Ethyl glucuronide concentration in hair for detecting heavy drinking and/or abstinence: a meta-analysis

Sex differences and driving impairment related to psychoactive substances

OBJECTIVE

The first aim of the study was to identify sex differences in the use of psychoactive substances among subjects with a previous driving under the influence (DUI) episode. The secondary objective was to propose specific strategies for medico-legal improvements.

METHODS

This was a retrospective observational study that took place between June 1, 2019, and August 31, 2023. It was conducted on DUI subjects examined for reinstatement of their driver's license using an integrated medico-legal and toxicological approach. Ethyl glucuronide (EtG) and illicit psychoactive substances were determined from hair samples. We performed descriptive statistical analyses for the entire sample as well as separately by sex. Additionally, we conducted binary logistic regression analyses separately for males and females to identify protective/risk factors associated with previous road accidents and judgments of unfitness to drive due to excessive alcohol consumption (EtG ≥ 30 pg/mg).

RESULTS

The study included 2,221 subjects, comprising 1,970 men and 251 women. Men exhibited a higher prevalence of tobacco, alcohol, and illicit psychoactive substance use. Women were more frequently co-users of alcohol and psychoactive substances and involved in road accidents at the time of DUI. Among the men, being married or having a partner was found to be a protective factor concerning past traffic accidents. For both sexes, a DUI episode with a blood alcohol concentration (BAC) exceeding 1.5 g/L or the co-ingestion of alcohol and drugs was identified as a risk factor for road accident involvement. For men, smoking more than 20 cigarettes per day and, for women, having a DUI episode with a BAC over 1.5 g/L were the main factors indicating unfitness to drive, as determined through high hair EtG levels (> 30 pg/mg). Women with a previous history of road accidents were less likely to have EtG levels of 30 pg/mg or more.

CONCLUSIONS

The study confirmed sex differences in subjects with a previous DUI episode. A BAC exceeding 1.5 g/L or the simultaneous use of alcohol and drugs at the time of DUI necessitate careful assessment of both men and women seeking driver's license reinstatement. In women, a BAC exceeding 1.5 g/L is considered a risk factor for a subsequent judgment of unfitness to drive. The medico-legal assessment should also involve a thorough investigation of smoking habits in men, as these habits could be related to an increased risk of excessive alcohol consumption.

The Impact of Alcohol Consumption and Oral Microbiota on Upper Aerodigestive Tract Carcinomas: A Pilot Study

Alcohol consumption is associated with oxidative stress and an increased risk of carcinoma of the upper aero-digestive tract (UADT). Recently, it has been found that some microorganisms in the human oral cavity may locally metabolize ethanol, forming acetaldehyde, a carcinogenic metabolite of alcohol. In a cohort of patients first visited for UADT cancers, we estimated their alcohol consumption by measuring Ethyl Glucuronide/EtG (a long-lasting metabolite of ethanol) in the hair and carbohydrate-deficient transferrin/CDT (short-term index of alcohol intake) in the serum. Moreover, we analyzed, by culture-based methods, the presence of Neisseria subflava, Streptococcus mitis, Candida albicans, and glabrata (microorganisms generating acetaldehyde) in the oral cavity. According to the EtG values, we correlated drinking alcohol with endogenous oxidative stress and the investigated microorganism's presence. We found that 55% of heavy drinkers presented microorganisms generating acetaldehyde locally. Moreover, we found that the presence of oral acetaldehyde-producing bacteria correlates with increased oxidative stress compared to patients without such bacteria. As for the study of alcohol dehydrogenase gene polymorphisms (the enzyme that transforms alcohol to acetaldehyde), we found that only the "CGTCGTCCC" haplotype was more frequent in the general population than in carcinoma patients. This pilot study suggests the importance of estimating alcohol consumption (EtG), the presence of bacteria producing acetaldehyde, and oxidative stress as risk factors for the onset of oral carcinomas.

Molecular Toxicology and Pathophysiology of Comorbid Alcohol Use Disorder and Post-Traumatic Stress Disorder Associated with Traumatic Brain Injury

The increasing comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) associated with traumatic brain injury (TBI) is a serious medical, economic, and social issue. However, the molecular toxicology and pathophysiological mechanisms of comorbid AUD and PTSD are not well understood and the identification of the comorbidity state markers is significantly challenging. This review summarizes the main characteristics of comorbidity between AUD and PTSD (AUD/PTSD) and highlights the significance of a comprehensive understanding of the molecular toxicology and pathophysiological mechanisms of AUD/PTSD, particularly following TBI, with a focus on the role of metabolomics, inflammation, neuroendocrine, signal transduction pathways, and genetic regulation. Instead of a separate disease state, a comprehensive examination of comorbid AUD and PTSD is emphasized by considering additive and synergistic interactions between the two diseases. Finally, we propose several hypotheses of molecular mechanisms for AUD/PTSD and discuss potential future research directions that may provide new insights and translational application opportunities.

