Breath alcohol test precision: an in vivo vs. in vitro evaluation

Random error is associated with breath alcohol measurements, as with all analytical methods. The total random uncertainty of a group of n measurements is typically determined by computing the standard deviation and requiring it to be less than some appropriate level (i.e., +/- 0.0042 g/210 l). The total random uncertainty has two primary sources; the instrumental method and the sample source. These are typically inseparable values. In breath alcohol testing the two primary sample sources are simulators and human breath. The present study evaluates ten groups of simulator samples consisting of ten measurements each on BAC Verifier Datamaster instruments. The data also includes ten breath alcohol measurements from each of 21 individuals following alcohol consumption. The range of standard deviations for the simulator samples was 0.0003-0.0022 g/210 l. The range of standard deviations for the human breath samples was 0.0015-0.0089 g/210 l. Two statistics that test for homogeneity for variances were applied. The simulator samples resulted in a Cochran's C test of 0.5000 and an Fmax test of 48.9. The human breath samples resulted in a Cochran's C test of 0.1519 and an Fmax test of 27.3. All were significant at P less than 0.001. The statistical tests demonstrated that the intragroup variability among the human subjects was comparable to the intragroup variability among the simulator samples. The data also demonstrates that the sample source (simulator or human) is probably the largest contributor to total random uncertainty. Therefore, when duplicate breath alcohol testing from individuals shows variability in the second decimal place the cause is differences in breath samples provided and not instrumental imprecision.     

Breath alcohol concentration determined with a new analyzer using free exhalation predicts almost precisely the arterial blood alcohol concentration

A new breath alcohol (ethanol) analyzer has been developed, which allows free exhalation, standardizes measured exhaled alcohol concentration to fully saturated water vapor at a body temperature of 37 degrees C (43.95 mg/L) and includes a built-in self-calibration system. We evaluated the performance of this instrument by comparing standardized alcohol concentration in freely expired breath (BrAC) with arterial (ABAC) and venous (VBAC) blood alcohol concentrations in fifteen healthy volunteers who drank 0.6 g of alcohol per kg body weight. The precision (coefficient of variation, CV) of the analyzer based on in vivo duplicate measurements in all phases of the alcohol metabolism was 1.7%. The ABAC/BrAC ratio was 2251+/-46 (mean+/-S.D.) in the post-absorptive phase and the mean bias between ABAC and BrAC x 2251 was 0.0035 g/L with 95% limits of agreement of 0.033 and -0.026. The ABAC and BrAC x 2251 were highly correlated (r=0.998, p<0.001) and the regression relationship was ABAC = 0.00045 + 1.0069 x (BrAC x 2251) indicating excellent agreement and no fixed or proportional bias. In the absorption phase, ABAC exceeded BrAC x 2251 by at most 0.04+/-0.03 g/L when tests were made at 10 min post-dosing (p<0.05). The VBAC/BrAC ratio never stabilized and varied continuously between 1834 and 3259. There was a proportional bias between VBAC and BrAC x 2251 (ABAC) in the post-absorptive phase (p<0.001). The pharmacokinetic analysis of the elimination rates of alcohol and times to zero BAC confirmed that BrAC x 2251 and ABAC agreed very well with each other, but not with VBAC (p<0.001). We conclude that this new breath analyzer using free exhalation has a high precision for in vivo testing. The BrAC reflects very accurately ABAC in the post-absorption phase and substantially well in the absorption phase and thereby reflects the concentration of alcohol reaching the brain. Our findings highlight the magnitude of arterio-venous differences in alcohol concentration and support the use of breath alcohol analyzers as a stand-alone test for medical and legal purposes.     

Breath alcohol analysis in one subject with gastroesophageal reflux disease.

