DOT HS 810 875

November 2007 

Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient’s Catalog No. 

4. Title and Subtitle 

Evaluating Transdermal Alcohol Measuring Devices 

5. Report Date 

November 2007 

6. Performing Organization Code 

7. Author(s) 

Paul R. Marques and A. Scott McKnight 

8. Performing Organization Report No. 

9. Performing Organization Name and Address 

Pacific Institute for Research and Evaluation 

11720 Beltsville Drive, Suite 900, Calverton, MD 20705 

Phone: 301-755-2700 Fax: 301-755-2799 

10. Work Unit No. (TRAIS) 

11. Contract or Grant No. 

DTNH22-02-D-95121 

12. Sponsoring Agency Name and Address 

National Highway Traffic Safety Administration 

1200 New Jersey Avenue SE., 

Washington, DC 20590 

13. Type of Report and Period Covered 

Final Report (8/31/04 – 2/28/06) 

14. Sponsoring Agency Code 

15. Supplementary Notes 

James F. Frank, initial COTR; DeCarlo Ciccel, final COTR 

16. Abstract 

This report is an evaluation study of two types of transdermal devices that detect alcohol at the skin surface 

representing two types of electrochemical sensing technology. The AMS SCRAMTM ankle device and the 

Giner WrisTASTM wrist device were worn concurrently for the evaluation by 22 paid research subjects (15 

males, 7 females), for a combined total of 96 weeks. Each subject participated in both laboratory drinking to 

.08 grams per deciliter (g/dL) BAC and normal drinking on their own. A total of 271 drinking episodes with 

BAC ≥.02 g/dL were logged: 60 were from laboratory dosing, and 211 were from self-dosed drinking. Both 

devices detected alcohol at the skin surface. The SCRAMTM unit has security features and automated 

reporting protocols that make it suitable for the offender market, whereas the WrisTASTM unit is a research 

prototype that has had trials as an aid to detection for alcohol treatment settings. Neither unit had falsepositive problems when true BAC was <.02 g/dL. False negatives were defined as TAC (transdermal alcohol 

concentration) response <.02 g/dL when true BAC ≥.02 g/dL. Overall, the true-positive hit rate detected by 

WrisTASTM was 24 percent. The low detection rate for the WrisTASTM was largely due to those devices’ 

erratic output or not recording during nearly 67 percent of all episodes. SCRAMTM correctly detected 57 

percent across all BAC events, with another 22 percent (total 79%) detected, but as <.02 g/dL. SCRAMTM 

devices were more accurate earlier than later in the trials and may have had problems with water 

accumulation that reduced sensitivity. When subjects dosed themselves to BAC ≥ .08 g/dL, SCRAMTM 

correctly detected 88 percent of these events. The report summarizes comments from research subjects, 

offenders, and vendors who manage transdermal detection programs. 

17. Key Words 

Alcohol, Transdermal, Detection, Laboratory, Field 

18. Distribution Statement 

Copy available from the NHTSA Web page: 

www.nhtsa.dot.gov 

19 Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21 No. of Pages 22. Price 

Form DOT F 1700.7 (8/72) Reproduction of completed page authorized 

i 

EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Table of Contents 

Technical Report Documentation Page..............................................................................................................i

Executive Summary..............................................................................................................................................1

Objective..................................................................................................................................................................4

Background ............................................................................................................................................................5

Controlling Convicted DWI Drivers ...........................................................................................................5

Literature Search..............................................................................................................................................5

Alternative Methods for Monitoring Alcohol Consumption.................................................................6

Measurement of Alcohol in Sweat...............................................................................................................7

Electrochemical Alcohol Sensors ........................................................................................................7

Methods ................................................................................................................................................................11

Subject Screening ...........................................................................................................................................11

Basic Data Elements ......................................................................................................................................12

Alcohol Consumption Procedures.............................................................................................................12

Laboratory Dosing...............................................................................................................................12

Self Dosing.............................................................................................................................................13

Device Acceptability .....................................................................................................................................13

Real World Emulation..................................................................................................................................13

Coding Notes..................................................................................................................................................14

Results ...................................................................................................................................................................16

A Priori Considerations................................................................................................................................16

Categories of Findings Reported................................................................................................................17

Drinking Data for Analysis..........................................................................................................................18

False Positives.................................................................................................................................................20

Simple Detection: Sensitivity When BAC≥ .02 g/dL .............................................................................20

WrisTASTM Judged Performance Detecting BAC≥.02 g/dL.......................................................21

SCRAMTM Judged Performance Detecting BAC≥.02 g/dL.........................................................22

SCRAMTM Automated Alerts............................................................................................................22

Plotted Example Charts ......................................................................................................................24

Other Measures of Coded Hits and Misses: SCRAMTM and WrisTASTM..........................................24

Magnitude of Peak Differences.........................................................................................................24

Time Delays in BAC to TAC Peaks ..................................................................................................26

Performance of SCRAMTM Before and After Check Valve Removal........................................28

Sex of Subject- SCRAMTM...................................................................................................................28

Sex of Subjects - WrisTASTM...............................................................................................................29

Within Subjects Change in Accuracy ........................................................................................................30

SCRAMTM within Subjects .................................................................................................................30

WrisTASTM within Subjects................................................................................................................30

SCRAMTM Accuracy over Time..................................................................................................................31

Rule-Based Sensitivity Analysis .................................................................................................................33

Setting up the Rules.............................................................................................................................33

Dealing with Spikes and Other Noise Parameters........................................................................35

Dealing with Shifting Baselines.........................................................................................................35

Signal Detection Statistics: d’ and A’.................................................................................................35

ROC (Receiver Operating Characteristic) Curves.........................................................................36

iii
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Circumvention Detection.............................................................................................................................38

Environmental Challenges ..........................................................................................................................39