Performance of self-reported measures of alcohol use and of harmful drinking patterns against ethyl glucuronide hair testing among young Swiss men

Background

There is a need for empirical studies assessing the psychometric properties of self-reported alcohol use as measures of excessive chronic drinking (ECD) compared to those of objective measures, such as ethyl glucuronide (EtG).

Objectives

To test the quality of self-reported measures of alcohol use and of risky single-occasion drinking (RSOD) to detect ECD assessed by EtG.

Methods

A total of 227 samples of hair from young Swiss men were used for the determination of EtG. Self-reported measures of alcohol use (previous twelve-month and previous-week alcohol use) and RSOD were assessed. Using EtG (<30 pg/mg) as the gold standard of ECD assessment, the sensitivity and specificity were computed, and the AUROC were compared for alcohol use measures and RSOD. Logistic regressions were used to test the contribution of RSOD to the understanding of ECD after controlling for alcohol use.

Results

A total of 23.3% of participants presented with ECD. Previous twelve-month alcohol use with a cut-off of >15 drinks per week (sensitivity = 75.5%, specificity = 78.7%) and weekly RSOD (sensitivity = 75.5%, specificity = 70.1%) yielded acceptable psychometric properties. No cut-off for previous-week alcohol use gave acceptable results. In the multivariate logistic regression, after controlling for the previous twelve months of alcohol use, RSOD was still significantly associated with EtG (p = .016).

Conclusion

Self-reported measures of the previous twelve months of alcohol use and RSOD were acceptable measures of ECD for population-based screening. Self-reported RSOD appeared to be an interesting screening measure, in addition to the previous twelve months of alcohol use, to understand ECD among young people.

Ethyl Glucuronide Concentration in Hair of Detainees: A Preliminary Study

Through the measurement of ethyl glucuronide in hair (hETG), it is possible to assess chronic alcohol abuse over time. In this paper, we present a study on hETG in Italian prison inmates. Analyses were performed by LC-MS according to a previously published method. Results were evaluated using the cut-offs established by the Society of Hair Testing. Positives samples (ETG > 30 pg/mg) accounted for 6% of all subjects, with concentrations ranging from 42 pg/mg up to 270 pg/mg, abstinent subjects (ETG < 7 pg/mg) accounted for 88%, and moderate alcohol consumption (7 < ETG < 30 pg/mg) for 6% of the subjects. No females displayed ETG values above 30 pg/mg. Among positive samples, only two subjects did not declare heavy alcohol consumption and were found strongly positive at 210 and 270 pg/mg. To the best of our knowledge, this represents the first study on ETG hair concentration on prison inmates.

Ethyl glucuronide hair testing: A review

Ethyl glucuronide (EtG) is a minor, non-oxidative ethanol metabolite that can be detected in several matrices (e.g. blood, urine, hair, meconium) for variable periods of time. Quantification of EtG in hair (hEtG) has established itself, over recent years, as one of the most reliable biomarkers of long-term alcohol consumption habits, with the Society of Hair Testing (SoHT) offering cut-off values for assessment of both abstinence and heavy drinking (>60 g/day). Despite its high diagnostic performance, however, issues concerning inter- and intra-laboratory variability as well as data interpretation are still being investigated and represent the ultimate barrier to widespread acceptance of hEtG in the forensic context. The aim of this review is to summarize currently available analytical methods of hEtG testing, provide a framework to understand current hEtG cut-offs and their possible upcoming changes (in particular, a lower abstinence cut-off has been proposed for the 2019 revision of the SoHT consensus), and offer a schematic but exhaustive overview of the pitfalls in result reproducibility and interpretation that may limit applications of hEtG testing in the forensic context. Ultimately, the purpose of the authors is not to undermine the reliability of hEtG as an alcohol use marker, but rather to enhance it by promoting familiarization with all aspects related to it, from ethanol pharmacokinetics and EtG incorporation into hair, to sample preparation and analytical methods, to specific cases warranting close attention and additional tests for correct interpretation of hEtG results.