A large number of people suffer from the heartburn symptoms associated with gastroesophageal reflux disease (GERD). Relatively little has been published on its potential for biasing a breath alcohol measurement. The present case describes an individual (white male, aged 23) who experimentally consumed 1.0 g/kg of an alcohol beverage and subsequently provided breath and blood samples for analysis. Breath expirograms were also collected following several different preexhalation breathing maneuvers. Shortly after the end of drinking the mean of replicate breath alcohol results exceeded that of the corresponding venous blood alcohol. A later paired comparison (during the postabsorptive phase) showed the blood alcohol to exceed the breath. None of the expirograms provided evidence that "mouth alcohol" due to gastroesophageal reflux had biased any test results. People with GERD can provide biased-free end-expiratory breath alcohol results where sound forensic practice is followed, which includes: 15-min. preexhalation observation, duplicate testing, instrumental detection systems, and trained alert operators who ask appropriate questions and watch for associated signs.     

Duplicate breath testing: some statistical analyses

Duplicate breath alcohol testing from each individual provides confidence in the results when reasonable agreement (i.e. +/- 0.02 g/210 L) is achieved. For this reason many jurisdictions require duplicate testing. The State of Washington has recently implemented an infrared breath testing program and now requires two breath samples from each individual. Statistical analysis of 1847 duplicate breath tests is presented. Three variables are analyzed: first alcohol result (ALC1), the absolute difference between the two breath samples (DIFFA), and the signed difference between the two breath samples (DIFFS). The first breath alcohol result ranged from 0.021 to 0.338 g/210 L with a mean of 0.157 g/210 L. The absolute difference ranged from 0.00 to 0.05 g/210 L. The signed difference ranged from -0.05 g/210 L to 0.05 g/210 L. The absolute difference was regressed upon the first alcohol result and resulted in poor linear correlation of r = 0.212. Duplicate breath test differences do not appear to be a function of subject's alcohol level, but rather of sample provision.     

Reflections on variability in the blood–breath ratio of ethanol and its importance when evidential breath-alcohol instruments are used in law enforcement

Variability in the blood–breath ratio (BBR) of alcohol is important, because it relates a measurement of the blood-alcohol concentration (BAC) with the co-existing breath-alcohol concentration (BrAC). The BBR is also used to establish the statutory BrAC limit for driving from the existing statutory BAC limits in different countries. The in-vivo BBR depends on a host of analytical, sampling and physiological factors, including subject demographics, time after end of drinking (rising or falling BAC), the nature of the blood draw (whether venous or arterial) and the subject’s breathing pattern prior to exhalation into the breath analyzer. The results from a controlled drinking study involving healthy volunteers (85 men and 15 women) from three ethnic groups (Caucasians, Hispanics and African Americans) were used to evaluate various factors influencing the BBR. Ethanol in breath was determined with a quantitative infrared analyzer (Intoxilyzer 8000) and BAC was determined by headspace gas chromatography (HS-GC). The BAC and BrAC were highly correlated (r = 0.948) and the BBR in the post-absorptive state was 2 382 ± 119 (mean ± SD). The BBR did not depend on gender (female: 2 396 ± 101 and male: 2 380 ± 123, P > 0.05) nor on racial group (Caucasians 2 398 ± 124, African Americans 2 344 ± 119 and Hispanics 2 364 ± 104, P > 0.05). The BBR was lower in subjects with higher breath- and body-temperatures (P < 0.05) and it also decreased with longer exhalation times into the breath-analyzer (P < 0.001). In the post-absorptive state, none of the 100 subjects had a BBR of less than 2 100:1.     