Wearability and Acceptability ....................................................................................................................41

Focus Groups of SCRAMTM Offenders .....................................................................................................41

Interview and Contacts with SCRAMTM Providers................................................................................42

Discussion.............................................................................................................................................................43

Giner WrisTASTM...........................................................................................................................................43

AMS SCRAMTM .............................................................................................................................................45

Accuracy and Sensitivity ....................................................................................................................45

Communications..................................................................................................................................46

Other Considerations ..........................................................................................................................47

Signal Detection Analysis...................................................................................................................48

Circumvention Detection ...................................................................................................................48

Perceptions: Offenders and Vendors ...............................................................................................49

Final Note and Recommendations...................................................................................................................50

References.............................................................................................................................................................51

Appendices 

Appendix A – Literature Search Sources........................................................................................................54

Appendix B – AMS Letter Regarding Check Valve......................................................................................56

Appendix C – Participant Agreements and Instructions.............................................................................58

Appendix D – Wearability of the SCRAMTM and WrisTASTM Devices ....................................................68

Appendix E – SCRAMTM Focus Group and Users Feedback......................................................................70

Appendix F – One Subject’s Four-Week Chart..............................................................................................73

Appendix G – Coded Judgment Examples....................................................................................................79

Appendix H – SCRAMTM Vendor Feedback..................................................................................................85

Figures 

Figure 1. The SCRAMTM Ankle Unit ....................................................................................................... 8

Figure 2. The WrisTASTM Wrist Unit....................................................................................................... 9

Figure 3a. BAC Maximum Recorded with Laboratory Dosing......................................................... 19 

Figure 3b. BAC Maximum Recorded with Self-Dosing...................................................................... 19

Figure 4. SCRAMTM Alerts (True Positive Detection) by BAC Cutoffs when Self-Dosed ............. 23

Figure 5. Alerts (True Positive Detection) by BAC Cutoffs when Dosed in the Laboratory......... 24 

Figure 6. Bland Altman Type Data Layout to Compare BAC and TAC for 

WrisTASTM (6a left), and SCRAMTM (6b right) over a Range of Measured Values ......... 25

Figure 7. Mean Percent Difference ± 1 Standard Error of TAC from BAC 

by Sex and Type of SCRAMTM Device ................................................................................... 29

Figure 8. Mean Percent Difference ± 1 Standard Error of TAC from BAC 

by Sex for WrisTASTM Device.................................................................................................. 30

Figure 9a. SCRAMTM TAC Percent Deviation from BAC by Days Wear 

Time ± 1 Standard Error........................................................................................................... 32 

iv
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Figure 9b. SCRAMTM Hit Rate (Y1) by Judgment or Alcohol Alerts and Accuracy (Y2) 

by Continuous Days of Wear .................................................................................................. 33

Figure 10. Signal Detection SCRAMTM at 4 BAC Values .................................................................... 37

Figure 11. Signal Detection WrisTASTM at 4 BAC Values................................................................... 37

Figure 12. AMS SCRAMTM Temperature Sensor Data Over 13 Days for 

Subject MS10a (1/29/05-2/10/05) ......................................................................................... 38

Figure 13. Skin Temperature on Arm and Leg of Subject While in the Cold Room....................... 40

Tables 

Table 1. BAC Characteristics Lab-Dosing and Self-Dosing Episodes............................................... 18

Table 2. WrisTASTM Performance Detecting BAC≥.02 g/dL ............................................................. 22

Table 3. SCRAMTM Performance Detecting BAC≥.02 g/dL............................................................... 22

Table 4. Agreement of Two Methods for Estimating SCRAMTM Hits ≥.02 g/dL ........................... 23

Table 5a. Characteristics of BAC Maxima and SCRAMTM TAC Maxima for True Positives 

(SCRAMTM HITS) by Type of Dosing..................................................................................... 27 

Table 5b. Characteristics of BAC Maxima and WrisTASTM Maxima for True Positives 

(Wrist HITS) by Type of Dosing ............................................................................................. 27

Table 6. Algorithm-based Signal Detection Statistics for SCRAMTM and WrisTAS ....................... 36

v

EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Executive Summary 

The objective of this research was to evaluate the accuracy and precision of two types of 

electrochemical transdermal alcohol sensors. 

Introduction 

There is only a very sparse research literature directly relevant to electrochemical transdermal 

alcohol detection. This includes papers published between 1992 and 2003 by project consultant 

Robert Swift, M.D., Ph.D., and his colleagues at Brown University reporting on the WrisTASTM 

device; and a 2006 paper by Joseph Sakai, M.D., and his colleagues at the University of Colorado, 

who evaluated the SCRAMTM device. In addition, a biophysical model of transdermal alcohol 

measurement was published in 2006 by Anderson and Hlastala, biophysicists from University of 

Washington. These papers plus a few additional abstracts from recent scientific meeting 

presentations constitute the published literature on transdermal alcohol devices. In addition to these 

directly relevant papers, this report also provides some context for transdermal alcohol estimation by 

summarizing some background literature related to other nontraditional means of estimating alcohol 

exposure such as alcohol biomarkers, sweat patches, and noninvasive approaches to estimating 

blood alcohol concentration (BAC) such as, near infrared spectroscopy. 

With respect to transdermal alcohol, Swift (2003) reported that approximately 1 percent of consumed 

alcohol is lost through the skin as a vapor. The concentration of alcohol at the skin surface reflects the 

concentration of alcohol in the blood (BAC), but curves plotted to represent the change at the skin 

surface show a delay of 2 or more hours on the ascending side and often somewhat more on the 

descending side relative to BAC. 

