ALL YOU NEED TO KNOW ABOUT ETG & ETS TESTING FOR ALCOHOL CONSUMPTION

 

With alcohol being the most widely abused drug — because of its legal status — being able to reliably test for its presence in people is important in situations where alcohol use is prohibited (in certain occupational situations or in individuals who have been prohibited from consuming alcohol, for example).

Alcohol is the only drug in the United States for which both state and federal governments have established levels of intoxication for being under the influence. No other drug has had these levels established by a governing body in the States.

It has been estimated that alcohol abuse costs the American economy $150 billion and that 80% of child abuse, domestic assaults and violent crimes have been committed under the influence of alcohol. Also, more than 1 million Americans have an alcohol addiction or abuse problem and more than 110 million emergency room visits per year are related to alcohol.

EtG vs Ethanol testing

With more traditional forms of alcohol testing, like breath, saliva or standard urine testing, it’s ethanol that is tested for. However, with EtG testing, it is Ethyl Glucuronide that is tested for.

An advantage of testing for EtG over ethanol is that EtG breaks down or metabolizes without oxidizing, creating an analyte that can be measured for a much longer period than ethanol can be measured for.

Ethanol can be excreted from the body in several ways, namely:

  • Direct excretion of ethanol (5-10%) in urine, breath and sweat.
  • Metabolic excretion by conversion to acetaldehyde.
  • Metabolic excretion by conversion of ethyl glucuronide and ethyl sulfate which are both eliminated through urination.

Most of these detectable excretory products in urine can be detected for short period of time.

Pat Pizzo, Director of Toxicology at Alere Toxicology, presented a webinar entitled “EtG & EtS: A New Way to Look at Alcohol Testing" to explain the ins and outs of EtG and EtS testing.

EtG is a direct, non-volatile, water-soluble, metabolite of ethanol. It’s a highly sensitive and specific biomarker and can be detected anywhere from four to five days after alcohol consumption as opposed to eight to 12 hours when testing for ethanol, making it useful for situations where a person needs to be monitored on a continuous basis. It can also be detected in urine, plasma, hair and body tissue.

Ethyl sulfate (EtS) is tested in conjunction with EtG for confirmation purposes. EtS is a direct biomarker of alcohol ingestion that is not susceptible to degradation by bacteria hydrolysis.

Testing for EtG

Confirmation of EtG results is done by Liquid Chromatography-Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS, which is the most sensitive and, therefore, preferred method); gas chromatography-mass spectrometry (GC/MS) or Liquid Chromatography-Mass Spectrometry (LC/MS).

EtG, in conjunction with EtS, is a scientifically accepted biomarker to show exposure to alcohol. It’s non-volatile, meaning it’s stable in urine and that means that if you have to keep specimens for extended periods, you won’t get a false positive due to fermentation and it doesn’t show up in the urine of sample donors that have not been exposed to ethanol.

EtG is also able to detect alcohol use in people who aren’t habitual users. This method is able to detect alcohol in multiple body fluids and hair as well making it a much clearer method of evaluating alcohol consumption with more options for testing. Standard alcohol testing generally requires the person being tested to be a consistent enough drinker to detect the presence of alcohol while instant EtG testing can detect the presence of alcohol in even casual drinkers.

The key benefits of using an EtG test are as follows:

  • Convenience: EtG testing can be done on urine samples along with other drug testing panels.
  • Accuracy: It is able to detect the most recent usage more accurately (up to 80 hours after consumption). EtG is only evident when alcohol is consumed.
  • Modern: The tests are performed by LC/MS/MS on modern equipment. This is ideal in cases when zero tolerance and abstinence to alcohol is a requirement.
  • Warning: It acts as an early warning system to detect trends towards relapse.
  • Longevity: It can determine alcohol ingestion in the last 3 to 4 days.
  • Support for treatment: It allows monitoring of alcohol treatment programs.

Disadvantages of EtG testing

EtG testing alone does have some disadvantages, the main one being false positives from donors who have not consumed alcoholic beverages but have been incidentally exposed to alcohol through some other means.

