Most laboratories flag ethyl sulfate (EtS) as positive at a cutoff of 25 ng/mL in urine, and levels well above that threshold, particularly in the hundreds or thousands of nanograms per milliliter, are generally considered high. But the number alone does not tell you much without knowing when the sample was collected relative to the last drink, how much alcohol was consumed, and which cutoff a particular program has chosen to apply. Unlike a cholesterol test where fixed ranges apply to everyone, EtS interpretation depends heavily on context, and the field has yet to settle on a single universal standard for what counts as “high.”
The Cutoffs Laboratories Actually Use
The most widely referenced positivity cutoff for urinary EtS is 25 ng/mL. This is the threshold used, for example, in studies of alcohol-dependent outpatients and liver disease patients, where detecting even small amounts of recent drinking matters clinically.1Alcoholism: Clinical and Experimental Research. Sensitivity and Specificity of Urinary Ethyl Glucuronide and Ethyl Sulfate in Liver Disease Patients Some programs raise the bar. One large study of professionals in health monitoring programs examined EtS at cutoffs of 25, 50, 75, and 100 ng/mL, finding that the higher cutoffs reduced the chance of catching incidental alcohol exposure at the cost of missing some genuine drinking episodes.2PubMed Central. The roles of phosphatidylethanol, ethyl glucuronide, and ethyl sulfate in identifying alcohol consumption among participants in professionals health programs
What this means in practice is that if your EtS result is below 25 ng/mL, most labs will report it as negative. A result between 25 and roughly 100 ng/mL sits in a gray zone: it could reflect light drinking, delayed clearance from a heavier episode a day or two earlier, or even heavy use of ethanol-containing consumer products. Results in the hundreds of ng/mL and above are much harder to explain away and point strongly toward beverage alcohol consumption.
A persistent frustration in this area is the lack of formal, universally adopted guidelines. Researchers have noted the absence of clear standards for interpreting EtS concentrations, especially regarding the threshold above which a test should be considered definitively positive for alcohol use.3PubMed Central. Ethylglucuronide and Ethyl Sulfate Assays in Clinical Trials, Interpretation and Limitations: Results of a Dose Ranging Alcohol Challenge Study and Two Clinical Trials Different treatment centers, court monitoring programs, and transplant centers may apply different cutoffs depending on how aggressively they want to screen.
What Levels Look Like After Actual Drinking
To understand whether a given EtS result is “high,” it helps to know what the body actually produces after someone drinks. When you consume alcohol, your liver metabolizes most of it through oxidation. A tiny fraction, less than about 0.1 to 0.2% of what you drank, gets converted through a different pathway into metabolites like ethyl glucuronide (EtG) and ethyl sulfate (EtS).4WIREs Forensic Science. Alcohol, its absorption, distribution, metabolism, and excretion in the body and pharmacokinetic calculations EtS is produced when an enzyme called sulfotransferase attaches a sulfate group to the ethanol molecule.5PubMed Central. Nonoxidative ethanol metabolism in humans—from biomarkers to bioactive lipids Despite being a small fraction of the total, this is more than enough to measure with modern lab equipment.
In a controlled study where healthy volunteers drank a moderate amount of alcohol, average urinary EtS concentrations peaked around five hours after drinking began, with mean peak levels in the hundreds of micromoles per liter range. There was wide individual variation; some people produced much more EtS than others from the same dose.6PubMed. Kinetics in serum and urinary excretion of ethyl sulfate and ethyl glucuronide after medium dose ethanol intake Another study measured urinary EtS concentrations at various time points after drinking and found averages of about 4,770 ng/mL at 30 minutes, climbing to roughly 30,140 ng/mL at four and a half hours.7Alcohol and Alcoholism. Ethyl Glucuronide and Ethyl Sulphate in Urine: Caution in their use as markers of recent alcohol use Those numbers dwarf the 25 ng/mL cutoff, which illustrates why the test is so sensitive at detecting recent drinking.
Dose matters a great deal. Volunteers who consumed four standard UK units of alcohol had median peak urinary EtS output of 1.3 mg per hour, while those who consumed eight units peaked at 3.5 mg per hour, nearly three times as much.8Alcohol and Alcoholism. Measurement of Ethyl Glucuronide, Ethyl Sulphate and Their Ratio in the Urine and Serum of Healthy Volunteers after Two Doses of Alcohol A study of Japanese adults confirmed this dose-dependent pattern: high-dose participants exceeded standard international cutoffs in their 24-hour urine, while low-dose participants remained below the quantification limit entirely.9Drug Testing and Analysis. Forensic implications of ethyl glucuronide and ethyl sulfate pharmacokinetics in Japanese adults: the influence of dose, genetic polymorphisms, and habitual alcohol consumption Together, the amount of alcohol consumed and the time since the last drink explained about 62% of the variance in serum EtS levels in one study.10PubMed Central. Value of Ethyl Glucuronide and Ethyl Sulfate in Serum as Biomarkers of Alcohol Consumption
Why a “High” Number Is Not Always What It Seems
A result of, say, 5,000 ng/mL collected three hours after someone had several drinks is entirely expected and does not necessarily indicate heavy chronic drinking. That same number collected more than 24 hours after the last reported drink would be far more concerning, because EtS typically clears the body within a day or so of moderate drinking. The peak urinary concentration is reached within roughly three to six hours after drinking starts, and concentrations decline steadily after that.