Methods 

Two devices, the Alcohol Monitoring Systems (AMS) Secure Continuous Remote Alcohol Monitor 

(SCRAMTM), and the Giner Inc Wrist Transdermal Alcohol Sensor (WrisTASTM) were used in 

combined laboratory and field trials for 96 total weeks of wear (an average of 4.3 weeks per subject) 

by 22 subjects (15 males, 7 females). The SCRAMTM device locks onto the ankle and is worn 24/7 for 

the full duration of the study, including showering, and cannot be removed by the subjects without 

activating an alert condition. The WrisTASTM device is a research prototype that affixes with a Velcro 

strap to the wrist and must be removed for showering. Neither device can be fully immersed. 

In the laboratory, subjects were dosed in the morning based on weight and sex to a BAC calculated to 

reach .08 grams per deciliter (g/dL); in 60 such dosing trials, the average BAC attained was .083 

g/dL. In the subjects’ own field-initiated drinking, the mean BAC attained was .077 g/dL during 211 

trials when the minimal BAC was ≥ .02 g/dL. The 271 episodes with BAC ≥ .02 g/dL formed the 

“signal” for detection analyses. All subjects had to provide daily drinking and eating logs, and each 

was given a handheld portable breath-test device to use for the study duration that enabled them to 

record BACs when drinking on their own. 

Transdermal alcohol detection evaluation proceeded in three ways: (1) coded judgments of response 

magnitude based on visual inspection of the device data, (2) alerts issued by the AMS Scramnetwork 

server denoting that an alcohol-positive event had occurred (SCRAMTM only), and (3) through use of 

an automated algorithm that smoothed spikes from the data and accommodated to shifting 

baselines. Alerts issued by the Scramnetwork showed a 93.5 percent concordance with the judged 

1
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

coding of human investigators for true positives, and a 91.5 percent concordance with false-negative 

judgments. This strong agreement represents a kappa=.85 (p=.000). Although there was no 

comparable alert system for WrisTASTM, this degree of concordance between judged events and 

automated alerts for SCRAMTM serves to endorse the accuracy of the coded judgments against an 

external referent. The judged detection of alcohol by the transdermal devices relative to BAC forms 

the primary outcome data in this evaluation. 

Results 

The results demonstrated neither device has problems with false positives, but both had problems 

with false negatives and/or with unreadable data. The SCRAMTM false-negative rate due to complete 

response failure was 15 percent, and across all BACs, the SCRAMTM overall true-positive rate was 57 

percent. The difference between the sum of those numbers and 100 percent represents some coding 

uncertainty explained in the report (another 22.5% was detected but as less than .02 g/dL BAC). 

Overall, the true-positive detection rate increased as the BAC increased from .02 to .08 g/dL. BAC 

episodes of .08 g/dL or greater that were attained during normal drinking were detected at a truepositive rate of .88 by SCRAMTM. The WrisTASTM sensor had a false-negative rate due to complete 

response failure of 8 percent (defined as on and working but not responding to ethanol), and an 

overall true-positive rate of 24 percent. The difference between the sum of those two numbers and 

100 percent represent WrisTAS’sTM missing or erratic data; 67 percent of the positive BAC episodes 

were either missing or unreadable from the WrisTASTM data. This aspect of WrisTASTM is the largest 

concern, and it has been suggested by the manufacturer that the problem is a consequence of a faulty 

chipset that controls data I/O functions. The WrisTASTM device tested, version 5, has now been 

replaced with version 6. We have no evaluation data on version 6. 

The SCRAMTM system’s sensitivity and accuracy declined over the duration of wear; an aggregate 

near-perfect accuracy and high rates of sensitivity during the first period of wear declined as a 

function of time in service. This finding emerged as the largest concern with SCRAMTM. The most 

likely cause of this problem is a consequence of water accumulation inside the sensor housing: as 

water accumulates the sensor’s ability to detect ethanol is reduced. The SCRAMTM device that was 

tested has now been replaced by a device with less dead airspace for holding water, and this has 

reportedly solved the problem of water accumulation. We have no evaluation data on this newer 

version of SCRAMTM. 

Results showed that laboratory studies in which the calculated dose of alcohol was consumed in a 

30-minute period yielded lower transdermal responses than when subjects dosed themselves (in 

normal self-initiated drinking). This was more of a problem with SCRAMTM, which samples every 30 

to 60 minutes, than with WrisTASTM, which samples continuously. In self-paced normal drinking, 

(self-dosed) subjects’ consumption ordinarily proceeded for several hours and this manner of intake 

provided for a more sustained BAC signal detectable by SCRAMTM than was possible with a brief 

spike following rapid dosing. 

Transdermal signals of female subjects were generally measured as lower than those of males 

relative to the BAC attained. This was the case for both types of transdermal sensors. Anderson and 

Hlastala (2006) have shown that the thickness of the stratum corneum, the outermost layer of the 

epidermis, and the hydration state of the subject are factors in the movement of ethanol across 

dermal barriers to the skin surface. The proportional body water content differs between the sexes, 

and this may partially explain this finding. 

2
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Discussion 

In evaluation of circumvention protection, the SCRAMTM system performed well. It may be possible 

for a highly motivated offender who is familiar with the SCRAMTM design to devise a procedure to 

temporarily block alcohol without blocking the infrared sensor that detects obstructions or the 

temperature sensor that monitors temperature near the skin surface. However, it seems unlikely that 

circumvention by obstruction can constitute a real threat to the integrity of this system while 

drinking because it would require constant vigilance by the offender. The communication protocols 

built into SCRAMTM that combine daily automated upload of data and the issuance of daily alerts to 

a program monitor will likely prevent most offenders from beating this system. The Scramnetwork 

server works well and proved to be a sophisticated and stable authorization and data-tracking 

system. 

