There are both direct and indirect markers used to establish alcohol consumption, however indirect markers are less accurate as they can be affected by other factors, such as medication, health issues, and previous alcohol consumption. Direct markers are only produced when a person has consumed alcohol or has increased blood alcohol levels, which ensures accuracy when establishing levels of alcohol consumption.
Alcohol consumption leads to the formation of direct metabolites, such as ethyl glucorinide (EtG), fatty acid ethyl esters (FAEEs), and phosphatidylethanol (PEth). These biomarkers are recognised as direct and specific markers of ethanol.
Ethyl Glucorinide (EtG) is produced through non-oxidative metabolism in the liver and through a reaction that is catalysed by isoenzymes. EtG appears in blood less than 45 minutes after alcohol consumption, and in urine in less than 60 minutes. EtG also accumulates in the hair and this allows for a larger window of time for alcohol consumption detection, enabling EtG to be used as a long-term alcohol marker.
EtG in nails is a specific and sensitive biomarker for the detection of alcohol use, with a sensitivity higher than hair (due to a higher degree of accumulation). Studies have shown a greater percentage of alcohol is absorbed into nails than hair on a per dose basis. As the fingernail grows, alcohol substances pass from the blood vessels located directly below the nails into the keratin fibres where they are trapped. Fingernails are four times thicker than the typical strand of hair, meaning you are often able to capture more of a substance than within hair. Testing nails for alcohol provides a detection period of 3-6 months.
EtG testing is the most reliable hair test when determining the levels of alcohol consumed. The EtG test is designed to show a change in pattern of alcohol consumption. From the time that an individual stops drinking, the levels of EtG in the hair decreases in a linear pattern over 3-6 months. However, there are a number of studies that show chemical treatments and bleaching reduce the levels of EtG from the hair, therefore the results should be interpreted carefully.
Fatty Acid Ethyl Esters (FAEE) hair testing is designed to show a long-term (10 months to 2 years) alcohol consumption habit. It is important to note that from the time an individual stops the consumption of alcohol, the levels of FAEE can rise, before dropping 6-9 months after abstinence has commenced. Regular use of hair cosmetics that contain alcohol can strongly increase FAEEs in hair, which can influence the results to show excessive alcohol consumption.
A basic level of FAEE is measured in everyone’s hair, even of those who are teetotal. FAEE and EtG complement one and other with respect to their different sensitivity to hair cosmetics, for example, false positive FAEE results due to use of hair cosmetics containing ethanol would not be confirmed because the same specimen would have a negative EtG result.
Phosphatidylethanol (PEth) testing is a highly accurate and reliable blood test for alcohol consumption. PEth is only produced when a person has consumed alcohol, meaning it has a sensitivity rate of over 99%. Unlike other blood testing methods, PEth is not affected by medications, illness, previous alcohol consumption, age, or health. When PEth is detected, you can be confident that this is as a result of alcohol consumption.
A PEth test can be carried out by collecting a blood spot/micro sample, making it less invasive than a needle and vial collection. The accepted detection period for PEth testing is up to 30 days (3-4 weeks), however the greater the exposure, the longer the period of detection. Furthermore, multiple binge sessions will also increase the period of detection. In order to generate enough detectable PEth, a person must consume alcohol in a way that raises their blood alcohol concentration level.
A PEth result with a reading of over 20ng/ml or above is equivalent to excessive alcohol abuse, and a result of over 100ng/ml is strong evidence of heavy binge drinking.
DNA Legal and Alcohol Testing
Although all these testing methods are highly accurate and reliable, it is recommended an individual undergoes a combination of tests, for example, both hair and blood testing. By combing two methods of testing, you minimise the chance of a false positive or negative result, heightening the accuracy of the results and providing a clear picture of the level of alcohol consumption. DNA Legal provide blood, hair, and nail alcohol testing. Please get in touch for more information or a quote.