An EtG test (ethyl glucuronide test) is often used for people on Operating While Intoxicated (OWI) probation in Oakland County to check for alcohol use. At Michigan Defense Law, we help people on probation who receive a positive EtG result protect their rights and their freedom. We examine laboratory protocols, verify whether proper testing cutoffs were applied, and investigate whether incidental alcohol exposure may have contributed to a positive result.
This guide explains how EtG tests detect alcohol, what causes false positives, how to get the most accurate result, and the reliability of EtG tests and its effect on your probation. Contact us at (248) 451-2200 today to schedule a consultation with our Oakland County probation violation lawyer to review your available defense options.
Why Do Probation Officers Order EtG Tests in Michigan?
If you are on probation in Michigan, you are required to avoid drinking alcohol. Testing can happen on a set schedule or with no advance notice, so you might be called in and tested the same day.
Probation officers rely on EtG testing because it can detect recent alcohol use after the fact, and a positive EtG result can lead to a probation violation being filed against you. The court can further increase your penalties, which can include jail time or probation revocation.
However, studies from SAMHSA and the NIH show that because the test is very sensitive, everyday products containing alcohol can cause positive results. For this reason, positive test results can be legally questioned or challenged.
How Does an EtG Test Detect Alcohol?
There are two basic types of tests used to check for alcohol exposure via biomarkers (physiological indicators):
- Direct Biomarkers (e.g., EtG, EtS, PEth, or ethanol itself): Direct breakdown products or metabolites created when the body processes alcohol. They are measured in urine, blood, or breath to check for recent alcohol consumption. For example, the EtG urine test is marketed to detect consumption up to 80 hours, though it is most reliable for drinking within the past 24 to 48 hours.
- Indirect Biomarkers (e.g., GGT, AST, ALT, MCV, or CDT): Indicators that measure functional or physiological body changes caused by chronic or heavy alcohol use (such as elevated liver enzymes or altered red blood cell size).
The table below compares an EtG urine test with the portable breath test (PBT) many people on probation also encounter.
| Feature | EtG Urine Test | PBT Breath Test |
|---|---|---|
| What it detects | Ethyl glucuronide, a byproduct of alcohol | Current blood alcohol concentration |
| Sample type | Urine | Breath |
| Detection window | Marketed up to 80 hours, often reliable for 1 to 2 days | Only alcohol present in the body at the moment |
| Typical purpose | Confirms recent drinking after the fact | Measures active alcohol level and impairment |
What Do SAMHSA and Michigan Courts Say About EtG Reliability?
Upon its introduction, Ethyl Glucuronide (EtG) testing was widely adopted by law enforcement, courts, probation departments, and employers due to its high sensitivity in detecting alcohol biomarkers. However, concerns eventually emerged regarding the test’s ability to distinguish between beverage alcohol consumption and non-beverage environmental exposure.
While EtG testing remains a standard screening method, federal guidelines highlight specific limitations. In 2006, the Substance Abuse and Mental Health Services Administration (SAMHSA) issued an advisory stating that EtG testing should not serve as the sole basis for legal or disciplinary action, calling such single-source reliance “scientifically unsupportable.”
A 2012 SAMHSA update reiterated that EtG and Ethyl Sulfate (EtS) tests are highly sensitive and can detect low-level exposures. To ensure accuracy, SAMHSA recommends that any presumptive positive result from an initial immunoassay screening be corroborated and confirmed using Gas Chromatography/Mass Spectrometry (GC/MS) or Liquid Chromatography with Tandem Mass Spectrometry (LC/MS/MS).
Due to its high sensitivity, an EtG test used during the probation process detects alcohol metabolites in urine but cannot determine the source of the alcohol. Incidental exposure to everyday products containing alcohol, such as hand sanitizers or mouthwashes, can produce measurable urinary EtG and EtS. Regular use of these products can result in a false positive. Consequently, established guidelines indicate that EtG results alone are insufficient to establish an OWI probation violation.
Key Takeaway: SAMHSA has explicitly warned that EtG results should never be the only basis for legal or disciplinary action. Michigan courts treat a positive result as evidence to be weighed, not as conclusive proof of drinking.
Oakland County Probation Defense Attorney: Michigan Defense Law
Paul J. Tafelski, Esq.
Paul J. Tafelski is a graduate of Michigan State University and the Detroit College of Law at Michigan State University, and is admitted to practice in all state and federal courts in Michigan. A practicing Michigan lawyer for more than two decades, he has successfully defended hundreds of clients from arraignment through jury trial. He is a member of the following bar associations: Michigan Bar Association, American Bar Association, Criminal Defense Lawyers of Michigan, Oakland County Bar Association, and the Advocates (Polish Bar Association).
He has been named one of the top criminal defense lawyers in Michigan by Super Lawyers (2011 to 2013 and 2017 to 2026) and as a Leading Lawyer in 2017. For Paul, the goal is always the same: obtaining the best possible result so clients can move forward, bringing a steady courtroom presence and careful strategic judgment to every probation and OWI matter he handles.
What Causes a False Positive on an EtG Test?
One of the main challenges with EtG testing is the potential for false positives. Many everyday products contain small amounts of alcohol, and using them before testing can sometimes lead to a positive result even if no alcoholic beverages were consumed.