This timing dependence is one reason why individual EtS results cannot be neatly mapped to a specific number of drinks. Peak serum concentrations of EtS showed wide variation between individuals even when they all drank the same amount, and the peaks did not correlate well with their blood alcohol concentrations.6PubMed. Kinetics in serum and urinary excretion of ethyl sulfate and ethyl glucuronide after medium dose ethanol intake Two people can drink identical amounts and produce very different EtS levels. A modeling study explored whether pharmacokinetic calculations could estimate the dose from the EtS concentration, but the wide parameter ranges involved make this an approximation at best.11PubMed. Computer assisted modeling of ethyl sulfate pharmacokinetics
Incidental Exposure Can Produce Low-Positive Results
One of the most common concerns about EtS testing is whether everyday products containing ethanol, like mouthwash or hand sanitizer, can trigger a positive. The answer is yes, but generally at low levels. In a study where ten volunteers gargled with a high-alcohol mouthwash (Listerine) four times daily for more than three days, EtS was detected in seven of them. The maximum concentration reached was 104 ng/mL, and only three participants produced results above 50 ng/mL.12Journal of Analytical Toxicology. Ethyl Glucuronide, Ethyl Sulfate, and Ethanol in Urine after Intensive Exposure to High Ethanol Content Mouthwash
Hand sanitizer produced a similar picture. Eleven volunteers applied an ethanol-based hand sanitizer every five minutes for ten hours on three consecutive days. The highest EtS concentration observed was 84 ng/mL.13PubMed. Ethyl glucuronide, ethyl sulfate, and ethanol in urine after sustained exposure to an ethanol-based hand sanitizer These are extreme exposure scenarios, far beyond typical daily use, yet the EtS levels still stayed below what you would expect from even modest beverage alcohol consumption. This is part of why higher cutoffs of 50 or 100 ng/mL are sometimes preferred in programs where incidental exposure is common: they reduce the risk of calling someone positive for drinking when they simply used too much hand sanitizer.
A helpful way to think about it: EtS levels from consumer products tend to stay in the double digits (ng/mL), while levels from a few drinks easily climb into the thousands or tens of thousands of ng/mL at peak. An EtS result in the low hundreds could be ambiguous, but results above a few hundred ng/mL are very difficult to attribute to anything other than beverage alcohol.
Why EtS Is Almost Always Reported Alongside EtG
If you receive an EtS result, you will almost certainly see an EtG (ethyl glucuronide) number paired with it. Both are direct metabolites of alcohol formed through similar nonoxidative pathways, and both appear in urine after drinking.14Oxford Academic (Clinical Chemistry). Urinary Tract Infection: A Risk Factor for False-Negative Urinary Ethyl Glucuronide but Not Ethyl Sulfate in the Detection of Recent Alcohol Consumption They are tested together because each one compensates for a weakness in the other.
The most important difference involves bacterial contamination. If a urine sample sits at room temperature or if the person providing the sample has a urinary tract infection, bacteria in the specimen can break down EtG, causing a positive sample to test negative. EtS, by contrast, is completely stable under these conditions.15PubMed. Postcollection synthesis of ethyl glucuronide by bacteria in urine may cause false identification of alcohol consumption Bacteria can also generate EtG in urine where none existed, producing a false positive for EtG. EtS is not susceptible to this kind of bacterial generation or degradation, which makes it a more reliable indicator when specimen handling is questionable.16PubMed. Inhibition of bacterial degradation of EtG by collection as dried urine spots (DUS)
So when both markers are tested together, a scenario where EtG is positive but EtS is negative could suggest bacterial contamination rather than drinking. A scenario where EtS is positive but EtG is negative could indicate that bacteria degraded the EtG after collection. When both are positive, the confidence that actual drinking occurred goes up substantially.
When Kidney Function Changes the Picture
Because EtS is cleared through the kidneys, anything that slows kidney filtration can keep EtS detectable for longer than expected. Patients with impaired kidney function had significantly longer detection times for both EtG and EtS compared to healthy volunteers given the same dose.17PubMed. Prolonged urinary detection times of EtG and EtS in patients with decreased renal function This matters especially in clinical settings where the patients being monitored for alcohol use often have liver or kidney disease. A person with compromised kidneys might still show elevated EtS levels well past the time window when a person with normal kidney function would have cleared the metabolite entirely.
