Markers of chronic alcohol use in hair: Comparison of ethyl glucuronide and cocaethylene in cocaine users

Is there a relationship between abuse of alcohol and illicit drugs seen in hair results?

Combined use of alcohol and illicit drugs is a serious health and social problem. In this study, it was examined, whether a relationship between alcohol and drug abuse can be ascertained by comparison of alcohol marker and drug concentrations in hair. In the frame of a social support system for families with parental abuse of illicit drugs, hair samples were analyzed between 2011 and 2022 for methadone, heroin (6-acetylmorphine), cocaine, amphetamine, ecstasy (MDMA), cannabinoids (THC), and the alcohol markers ethyl glucuronide (EtG) and ethyl palmitate (EtPa). For 1314 hair samples from adolescent and adult family members, the hair results show a prevalence of combined occasional or regular drug use and social or abusive alcohol use of 41%-60% except heroin (35%). The drug concentrations were statistically compared in the three categories of abstinence or moderate drinking, social drinking, and alcohol abuse. For the most frequently detected drug cocaine (n = 703), a significant increase of the concentrations with rising alcohol consumption was found. The frequent detection of cocaethylene proved the preferred simultaneous intake of both substances. For THC (n = 489), no significant difference between the alcohol consumer groups was seen. Concerning the less frequently detected methadone (n = 89), 6-acetylmorphine (n = 92), amphetamine (n = 123), and MDMA (n = 105), no clear trend between drug and alcohol marker results was determined. It is concluded that the evaluation of hair results is an appropriate way to study the extent of combined drug-alcohol consumption and complements other studies based on acquisition of consumption data by interview or questionnaire.

Unlocking the potential of forensic traces: Analytical approaches to generate investigative leads

Forensic investigation involves gathering the information necessary to understand the criminal events as well as linking objects or individuals to an item, location or other individual(s) for investigative purposes. For years techniques such as presumptive chemical tests, DNA profiling or fingermark analysis have been of great value to this process. However, these techniques have their limitations, whether it is a lack of confidence in the results obtained due to cross-reactivity, subjectivity and low sensitivity; or because they are dependent on holding reference samples in a pre-existing database. There is currently a need to devise new ways to gather as much information as possible from a single trace, particularly from biological traces commonly encountered in forensic casework. This review outlines the most recent advancements in the forensic analysis of biological fluids, fingermarks and hair. Special emphasis is placed on analytical methods that can expand the information obtained from the trace beyond what is achieved in the usual practices. Special attention is paid to those methods that accurately determine the nature of the sample, as well as how long it has been at the crime scene, along with individualising information regarding the donor source of the trace.

Cocaine: An Updated Overview on Chemistry, Detection, Biokinetics, and Pharmacotoxicological Aspects including Abuse Pattern

Cocaine is one of the most consumed stimulants throughout the world, as official sources report. It is a naturally occurring sympathomimetic tropane alkaloid derived from the leaves of Erythroxylon coca, which has been used by South American locals for millennia. Cocaine can usually be found in two forms, cocaine hydrochloride, a white powder, or ‘crack’ cocaine, the free base. While the first is commonly administered by insufflation (‘snorting’) or intravenously, the second is adapted for inhalation (smoking). Cocaine can exert local anaesthetic action by inhibiting voltage-gated sodium channels, thus halting electrical impulse propagation; cocaine also impacts neurotransmission by hindering monoamine reuptake, particularly dopamine, from the synaptic cleft. The excess of available dopamine for postsynaptic activation mediates the pleasurable effects reported by users and contributes to the addictive potential and toxic effects of the drug. Cocaine is metabolised (mostly hepatically) into two main metabolites, ecgonine methyl ester and benzoylecgonine. Other metabolites include, for example, norcocaine and cocaethylene, both displaying pharmacological action, and the last one constituting a biomarker for co-consumption of cocaine with alcohol. This review provides a brief overview of cocaine’s prevalence and patterns of use, its physical-chemical properties and methods for analysis, pharmacokinetics, pharmacodynamics, and multi-level toxicity.

Validation of hair ethyl glucuronide using transdermal monitoring and self-reported alcohol use in women of childbearing potential

Aim

The present study aimed to evaluate the validity of hair ethyl glucuronide concentrations compared with transdermal alcohol concentration and self‐reported alcohol use.

