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Foundational Research

The PEth Blood Test in the Security Environment: What it is? Why it is Important? And Interpretative Guidelines?

William Ulwelling M.D., M.P.H., Kim Smith Ph.D., ABPP
First published: 13 July 2018


Doctor holding blood sample

Doctor holding blood sample | Sourced by Freepik©Stock

Testing for phosphatidylethanol (PEth) is a relatively new tool for detecting and grossly quantifying a person’s use of alcohol in a variety of security, medical, and legal environments. The basic chemistry of PEth is explained with a particular focus on factors that make it highly suitable as a biomarker for alcohol use in such situations. This article meets the need for a literature review that synthesizes PEth laboratory findings and suggests updated guidelines for interpretation. Several ethanol biomarkers have been used for detection or monitoring alcohol use but have significant limitations. Based on this review, the authors propose three guidelines for evaluating PEth values: Light or no Consumption (<20 ng/mL), Significant Consumption (20–199 ng/mL), and Heavy Consumption (>200 ng/mL). These guidelines are important in employment and security environments but also have applicability in such diverse activities as alcohol treatment programs, organ transplant decisions, and monitoring impaired medical professionals.


Among the threats to maintaining secrets or propriety information in businesses, financial institutions, national research facilities, and government institutions are employees who become alcohol intoxicated. Confidential or secret information is very difficult to protect, often due to the private agendas of employees who, for instance, wish to sway opinions about a congressional bill, discredit others, influence the debate about military weapon systems, or reveal programs that are secret but which the employee may judge to be unethical. Just as important, however, is the leaking of private information due to the disinhibiting effect of excessive alcohol consumption. In an intoxicated state, the wish to impress others with insider information about special processes or the impressive capabilities of machines or weapons has been divulged. Sometimes sensitive information is shared inadvertently in competitive storytelling at a bar among work colleagues. At times, an employee can drink to the point of amnesia and not remember what he/she said while socializing in a professional engagement. Intoxication reduces inhibitions, making one more vulnerable to efforts to extract information. Sometimes, frequent intoxication is the only detectable indicator that the subject lies within the subset of people unwilling or unable to safeguard sensitive information.

The more frequently an employee drinks to a level of intoxication that impairs his judgment or awareness, the greater is the risk of inappropriate disclosures. When excessive alcohol use becomes a response to marital discord, financial pressures, or perceived unfair treatment at work, it sometimes facilitates the purposeful criminal sharing of information or acting to sabotage computers and files. An employee who frequently uses alcohol excessively or binge drinks or is addicted to alcohol poses an elevated risk for a company and is therefore important to identify.

Because companies and security institutions realize the heightened risk arising from the excessive use of alcohol, such employees, when discovered, can lose their position, status, or security access. The knowledge of such consequences makes it difficult for employees to be candid about their use of alcohol. In employment situations, interviews relying on the person’s self-report of their alcohol use are unreliable 15. Evaluation protocols based on instruments such as the Substance Abuse Subtle Screening Inventory (SASSI-3), Alcohol Use Disorders Identification Test (AUDIT-C), CAGE (an acronym derived from the four questions that compose it), and the Michigan Alcohol Screening Test (MAST) are useful in clinical situations where the subject is a “patient” wishing to be helped by treatment, rather than an “employee” concerned about maintaining employment. The remaining option for determining an employee’s use of alcohol is to include “alcohol-sensitive” biomarkers in the evaluation. Direct biomarkers measure ethyl alcohol or its metabolites and include the blood and breath alcohol concentration tests, ethyl glucuronide (EtG), and phosphatidyl ethanol (PEth). Indirect biomarkers measure the effects of alcohol on the body and thus indirectly estimate the use of alcohol.

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