What Are the Causes of a False Positive in ETS or ETG Alcohol Testing?

Two friends drinking whiskey shots
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Many schools and employers employ drug testing to screen previous alcohol abusers for current alcohol use. Traditional alcohol tests utilize urine or breath samples to directly test for the presence of alcohol in the body. These methods are limited because they can only detect recently consumed alcohol. Newer techniques, such as the EtS and EtG urine tests, measure a product that results from the breakdown of alcohol. These tests are sensitive to alcohol consumed up to 80 hours previously. However, a number of conditions increase the risk of false positives with these tests.

Alcohol-Containing Food and Beverage

Foods containing alcohol or fermented products may cause EtS or EtG urine tests to show positive even if a drink of alcohol has not been consumed. For example, a jug of expired fruit juice may contain enough alcohol to cause a false positive. Some desserts that commonly contain small amounts of alcohol may increase levels of EtS or EtG. Salad dressings or other recipes that use wine vinegar may also trigger a false positive.

Swallowing Mouthwash

Since an EtG measures the level of substances left behind after alcohol is metabolized, it detects alcohol ingestion over a much longer period. Mouthwash commonly contains high amounts of alcohol. This causes false positives in traditional alcohol tests such as a breathalyzer. If small amounts of mouthwash are swallowed or absorbed in the mouth, even many hours ago, an EtS or EtG urine alcohol test could show up as a false positive.

Regular Use of Hand Sanitizer

Some researchers are concerned that common personal care products such as hand sanitizers may trigger false positives in urine alcohol tests. Hand sanitizer contains ethanol, which is the type of alcohol found in alcoholic beverages. Absorption of ethanol into the skin may cause the metabolites of alcohol to be present in the urine, even in the absence of alcoholic beverage consumption. The problem is more acute where someone uses an alcohol-based hand sanitizer every few minutes, such as healthcare professionals. Regular use significantly raises the risk of a positive screen for alcohol.

Cleaning Products

Certain cleaning products, such as cleansing sprays and scrubs, also contain high concentrations of alcohol. People who clean extensively without using protective gloves may experience uptake of small amounts of alcohol through the hands. The alcohol, when broken down, may lead to a false positive urine alcohol test.

How False Positives Occur

All of these products contain ethyl alcohol, which is the same type of alcohol found in alcoholic drinks. Your body breaks down the ethyl alcohol in hand sanitizer exactly the same way as it breaks down the ethyl alcohol in a bottle of gin. The test cannot distinguish between the different sources. Anyone who requires testing should be aware of the alcohol that may be hidden in every day products, and notify the tester if there's any chance that they've absorbed ethyl alcohol through the mouth or skin.

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