The effects of dosed tobacco in evidentiary breath testing using non-drinking subjects

A total of seventeen subjects were administered breath tests with alcohol dosed tobacco to see if there was an interference with the evidentiary breath testing. Fourteen subjects provided one set of two breath samples without the dosed tobacco followed by a set of two breath samples with the dosed tobacco. The other three subjects provided one breath sample without the dosed tobacco and then one breath sample with the dosed tobacco within the same testing sequence. Eight subjects had breath test readings of 0.00g/210L with the dosed tobacco. Mouth alcohol was detected with the dosed tobacco in six of the subjects, and a reading of 0.01g/210L, 0.04g/210L, and 0.05g/210L were found in five of the subjects. If the officer follows the directive of checking the mouth for a foreign substance and following a 15-20min observation/deprivation period, a false positive result will likely be avoided. If the officer does not find tobacco when checking the mouth for a foreign substance, and dosed tobacco is present during the breath test, most likely there would not be a measurable amount of alcohol to report or there would be a mouth alcohol reading from the sample.     

血液乙醇检测内外标法比较研究

目的通过比较内标法和外标法对血液乙醇含量检测结果,探讨外标法在法医学实践中的应用价值。方法通过收集2005年10月~2006年12月间本中心符合检测要求的血液样品263例,每例分别采用内标法和外标法进行血液样品乙醇含量检测,比较其检测结果。结果外标法检测时间短(2.5min),用量0.5ml,而内标法检测时间长(6.5min),样品量1.0ml;外标法检测血乙醇平均浓度为89.30mg/100ml,内标法检测血乙醇平均浓度为92.37mg/100ml,P=0.001。结论外标法检测时间短(2.5min),用量少,节约检材,可作为大量待测血液样本的筛选检查手段。     

The Effects of Gastroesophageal Reflux Disease on Forensic Breath Alcohol Testing

Fifteen test subjects, 10 of whom were diagnosed with gastroesophageal reflux disease (GERD), were dosed with alcohol to BACs above 0.150 g/dL. Blood and breath assays taken at 20-min intervals for 8 h after dosing demonstrated close agreement between postabsorptive BAC and BrAC values. Three subjects exhibited elevated breath alcohol concentrations up to 0.105 g/dL during the absorptive phase that were apparently due to the passage of gastric alcohol through the lower esophageal sphincter not attributable to eruction or regurgitation. The effect of gastric alcohol was not consistently proportional to the amount of unabsorbed gastric alcohol. Absorption of alcohol in the esophagus explains the nonproportionality. Breath samples contaminated by GERD-related alcohol leakage from the stomach into a breath sample were found only when there was a high concentration of alcohol in the stomach. When contaminated breath samples were encountered, they were irreproducible in magnitude.     

The elimination rate of mouth alcohol: mathematical modeling and implications in breath alcohol analysis.

Mouth alcohol, if present in high enough concentrations, can falsely bias the accurate measurement of end-expiratory breath alcohol. Mouth alcohol will be eliminated over time, however, and can be modeled with a single term decaying exponential of the form: B0e-kt + C. It is important, however, to determine the model and its parameters when alcohol is already present within the biologic system. Using three individuals as their own controls, mouth alcohol was administered both before and after alcohol consumption followed by breath alcohol analysis performed at approximately 0.5 min intervals. The results showed that both model parameters (B0 and k) are effected and that the asymptotic value (C) is reached much sooner when alcohol already exists in the end-expiratory breath. Considering only three individuals were involved, the forensic-science importance appears to be that, as the end-expiratory breath alcohol concentration increases, the time necessary for the mouth alcohol to decrease to unbiased levels is decreased. Fifteen min of observation time prior to breath alcohol analysis appears to be more than adequate at forensically relevant concentrations.     

Oral fluid results compared to self reports of recent cocaine and heroin use by methadone maintenance patients