The association between alcohol consumption, cardiac biomarkers, left atrial size and re-ablation in patients with atrial fibrillation referred for catheter ablation

Background

Information on alcohol consumption in patients undergoing radiofrequency ablation (RFA) of atrial fibrillation (AF) is often limited by the reliance on self-reports. The aim of this study was to describe the long-term alcohol consumption, measured as ethyl glucuronide in hair (hEtG), in patients undergoing RFA due to AF, and to examine potential associations with cardiac biomarkers, left atrial size and re-ablation within one year after the initial RFA.

Methods

The amount of hEtG was measured in patients referred for RFA, and a cut-off of 7 pg/mg was used. N-terminal pro B-type natriuretic peptide (NT-proBNP) and the mid-regional fragment of pro atrial natriuretic peptide (MR-proANP) were examined and maximum left atrium volume index (LAVI) was measured. The number of re-ablations was examined up to one year after the initial RFA. Analyses were stratified by gender, and adjusted for age, systolic blood pressure, body mass index, presence of heart failure and heart rhythm for analyses regarding NT-proBNP, MR-proANP and LAVI and heart rhythm being replaced by type of AF for analyses regarding re-ablation.

Results

In total, 192 patients were included in the study. Median (25th– 75^th percentile) NT-proBNP in men with hEtG ≥ 7 vs. < 7 pg/mg was 250 (96–695) vs. 130 (49–346) pg/ml (p = 0.010), and in women it was 230 (125–480) vs. 230 (125–910) pg/ml (p = 0.810). Median MR-proANP in men with hEtG ≥ 7 vs. < 7 pg/mg was 142 (100–224) vs. 117 (83–179) pmol/l (p = 0.120) and in women it was 139 (112–206) vs. 153 (93–249) pmol/l (p = 0.965). The median of maximum LAVI was 30.1 (26.7–33.9) vs. 25.8 (21.4–32.0) ml/m² (p = 0.017) in men, and 25.0 (18.9–29.6) vs. 25.7 (21.7–34.6) ml/m² (p = 0.438) in women, with hEtG ≥ 7 vs. < 7 pg/ml, respectively. Adjusted analyses showed similar results, except for MR-proANP turning out significant in men with hEtG ≥ 7 vs. < 7 pg/mg (p = 0.047). The odds ratio of having a re-ablation was 3.5 (95% CI 1.3–9.6, p = 0.017) in men with hEtG ≥ 7 vs. < 7 pg/mg, while there was no significant difference in women.

Conclusions

In male patients with AF and hEtG ≥ 7 pg/mg, NT-proBNP and MR-proANP were higher, LA volumes larger, and there was a higher rate of re-ablations, as compared to men with hEtG < 7 pg/mg. This implies that men with an alcohol consumption corresponding to an hEtG-value ≥ 7, have a higher risk for LA remodelling that could potentially lead to a deterioration of the AF situation.

Occupational Exposure to Alcohol-Based Hand Sanitizers: The Diagnostic Role of Alcohol Biomarkers in Hair

Ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs) in hair are effective direct biomarkers of ethanol ingestion, whose analytical determination can be used to discriminate between chronic and occasional ethanol intake. Ethanol is a compound widely used in some workplaces (e.g., clinics, hospitals) and is present in considerable amounts in mouthwash for oral cleaning, medications, cosmetic products, hydro-alcoholic disinfectants and antiseptics for hands. This study examined the ethyl alcohol exposure derived from hand disinfectants (in gel form) by simulating the typical occupational situation of medical-health workers (healthcare workers, nurses, surgeons, etc.) who frequently wash their hands with antiseptic sanitizer. Two types of hand disinfectants with 62% w/w of ethanol content were daily applied to the hands of a teetotaler for 20 times a day, for 4 consecutive weeks, thus simulating a typical workplace situation and a cumulative dermal exposure to ethanol of ~1,100 g. Different matrices (head, chest and beard hair, urine) were regularly sampled and analyzed using a ultra high-performance liquid chromatography tandem massspectrometry validated method for EtG and a (HS)SPME-GC-MS validated technique for FAEEs. The data obtained showed that a significant dermal absorption and/or inhalation of ethanol occurred, and that the use of detergents produce urinary EtG concentrations both higher than the cut-offs normally used for clinical and forensic analyses (either 100 and 500 ng/mL, depending on the context). The concentrations of the ethanol metabolites in the keratin matrices were, respectively, below the cut-off of 7 pg/mg for EtG and below 0.5 ng/mg for FAAEs (0.35 ng/mg for ethyl palmitate). In conclusion, the regular use of alcohol-based hand sanitizers can affect the concentration of urinary EtG and lead to positive analytical results, particularly when specimens are obtained shortly after sustained use of ethanol-containing hand sanitizer. On the other hand, direct biomarkers of alcohol abuse in the keratin matrix are capable of distinguishing between ethanol consumption and incidental exposures.

