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Widely-Use EtG Test for Alcohol Unreliable

Cannot Distinguish Between Consumption and Exposure


Updated June 20, 2014

Is Urine Testing Effective?
Peter Dazeley Collection/Photographer's Choice/Getty Images
A widely-used urine test, utilized by drug-testing laboratories to detect alcohol consumption, may be too inaccurate to be reliable, according to an advisory issued by the Substance Abuse and Mental Health Services Administration.

The EtG (Ethyl Glucuronide) test, which has recently come into popular use by many laboratories, is too sensitive to distinguish between actual alcohol consumption and exposure to small amounts of alcohol found in many household and personal hygiene products, the advisory said.

What Is a EtG Test?

The EtG test is a biomarker test that detects the presence of ethyl glucuronide in urine samples. Usually, it is used to monitor alcohol consumption in individuals who are legally prohibited from drinking alcohol by the justice system or restricted from drinking by their employers.

The EtG test is just one of many biomarker tests available to confirm the presence of alcohol in urine samples. These tests are used to document abstinence and detect relapse, but they can also be used in clinical settings to screen for drinking problems, evaluate interventions for alcohol problems and motivate changes in drinking behavior.

The Problem With the EtG Test

The EtG test is sensitive to the presence of any alcohol, even low-levels, and can detect alcohol in the urine several days after consumption. But the test is so sensitive, it can produce a positive test for ethyl glucoronide from the mere exposure to alcohol that is present in many daily use products.

The EtG test came under scrutiny when a significant number of people, who insisted they had abstained from drinking alcohol, failed the test. SAMHSA used many of those protested cases to research the accuracy of the EtG test and determine the cause of the false positives.

What Causes False Positives?

According to SAMHSA's research, positive EtG tests can result from the use of hand sanitizers, medications, hygiene products, cosmetics, foods and other products that contain even small levels of alcohol. People can test positive for alcohol consumption after being exposed to laundry detergent, antiperspirant, aftershave and even hair spray.

There are hundreds of household products that contain ethanol, according to the National Library of Health's Household Products Database, which could possibly cause a false positive with the EtG urine test.

The advisory also said that gender, age, or ethnicity may also affect EtG test results, but more research is needed to find out for sure.

Where It Stands Now

The EtG test is simply not reliable by itself to determine alcohol consumption. According to the SAMHSA advisory:

"Currently, the use of an EtG test in determining abstinence lacks sufficient proven specificity for use as primary or sole evidence that an individual prohibited from drinking, in a criminal justice or a regulatory compliance context, has truly been drinking.

"Legal or disciplinary action based solely on a positive EtG ... is inappropriate and scientifically unsupportable at this time. These tests should currently be considered as potential valuable clinical tools, but their use in forensic settings is premature."

SAMHSA recommends that biomarker tests be used as a tool to launch a more extensive investigation into possible alcohol use, but not as a stand-alone confirmation.

The Role of Biomarkers in the Treatment of Alcohol Use Disorders (PDF), September 2006, Substance Abuse and Mental Health Services Administration

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