Sources of alcohol that lead to incidental exposure include:

  • cough syrup
  • mouthwash
  • insect repellant
  • hand sanitizers
  • non-alcoholic beer
  • some kinds of canned or bottled iced tea
  • perfumes/colognes & body sprays
  • food products made or cooked with alcohol

Many of these products contain minute traces of alcohol but could prove problematic for people who are in programs where there is zero tolerance for alcohol.

Scientific studies have found that EtG may show up in urine samples from people who regularly use things like mouthwash and hand sanitizer, however, these levels will almost always be below the commonly accepted cut off limit of 500 nanograms per milliliter (ng/ml).

False negative and false positive results have also been noted in test results due to bacterial contamination from the presence of E. coli bacteria.

Avoiding these false negatives is why it is important to test for EtS at the same time as EtG. The inclusion of testing for EtS in conjunction with EtG has proven effective in avoiding most false positives and false negatives and provides analytical results that are acceptable in court.

Due to the concerns about incidental exposure, positive results need to be backed up with a second test that verifies those results. This is especially true in any case that involves a court and a judge overseeing the matter. There are already plans in place to find the right level at which it is appropriate to consider a true positive on the test. Once this aspect of the EtG test has been established and it gains FDA approval, EtG stands to be a much improved and more consistent way of testing for alcohol use in employees. With its help, many businesses will be able to improve the way they run their business.

Interpreting test results

When interpreting results for alcohol EtG tests, it’s important to consider the cutoff levels, normalization of results and the use of both EtG and EtS for confirmation results.

As previously mentioned, a commonly accepted cutoff level for EtG is greater than or equal to 500 ng/ml and a commonly accepted cutoff level for testing for EtS is 25 ng/ml.

If cutoff levels of below 500 ng/ml are used, the test runs the risk of giving false positives for samples of individuals who may have experienced incidental exposure to alcohol through items like hand sanitizers and food made with alcohol.

If an EtG test shows a level of greater than 500 ng/ml, that is considered as a result that is consistent with the recent ingestion of alcohol.

Normalization

When testing a urine sample for EtG and EtS, it is important to not just look at the EtG level but to calculate the normalized level, because that’s the only way you can account for possible dilution of the sample.

Normalization is the consideration of how the dilution or concentration of a urine sample impacts the result of a drug screen test. Drugs are measured in ng/ml and the more dilute the urine, the lower the drug concentration.

When testing is being done to monitor a person for alcohol intake, normalization is used to determine whether the EtG that shows up in a urine sample represents the recent use of alcohol or whether it represents older consumption that has not yet been eliminated from the body.

It is done by using a calculation that requires not only the EtG levels of the sample but also the levels of creatinine, which is a product created by the breakdown of creatine phosphate in muscle, usually produced at a constant rate by the body.

Creatinine levels, on average, should be around 190 milligrams per deciliter (mg/dl) for males and 140 mg/dl for females. Testers use the range of 100 - 200 mg/dl to judge whether creatinine levels are normal for a sample.

Testers also compare the specific gravity of the sample to water, specific gravity being the ratio of the density of a substance (urine) to the density (mass of the same unit volume) of a reference substance (water). The normal range of specific gravity for urine compared to water is 1.010 - 1.025.

The calculation for getting a normalized reading is done by taking the amount of drug in the sample divided by the amount of creatinine in the sample and multiplying that by 100, which gives you nanograms of drug per milligram of creatinine. The results of this calculation enable testers to determine if the sample has been diluted (by excessive water consumption, for example).

This normalization calculation helps testers recognize when a drug user who is being monitored by giving samples at set intervals is reusing the drug or if the user’s body is still processing drugs from older usage but has not reused, referred to as residual elimination.

Workplace testing

For corporate alcohol testing, it is important to specifically mention testing for both EtG and EtS in your corporate drug testing policy and educate your employees on the risk of incidental alcohol exposure and give them a list of things that could expose them to alcohol and also notify them that it is only a partial listing, as opposed to a complete listing.

EtG and EtS testing will likely have employers seeing more positive test results than if they were to test for ethanol metabolites alone because of the longer detection window of EtG (4-5 days as opposed to 8-12 hours).

EtG is not meant to prove impairment from alcohol or whether someone is currently under the influence of alcohol. The only tests that can be used to determine impairment are blood, saliva, breath and -- only in California -- urine, based on ethanol levels.