Evidence of seasonal variation of ethyl glucuronide in hair: Modeling a seven-year data series

The assessment of chronic excessive alcohol consumption by ethyl glucuronide (EtG) determination in hair is generally based on a cut-off value of 30 pg/mg recognized by regulatory authorities and scientific societies that guide the decision process. The ongoing debate about the risks connected with the straightforward application of this cut-off refers to the factors that may influence the detected EtG concentration. The present contribution to this debate evaluates the seasonal variation of the averaged EtG values along a seven-year period. Over 65 000 data points have been statistically analyzed to provide a mathematical model that interprets the data, gives insight into several influencing factors, and forecasts progressive data-points of the time series. This model shows that there is an annual pattern in the data exhibiting lower EtG concentrations during warm seasons and higher values in cold seasons. The estimated EtG cycles are characterized by the seasonal variation of ±2.78 pg/mg above and below the overall mean (with 5.56 pg/mg absolute difference overall). This seasonal factor associated with EtG quantification might result in a potential source of bias, at least in the regional/climatic conditions observed in the samples' collection area. Moreover, the EtG time series reveals that the change in the sample pre-treatment procedure has an effect on the modeled pattern as an abrupt increment (+38%) in the mean value of the EtG concentration. This change corresponds to the time when the former protocol of cutting hair into small segments before extraction was substituted by pulverization with a ball mill.

Biosignature Discovery for Substance Use Disorders Using Statistical Learning

There are limited biomarkers for substance use disorders (SUDs). Traditional statistical approaches are identifying simple biomarkers in large samples, but clinical use cases are still being established. High-throughput clinical, imaging, and 'omic' technologies are generating data from SUD studies and may lead to more sophisticated and clinically useful models. However, analytic strategies suited for high-dimensional data are not regularly used. We review strategies for identifying biomarkers and biosignatures from high-dimensional data types. Focusing on penalized regression and Bayesian approaches, we address how to leverage evidence from existing studies and knowledge bases, using nicotine metabolism as an example. We posit that big data and machine learning approaches will considerably advance SUD biomarker discovery. However, translation to clinical practice, will require integrated scientific efforts.

Assessing phosphatidylethanol (PEth) levels reflecting different drinking habits in comparison to the alcohol use disorders identification test - C (AUDIT-C)

In addition to monitoring problematic or harmful alcohol consumption, drinking experiments indicated the potential of phosphatidylethanols (PEth) in abstinence monitoring. To date, no profound evaluation of thresholds for the differentiation of abstinence from moderate drinking and for detection of excessive consumption based on PEth homologues exists. Investigations with a large group of healthy volunteers (n=300) were performed to establish PEth reference values reflecting different drinking habits. Blood samples were analyzed for PEth 16:0/18:1 and 16:0/18:2 by online-SPE-LC-MS/MS method. Results were compared to AUDIT-C questionnaires, to the amounts of alcohol consumed during the two-weeks prior to blood sampling, and were statistically evaluated. PEth concentrations were significantly correlated with self-reported alcohol consumption (r>0.69) and with AUDIT-C scores (r>0.65). 4.0% of 300 volunteers reported abstinence (AUDIT-C score: 0), no PEth was detectable in their blood. PEth 16:0/18:1 concentrations below the limit of detection of 10.0ng/mL match with abstinence and light drinking habits (≤10g pure alcohol/day). However, some volunteers classified as "excessive alcohol consumers" had negative PEth results. In the group of volunteers classified as "moderate drinkers" (AUDIT-C score: 1-3 (women) and 1-4 (men)), 95% of the test persons had PEth 16:0/18:1 ranging from not detected to 112ng/mL, and PEth 16:0/18:2 ranging from not detected to 67.0ng/mL. Combination of self-reported alcohol consumption and AUDIT-C score showed that negative PEth results match with abstinence or light drinking. Moderate alcohol consumption resulted in PEth 16:0/18:1 from 0 to 112ng/mL and for PEth 16:0/18:2 ranged from 0 to 67.0ng/mL. Higher PEth concentrations indicated excessive alcohol consumption.

Alcohol, caffeine, and nicotine consumption in adolescents: hair analysis versus self-report

BACKGROUND

Clinical reliability of self-reported data for alcohol, caffeine, and nicotine consumptions is lacking, particularly in adolescents.