Methods

This trial included 25 adolescent and young adult females, aged 16‐24, who reported at least one heavy drinking episode (≥4 drinks) in the two weeks prior to baseline. All participants were asked to wear an alcohol biosensor over a one‐month prospective study. Detailed self‐report of drinking behaviors was assessed weekly. Estimates of blood alcohol concentration were computed from self‐report data using the National Highway and Transportation Safety Administration equation. Transdermal alcohol concentration and estimated blood alcohol concentration data were categorized into at‐risk (>0.05 g/dL alcohol) and high‐risk (>0.08 g/dL alcohol) drinking events. Hair ethyl glucuronide concentration, total number of drinking events, moderate (>0.05 g/dL) and high level (>0.08 g/dL) of transdermal alcohol concentration, and estimated blood alcohol concentration drinking events were analyzed with Spearman's rank correlation test for validity comparisons.

Results

No significant correlations were found between hair ethyl glucuronide values and total number, and moderate or high levels of detected drinking events by estimated blood alcohol concentration or transdermal alcohol concentration. Total number of drinking events detected and number of drinking events >0.08 g/dL using estimated blood alcohol concentration and transdermal alcohol concentration methods were significantly correlated with each other (respectively, R = .33, P < .05; R = .42, P < .05).

Conclusion

Our findings indicate that, due to the number of false negatives, hair ethyl glucuronide concentrations should be used with caution for monitoring abstinence from alcohol use.

Positive findings of ethyl glucuronide in hair of young children from families with addiction background

AIMS

Small children are expected to be abstinent from alcohol, and children's hair is frequently used as the blank matrix for calibration of the alcohol consumption marker ethyl glucuronide (EtG). The basal EtG concentrations of total abstainers were described to be 0.3-2.1 pg/mg (Pirro et al. 2013). It is examined whether this assumption is valid for children from families with addiction background.

METHODS

In a social support system for families with drug and/or alcohol addicted parents, 161 hair samples from 126 children (age 1-14 years, hair segment 0-3 cm) were analyzed for EtG by a validated LC-MS/MS method (LOD 0.56 pg/mg, LLOQ 2.3 pg/mg). For comparison, ethyl palmitate (EtPa) was measured and hair samples from parents were included. EtG ≥ 3 pg/mg was considered as an alarming result for children.

RESULTS AND DISCUSSION

EtG concentrations between 3.0 and 42.6 pg/mg (mean 9.55 pg/mg, median 6.40 pg/mg) were measured for 25 samples (15.5%, age 22 × 1-5 years, 3 × 9-11 years). Elevated EtPa (0.15-0.46 ng/mg) was found in 6 samples and cocaethylene (0.02-0.07 ng/mg) was detected in 5 samples with high cocaine findings. Hair results of one or both parents indicated drug abuse in 12 from 14 cases (85.7%) if both parents were tested.

CONCLUSION

Although accidental or voluntary intake of alcoholic beverages cannot be excluded, the external contamination of children's hair by EtG-containing wine and sweat or urine of the alcohol abusing parents is assumed to be the most probable explanation for the positive EtG results in hair of 1-5-year-old children.

The Dangerous Pattern of Concurrent Use of Alcohol and Cocaine Among Drunk-Drivers of Northeast Italy

Aim

To estimate the prevalence of drug and polydrug use among drunk-drivers during the driving license regranting program, in order to assess the inclusion of toxicological tests on hair and urine samples in the systematic methodology in this category of subjects.

Short summary

A total of 2160 drunk-drivers were tested for alcohol and drugs during driving license regranting. Thirty-one subjects showed alcohol use, 212 illicit drug use and, among these, 131 were polydrug users. Nineteen different patterns of drug and polydrug use were found. Cocaine was detected in 165 subjects.

Methods

The study was performed on 2160 drunk-drivers examined at Legal Medicine and Toxicology Unit of the University of Padova, in a 3-year-period (2014-2017). The positivity for one or more illicit drugs in hair or urine samples was confirmed by LC/MS and GC/MS methods. Chi-square test, Fischer's exact test and Cochran-Armitage Trend test were used to study the correlation between general characteristics of the examined sample and the presence of drug/polydrug use.