These are the common products and exposures that can contribute to an accidental positive:
- Hand sanitizers, which alone have produced measurable EtG and EtS in urine
- Mouthwash, aftershave, perfume, and alcohol-based hair products
- Household cleaning sprays and occupational solvent exposure
- Cough syrups, tinctures, and herbal drops that use an alcohol base
- Kombucha, kefir, non-alcoholic beer or wine, and fermented foods
Key Takeaway: Everyday products with trace alcohol can trigger a positive EtG result even without drinking, because the test cannot tell the difference between beverage alcohol and incidental exposure.
How Can You Get the Most Accurate EtG Test Result?
There is no single accuracy percentage for EtG tests, because sensitivity and specificity vary by cutoff and timing. For example, a commonly used 500 ng/mL point-of-care test marketed as an 80-hour screen was only reliable for detecting past 24-hour use in heavy drinkers in one study. Lowering the test cutoff increases sensitivity and the chance of detecting incidental alcohol exposure. The testing method matters because the way a sample is handled, screened, and confirmed can affect the reliability of the result.
The best practice is to use EtG together with EtS and to confirm any presumptive positive result by LC/MS/MS rather than relying on an immunoassay alone. To protect yourself and give any later challenge the strongest footing, take these steps:
- Request dual biomarker testing: Ask that EtG be tested together with EtS so the two markers can be compared for accuracy.
- Require LC/MS/MS confirmation: Request that any positive immunoassay screening result be further confirmed by Liquid Chromatography with Tandem Mass Spectrometry (LC/MS/MS) rather than accepting the initial screen result.
- Discuss screening cutoffs: Address the testing threshold, as using the 500 ng/mL EtG cutoff can help reduce false-positive results that were caused by incidental alcohol exposure.
- Plan for a detection buffer: Ensure zero alcohol exposure prior to testing, as EtG and EtS are generally detectable for 1 to 2 days, and some labs report detection up to 5 days depending on the cutoff levels used.
- Maintain standard hydration: Stay hydrated and use the restroom regularly, but avoid extreme fluid loading, which can complicate creatinine correction calculations.
- Keep a detailed exposure log: Document the dates, products, and doses of any items used that may contain alcohol, and save receipts for any medications.
- Disclose product use on test day: Inform the test collector about all specific products and medications you have recently used before providing the sample.
Key Takeaway: EtG test results are not always accurate because test settings and timing can cause false positives from everyday products. To protect yourself, always ask to double-check positive results with a detailed lab test (LC/MS/MS), test for EtS at the same time, and keep a record of any products you use.
Get Help from an Oakland County OWI Probation Attorney
A failed EtG test can lead to a probation violation hearing, possible jail time, or changes to your probation terms. However, one positive result does not automatically prove alcohol use. You have the right to challenge the test, question its reliability, and present evidence explaining the result.
An Oakland County OWI probation attorney can review the laboratory data, preserve the sample, request confirmation testing, and examine creatinine, pH, medications, product use, and possible environmental exposure. Taking action before the hearing gives your lawyer more time to gather records, compare the result with your exposure history, and build a factual challenge to the alleged violation.
Paul J. Tafelski has more than two decades of experience representing clients throughout Oakland County and Michigan. Call Michigan Defense Law at (248) 451-2200 or visit our office at 2525 S Telegraph Road, Suite 100, Bloomfield Hills, MI 48302 to discuss a failed EtG test or probation violation.
Frequently Asked Questions
How long does alcohol stay detectable in an EtG test?
EtG and EtS are usually detectable for about 1 to 2 days in urine, and some labs report up to 3 to 5 days at certain cutoffs. The window depends on how much was consumed, timing, and the assay cutoff the lab uses.
Can hand sanitizer really cause a positive EtG result?
Yes. Hand sanitizers alone have produced measurable EtG and EtS in urine. Heavy or frequent use has even produced positive results without any drinking. This is one reason soap and water is the safer option before and during a testing period.
Is a positive EtG test enough to revoke probation in Michigan?
Not by itself. A positive result is evidence, but SAMHSA has warned it should not be the sole basis for legal or disciplinary action, and Michigan courts weigh it against the preponderance-of-the-evidence standard. Challenging the reliability of the result can prevent a finding of violation.
What is the difference between EtG and a breathalyzer test?
An EtG urine test looks for a byproduct of alcohol and can detect use after the fact, up to a marketed 80 hours. A breathalyzer or portable breath test measures the alcohol present in your body at that moment, so it reflects the current level rather than past use.
Can I request a retest if I fail an EtG test?
Yes. Your attorney can request retesting, ask for LC/MS/MS confirmation of a screening positive, and have the lab check creatinine and pH. Confirmation testing is important because an immunoassay screen alone can pick up incidental exposure.
Does mouthwash or cough syrup affect EtG results?
They can. Many mouthwashes, cough syrups, tinctures, and herbal drops use an alcohol base that can contribute to a positive reading. Switching to alcohol-free formulations and disclosing every product to the collector helps reduce that risk.
What should I say to my probation officer after a failed test?
Report the products and medications you have used, but do not try to argue the case on your own or admit to a violation. Contact an Oakland County criminal defense attorney promptly so your response is accurate and does not undermine a later challenge.
