Alcohol Testing

Alcohol Testing Guide

A source-backed overview of what different alcohol tests are actually measuring: parent alcohol, short-window BAC, and longer-window urine metabolites.

BAC SHORT WINDOW

ETG / ETS RECENT USE

CUTOFFS MATTER

Alcohol tests answer different questions. Breath and blood alcohol measure ethanol itself. Urine EtG and EtS measure metabolites made after the body processes ethanol. They can overlap in time, but they are not interchangeable.

Current Or Very Recent Alcohol

BAC, breath, and blood

BAC is a short-window ethanol measurement. It depends on dose, drink strength, food, timing, sex, body size, total body water, absorption, and elimination. Breath alcohol is related to blood alcohol, but a single result still depends on where the person is on the absorption/elimination curve.

Recent Use Or Abstinence Monitoring

EtG and EtS urine metabolites

EtG and EtS are direct ethanol metabolites. They can remain useful after ethanol itself is gone, so they are commonly used when the question is recent drinking or abstinence monitoring rather than current impairment.

Open EtG calculator Open EtS calculator

Cutoffs

Cutoffs change the meaning

The cutoff is the line a program or lab uses to decide what gets reported. The same measured concentration can be treated differently under different rules.

Lower EtG/EtS cutoffs are more sensitive.
Higher cutoffs reduce some low-level incidental-exposure disputes.
EtS is often paired with EtG, but EtS cutoffs are less standardized.
Confirmation method, specimen timing, dilution, and the ordering program's written rule matter.

References

NIAAA. What Is A Standard Drink?
Defines a U.S. standard drink as about 14 g, or 0.6 fl oz, of pure alcohol and gives beer, wine, and spirits examples.
niaaa.nih.gov
Jones AW (2019). Alcohol, its absorption, distribution, metabolism, and excretion in the body and pharmacokinetic calculations.
WIREs Forensic Science. Review used for BAC pharmacokinetic framing.
doi.org/10.1002/wfs2.1340
SAMHSA (2012). The Role of Biomarkers in the Treatment of Alcohol Use Disorders.
HHS advisory discussing alcohol biomarkers, incidental exposure, and cautions around sensitive tests.
store.samhsa.gov
Walsham NE, Sherwood RA (2014). Ethyl glucuronide and ethyl sulfate.
Advances in Clinical Chemistry 67:47-71. Clinical chemistry review of EtG and EtS as direct ethanol biomarkers.
PubMed
Helander A et al. (2009). Detection times for urinary ethyl glucuronide and ethyl sulfate in heavy drinkers during alcohol detoxification.
Alcohol and Alcoholism 44(1):55-61. Reports multi-day urinary EtG/EtS detection and wide individual variation.
doi.org/10.1093/alcalc/agn084