OBJECTIVES

To compare a self-report questionnaire and hair analysis to assess the reliability and effectiveness of the self-report.

METHODS

A cross-sectional study on 14-15-year-old Italian students (n = 874, 38% males, 62% females) was performed comparing self-reported data to hair analysis. The latter quantified hair concentrations of caffeine, nicotine, cotinine, ethyl glucuronide (EtG), and fatty acid ethyl esters (FAEEs) using mass spectrometry.

RESULTS

Concordance between self-report and hair testing ranged from good to poor across substances and levels of use: poor for heavy alcohol intake (EtG: k = 0.36, 20 positive cases by hair analysis, false negative by self-report, 2.3% of total sample; FAEE k = 0.31, 25 positive cases, 2.9% of total sample); fair to poor for active smokers (k = 0.40, 125 positive cases, 14.3% of total sample); and moderate for caffeine (k = 0.57, 56 positive cases, 6.4% of total sample).

CONCLUSIONS

Epidemiological studies on alcohol, caffeine, and nicotine consumption in adolescents may benefit from the inclusion of toxicological analysis on hair samples to overcome the under-reporting phenomenon of questionnaires and detect more cases of problematic substance use.

Effects of various sample pretreatment procedures on ethyl glucuronide quantification in hair samples: Comparison of positivity rates and appraisal of cut-off values

The quantification of ethylglucuronide (EtG) in hair is nowadays recognized as the approach with the highest diagnostic performance to evaluate harmful drinking. A widely accepted cut-off of 30pg/mg has been selected after several accurate compared studies. While most of the studies that were used to establish the appropriate cut-off value prescribed to cut hair into small segments before their extraction, hair milling has subsequently been identified as the most efficient pretreatment procedure and was therefore recommended in the last Consensus document issued by the Society of Hair Testing. In this study, we initially compared the results obtained with the two sample preparations, namely cutting and milling, both being applied to the same specimens (n=781). Among these, 205 samples produced measurable EtG values with both methods, with differences ranging from -41.7% up to +415% (the mean increase in EtG concentration, switching from cutting to milling, was +62.1% and the median was +42.3%). Among the aforementioned 205 samples, 29 specimens (3.7% of the total 781 samples) produced significantly different outcome, being classified as negative (i.e., below 30pg/mg) if the cutting procedure is used, but largely positive (above 40pg/mg) when milling is used. Subsequently, the positivity rates obtained on a large population dataset (>27,000 samples) with the two procedures, were retrospectively compared using variable cut-offs values. The percentage of head hair samples with EtG concentration exceeding 30pg/mg upon application of the milling procedure shows a 45% increase (from 10.9% to 15.8%) with respect to cutting procedure, whereas the fraction of hair samples with EtG exceeding 40pg/mg (10.5%) overlaps the percentage of positive samples obtained after cutting pretreatment and applying a cut-off of 30pg/mg. On the basis of these results, it would be worth considering the application of cut-off values linked with the pretreatment procedure, taking into account the results of forthcoming inter-laboratory calibrations.

Biomolecules and Biomarkers Used in Diagnosis of Alcohol Drinking and in Monitoring Therapeutic Interventions

BACKGROUND

The quantitative, measurable detection of drinking is important for the successful treatment of alcohol misuse in transplantation of patients with alcohol disorders, people living with human immunodeficiency virus that need to adhere to medication, and special occupational hazard offenders, many of whom continually deny drinking. Their initial misconduct usually leads to medical problems associated with drinking, impulsive social behavior, and drunk driving. The accurate identification of alcohol consumption via biochemical tests contributes significantly to the monitoring of drinking behavior.

METHODS

A systematic review of the current methods used to measure biomarkers of alcohol consumption was conducted using PubMed and Google Scholar databases (2010-2015). The names of the tests have been identified. The methods and publications that correlate between the social instruments and the biochemical tests were further investigated. There is a clear need for assays standardization to ensure the use of these biochemical tests as routine biomarkers.

FINDINGS

Alcohol ingestion can be measured using a breath test. Because alcohol is rapidly eliminated from the circulation, the time for detection by this analysis is in the range of hours. Alcohol consumption can alternatively be detected by direct measurement of ethanol concentration in blood or urine. Several markers have been proposed to extend the interval and sensitivities of detection, including ethyl glucuronide and ethyl sulfate in urine, phosphatidylethanol in blood, and ethyl glucuronide and fatty acid ethyl esters in hair, among others. Moreover, there is a need to correlate the indirect biomarker carbohydrate deficient transferrin, which reflects longer lasting consumption of higher amounts of alcohol, with serum γ-glutamyl transpeptidase, another long term indirect biomarker that is routinely used and standardized in laboratory medicine.

