Issue Date: September 8, 2008
To Catch A Cheat
EAGER JOB CANDIDATES who receive an offer of employment might feel as though they have won an Olympic gold medal—especially when they are asked to provide a sample for a drug test. And just like at the Olympics, some test subjects will try to beat the system.
But unlike at the Olympics, where officials test athletes for performance-enhancing substances (C&EN, Aug. 11, page 25), workplace drug tests are performed to identify those whose use of illicit substances may impair their job performance and create liabilities for their employers.
According to Amitava Dasgupta, professor of pathology and laboratory medicine at the University of Texas Medical School, Houston, many products are on the market that prospective employees can use to dilute, substitute, or adulterate their test samples. In a talk at the annual meeting of the American Association of Clinical Chemists in Washington, D.C., in late July, he advised laboratory chemists to be vigilant in their pursuit of valid test results. "Toxicologists are smarter than drug users," he said, but they need to know the tricks of the trade.
President Ronald Reagan started the drug-testing arms race in 1986 when he issued an executive order directing federal agencies to achieve a drug-free workplace. Since then, all federal agencies have followed the mandatory guidelines of the Federal Drug-Free Workplace programs administered by the Department of Health & Human Services (DHHS). The guidelines cover testing for marijuana, cocaine, opiates, amphetamines, and phenylcyclohexylpiperidine (PCP).
Many private employers use similar procedures to create a drug-free workplace. In a survey by the Society for Human Resource Management (SHRM), 84% of employers said they conduct preemployment drug testing.
According to R. H. Barry Sample, director of science and technology in the employer solutions division of Quest Diagnostics, a leading test firm, federally mandated test programs currently require the use of urine samples. DHHS has drafted revised regulations that would permit hair and saliva collection, but they are not yet in effect. Almost 90% of drug tests performed by Quest are on urine samples, and saliva tests are the second most common.
Many products that enable cheating target urine tests. Easily found on the Internet, they are marketed under names such as Urine Luck, Ultra Klean Detox Drink, Power Flush, Tinkle, and the Wizzinator.
In his talk Dasgupta described how most methods for cheating on drug tests focus on the first of two testing hurdles—the initial quick-result screening test. The screen is an immunoassay, similar to the at-home drug screens available at many pharmacies. Usually, test administrators at sample collection sites send only nonnegative results to a lab for confirmation testing by gas chromatography/mass spectrometry.
The hundreds of products marketed to help drug users circumvent urine drug tests fall into three main categories: products that are consumed prior to the test, products that are added to the test sample, and devices for smuggling synthetic or borrowed "clean" urine into the testing facility. Toxicologists focus on the first two because, as Sample pointed out, "if it's someone else's urine, there is not a lab test in the world that would tell you that."
Spectrum Labs' Aqua Clean effervescent tablet, available from detoks.com, is a consumable product that claims to clean the body of drugs and drug metabolites. Like all similar products, it requires the user to drink a vast quantity of water, between 40 and 60 oz, in a short amount of time. Dasgupta's examination of these products has shown they are nothing more than expensive caffeine pills, diuretics that create a lot of urine and dilute drug content to below the screening cutoff values.
IN ADDITION to lowering the concentration of drugs in the urine, however, the excess water also decreases creatinine levels to below 20 mg/dL and specific gravity to less than 1.003, both key indicators of a diluted specimen. Creatinine is a breakdown product of creatine from muscle tissue, and in healthy people it is excreted by the kidneys at a constant rate. Dasgupta recommended creatinine and specific gravity tests on all samples and suggested that lowering drug cutoff values on the screening test would catch most dilutions.
Test takers also try to beat the immunoassays by adding adulterants—including common household chemicals—to their urine sample. Drano drain opener, for example, inactivates the antibodies used in the screen. Table salt, vinegar, and liquid soap can all interfere with the enzyme-multiplied immunoassay technique and the fluorescence polarization immunoassay.
