Testing for synthetic urine

What is synthetic urine?

Workplace health and safety legislation places the responsibility on employers to provide a healthy and safe working environment and to identify and manage hazards in the workplace. One part of that responsibility is detecting and managing the risks of drug and alcohol misuse by employees and contractors.

Detecting drug abuse can be complicated by active efforts to defeat the test. Synthetic urine is a fluid designed to be similar to human urine. It is commonly used by drug users to cheat urinary drug tests, whether for mandatory pre-employment checks or routine workplace testing.

Synthetic urine does have legitimate uses, primarily to calibrate the screening equipment used for urine examination, and to assess urine leakage from collection devices and diapers.

How widespread is the problem?

The popularity of synthetic urine rose with the widespread introduction of workplace drug testing in the US, and has led to a large number of products. Common brands available in Australia include QuickFix, Agent X and TestClear, among many others.

Although synthetic urine is similar in composition to human urine, it lacks many of the constituents of real urine. In 2010, testing for these missing constituents led to a marked decline in the use of synthetic urine as cheaters began to get caught. That decline slowly reversed over the next four years as manufacturers improved their products.

Urine substitution is widespread and growing. Validakis (2012), writing in Australian Mining, noted a recurring rise in the practice among miners in the Pilbara. In 2014, Gill, writing in Pacific Business News, noted a sudden and sustained jump in synthetic urine use in Hawaii, from 0.4% of all collected specimens in early 2014 to 0.9% after the third quarter of that year. This has been mirrored by a similar rise in Australia (see also Perallon 2014).

Synthetic urine is easy to buy and cheap, with prices ranging from AU$30 to AU$95. The legal position is also unclear. Many US states have outlawed synthetic urine and Australia may eventually follow, but at present Australian law is not clear on whether selling fake urine is illegal, and possession has not yet been addressed by lawmakers (Kruger 2010, Passmore 2012).

How do we deal with it?

Drug test cheats often try to adulterate their specimens with household chemicals, or to substitute synthetic urine to mislead the test. The vast majority of these cases can be detected by specimen integrity testing.

As Dasgupta (2015) points out, and Pidd et al. (2014) reiterated, five common indices will detect the overwhelming majority of synthetic, adulterated or substituted urine:

1. Temperature. The urine temperature is measured at the time of collection. The Australian Standard AS/NZS 4308 states that the sample should be 33 to 38°C within 4 minutes of collection. Substitute urine products such as SweetPee and Whizzinator come with prosthetic devices to help with substitution, but even the most skilled substitutor would find it difficult to keep the sample at the correct temperature, as AS/NZS 4308 requires, without sufficient prior warning.
2. Specific gravity (SG). SG is the ratio of the density of the urine sample to the density of pure water. It should be between 1.005 and 1.020, and any SG above 1.035 is rejected outright. Measuring SG often detects attempts to adulterate, dilute or substitute the urine. Adding sodium chloride (kitchen salt) is a common, time-honoured adulteration method that interferes with drug screening tests but not confirmatory tests. At concentrations high enough to produce a false-negative screening result, it raises SG above 1.035 and is easily detected.
3. pH. pH, a measure of the sample’s acidity, should always be between 4.0 and 10.0. Most synthetic urines are poorly buffered, so a sample with a pH outside the physiological range, in the absence of significant renal or urinary tract disease, is taken as proof of adulteration or of a cheap urine substitute.
4. Creatinine. Creatinine is a breakdown product of creatine, principally from muscle. In an otherwise healthy adult the concentration is between 10 mg/dL (below 884 µmol/L) and 400 mg/dL (35,360 µmol/L). Many laboratories use a lower cut-off of 15 mg/dL (1,326 µmol/L) to detect synthetic urine, because levels below this are very rare in healthy adults. Many synthetic urines have low creatinine concentrations and are easily detected. A creatinine level that does not match the urinary SG and urea concentration also suggests substitution or adulteration.
5. Uric acid. Uric acid is a breakdown product of nucleic acids and is rarely included in synthetic urines. Undetectable uric acid is almost always proof of synthetic urine (US Substance Abuse and Mental Health Services Administration guidelines 2012; Sterling Reference Laboratories 2013). Some rare clinical conditions, such as hereditary xanthinuria, lead toxicity or folic acid deficiency, are associated with low or undetectable uric acid, but they cause significant medical problems and are easy to diagnose.