User comments allude to some discomfort, especially among females, and one female research 

subject showed evidence of bruising after a week of wear. Court-ordered users (including women) 

who were part of a focus group found SCRAMTM to be occasionally annoying but acceptable, and a 

tolerable alternative to jail time. Two commented that it helped goad them toward sobriety in a way 

that other motivators were unable to do. Vendors and others who manage SCRAMTM programs were 

generally positive about their experiences with it. Alcohol Monitoring Systems (AMS) staff 

commented that about 20 percent of the offenders seemed unable to control their drinking and had 

to be removed from the SCRAMTM program. However, we can provide no external corroboration of 

this estimate. 

Overall, these devices performed more poorly than we expected with respect to sensitivity and 

accuracy; however, with independent evaluations, the manufacturers can improve their products. 

The attainable accuracy, however, may only be an approximation of BAC due to subject-specific 

factors that influence ethanol gas concentration at the skin surface. There is no doubt that the 

transdermal concept is valid as long as expectations of quantitative parity with BAC are moderated. 

There is a parallel in these early findings about the accuracy of transdermal devices that is 

reminiscent of the early accuracy of alcohol ignition interlock devices. First generation interlock 

devices were often criticized for failing to match the performance characteristics of more 

conventional breath-test devices, despite interlocks having to operate in an often hostile automotive 

environment of heat, cold, dust, and vibration. Similarly, TAC is not BAC, and the expectation of 

parity is an impractical expectation to place on this nascent technology. Both interlocks and 

transdermal sensing need to be judged first on their potential contributions to public safety. 

Moreover, just as interlock devices have improved in the 20 years since their first adoption, it is 

reasonable to expect that the transdermal-sensing equipment will also improve. These devices 

warrant further development and further study. 

3
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Objective 

The objective of this study was to obtain laboratory data on the precision and accuracy of 

commercially available transdermal alcohol-detecting and monitoring devices. 

Before initiating this research study, we conducted a preliminary search of the literature. This 

resulted in information on two devices that, based on the research literature or their use in 

correctional settings, were sufficiently far along in their development to warrant evaluation. These 

two devices are from Alcohol Monitoring Systems Inc.--known as Secure Continuous Remote 

Alcohol Monitoring (SCRAMTM)—and from Giner Inc.--known as the WrisTASTM, which denotes 

Wrist Transdermal Alcohol Sensor. 

To more completely evaluate performance of these devices, the research design was extended to a 

study of their performance with self-initiated drinking in the field. This comparison of performance 

in the laboratory and under field conditions constitutes the primary evaluation in this study. The 

addition of a field element to the evaluation was considered important because field self-dosing with 

alcohol overcomes some of the contrivances of laboratory study and more closely emulates regular 

drinking in the real world. This emulation extends to both the pattern of drinking and the level of 

drinking. Research ethics necessarily imposes dosing limitations that are usually more conservative 

than self-dosing. In the laboratory, we calculated a dose of alcohol for each subject that would bring 

the BAC up to .08 g/dL (80 mg/dL) within 30 to 60 minutes of initiating drinking. For field 

evaluation of BAC levels, subjects were entrusted with and trained to use handheld evidential 

breath-test devices and requested to maintain a drinking log. 

Beyond evaluating the primary variables, we also evaluated the effects of the participant sex, 

duration of wear, the effect of cold exposure, and exercise-induced sweating. Attempts to circumvent 

the devices (to consume alcohol without detection) were conducted, as were evaluations of wear 

acceptability and appraisal of the programs both from the perspectives of users and program 

administrators. 

This report provides background on the nature of transdermal alcohol sensors. It describes the 

experimental methods used to conduct the evaluation, reports on the findings of the evaluation, 

discusses those findings, and offers conclusions and recommendations based upon the research. 

4
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Background 

Controlling Convicted DWI Drivers 

A major objective of driving while intoxicated (DWI) offender sanctioning programs is to protect the 

public by preventing future impaired driving. Logically, there are three ways to accomplish this 

objective: (1) prevent all driving, (2) prevent all driving after drinking, or (3) prevent all drinking. The 

most widely used approach has been an attempt to prevent all driving by DWI offenders by 

suspending their licenses. Many studies have demonstrated that this effectively reduces DWI 

recidivism in addition to serving as a general deterrent to drinking and driving. However, the large 

growth in vehicle travel in recent years has contributed to the decline in enforcement of the laws 

against driving while suspended (DWS), so the effectiveness of this approach has been 

compromised. A study sponsored by the National Highway Traffic Safety Administration (NHTSA) 

suggests that anywhere from 36 to 88 percent of suspended DWI offenders continue to drive 

(McCartt, Geary, & Nissen, 2002). One response to this has been the vehicle or license plate 

impoundment sanctions that deprive offenders’ use of their cars. Such laws also have been effective 

but are limited as many offenders drive vehicles registered to others. 

Alcohol ignition interlocks on vehicles offer another straightforward approach to protecting the 

public by preventing impaired driving. Interlocks allow offenders to continue to drive while sober 

for employment and family support purposes. However, it has proven difficult to motivate offenders 

to install interlocks on their vehicles, and the use of a non-interlock-equipped vehicle remains a 

threat to the effectiveness of interlock programs (Marques et al., 2001). Although the growth of 

interlock programs as a proportion of all DWI arrestees in the United States is promising, there will 

always be some segment of the population who will not comply with the requirements of those 

programs. 

The third approach, preventing drinking, offers a strategy that not only would protect the public 

from alcohol-related crashes, but also would reduce other alcohol-related problems such as violence, 

non traffic injuries, and alcohol addiction. In the past, courts have attempted to control drinking by 

requiring the administration of AntabuseTM (disulfiram) or by intensive supervision probation 

programs involving random, surprise breath tests for alcohol use. For the most part, those efforts 

have not been adequately evaluated. Somewhat more efficient monitoring of alcohol use is provided 

by house arrest and interlock programs. Typically, house arrest BAC1 test units are stationary 

devices that use video images or voice recognition to identify the user and transmit the breath-test 

result over a telephone line. They do not, however, provide such information when the offender is at 

work or away from home. Similarly, interlock data loggers provide information on drinking but only 

when an attempt is made to start the offender’s vehicle, and the vehicle operator is not guaranteed to 

be the offender of interest. 

