in July at the annual meeting of the American Association for Clinical Chemistry in Washington, D.C. Sometimes the effects of these substances on pH or specific gravity can be detected easily, since lemon juice acidifies the urine, and bleach and Drano raise the pH to over 10. Some commercially available chemical kits can detect some of these adulterants, but more sophisticated immunoassay screens or gas chromatography/mass spectrometer techniques may be needed to detect others.

Finally, some users try to surreptitiously import clean urine into the testing room.

They may “borrow” a (presumably) clean friend's urine, smuggled in a condom taped to the thigh. Alternatively, synthetic or freeze-dried“ clean” urine is available over the Internet for dilution on the spot. Thirteen states have laws prohibiting sale of these products, but federal legislation is needed to put suppliers out of business, said Dasgupta.

To minimize the chance to rehydrate freeze-dried urine, water or at least hot water sources should be eliminated from the area where subjects urinate, he said. Federal guidelines even suggest adding a blue toilet-bowl cleaner to keep an abuser from using the water in the toilet as a source.

A last resort for the male job applicant to fool a directly observing technician combines synthetic urine with a molded, prosthetic penis—available via the Internet in five life-like skin tones.

Presumably, some users get away with some of the fakery some of the time, but Dasgupta is betting on the people in the white lab coats.

“Toxicologists are smarter than drug abusers,” he said.

The U.S. Department of Transportation's Office of Drug and Alcohol Policy and Compliance Web site is<www.dot.gov/ost/dapc/>.▪