New: Ethanol-based handsanitizing gel vapor causes positive alcohol marker, EtG, - unpublished but available for viewing <here>.
New Alcohol Markers - Proper use and interpretation
History
Ethylglucuronide (EtG) was described as early as the 1950's, however, clinical use of the test as an alcohol marker began in 2001 when Dr. Friedrich Wurst, in Switzerland, and Dr. Gregory Skipper, in the USA reported a study of alcoholics in a psychiatric facility in Germany. Their findings demonstrated that EtG was a more sensitive and reliable indicator of both drinking and abstinence than was urine alcohol. Dr. Skipper, who oversees a monitoring program for physicians, had been looking for a more reliable means of documenting alcohol abstinence. It soon became clear that urine EtG would be a valuable test in monitoring professionals. The Federation of State Physician Health Programs estimates that over 9,000 physicians are in monitoring in the USA. An essential issue in justifying the continued safe practice of recovering physicians involves the ability to reliably document their abstinence.
In order for EtG testing to be practical in the United States it was important to convince a lab in this country to implement testing. In 2002 Dr. Skipper appealed to the owner and chief toxicologist at National Medical Services and "made the case for EtG testing." Through coordination with Wolfgang Weinmann's lab in Germany, the only lab then performing EtG testing, the necessary "deuterized standards" from Germany were obtained and NMS soon began performing EtG testing at a cost of $75 per test.
Once EtG testing was available in the USA additional studies were conducted that reported the effectiveness of the test in monitoring health professionals (example). Use of EtG testing spread very rapidly among physician health programs and others.
Several important issues began to emerge that frame the complexities of interpreting these tests. It's important to understand their limitations, as with all tests, to use them properly. Some of these issues are discussed in more depth elsewhere on this site and include:
- Incidental Exposure: Claims of "false positive EtG tests" from incidental exposure to alcohol began to occur. An online registry and listserve was developed for for those who claimed they'd been falsely accussed of drinking. The clamor of concern among this group rose rapidly and became extremely vigorous. This phenomenon of incidental exposure is very similar to the phenomenon of poppy seeds causing positive tests for morphine and is discussed in more depth in a separate section of this website.
- Informed Consent: Individuals being tested with EtG and/or EtS should be informed regarding items to avoid. A statement or contract addendum can be useful. (Download sample addendum used by drug courts.)
- Topical Alcohol as a Source of Incidental Exposure: Based on a particular participant's insistence that she had not consumed alcohol but likely had a positive test from alcohol-based handgel, further testing was performed to test this hypothesis. To do this she was admitted to a treatment center in California where pre and post handgel use EtG tests were performed. This trial demonstrated that alcohol-based handsanitizing gel absolutely caused positive EtG tests. This was later corroborated in the lab using 24 volunteers. The surprise finding, in this later study, was that alcohol absorbed through inhalation of vapor, rather than through skin, was the chief source of exposure. (see unpublished study)
- Stability and Synthesis of EtG: It was known that EtG could occasionally disappear (or be degraded) in urine stored at room temperature but not if frozen or heated. Researchers in Scandinavia further clarified this phenomenon when they reported that EtG (but not EtS) could be degraded in urine due to certain bacteria (explaining why heating or cooling samples resulted in less degradation). Furthermore, they then reported that in the presence of alcohol (fermented or added to urine) EtG could be synthesized by similar bacteria in-vitro if alcohol were present. This finding supported the likelihood that ethylsulfate (EtS), another minor metabolite of alcohol, may be a superior marker to EtG, in that it is more sensitive and specific.
- Reliability: Despite the possibility of incidental exposure most people who test positive for EtG actually did drink as the cause of the positive test. In one programs review, approximately 50% of individuals admitted drinking when supportively confronted. Another 40% subsequently admitted drinking at a later date. Those who initially deny drinking should receive more careful monitoring, testing, or other treatment, however, without other proof, they should not be presumed to have been drinking (An advisory was issued by Dr. Skipper to this effect in 2004 but it went largely unheeded, therefore, SAMHSA later issued an advisory. SAMHSA advisory warning against over reliance on a positive EtG as sole proof of drinking.)