Literature Search 

The advent of continuous, passive methods for monitoring alcohol use provides an opportunity to 

determine whether such methodology holds promise for controlling the impaired driving of DWI 

offenders with a minimum effect on their ability to maintain a normal lifestyle and support their 

 

1 Throughout this report, BAC, whether represented as g/dL or mg/dL, indicates BrAC (breath alcohol concentration 

measurement or grams of alcohol /210L breath). 

5
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

families. Accordingly, we conducted a thorough search of the literature in an effort to identify 

transdermal alcohol detection literature and products that were otherwise unknown to the 

investigators. A comprehensive scan was undertaken using computer searchable databases, 

including Medline, Dialog (with hundreds of databases), ERIC, Lexis-Nexis, and other 

databases/catalogs. 

To accomplish this objective, we used various combinations of key words such as transdermal 

alcohol/ethanol and measuring, monitoring, skin, sweat, and vapor. We examined Dialog databases 

in the areas of law enforcement, social science, psychology, medicine, transportation, and safety (see 

Appendix A for a list of screened databases). In searching the literature, we were most attentive to 

descriptions of the precision and accuracy of such measurements and the physiological and 

environmental conditions that affect transdermal alcohol measurement. Although there are a few 

papers on the transdermal alcohol measuring devices and more on environmental conditions that 

affect alcohol measurement, it is rare to find papers on factors affecting transdermal alcohol 

measurement. There is not yet a mainstream of research on transdermal alcohol measurement in the 

physiology, pharmacology, medical, or safety literature other than as represented by the citations 

reviewed here. 

Alternative Methods for Monitoring Alcohol Consumption 

Alcohol’s presence in the body can be determined through the use of bodily specimens, most 

typically blood or breath, but also urine and oral fluid from saliva. Most ethanol is transformed to 

acetaldehyde and acetate through liver enzymes in a well-known detoxification process that has a 

predictable time course and is described by the Widmark equation (Widmark, 1932). This is not the 

only pathway by which alcohol is biotransformed into more inert substances, but it is the most 

widely known. 

The presence and measurement of alcohol markers (such as carbohydrate deficient transferrin, 

gamma glutamyl transferase, ethyl glucuronide, or fatty acid ethyl esters) is possible due to minor 

metabolic pathways that are consequential to ethanol exposure or play a role in degrading the 

ethanol. These alternate pathways yield measurable products that persist for many days or weeks 

after the ethanol per se has been changed or lost. The surveillance window, the period following 

exposure to a drug when traces can be detected, is substantially extended for alcohol by examination 

of these ethanol biomarker or metabolites. Gilg, Buchholtz, and Huth (2000); Gjerde and Morland 

(1987); Gjerde, Sakshaug, and Morland (1986); and Bjerre (2003) have all reported the extent to which 

these substances can aid in the profiling of high-risk alcohol-involved drivers. 

Those measurement options aside, the forensic measurement of alcohol has most often depended 

upon direct measurement of ethanol before it is transformed. At present, there are still very few 

forensic applications of the alcohol markers that persist beyond the brief hours it takes to transform 

and degrade the ethanol consumed in a drinking session. The most widely used ethanol 

measurements in blood or breath are closely similar due to the equilibrium between capillary ethanol 

concentration and ethanol vapor on opposite sides of the membranes in the lung alveoli. Breath 

ethanol measurement uses a conservative partition coefficient to relate the BAC and BrAC (breath 

alcohol concentration) as sources of information. The efficient and predictable disposal of ethanol by 

the dehydrogenase enzymes in the liver requires that BAC or BrAC ordinarily be sampled several 

times per day to reconstruct an alcohol consumption curve. During the time transformation and 

deactivation of ethanol is proceeding in the bloodstream, a small proportion (less than 1%) of the 

6
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

ethanol is lost through the skin as vapor through two processes: passive diffusion through the skin 

and active excretion from the eccrine or sweat glands (Swift, 2003). 

Because alcohol eventually becomes distributed freely in all body compartments, it can be measured 

in any body fluid, including compartments as remote as the vitreous in the eyes and cerebrospinal 

fluid in the brain and as large as the interstitial fluid that bathes cells throughout the body. 

A device under development by Spectrx, Inc., samples alcohol in interstitial fluid under the skin by 

using a laser to shoot miniature holes in the skin and then samples the concentration of alcohol in the 

fluid of this extra-cellular interstitial compartment. This company has been aided by Small Business 

Innovative Research (SBIR) funds from the National Institutes of Health (NIH) and may someday 

have an alcohol-sensing product ready for commercial application. Spectrx’s interest in alcohol as a 

target substance follows from its primary product development research in glucose monitoring and 

determination of therapeutic medication levels. All its products are and will be subject to Federal 

Drug Administration (FDA) approval because the laser approach to sampling crosses the dermal 

barrier. Another company of interest is TruTouch Inc., staffed by former defense physicists who are 

skilled in the uses of near-infrared spectroscopy. They have developed a device that can passively 

evaluate alcohol concentration in the interstitium without breaking the skin surface (Brown & 

Ridder, 2005; Ridder, Brown, & Ver Steeg, 2005; Ridder, Hendee, & Brown, 2005). 

Measurement of Alcohol in Sweat 

Among the most accessible of the nontraditional sampling media for alcohol concentration 

determination is sweat. Several methods have been used to estimate alcohol consumption by 

detection and attempts at measurement of ethanol in sweat, which will hereafter be referred to 

generically as transdermal alcohol concentration (TAC). These include the sweat patch that 

accumulates alcohol over several days (Phillips, Greenberg, & Andrzejewski, 1995), a little known 

ethanol band-aid that uses colorimetric technology (Roizen, Lichtor, & Lane, 1990), and the 

electrochemical methods that convert alcohol into an electrical signal proportional to concentration. 