A novel breath-alcohol analyzer based on the standardization of the breath alcohol concentration (BrAC) to the alveolar-air water vapour concentration has been developed and evaluated. The present study compares results with this particular breath analyzer with arterial blood alcohol concentrations (ABAC), the most relevant quantitative measure of brain alcohol exposure. The precision of analysis of alcohol in arterial blood and breath were determined as well as the agreement between ABAC and BrAC over time post-dosing. Twelve healthy volunteers were administered 0.6g alcohol/kg bodyweight via an orogastric tube. Duplicate breath and arterial blood samples were obtained simultaneously during the absorption, distribution and elimination phases of the alcohol metabolism with particular emphasis on the absorption phase. The precision of the breath analyzer was similar to the determination of blood alcohol concentration by headspace gas chromatography (CV 2.40 vs. 2.38%, p=0.43). The ABAC/BrAC ratio stabilized 30min post-dosing (2089±99; mean±SD). Before this the BrAC tended to underestimate the coexisting ABAC. In conclusion, breath alcohol analysis utilizing standardization of alcohol to water vapour was as precise as blood alcohol analysis, the present "gold standard" method. The BrAC reliably predicted the coexisting ABAC from 30min onwards after the intake of alcohol.     

Determination of mouth alcohol using the Dräger Evidential Portable Alcohol System

Drivers suspected of alcohol intoxication are observed for a period of 15 min prior to quantitative breath alcohol testing. This is to preclude the interference of alcohol-based substances such as cough medicine, mouthwash, and breath spray just prior to actual evidential testing. To determine whether a 15 min observation period was necessary when performing evidential breath tests in the field, a mouth alcohol experiment was performed using the Dräger Evidential Portable Alcohol System (EPAS). Five types of alcohol beverages and the effects of expectorating versus swallowing were tested on twenty-five volunteer subjects. Serial measurements of breath and blood alcohol levels were performed at fixed time intervals. All alcohol beverage types gave two sequential measurements within 0.02 g/210 L of each other before 15 min had passed. Fifteen minutes was necessary to ensure there was no residual mouth alcohol. If the 15 min waiting period was not observed, the safety feature of the EPAS requiring two sequential measurements 2 min apart within 0.02 g/210 L would not ensure against mouth alcohol interference.     

The effect of breath freshener strips on two types of breath alcohol testing instruments

The potential for breath freshener strips to interfere with the accuracy of a breath alcohol test was studied. Twelve varieties of breath freshener strips from five manufacturers were examined. Breath tests were conducted using the infrared based BAC DataMaster or the fuel cell based Alco-Sensor IV-XL, 30 and 150 seconds after placing a breath strip on the tongue. No effect was observed using the Alco-Sensor system. Some of the strips gave a small reading at 30 seconds (less than or equal to 0.010 g/210 L apparent alcohol) using the DataMaster. Readings on the DataMaster returned to zero by the 150 second test. A proper pre-test observation and deprivation period should prevent any interference from breath freshener strips on breath alcohol testing.     

Can wine tasting be used as a defence to a charge of excess alcohol?

Wine-tasting has been used as a defence in the UK to charges of driving with excess alcohol on the breath. There is little scientific data to support this explanation. The authors carried out an experimental wine-tasting using twelve volunteer subjects. Breath alcohol samples were taken at the start of the experiment and fifteen minutes after the end. All subjects after wine-tasting had breath alcohol levels below the instrumental limit of detection. The authors conclude that the wine-tasting defence is not credible.     

Evaluation of breath-alcohol instruments. III. Controlled field trial with Alcolmeter pocket model

A breath-alcohol screening device, Alcolmeter pocket model, was evaluated in a controlled field trial with policeman operating the instruments. The results of tests made with subjects before they drank alcohol were always zero. The standard deviation (S.D.) of breath alcohol determinations increased with increase in the concentration of alcohol in the sample, being 0.036 mg/ml at a mean blood-ethanol concentration of 0.53 mg/ml. The S.D. varied among subjects tested (from 0.022 to 0.053 mg/ml) as well as among the instruments used (from 0.023 to 0.054 mg/ml). The breath test results were on average less than the actual blood-ethanol concentrations when a 2100: 1 blood/breath ratio was used to calibrate the Alcolmeter device. Blood ethanol (x) and Alcolmeter readings (y) were highly correlated (r = 0.95 +/- 0.018) and the regression equation was y = -0.017 + 0.95x. At a mean blood-ethanol concentration of 0.50 mg/ml, the Alcolmeter instrument will indicate 0.46 mg/ml on average. The standard error estimate was 0.085 mg/ml, being 17% of the mean Alcolmeter reading and this corresponds to 95% confidence limits of +/- 0.17 mg/ml. The results of this study show that Alcolmeter pocket-model is a useful device for breath-alcohol screening purposes at a blood-alcohol level of 0.50 mg/ml. A blood/breath ratio of 2300 should be used to calibrate the Alcolmeter device.     