Progress in monitoring alcohol consumption and alcohol abuse by phosphatidylethanol

For early diagnosis and therapy of alcohol-related disorders, alcohol biomarkers are highly valuable. Concerning specificity, indirect markers can be influenced by nonethanol-related factors, whereas direct markers are only formed after ethanol consumption. Sensitivity of the direct markers depends on cut-offs of analytical methods, material for analysis and plays an important role for their utilization in different fields of application. Until recently, the biomarker phosphatidylethanol has been used to differentiate between social drinking and alcohol abuse. After method optimization, the detection limit could be lowered and phosphatidylethanol became sensitive enough to even detect the consumption of low amounts of alcohol. This perspective gives a summary of most common alcohol biomarkers and summarizes new developments for monitoring alcohol consumption habits.

Ethyl glucuronide and ethyl sulfate

Alcohol misuse is associated with significant morbidity and mortality. Although clinical history, examination, and the use of self-report questionnaires may identify subjects with harmful patterns of alcohol use, denial or under-reporting of alcohol intake is common. Existing biomarkers for detecting alcohol misuse include measurement of blood or urine ethanol for acute alcohol consumption, and carbohydrate-deficient transferrin and gamma-glutamyl transferase for chronic alcohol misuse. There is a need for a biomarker that can detect excessive alcohol consumption in the timeframe between 1 day and several weeks. Ethyl glucuronide (EtG) is a direct metabolite of ethanol detectable in urine for up to 90 h and longer in hair. Because EtG has high specificity for excess alcohol intake, it has great potential for use in detecting "binge" drinking. Using urine or hair, this noninvasive marker has a role in a variety of clinical and forensic settings.

Hair ethyl glucuronide levels as a marker for alcohol use and abuse: a review of the current state of the art

BACKGROUND

Ethyl glucuronide (EtG) is a minor alcohol metabolite that has been proposed as a stable marker in hair to detect and quantify alcohol consumption over long time periods.

METHODS

We provide an outline of currently available techniques for EtG hair sample analysis and highlight the pitfalls related to data interpretation. The literature of EtG analysis has been reviewed from January 1980 up to August 2013. In addition, we present an overview of the clinical and forensic studies which have used EtG quantification in hair as a marker for alcohol consumption/abstinence and we provide suggestions for future research.

RESULTS

EtG is a stable marker in hair that can be used to detect and quantify alcohol consumption over long time periods. This alcohol metabolite remains in hair after complete elimination of alcohol. Currently, there are three main analytical techniques used to quantify EtG in hair: gas chromatography-mass spectrometry (GC-MS), gas chromatography-tandem mass spectrometry (GC-MS/MS), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). No standardized protocols are yet available for the analysis of EtG levels in hair samples, and the current protocols vary in sample preparation and extraction procedures. Variables such as hair length, cosmetic treatment, gender, and pathophysiological conditions influence the final results and should be taken into account.

CONCLUSIONS

EtG quantification in hair is a useful tool for the objective detection of alcohol consumption over extended time periods, but care should be taken when interpreting the results.

[What ethanol metabolites as biological markers tell us about alcohol use]

Alcohol and tobacco related disorders are the two leading and most expensive causes of illness in central Europe. In addition to self reports and questionnaires, biomarkers are of relevance in diagnosis and therapy of alcohol use disorders. Traditional biomarkers such as gamma glutamyl transpeptidase or mean corpuscular volume are indirect biomarkers and are subject to influence of age, gender and non alcohol related diseases, among others.Direct ethanol metabolites such as ethyl glucuronide (EtG), ethyl sulphate (EtS) and phosphatidylethanol (PEth) are direct metabolites of ethanol, that are positive after intake of ethyl alcohol. They represent useful diagnostic tools for identifying alcohol use even more accurately than traditional biomarkers. Each of these drinking indicators remains positive in serum and urine for a characteristic time spectrum after the cessation of ethanol intake--EtG and EtS in urine up to 7 days, EtG in hair for months after ethanol has left the body. Applications include clinical routine use, emergency room settings, proof of abstinence in alcohol rehabilitation programs, driving under influence offenders, workplace testing, assessment of alcohol intake in the context of liver transplantation and fetal alcohol syndrome.