The two electrochemical devices that exist today—and the two evaluated in this report—are based 

on different technologies. At their current stages of development, they are suited to different problem 

populations. 

Menssana Research, Inc., is the company that produced the alcohol sweat patch and its chief 

executive officer, Michael Phillips, M.D., holds the patent. Menssana has developed several products 

that have grown from an interest in the detection of volatile organic compounds in breath and sweat. 

This company’s interest in alcohol appears to have been a tangential development, as its primary 

business is in making detectors of minute, picomolar quantities of exhaled or expired volatiles that 

are often indicative of disease states. The company’s business model has historic lines dating back to 

the Hippocratic era when diagnosticians were trained to use their noses to help in the detection of 

disease states. Breath volatiles may indicate cancer, diabetes, transplant rejection, and other diseases. 

Despite an active research program in alcohol detection that lasted 15 years (1980-1995), published 

literature about the Alcopatch, with Phillips usually the lead author, ended in 1995. The original 

work on the Alcopatch was supported by NIH development funds, and once the SBIR support 

ended, so too did further development. 

Electrochemical Alcohol Sensors 

The main transdermal sensing systems available today are shown in Figures 1 and 2. The AMS 

device, the SCRAMTM (see Figure 1), introduced into the forensic market a few years ago, puffs air at 

7
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

specific intervals to volatilize ethanol and then samples the ethanol vapor in the space between the 

skin and the fuel-cell sensor. Sampling intervals are variable, but in most applications, the device 

draws air into the fuel cell hourly. If alcohol is detected, the sampling frequency increases to every 30 

minutes. The Giner device, the WrisTASTM (see Figure 2), developed during the 1990s, samples 

alcohol vapor almost continuously and then records averaged data once every 30 seconds to 10 

minutes. The data are later downloaded via a serial port on the device to a computer. In most 

applications, 5-minute averages of data are stored for later download. 

SCRAMTM 

The SCRAMTM consists of three components: (1) a small SCRAMTM bracelet worn on the ankle, (2) a 

SCRAMTM modem, and (3) a remote server for 

aggregating data from offenders and for reporting these 

data to the monitoring staff. The unit is locked on and 

worn 24 hours a day, 7 days a week, for up to 6 months 

based on current practice. The AMS device uses an 

automated daily uplink feature for data transfer to the 

remote server via the modem; this product was 

designed for security and remote reporting to minimize 

circumvention and to render data usable by courts or 

corrections. In most applications, the SCRAMTM 

modem is scheduled to transfer data from the ankle bracelet during normal sleeping hours. The AMS 

ankle bracelet weighs about 8 ounces (Figure 1) and is approximately the size of two demitasse coffee 

cups linked by a data cable embedded in strong straps. One side houses the sensors, and the other 

side, the digital signal processing hardware. The sensor side of SCRAMTM includes an air pump that 

actively draws in ethanol vapor from the skin surface into the fuel cell. In addition to alcohol, sensors 

detect changes in the temperature and infrared signals near the skin. The two non-alcohol sensors are 

important parts of the circumvention detection protocols. In addition to the sensors that aid in 

detecting circumvention, if the strap is cut or the offender ceases to accommodate the requirements 

of the program, a probation officer or program administrator would be alerted within 24 hours that a 

break in continuity had occurred or that the modem had failed to uplink. When properly installed on 

an ankle, a lock-in retainer makes it very difficult for an offender to remove the SCRAMTM without 

cutting the strap. The device cannot be immersed but it can be worn while showering and while 

maintaining personal hygiene inside the rubber muffs. 

Figure 1. The SCRAMTM Ankle Unit 

AMS Inc. is a technology company privately held by the principals who also hold the senior 

management positions. Many of the senior staff at AMS had previously worked in the computer 

industry and have expertise in data management. AMS has funded its own unpublished 

developmental research on the SCRAMTM device (Zettl, 2002). In the Journal of Offender Monitoring, 

Steven Bock (2003) from Michigan’s Electronic Monitoring Center reported on characteristics of the 

SCRAMTM device on 19 offenders under study. The offenders were reportedly satisfied with the 

device, but Bock reported AMS modified the strap following efforts by some in this group to tamper 

with the strap. 

In 2003, AMS funded a study by Drs. Thomas Crowley and Joseph Sakai at the University of 

Colorado Health Sciences Center. The Colorado study design had two parts. Part 1 included a oneday laboratory analysis in which subjects arrived, were hooked up, drank, and had the bracelet 

removed. Part 2 was a 7-day wear study in which subjects (alcohol and nonalcohol dependent) 

logged drinking while wearing their SCRAMTM bracelets. Published results (Sakai, Mikulich8
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Gilbertson, Long, & Crowley, 2006) reported no episodes of false positives based on either lab dosing 

or reported consumption. BAC and TAC findings could not be considered quantitatively equivalent, 

but there was qualitative parity between reported drinking and SCRAMTM results. The devices were 

reported to be reasonably comfortable, and they capably discriminated between alcohol-dependent 

and social drinkers. 

Because the SCRAMTM device is used with a court-ordered or a corrections population, it is 

important to anticipate and have a means to detect efforts to circumvent the alcohol sensing and 

reporting protocols built into the device. AMS has evaluated the characteristics of several types of 

materials and reports that all known materials capable of blocking alcohol can be detected due to the 

infrared sensor. The AMS principals note that data interpretation protocols can distinguish a wide 

range of attempts to block the air sampling with plastic, Mylar, and other interferents (i.e., sources of 

interference). The algorithms to detect circumvention are not capable of full automation, so the 

software flags suspicious results and this sends an alert to an expert human monitor who must view 

these questionable cases to distinguish between true positives, various classes of circumvention, and 

true negatives. The circumvention detection logic is dependent upon the signals from all three types 

of sensors in the device. Basic circumvention attempts are easily detected when the skin temperature 

or infrared sensor readings suggest the proximity of the sensor to the skin has changed. 