The collection site and laboratory can detect samples contaminated with "do it yourself" adulterants, Dasgupta said, by ensuring that the temperature is between 90.5 and 98.9 ºF, specific gravity is between 1.005 and 1.030, and pH is between 4.0 and 10.0. A common adulterant is plain tap water, so labs should ensure that creatinine concentration is 20–400 mg/dL. If the test sample does not meet the criteria, then it would be considered invalid, likely resulting in the employee not being hired.
On the Internet other adulterants are available that Dasgupta acknowledged are "very tricky." He commonly sees two types. One product, Urine Luck, comes in small tubes and contains the active ingredient pyridinium chlorochromate (PCC) to reduce the response rate of tests for opiates and THC (marijuana). The other, marketed as Klear, consists of white crystalline potassium nitrite. These oxidizers are most effective on tests for THC. "They are very strong oxidizing agents. They destroy the drug molecule so you can cheat the drug test in both the screening and the confirmation," Dasgupta said.
Dasgupta reassured the clinical chemists in the audience that simple spot tests can identify the oxidizers. The addition of a few drops of hydrogen peroxide to PCC-adulterated urine creates a dark brown precipitate. To detect nitrite he suggested adding a small amount of the suspect sample to potassium permanganate solution and then adding a few drops of hydrochloric acid. The pink permanganate solution will immediately become colorless and effervescent if nitrite is present.
Because most negative samples are not sent to the laboratory for confirmation testing, companies such as Sciteck Diagnostics have found a market niche for instant test strips that detect urine adulteration. The company makes several versions of AdultaCheck test strips in various combinations to check creatinine and pH levels, as well as nitrites and other commercial additives.
Data from Quest Diagnostics show that positive drug test results have decreased by 72% since 1988, when workplace testing became common. Experts attribute this reduction to the deterrent effect of the tests rather than successful cheating; habitual drug users shy away from applying for jobs that require testing.
According to Quest's Sample, the data also show that over the past six years, the number of invalid and adulterated samples has remained constant at about 0.15%. That figure does not include altered samples that show a positive result despite the best efforts of the donor. "With adulterants, not everything is effective," Sample said. "Even in the case of oxidants, they are only effective against the detection of marijuana and have no impact on amphetamines, cocaine, or PCP."
Because of the possibility of cheating, employers who want to ensure a drug-free workplace should work closely with their diagnostics labs and take advantage of new testing methods, Sample advised.
IF EMPLOYERS are concerned about substituted or synthetic urine, they should consider hair or saliva testing because sample collection can be observed, whereas sample collection for urine tests is usually not monitored. One notable benefit of hair tests is that drug residue stays in the hair shaft for 90 days, a far longer residence time than in urine.
Robert G. Miller, director of human resources for the Greater Los Angeles County Vector Control District, a pest control agency, agreed that hiring companies depend heavily on the expertise of their diagnostics lab partners. "Employers are not experts in drug testing and should not be," he said. Miller's agency works with hazardous pesticides and thus requires a safe working environment. "We are extremely dependent on the industrial lab," he said. Miller suggested visiting the diagnostic lab's facility to see how the testing is done and to review security procedures.
In his role as a member of SHRM's Employee Health, Safety & Security Panel, Miller advises human resource managers about the necessity of providing a drug-free workplace. "The point of preemployment testing is to ensure that you are not buying a liability and to weed out those individuals that might have a propensity to drug use, which could lead to accidents on the job."
Although today's employers focus on controlling liability insurance and absentee worker costs, Miller sees a future for tests that monitor the lifestyles of prospective employees. "Anything external to the organization—tobacco, alcohol, and drug use that affects the employee's wellness—may be something that employers restrict in hiring," he said. Employers who offer health benefits have a vested interest in showing they have healthy employees, Miller said. "The line is going to get a little blurred on the responsibility of employees for their own private habits," he predicted.
As trends in employee drug testing change, so will the market for products aimed at helping drug users avoid detection. Quest's Sample continually monitors the Internet to stay abreast of the latest technologies. "That means Googling to find out what's new, obtaining those products, and testing them to see what impact they have. We need to know what else is going on out there," he said.
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