Aside from workplaces, EtG and EtS testing is done in the criminal justice system and in rehabilitation programs and is especially useful in court cases involving driving under the influence (DUI), custody battles and when determining a cause of death.

Frequently Asked Questions

Here are some of the most frequently asked questions about alcohol EtG test, and the answer corresponding to each:

How long can EtG be detected in urine?
The actual alcohol in the body can be detected by using traditional laboratory methods that reflect current use within the past few hours, depending on the amount of alcohol consumed. The presence of EtG in urine can be determined up to 3-4 days after ingestion or approximately 80 hours after ethanol has been eliminated from the body.

EtG urine test is more accurate in determining the recent injection of alcohol than measuring the presence of ethanol itself.

Why choose EtG alcohol test over saliva and breath tests?
EtG Alcohol Urine test can provide you with an immediate result with accuracy comparable to a test performed in a laboratory. The saliva and breath tests may also detect the presence of alcohol; however, the EtG test allows detection of alcohol up to after 80 hours after the last ingestion.

How accurate and reliable is EtG test?
EtG is a direct metabolite of ethanol and its detection in urine is very highly specific. Because EtG occurs only in the presence of ethanol, detecting the compound is synonymous with saying that there is ethanol in the system.

Can the exact amount of alcohol be determined by EtG test?
A higher amount of EtG may indicate a large amount of alcohol consumption but could not exactly measure or determine the amount of alcohol intake as well as how recent the alcohol was consumed. The presence of EtG in urine can only be a determinant of alcohol in urine within the past 80 hours prior to testing.

Can residual EtG be detected in the urine of long-term alcoholics who abstain?
The limitation of EtG test is that it cannot detect the presence of ethanol in people who have consumed it more than 80 hours prior to the test.

Will urine alcohol produced by fermentation affect EtG results?
Ethanol in vitro is the produced in the bladder or specimen container due to fermentation of urine samples containing sugar in diabetes, bacteria or yeast. Since the ethanol produced is not metabolized in the liver, EtG will not be produced and will not be detected in the urine containing alcohol as a result of fermentation. Only EtG that comes directly from consumed alcohol is detected by the EtG test.

How stable is EtG in urine at room temperature?
It is believed that EtG in urine for more than 4 days is stable at room temperature. Recent studies indicate that heating the urine sample at 100 degrees Celsius can increase the stability of EtG. This clearly shows that heat does not cause any breakdown of EtG.  There is no artificial formation of EtG found to occur following a prolonged storage of urine sample at room temperature.

Will using “incidental alcohol” trigger a positive result?
Incidental exposure to alcohol such as mouthwash and over-the-counter drugs may produce EtG concentrations in excess of 100ng/l. However, if the ethanol detected in urine indicates >250 ng/ml, then it is a clear evidence of alcohol ingestion.

For cases where there has been a positive result from a previous test on the presence of alcohol, the EtG test confirms if the alcohol level is indeed coming from alcohol ingestion and is not a result of alcohol fermentation in the body.

What are the methods used to detect EtG?
Here are the scientific methods used in detecting EtG:

  • Immunoassay (EIA or ELISA): This has a limited specificity and sensitivity with a limit of detection of approximately 1000 ng/ml.
  • Gas Chromatography/Mass Spectrometry (GC/MS)
  • Liquid Chromatography/Mass Spectrometry (LC/MS)
  • Liquid Chromatography/Mass Spectrometry/Mass Spectrometry (LC/MS/MS): This method utilizes the most technologically advanced instrumentation that is currently available in forensic and clinical toxicology and provides the highest sensitivity of all methods. The limit of detection is 250 ng/ml.

How is EtG Alcohol Urine Test done?
A sample of urine is taken from the individual wherein the dipstick is immersed into the urine specimen. Compare the color obtained from the dipstick from the provided alcohol color chart for results.

A positive indication of alcohol in the urine specimen occurs when it exceeds 300ng/ml.

Can EtG result be accepted as valid evidence in courts of law?
An EtG result may be presented as evidence in hearings and court proceedings. It has become a very helpful tool in persecuting offenders who were charged with DUI and alcohol-related injuries and fatalities.


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