WrisTASTM 

The Giner device, WrisTASTM, which was developed primarily for use in 

medical settings with more compliant subjects, lacks the protocols for 

detecting tampering and has not yet been adapted for court use. 

Nonetheless, the device does have a skin resistance/conductance sensor 

and a temperature sensor. These sensors, when operative, can aid in 

determining if a person removed or blocked the device. When in service, 

data from the device are periodically downloaded to a computer via a 

serial port interface. A new version (WrisTASTM version 6) can send radio 

frequency data without having to conduct a manual download to a 

computer. The Giner device has had research trials primarily aimed at alcohol treatment applications 

for monitoring patient compliance and for early detection of lapses in an abstinence program. The 

Giner device (Figure 2), shaped and worn like a wristwatch, is much smaller than SCRAMTM, and its 

location is very convenient. Were it to be used with an offender population, it would need protocols 

to prevent unauthorized removal because, currently, it is secured to the wrist with a Velcro strap. It 

cannot get wet and must be removed for showering. 

Figure 2. The WrisTASTM 

Wrist Unit 

The Giner device has been reported to be linear within physiologic (normal pharmacologic ranges) of 

ethanol dosing. There has been somewhat more scientific investigation of the Giner than of the AMS 

device due to developmental support from the National Institute on Alcohol Abuse and Alcoholism 

(NIAAA). Swift, Martin, Swette, LaConti, and Kackley (1992) and Swift (2000) reported that the 

WrisTASTM linearity extends from 5 to 500 mg/dL (.005 to .50 g/dL). Transdermal devices output a 

TAC that reportedly parallels the more familiar BAC curves but is shifted to the right with a 1- to 2-

hour delay. Swift (2003) reports that the area under the curve for TAC and BAC of Giner devices 

correlate with r=.8. It should be noted that Dr. Swift has served as a consultant to this NHTSA 

evaluation. He informs us that published evaluations of the WrisTASTM are based on devices that 

have been specifically selected for a high-fidelity response to allow a proper appreciation of the 

potential of the sensor. However, many WrisTASTM devices have a relatively high failure rate, 

resulting in data loss. Loss of data may be caused by problems in voltage regulation or chipset 

9
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

failure. A conference report in June of 2005 by Greenfield, Tujague, Bond, and Kerr (2005) found that 

version 5 WrisTASTM devices when not pre-selected for a high-fidelity response could be considered 

high quality only on about 20 percent of the evaluation days. Newer versions of the WrisTASTM 

devices that were not available for this evaluation project are reportedly more reliable. 

The underlying technology that allows the WrisTASTM to rapidly sample ethanol vapor is different 

from conventional fuel cell sensors that require some delay after sampling while the alcohol fuel is 

oxidized. Where a traditional fuel cell could not easily be cleared quickly after sampling, the 

WrisTASTM sensor is not affected by rapid sampling because it measures a continuous oxidation 

current. The SCRAMTM and WrisTASTM devices measure transdermal ethanol by different 

approaches to the problem, and each have stronger and weaker points, but both are actively being 

modified in an attempt to improve the technology. 

Both of these transdermal devices are high technology in the best sense. The SCRAMTM device uses 

conventional fuel-cell sensors but marries them to sophisticated computer algorithms and data 

transfer technologies in a secure device that is already used in forensic applications. The WrisTASTM 

device uses a constant hydrated platinum electrode maintained at a controlled potential and bathed 

in aqueous electrolyte held in a reservoir. In the WrisTASTM, an electrode oxidizes the ethanol and 

forms acetic acid that diffuses into the reservoir. The current is converted to a digital signal that is 

averaged and stored at preset time intervals from 30 seconds to 10 minutes. The data capacity is 3 

weeks at 10-minute intervals. Data are downloaded to a computer serial port. The reservoir must be 

repleted about once a month with a few drops of de-ionized water. 

Based on this literature search described above, we have determined that the two transdermal 

devices identified are the only ones that are available for study, though only one of these, the 

SCRAMTM, is being leased commercially. Nonetheless, we included both the SCRAMTM and 

WrisTASTM devices as part of the precision and accuracy evaluation as they represent two different 

approaches to electrochemical alcohol detection at the skin surface. 

As part of this evaluation, we made an effort to determine the ease with which a user could 

circumvent the device without detection. We evaluated the effects of chilled air (and therefore 

reduced skin temperatures) and mild exercise-induced sweating on the precision and accuracy of 

transdermal devices relative to known BrAC levels from a fuel-cell based handheld breath tester. 

10
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Methods 

Subject Screening 

Subjects between the ages of 21 and 35 were invited to give signed consent and then participate in a 

screening process for subject selection. The consent procedure was reviewed by the PIRE East IRB, a 

human subjects review body that operates under Federalwide Assurance Number FWA # 00007038. 

Subjects were selected based on the following criteria: (1) they must report drinking regularly but 

must not drink to extreme excess and must not have drug- or alcohol-related health or criminal 

problems, and (2) they should not use contraindicated medications or be pregnant. Subjects were 

asked to provide a urine sample upon entry into the subject pool to confirm that they showed no 

positives for benzodiazepines (e.g., Valium/Xanax/Ativan type drugs) or the NIDA 5 panel drugs 

(opiates, amphetamines, cocaine, phencyclidine, or marijuana). The urine toxicology screening 

devices were Biosites Triage Tox Screens, and the results were machine read from the Biosites Triage 

Meter Plus. Pregnancy tests were performed with over-the-counter, e.p.t. TM, early pregnancy tests 

for home use. 

