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.
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.
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, an EtS or EtG urine alcohol test could show up as a false positive.
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.
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.