Results

Thirty-one subjects showed alcohol use, 212 illicit drug use and, among these, 131 were polydrug users. Nineteen different patterns of drug and polydrug use were found. Cocaine was detected in 165 subjects in whom 122 showed a concurrent use of alcohol and cocaine, identified through the detection of cocaethylene in hair samples. No significant association and/or trends between drug/polydrug use and the general characteristics of the sample were detected.

Conclusions

The results show that drug and polydrug use among drunk-drivers should be subjected to toxicological as well as alcohological monitoring, especially in the regranting procedure. The implementation of this procedure could improve the knowledge of dimensions of the issue, providing a powerful means for the reduction of phenomenon of driving under the influence of alcohol and drugs.

Integration of Clinical Examination, Self-Report, and Hair Ethyl Glucuronide Analysis for Evaluation of Patients With Alcoholic Liver Disease Prior to Liver Transplantation

Context:

A large proportion of liver transplants (LTXs) are performed due to alcoholic liver disease (ALD) in the final stage of organ insufficiency. In order to list patients for LTX, transplant centers commonly require 6 months abstinence from alcohol. However, significant differences have been reported between alcohol intake as indicated by self-report and biochemical markers of alcohol.

Objective:

In the present study, the usefulness of ethyl glucuronide analysis in hair (hETG) was examined during the evaluation procedure before listing patients with ALD for an LTX.

Design:

Cross-sectional survey.

Setting:

Psychosomatic evaluation.

Patients:

Seventy patients with ALD prior to listing for an LTX.

Interventions:

According to clinical assessment before listing patients with ALD (n = 233) for an LTX, hETG analysis was only performed in the patients who were assumed to deny or underreport their alcohol consumption (n = 70).

Main Outcome Measures:

The analysis of hETG by liquid chromatography–mass spectrometry, clinical interview.

Results:

By hETG analyses, 27 (38.6%) of the 70 patients tested positive for ongoing alcohol consumption.

Conclusions:

Selective use of hETG based on the clinical interview rather than widespread screening is a possible way to detect excessive alcohol consumption in patients with ALD in the transplant setting. The primary evaluation of a patient’s situation in its entirety should remain the superordinate standard procedure. An interdisciplinary approach to transplant candidates with an ALD is asked for.

The usefulness of biomarkers of alcohol abuse in hair and serum carbohydrate-deficient transferrin: a case report

The detection of carbohydrate-deficient transferrin (CDT) in serum is widely accepted to identify chronic alcohol consumption over the previous two weeks, but minor ethanol metabolites detected in hair often complete the information obtained. In particular, ethylglucuronide and cocaethylene (a marker of simultaneous intake of cocaine and alcohol) allow correct interpretation of data obtained in forensic cases. We refer to a negative CDT value obtained from a serum sample collected during hospitalization of a man admitted for cardiac arrest who died about 14 h later. Clinical analysis performed on admission showed a high ethanol level and a positive urinary screening for cocaine. The toxicological analyses of post-mortem samples found cocaine metabolites in his urine and blood. The negative CDT level suggested the ethanol concentration at admission to be an acute episode. Cocaine and cocaethylene well above the cut-off suggested by the literature were found in hair analyzed for the entire length (about 1 cm). Ethylglucuronide detected on the same hair sample confirmed chronic abuse of ethanol in the previous month, at least. The present report suggests caution in the interpretation of biomarkers of alcohol abuse, encouraging the detection of more than one marker to avoid misinterpretation.

Demonstration of ethyl glucuronide in dental tissue samples by liquid chromatography/electro-spray tandem mass spectrometry

INTRODUCTION

Ethyl glucuronide (EtG) has been studied in various tissues and body fluid for determination of alcohol intake. However, no study, dealing with EtG analysis in dental tissue, was performed so far. In this study, we aimed to demonstrate EtG levels in dental tissue.

MATERIALS AND METHODS

Michigan Alcohol Screening Test (MAST) was performed to 29 participants. Following the test, cases were divided into three groups as non-hazardous alcohol users, alcohol abusers and 6 controls who verbally declared that they were abstainers. A total of 29 tooth specimens, obtained from participants, was included in the study. These specimens were analyzed using LC/MS/MS.

