Urine Tests for Alcohol
"After years of research, Ethyl Glucuronide (EtG) was found to be a direct metabolite of the alcohol (ethanol). EtG has emerged as the marker of choice for alcohol and due to the advances in technologies is now routinely available. Its presence in urine may be used to detect recent alcohol consumption, even after ethanol is no longer measurable using the older methods. The presence of EtG in urine is a definitive indicator that alcohol was ingested. Other types of alcohol, such a stearyl, acetyl and dodecanol, metabolizes differently and will not cause a positive result on an EtG test.
"The EtG test has become known as the “80 hour test” for detecting any amount of consumed ethyl alcohol. This is not totally true. It is true that EtG can be detected in chronic drinkers for 80 hours or even up to 5 days. During this period of chronic use, the EtG level can exceed 100,000 ng/mL. Two primary factors to determine the window of detection is based on volume of alcohol consumed and the time between each drink. A person that consumes 3 drinks can only have a detectable level of EtG for approximately 20 to 24 hours and peaks at approximately 9 hours with an EtG level around 15,000 ng/mL.
"Therefore, the presence of EtG in urine indicates that ethanol was ingested. EtG is a more accurate indicator of recent consumption of alcohol than measuring for the presence of ethanol itself."
Turnage, Jim, "Innovations in Substance Abuse Testing," presented for the State Bar of Texas (Dallax, TX: Forensic DNA & Drug Testing Services, Inc., April 17, 2011), p. 17.