Habitual drinking patterns and genetic differences in sulfotransferase enzymes may also play a role. The Japanese pharmacokinetics study found a modest association between self-reported typical drinking habits and the rate at which EtS was formed, though the relationship with EtG was not as clear.9Drug Testing and Analysis. Forensic implications of ethyl glucuronide and ethyl sulfate pharmacokinetics in Japanese adults: the influence of dose, genetic polymorphisms, and habitual alcohol consumption The practical takeaway is that two people drinking the same amount can produce meaningfully different EtS levels, and the variation is large enough that clinicians and forensic experts are cautious about pinning a specific drinking quantity to a specific EtS number.
How EtS Stacks Up Against Other Alcohol Biomarkers
EtS and EtG are not the only tools for detecting alcohol use. Phosphatidylethanol (PEth), a blood-based biomarker, has gained popularity in recent years, particularly in transplant programs. In a study comparing the three markers in participants enrolled in professional health monitoring programs, PEth at a cutoff of 20 ng/mL detected alcohol use more frequently than EtG or EtS at their standard cutoffs of 100 and 25 ng/mL respectively. PEth was also more sensitive among participants who had previously been diagnosed with an alcohol use disorder.2PubMed Central. The roles of phosphatidylethanol, ethyl glucuronide, and ethyl sulfate in identifying alcohol consumption among participants in professionals health programs
The trade-off is that PEth is a blood test, which makes it less convenient than a urine test for routine monitoring. PEth also reflects a longer window of use, accumulating with repeated drinking over weeks, whereas EtS captures the last day or two. In situations where the question is “did this person drink in the last 24 to 48 hours,” urine EtS is the more appropriate choice. Where the question is “has this person been drinking regularly over the past several weeks,” PEth is more informative.
Older markers like gamma-glutamyl transferase (GGT), mean corpuscular volume (MCV), and carbohydrate-deficient transferrin (CDT) are still used in some settings, but they are far less specific to alcohol. Elevated GGT can come from liver disease of any cause, and elevated MCV can reflect vitamin deficiencies. EtS and EtG are direct products of ethanol metabolism, which gives them an inherent specificity advantage. No EtS was detected in study participants who had abstained from ethanol for several days prior to sampling, confirming that it does not appear without alcohol exposure.18Journal of Analytical Toxicology. Ethyl Sulfate: A Metabolite of Ethanol in Humans and a Potential Biomarker of Acute Alcohol Intake
EtS Stability in Forensic and Postmortem Settings
One reason EtS has gained traction in forensic work is its unusual stability. In postmortem blood samples, EtS showed no change over time in any of the tested groups, earning it a reputation as a reliable marker even when specimens are collected hours or days after death.19PubMed. Stability of Ethyl Glucuronide, Ethyl Sulfate, Phosphatidylethanols and Fatty Acid Ethyl Esters in Postmortem Human Blood By contrast, ethanol itself can be produced or consumed by bacteria in a body after death, making postmortem blood alcohol readings notoriously unreliable. EtG faces a similar vulnerability: bacteria can break it down, as discussed above. EtS resists both types of bacterial interference, which is why it is increasingly valued in death investigations where the question of whether someone was drinking before they died carries legal weight.
Modern laboratory methods for measuring EtS are highly sensitive. A validated mass spectrometry method achieved limits of detection as low as 5 ng/L (0.005 mg/L) for EtS in urine, with a linear calibration range extending well beyond the concentrations typically seen in clinical or forensic samples.20PubMed Central. A high-performance liquid chromatographic-tandem mass spectrometric method for the determination of ethyl glucuronide and ethyl sulfate in urine validated according to forensic guidelines Researchers have also explored measuring EtS in hair as a longer-term marker of alcohol use, though the field is still developing reference ranges for that matrix.21Drug Testing and Analysis. Assessment of ethyl sulphate in hair as a marker for alcohol consumption using liquid chromatography–tandem mass spectrometry
Rapid Point-of-Care Tests and What They Can Tell You
Laboratory-grade mass spectrometry is the gold standard for EtS measurement, but not every setting has access to it. Point-of-care dipcard tests exist for EtG (though not widely for EtS alone) and can deliver results in minutes. One study found 98% agreement between a dipcard EtG test and the benchtop immunoassay, with sensitivity of 100% and specificity of 97%.22PubMed Central. High agreement between benchtop and point-of-care dipcard tests for ethyl glucuronide These rapid tests typically report EtG rather than EtS, but a positive rapid EtG screen is often followed by confirmatory laboratory testing that includes EtS. If you are tested in a clinic or probation office with a dip test and the result is positive, the confirmation step is where EtS comes into play, serving as the independent second marker that helps rule out bacterial artifact.
For anyone being monitored through a program that reports both EtG and EtS concentrations, looking at the ratio between the two can sometimes be informative. A very high EtG with a very low EtS, or vice versa, raises questions about specimen integrity or unusual metabolism. When both track in the same direction and the concentrations are consistent with each other, the results carry more interpretive weight. This kind of dual-marker reasoning is part of why the field has moved toward testing both metabolites rather than relying on either one alone.