RESULTS

All of the participants included in the study were male. According to the MAST outcomes 14 of the participants were non-hazardous alcohol users, and 9 were alcohol abusers, while 6 patients verbally declared that they were abstainers. Dental tissue analyses revealed EtG levels ranging between EtG<LOD and 23.39 pg/mg. EtG levels were observed to be <LOD in dental specimens of 6 abstainer cases. A significant correlation was found between EtG levels measured in the dental tissues and MAST outcomes on the statistical analyses (r=0.914).

CONCLUSION

The findings of the present study demonstrated that dental tissue can be used for detection of alcohol intake, using LC/MS/MS.

Comparison of ethyl glucuronide in hair with self-reported alcohol consumption

AIMS

Ethyl glucuronide (EtG) in hair is a proposed biomarker for alcohol consumption. This study compares hair EtG concentrations with self-reported alcohol consumption data, in individuals with a range of alcohol use.

METHODS

Hair was collected from 100 participants with a range of alcohol use. Participants completed an Alcohol Use Disorders Identification Test C questionnaire to record alcohol consumption. Participants were categorized into one of the four groups: tee-totallers (consuming 0 units a week), lower-risk drinkers (1-21 units a week), increasing-risk drinkers' consuming (22-50 units a week) and high-risk drinkers (over 50 units a week). Hair from the proximal 3 cm was analysed for EtG using gas chromatography-mass spectrometry/mass spectrometry.

RESULTS

EtG was detected in 29 out of 100 hair samples. Based on the Society of Hair Testing (SOHT) threshold of 30 pg/mg EtG, the hair test identified alcohol consumption in 57.9% of high-risk drinkers, 45.5% of increasing-risk drinkers and only 9.8% of lower-risk drinkers. EtG sensitivity was highest for high-risk drinkers (consuming more than 50 units a week), identified to be 0.52 using a 30 pg/mg threshold and 0.58 using a 45 pg/mg threshold. A positive result is highly likely to indicate any drinking (positive predictive value, 1.00). A negative result does not provide good evidence for abstinence (negative predictive value, 0.23).

CONCLUSIONS

EtG has been identified to be a low sensitivity marker that cannot be used quantitatively to determine alcohol exposure. EtG can be used qualitatively to indicate alcohol consumption with a positive result providing strong evidence for an individual drinking within the past 3 months.

Chronic excessive alcohol consumption diagnosis: comparison between traditional biomarkers and ethyl glucuronide in hair, a study on a real population

BACKGROUND

The study aimed to evaluate the diagnostic sensitivity (SE) and specificity (SP) of chronic alcohol misuse diagnosis by comparing traditional biomarkers with ethyl glucuronide (EtG), an ethanol direct metabolite, detected in the keratinic matrix.

METHODS

Seventy-six subjects tested for chronic alcohol abuse for different purposes were recruited. EtG was detected in hair, whereas the analyses of carbohydrate-deficient transferrin (CDT), alanine transaminase, aspartate transaminase, gamma-glutamyl transferase, mean corpuscular volume, and mean corpuscular hemoglobin were performed in serum samples.

RESULTS

Of the 76 patients examined, 26 were judged by the medical doctors as subjects with alcohol abuse problems and, therefore, not eligible for driving license renewal or liver transplant. EtG in hair (SE = 0.68, SP = 1.00) showed the best diagnostic SE and SP compared with the other biomarkers investigated. Among the traditional biomarkers, only CDT proved to be suitable for forensic purposes because of the high diagnostic specificity (SP = 1.00) although it showed poor diagnostic SE (0.27). The percentage of positive samples decreased for all the biomarkers by excluding the subjects with hepatic diseases, except for EtG and CDT, suggesting that these 2 biomarkers could be less affected by false positive results, because of hepatic diseases.

CONCLUSIONS

This study showed that when EtG in hair and CDT results are combined, diagnostic SE in chronic alcohol abuse diagnosis clearly improved, suggesting that complementary analysis of both these biomarkers provides the best diagnostic tool in suspected cases of chronic excessive alcohol consumption.

