Hair, Saliva and Sweat Patch Alcohol Tests

Ethyl Glucuronide (EtG) Hair Test

Ethyl glucuronide (EtG) is a product of alcohol degradation in the body; it is incorporated into the hair through the blood vessels in the hair follicle and from the scalp sweat. EtG can be produced only from ethanol and not from other alcohols, such as methanol or isopropanol, or other metabolic processes in the body ^[2]. An EtG hair test can detect alcohol consumption within the recent 3 months ^[1,3].

When is an EtG hair test done?

In general, the test is done to detect excessive drinking (60 or more grams of alcohol or about 4 drinks per day in average) and may be used, for example, in pre-employment drug testing, child-custody cases, alcohol treatment programs, individuals on probation due to alcohol offences or to test for suitability for surgery ^[3].

In Germany, an EtG hair test is used to monitor for 1 year sobriety in individuals whose driving licences have been suspended in order for their licences to be re-granted ^[4]. For this purpose, the test is considered positive when the EtG level is at or above 7 pg/mg hair [pg = picogram = 10^-12 g] ^[4].

How is an EtG hair test done?

About 100 strands of scalp hair (for a thickness of a pencil) are cut. 3 cm long pieces of hair nearest to scalp are usually used for the test ^[4]. Other body hair can be used if necessary, but pubic hair may contain extra EtG from urine, so it should be avoided ^[4].

How accurate is an EtG hair test?

Hair grows at a rate about 1 centimeter per month, so from the amount of EtG incorporated in the first 3 cm of hair the amount of alcohol drunk in the last 3 months can be roughly estimated ^[1,3]. Using only 1 cm long hair for the test does not give an accurate estimation of the alcohol drunk in the last month, since EtG needs some time to be incorporated into the hair ^[1].

• The levels below 7 pg EtG/mg hair speak for alcohol abstinence or very seldom drinking in the last 3 months ^[3]. The test cannot reliably prove abstinence.
• The levels between 7-30 pg/mg speak for social drinking (up to 4 drinks/day) in the last three months ^[3].
• The levels above 30 pg/mg speak for excessive drinking ( more than 4 drinks or 60 g alcohol/day) in the last three months ^[3].
• The test cannot distinguish between daily and binge drinking ^[2].
• The EtG hair test is probably not affected by the individual’s age, sex, body mass index, natural hair color or alcohol-containing foods, mouthwash, hair cosmetics, hand sanitizers, or tobacco smoking ^[1,4,5]. Still, there may be great differences in the hair EtG levels among individuals after the same amount of alcohol drunk.

False Positive EtG Hair Test

A false positive EtG hair test in a woman after regular use of EtG-containing hair lotion (rare) not being washed out after use, was described in one study ^[6]. Ethanol from hair cosmetics or other sources absorbed into the hair from the outside (not from the body) are not converted to EtG in the hair, and does not cause a false positive EtG hair test ^[5].

False Negative EtG Hair Test

False negative results are possible, especially in mild drinkers, since the sensitivity of an EtG hair test is not 100% ^[7].

Normal hair hygiene over few months might wash out some EtG from the hair ^[8] and hair dying or bleaching could potentially result in a false negative test ^[9], but in one study these factors have not affected the test ^[9].

An EtG hair test is often done in combination with a FAEE hair test (see below).

Fatty Acid Ethyl Esters (FAEE) Hair Test

Fatty acid ethyl esters (FAEE) are degradation products of ethanol in the body ^[10]. FAEE may be produced only from ethanol, not from other alcohols, such as methanol or isopropanol, and not by other metabolic processes in the body ^[2]. FAEE are incorporated into the hair from the blood circulation and from the oil in the sebaceous glands ^[15]. FAEE may be detected in the hair in the recent 6 months (according to certain test producers).

How is a FAEE  hair test done?

About 100 strands of scalp hair (a thickness of a pencil) are cut. 3 cm or 6 cm long pieces nearest to scalp are usually used for the test ^[4].

Why is FAEE hair test done?

FAEE hair test is done to detect chronic excessive drinking, usually in combination with a EtG hair test (see above).

How accurate is a FAEE hair test?

A FAEE level above 0.5 ng FAEE/mg hair (in 3 cm hair samples) and 1 ng/mg (in 6 cm samples) speak for excessive drinking (> 60 g alcohol or 4 drinks per day) in last 3 and 6 months respectively ^[11]. FAEE hair test is not done to distinguish between drinking and abstinence ^[12].

Natural hair pigment, regular hair hygiene, hair gels, oils, bleaching or dying probably do NOT significantly affect hair FAEE levels ^[13,14].

The test cannot distinguish between daily and binge drinking ^[2].

False positive FAEE hair test

Ethanol-containing hair products may cause false positive results ^[16].

False negative FAEE hair test

Sensitivity of the test is about 90% ^[17], which means that about 10% individuals who drink excessively may have a false negative test.

Alcohol Saliva Test (AST)

Alcohol saliva test (AST) is intended for a quick check of the presence and, roughly, the amount of alcohol in the saliva, for example in emergency departments ^[18]. The result of an AST alone cannot be used in the legal procedures, so, if the test is positive, other tests, such as breath or blood alcohol test, need to be done to determine the amount of alcohol in the blood.

How is alcohol saliva test done?

10-15 minutes after the tested person has put anything in the mouth, an AST can be done by swabbing the mouth and applying collected alcohol to a thermometer-like device, or by using a testing strip. If there is alcohol in the saliva sample (in concentration corresponding to 0.02 grams/100 mL blood or higher), the measuring device will roughly show its concentration, or the color of the strip will change. It takes about 2 minutes to get a result.

How accurate is an alcohol saliva test?

AST can detect the saliva alcohol concentration 0.02 g/100 mL saliva or greater ^[24].

Alcohol in the saliva can be detected for about as long as in the blood, that is for up to 14 hours or more, depending on the amount of alcohol drunk (1 drink or 14 g alcohol is eliminated from the blood each hour) ^[24].

Saliva might not be available in individuals who have dry mouth (dehydration, Sjögren’s syndrome, certain medications) ^[24].

False negative results are possible after storage of the device at temperatures higher than 80 °F (27 °C) prior the test ^[19], drinking water or other nonalcoholic drinks or eating foods within 15 minutes prior the test.

False positive results are possible when the test is performed within 15 minutes after consumption of alcohol, alcohol-containing mouthwash or other products, vitamin C (fruits, fruit juices, supplements) or when the result is checked later than 2 minutes after starting the test ^[24].

Transdermal Alcohol Content (TAC)

About 1% of the ingested alcohol is eliminated through the skin ^[20].

A sweat patch test for alcohol can reveal if, and, roughly, how much a person was drinking during the testing days (7-14). It can detect alcohol consumption of 2-3 drinks per day or more. A testing patch is usually applied on an upper arm. Researches performed between y. 1980-1984, have revealed no false positive or negative results of a sweat patch test ^[21].

Secure Continuous Remote Alcohol Monitoring (SCRAM) device may continuously detect alcohol evaporating from the skin and distinguish between sobriety, mild, moderate and heavy drinking ^[20]. The tested person wears a device as a wrist or ankle bracelet and measurements are sent by radio waves to appropriate enforcement agency. False positive results due to consumption of alcohol-containing foods are not likely; false positives from the environmental alcohol are possible, but easily detectable ^[20]. According to various sources, false negative results may occur in 7-43% measurements ^[22,23]. The device is intended to monitor for abstinence in impaired driving or domestic violence offenders, licensed professionals or others ^[20].