The effect of dentures and denture adhesives on mouth alcohol retention.

A total of 24 alcohol-free, denture-wearing subjects were tested for mouth-alcohol retention times with an Intoxilyzer 5000. The subjects were given 30 mL doses of 80 proof brandy to swish in their mouths without swallowing for 2 min prior to expectorating the dose. Subjects were tested under three conditions: 1) with dentures removed, 2) with dentures held loosely in place without an adhesive, and 3) with dentures plus an adhesive. Beyond 20 min following expectoration, mouth alcohol made no significant contribution to the apparent breath alcohol concentration (BrAC), with trace (less than or equal to 0.01 g/210 L) readings found in only two of the subjects. Denture use, both with and without the concurrent use of adhesives does not significantly affect BrAC as long as a pretest alcohol deprivation period of 20 min is observed.     

Evaluation of breath-alcohol instruments. IV. Roadside tests with Alcolmeter pocket model

This paper reports results from a field trial with a breath-alcohol screening device--Alcolmeter pocket model. Breath tests were made with drivers apprehended during routine controls (road-blocks), for traffic violations and those involved in traffic accidents. Of 908 roadside breath tests made with chemical reagent tubes, 343 showed zero alcohol (no colour change) and these results were confirmed by Alcolmeter. Alcohol was detected in 191 tests but the level was judged as being below the legal limit of 0.50 mg/ml. The Alcolmeter results, however, ranged from 0 to 1.22 mg/ml (mean 0.21 mg/ml) and 15 individuals (7.8%) were above the legal limit. There were 373 positive chemical tube breath screening tests whereas in 5 cases (1.3%) Alcolmeter indicated a blood-alcohol level below 0.50 mg/ml. Duplicate determinations with the Alcolmeter device were highly correlated r = 0.93 +/- 0.02 (+/- S.E.), P less than 0.001. The standard deviation of a single breath-alcohol analysis under field conditions was +/- 0.10 mg/ml which corresponds to a coefficient of variation of 10%. The time interval between positive roadside breath test and blood-sampling ranged from 5 to 220 min (median 62 min). The results were therefore adjusted by 0.15 mg/ml per hour to compensate for ethanol metabolised between the time of sampling blood and breath. The corrected blood and breath values were well correlated r = 0.84 +/- 0.03, P less than 0.001 but the predictive power of the regression relationship was poor. The regression equation was y = 0.27 +/- 0.65x and the standard error estimate was +/- 0.21 mg/ml at the mean concentration of ethanol of 1.0 mg/ml.     

Evaluation of the Analytical Performance of a Fuel Cell Breath Alcohol Testing Instrument: A Seven‐Year Comprehensive Study

Abstract: Between 2003 and 2009, 54,255 breath test sequences were performed on 129 AlcoSensor IV–XL evidential instruments in Orange County, CA. The overall mean breath alcohol concentration and standard deviation from these tests was 0.141 ± 0.051 g/210 L. Of these test sequences, 38,580 successfully resulted in two valid breath alcohol results, with 97.5% of these results agreeing within ±0.020 g/210 L of each other and 86.3% within ±0.010 g/210 L. The mean absolute difference between duplicate tests was 0.006 g/210 L with a median of 0.004 g/210 L. Of the 2.5% of duplicate test results that did not agree within ±0.020 g/210 L, 95% of these had a breath alcohol concentration of 0.10 g/210 L or greater and 77% had an alcohol concentration of 0.15 g/210 L or greater. The data indicate that the AlcoSensor IV–XL can measure a breath sample for alcohol concentration with adequate precision even amid the effects of biological variations.     