Determination of ethyl glucuronide in nails by liquid chromatography tandem mass spectrometry as a potential new biomarker for chronic alcohol abuse and binge drinking behavior

A liquid chromatography tandem mass spectrometry method for ethyl glucuronide (EtG) detection and quantification in nails was developed and fully validated. Nails were extracted in 700 μL double-distilled water. EtG-d(5) was used as an internal standard. Reversed-phase separation was obtained with an isocratic mobile phase composed of 0.1% formic acid and acetonitrile (99:1) for 10 min. Quantification was performed by multiple reaction monitoring of two transitions per compound (EtG and internal standard). The assay was linear from 10 to 500 pg/mg. Validation parameters were studied at three different quality control levels (10, 50, and 300 pg/mg). Intraday, interday, and total imprecision had a coefficient of variation of less than 9.5%. Ion suppression and ion enhancement were negligible (less than 20%). No carryover was detected. The method was applied to several real cases, among teetotalers, social drinkers, and heavy drinkers. A questionnaire, together with the informed consent form, was given to all the participants in order to evaluate alcohol intake in the one month before sample collection. Nail EtG levels in a social drinker were much higher than the concentrations of EtG in hair provided by the same subject, thus suggesting potential high sensitivity in evaluating both chronic excessive alcohol consumption and binge drinking habits.

Bioanalytical methods for the determination of cocaine and metabolites in human biological samples

Determination of cocaine and its metabolites in biological specimens is of great importance, not only in clinical and forensic toxicology, but also in workplace drug testing. These compounds are normally screened for using sensitive immunological methods. However, screening methods are unspecific and, therefore, the posterior confirmation of presumably positive samples by a specific technique is mandatory. Although GC-MS-based techniques are still the most commonly used for confirmation purposes of cocaine and its metabolites in biological specimens, the advent of LC-MS and LC-MS/MS has enabled the detection of even lower amounts of these drugs, which assumes particular importance when sample volume available is small, as frequently occurs with oral fluid. This paper will review recently-published papers that describe procedures for detection of cocaine and metabolites, not only in the most commonly used specimens, such as blood and urine, but also in other 'alternative' matrices (e.g., oral fluid and hair) with a special focus on sample preparation and chromatographic analysis.

Analytical methods for abused drugs in hair and their applications

Hair has been focused on for its usability as an alternative biological specimen to blood and urine for determining drugs of abuse in fields such as forensic and toxicological sciences because hair can be used to elucidate the long intake history of abused drugs compared with blood and urine. Hair analysis consists of several pretreatment steps, such as washing out contaminates from hair, extraction of target compounds from hair, and cleanup for instrumental analysis. Each step includes characteristic and independent features for the class of drugs, e.g., stimulants, narcotics, cannabis, and other medicaments. In this review, recently developed methods to determine drugs of abuse are summarized, and the pretreatment steps as well as the sensitivity and applicability are critically discussed.

Computer assisted modeling of ethyl sulfate pharmacokinetics

For 12 volunteers of a drinking experiment the concentration-time-courses of ethyl sulfate (EtS) and ethanol were simulated and fitted to the experimental data. The concentration-time-courses were described with the same mathematical model as previously used for ethyl glucuronide (EtG). The kinetic model based on the following assumptions and simplifications: a velocity constant k(form) for the first order formation of ethyl sulfate from ethanol and an exponential elimination constant k(el). The mean values (and standard deviations) obtained for k(form) and k(el) were 0.00052 h(-1) (0.00014) and 0.561 h(-1) (0.131), respectively. Using the ranges of these parameters it is possible to calculate minimum and maximum serum concentrations of EtS based on stated ethanol doses and drinking times. The comparison of calculated and measured concentrations can prove the plausibility of alleged ethanol consumption and add evidence to the retrospective calculation of ethanol concentrations based on EtG concentrations.

Ethyl glucuronide in hair. A sensitive and specific marker of chronic heavy drinking

AIMS

This study aims to define a cut-off concentration for ethyl glucuronide in hair to determine if there was a history of heavy drinking.

SETTINGS

Pavia, Italy.

PARTICIPANTS

We analysed hair samples from 98 volunteers among teetotallers, social drinkers and heavy drinkers, whose ethanol daily intake (EDI) was estimated by means of a written questionnaire.

MEASUREMENTS

Ethyl glucuronide hair concentration (HEtG) was measured by liquid chromatography-tandem mass spectrometry (lower limit of quantification: 3 pg/mg) using a fully validated method.

FINDINGS

The HEtG level providing the best compromise between sensitivity (0.92) and specificity (0.96) at detecting an EDI of 60 g or higher during the last 3 months was 27 pg/mg. None of the factors examined among those known to affect ethanol metabolism and/or the diagnostic power of other markers of ethanol use or hair analyses, including age, gender, body mass index, tobacco smoke, prevalent beverage, hair colour, cosmetic treatments and hygienic habits was found to influence marker performance significantly. However, the slight differences in HEtG performance observed for some factors (e.g. body mass index, smoke and hair treatments) require further studies on larger groups of individuals in order to assess their influence more precisely.