Flushing products and adulterants

As well as substituting natural urine with a synthetic analogue, drug test cheats may take commercial products to flush out drugs, or add an adulterant to the specimen immediately after collection.

Flushing products include fluids and tablets that, along with drinking large amounts of water, dilute the urine and push drug concentrations below the reportable threshold. Examples include Absolute Detox XXL drink, Absolute Carbo Drinks, Ready Clean Drug Detox Drink, Fast Flush Capsules and Ready Clean Gel Capsules. These efforts are wasted, because dilution can be detected by testing specific gravity, urea and creatinine, any or all of which may be inappropriately low.

Urinary adulterants are substances added to urine after collection to interfere with drug tests. Examples include Stealth (peroxidase and peroxide), Klear (nitrite), Clean ADD-IT-ive (glutaraldehyde) and Urine Luck (pyridinium chlorochromate).

These products are often not as potent as they claim. Wu et al. (1999) reported that Urine Luck, a popular adulterant containing a strong oxidising agent, affected only EMIT II drug screens and not other commercially available screening assays, such as those used by Safe Work Laboratories. Urine Luck often produces a false-positive amphetamine result on screening tests, which alerts the laboratory that the sample may not be real urine. None of the commercially available adulterants interfere with LCMS confirmatory testing.

Nitrite-containing products such as Klear (potassium nitrite) can interfere with the GC/MS confirmatory test for THC from cannabis, but do not significantly affect LCMS confirmatory methods such as those used by Safe Work Laboratories (ElSohly et al. 1997). Small amounts of nitrite are found in the urine of people with urinary tract infections or taking medications such as nitroglycerin and nitroprusside, but in those cases the concentration is always below 36 µg/mL. In adulterated specimens it is typically above 1900 µg/mL (Urry et al. 1998), which simple spot urine tests easily detect.

Specially designed urine dipsticks such as AdultaCheck 4, AdultaCheck 6 or Intect 7 can detect nearly all commercially available adulterants. They check for oxidants, nitrite, glutaraldehyde (which only affects EMIT II screening immunoassays, not those used by Safe Work Laboratories), pH, and chromate, the principal component of the adulterant Stealth (Dasgupta 2015).

Conclusion

Synthetic urine and adulterants are a growing problem for workplace drug testing programs, but the challenge is not insurmountable. Performing specimen integrity checks properly, collecting samples under controlled conditions and relying on the diagnostic skills of an experienced laboratory can curtail cheating (Pidd et al. 2014).

References

• Dasgupta A. How people try to beat drug testing. Clinical Laboratory News, 1 February 2015.
• Dasgupta A, Wahed A, Wells A. Rapid spot tests for detecting the presence of adulterants in urine specimens submitted for drug testing. Am J Clin Pathol 2002;117:325–9.
• ElSohly MA, Feng S, Kopycki WJ, et al. A procedure to overcome interferences caused by adulterant ‘Klear’ in the GC-MS analysis of 11-nor-D9-THC-9-COOH. J Anal Toxicol 1997;20:240–2.
• Kruger P. Fake urine compromises workplace drug testing. ABC News PM, 16 September 2010.
• Passmore D. Miners use substitute urine kits. news.com.au, 11 November 2012.
• Perallon D. Taking Action investigation: are your employees acing drug tests with fake urine? WHNT News, 24 September 2014.
• Pidd K, Roche AM. How effective is drug testing as a workplace safety strategy? A systematic review of the evidence. Accid Anal Prev 2014;71:154–65.
• Urry F, Komaromy-Hiller G, Staley B, et al. Nitrite adulteration of workplace drug testing specimens: sources and associated concentrations of nitrite and distinction between natural sources and adulteration. J Anal Toxicol 1998;22:89–95.
• Validakis V. New tests target miners using fake urine. Australian Mining, 22 November 2012.
• Wu A, Bristol B, Sexton K, et al. Adulteration of urine by Urine Luck. Clin Chem 1999;45:1051–7.

Source: Safe Work Laboratories.