The Effect of Alcohol‐Based Hand Sanitizer Vapors on Evidential Breath Alcohol Test Results

This study was undertaken to determine if the application of alcohol‐based hand sanitizers (ABHSs) to the hands of a breath test operator will affect the results obtained on evidential breath alcohol instruments (EBTs). This study obtained breath samples on three different EBTs immediately after application of either gel or foam ABHS to the operator's hands. A small, but significant, number of initial analyses (13 of 130, 10%) resulted in positive breath alcohol concentrations, while 41 samples (31.5%) resulted in a status code. These status codes were caused by ethanol vapors either in the room air or their inhalation by the subject, thereby causing a mouth alcohol effect. Replicate subject samples did not yield any consecutive positive numeric results. As ABHS application can cause a transitory mouth alcohol effect via inhalation of ABHS vapors, EBT operators should forego the use of ABHS in the 15 min preceding subject testing.     

Y-STR profiling in extended interval (> or = 3 days) postcoital cervicovaginal samples

Depending upon specific situations, some victims of sexual assault provide vaginal samples more than 36-48 h after the incident. We have tested the ability of commercial and in-house Y-STR systems to provide DNA profiles from extended interval (> or =3 days) postcoital samples. The commercial Y-STR systems tested included the AmpFlSTR Yfiler (Applied Biosystems), PowerPlex Y (Promega) and Y-PLEX 12 (Reliagene) products whereas the in-house systems comprised Multiplex I (MPI) and Multiplex B (MPB). Three donor couples were recruited for the study. Postcoital cervicovaginal swabs (x2) were recovered by each of the three females at specified intervals after sexual intercourse (3-7 days). Each time point sample was collected after a separate act of sexual intercourse and was preceded by a 7-day abstention period. As a negative control, a precoital swab was also recovered prior to coitus for each sampling and only data from postcoital samples that demonstrated a lack of male DNA in the associated precoital sample was used. A number of DNA profile enhancement strategies were employed including sampling by cervical brushing, nondifferential DNA extraction methodology, and post-PCR purification. Full Y-STR profiles from cervicovaginal samples recovered 3-4 days after intercourse were routinely obtained. Profiles were also obtainable 5-6 days postcoitus although by this stage partial profiles rather than full profiles were a more likely outcome. The DNA profiles from the sperm fraction of a differential lysis were superior to that obtained when a nondifferential method was employed in that the allelic signal intensities were generally higher and more balanced and exhibited less baseline noise. The incorporation of a simple post-PCR purification process significantly increased the ability to obtain Y-STR profiles, particularly from 5- to 6-day postcoital samples. Remarkably an 8 locus Y-STR profile was obtained from a 7-day postcoital sample, which is approaching the reported time limit for sperm detection in the cervix.     

Comparison of the analytical capabilities of the BAC Datamaster and Datamaster DMT forensic breath testing devices

The State of Michigan uses the Datamaster as an evidential breath testing device. The newest version, the DMT, will replace current instruments in the field as they are retired from service. The Michigan State Police conducted comparison studies to test the analytical properties of the new instrument and to evaluate its response to conditions commonly cited in court defenses. The effects of mouth alcohol, objects in the mouth, and radiofrequency interference on paired samples from drinking subjects were assessed on the DMT. The effects of sample duration and chemical interferents were assessed on both instruments, using drinking subjects and wet-bath simulators, respectively. Our testing shows that Datamaster and DMT results are essentially identical; the DMT gave accurate readings as compared with measurements made using simulators containing standard ethanol solutions and that the DMT did not give falsely elevated breath alcohol results from any of the influences tested.