CONCLUSIONS

Our results confirm further that HEtG is a sensitive and specific marker of chronic heavy drinking.

Comparison of ethyl glucuronide in hair with carbohydrate-deficient transferrin in serum as markers of chronic high levels of alcohol consumption

This study was designed with the aim to compare sensitivity and specificity of ethyl glucuronide in hair (HEtG) and carbohydrate-deficient transferrin (CDT) in serum as markers of heavy drinking. Eighty-six volunteers, including teetotalers, social, and heavy drinkers, were interviewed to evaluate their ethanol daily intake (EDI) during the last 2-week and 3-month periods. HEtG determination was performed by a fully validated LC-MS-MS procedure and ranged from <LOD (2 pg/mg) to 890.5 pg/mg. CDT was measured by immunonephelometry or by HPLC. Sensitivity and specificity of the two markers as indicators of an EDI higher than 60 g/day were calculated, with cut-off at 27 pg/mg (HEtG) and 2.5% (CDT). Considering the EDI of the last 2 weeks, HEtG showed equal selectivity (0.93 for both HEtG and CDT-immunonephelometry; 0.70 for both HEtG and CDT-HPLC) and 2 times the sensitivity of either of the two CDT methods (1.00 vs. 0.44 for CDT-immunonephelometry; 0.96 vs. 0.50 for CDT-HPLC). The same difference in performances but with higher absolute sensitivity and selectivity values for HEtG were observed considering the EDI of the last 3-months (selectivity: 1.00 for both HEtG and CDT-immunonephelometry, 0.89 and 0.78 for HEtG and CDT-HPLC, respectively; sensitivity: 1.00 vs. 0.47 for CDT-immunonephelometry; 0.98 vs. 0.51 for CDT-HPLC). Our results indicate that HEtG, as compared to CDT measured using different methods, is a selective marker of ethanol heavy chronic use providing considerably higher sensitivity.

A review of the use of ethyl glucuronide as a marker for ethanol consumption in forensic and clinical medicine

Ethyl glucuronide (EtG) is a direct phase-II metabolite of ethanol formed through the UDP-glucuronosyl transferase catalyzed conjugation of ethanol with glucuronic acid. It has been detected in many antemortem and postmortem biological matrices using a variety of analytical methods. Due to its long urinary elimination time, detectability in hair, specificity for ethanol exposure, and low detection limits of assays, the use of EtG has been proposed as a marker of recent ethanol intake in a variety of clinical and legal settings, including medical monitoring for relapse, emergency department patient evaluation, postmortem assessments, and transportation accident investigation. However, challenges associated with factors such as establishing appropriate cut-off levels capable of distinguishing between drinking and nonbeverage sources of ethanol exposure, nonuniform laboratory reporting limits, sample stability, and microbial activity substantially complicate accurate interpretation of results. The following review briefly explores the history, utility, and limitations of EtG in contemporary medical and forensic practice.

Assessment of the stability of the ethanol metabolite ethyl sulfate in standardised degradation tests

Ethyl sulfate (EtS) is a non-oxidative metabolite of ethanol, used for forensic purposes as an ethanol consumption marker in addition to the ethanol metabolite ethyl glucuronide (EtG) which after certain scientific publications is prone to biological degradation. As ethanol is widely consumed in many western cultures, knowledge about the stability of ethyl sulfate against biodegradation is of importance for forensic investigations-where EtS until now was thought to be stable against bacterial degradation. Using standardized test methods from the panel of OECD tests, the stability of EtS against bacterial degradation was assessed in this study. These experiments showed that EtS was stable in the closed bottle test (CBT) (OECD 301 D), but not in the manometric respiratory test (MRT) (OECD 301 F) with higher bacterial density. With respect to forensic investigations the assumption of EtS stability could be disproved and the possibility of bacterial degradation of EtS should be taken into account when alcohol uptake some hours prior to death needs to be ruled out by determination of alcohol consumption markers in putrefied corpses, where ethanol concentration could have been generated post-mortem by fermentation processes.