In addition, a prospective subject’s normal level of alcohol consumption was assessed by requiring 

that he or she fill in the AUDIT (Alcohol Use Disorders Inventory), and respond to a subset of 

questions from the AUDADIS (Alcohol Use Disorders and Associated Disabilities Schedule). The 

former assessment is a high-sensitivity screen for potential problem-level drinking, whereas the latter 

is more attuned to diagnosable DSM-IV criteria for alcohol abuse or alcohol dependence. 

Of the 55 contacts (mean age 26.2, 56% male) made with prospective subjects during the 7 months of 

active testing, 32 contacts were eventually screened for consideration according to the described 

criteria. Of those screened, 10 were excluded. Two people tested positive for marijuana, one tested 

positive for benzodiazapines (prescription anti-anxiety medicine), and eight reported risk levels of 

alcohol consumption. 

There were two phases of transdermal device evaluation, a 4-week wear phase and a 2-week wear 

phase. The two week trials were added as a supplement following the basic 4-week phase in order to 

answer an emergent question about SCRAMTM related to a check valve (described later). Eight of the 

original 18 subjects from the 4-week phase (studied in 3 waves of 6 subjects) agreed to serve again as 

subjects in the 2-week phase to address the emergent questions. For that purpose, this group was 

supplemented by four new subjects. The repeat assessment was desirable for two reasons: (1) it 

allowed for a within-subjects pre-post evaluation of the SCRAMTM device after the check valve 

design change (see Appendix B), and (2) using the same subjects reduced the amount of preliminary 

explanation and training required for participants. There was nothing about repeat participation that 

could adversely affect device sensitivity or any of the dependent measures collected, and the repeat 

subjects attained comparable BACs and TACs as the four new subjects with similar SCRAMTM 

devices. All together, the final subject pool participating in the research included 15 males (5 repeated 

for phase 2) and 7 females (3 repeated for phase 2) for a total of 30 trials (mean age 26.7, 68% male) 

covering 96 weeks of wear among 22 subjects. A trial in this case is defined as the duration that a 

subject was attached continuously to the transdermal device. 

Participant Consent Forms, Participant Agreement, and Instructions for Participants are found in 

Appendix C. Subjects were paid $100 a week for participation, plus a bonus paid at the end of the 

study if they stayed for the full duration of 4 weeks ($400) or 2 weeks ($200). The bonus was deemed 

11
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

warranted due to the disruptive effects of subjects dropping out of a study with a tight timeframe. 

No one dropped out. 

Basic Data Elements 

This study required subjects to log all alcohol drinks or drink equivalents during the study period 

and to periodically self-test their BACs with a handheld portable breath tester (PBT), a CMI 

Intoxylizer SD-400. Whenever a subject consumed more than one drink, he or she was instructed to 

follow standard procedure of either performing a mouth rinse with water and/or waiting 15 minutes 

after the last beverage sip before testing with the PBT. This was accomplished outside the office by 

entrusting all subjects with a breath-test device that they were to bring with them whenever they 

might be drinking away from home. Accordingly, with two transdermal sensors (the WrisTASTM and 

the SCRAMTM), a fuel-cell PBT, and a log of drinking, we have four data elements that represent 

ethanol consumption during the study. 

Alcohol Consumption Procedures 

There were two types of alcohol consumption in this study: (1) laboratory dosing in which subjects 

came to the PIRE offices and drank in the morning on an empty stomach, and (2) self-dosing or freeform alcohol consumption of their own choosing. Each episode of alcohol consumption is coded and 

logged for each subject. Lab-dosed and self-dosed drinking events are tracked separately since the 

method of dosing is quite different. 

Laboratory Dosing 

In the lab, subjects were given an amount of distilled spirits calculated from Widmark equations to 

bring their BACs to 80 mg/dL (.08 g/dL) when consumed over a 30-minute period. The theoretical 

dose for males was .64 gm/kg and for females .56 gm/kg. A spreadsheet was programmed for this 

calculation. The program recorded information about subject sex, bodyweight, percentage of alcohol 

of preferred beverage, and duration of the drinking (to account for concurrent metabolism). The 

program returned a dose suitable for achieving a target BAC of .08 g/dL after 30 minutes. In practice, 

subjects selected vodka, rum or gin; all were 80 proof (40% alcohol). Subjects were permitted to add 

soft drinks or juice to their drinks. Subjects were instructed to space their consumption over the full 

30-minute period. We waited an additional 15 minutes after drinks were finished before the start of 

breath testing. BAC readings in the laboratory phase represent the average of two PBT fuel-cell 

testers used successively within the same 1-minute period. The agreement between the two readings 

was very high. Whenever subjects were dosed in the laboratory condition, a nurse or EMT was 

present in the event of any adverse reaction, such as aspiration of vomit, severe flushing reaction, or 

other reactions (there were none). BAC levels in lab dosing were expected to rise to a peak within 30 

to 60 minutes of beginning consumption. Subjects were instructed to arrive for laboratory dosing 

with no measurable BAC, and to limit drinking the night before so that TAC would have a chance to 

return to zero before lab dosing. They were also asked to avoid drinking for several hours after 

laboratory dosing so that TAC could return to .00 g/dL before any further self-dosing. There were a 

few occasions when laboratory and self-dosing TAC levels overlapped. There were no cases where 

laboratory dosing began with measurable BACs. On two occasions, subjects arrived for dosing with 

measurable BACs from the night before. In these cases, dosing was rescheduled for a later time. 

There were 2 lab-dosed drinking events for each of the 30 subject trials for a total of 60 dosing events. 

12
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Self-Dosing 

When self-dosing, subjects were instructed to keep a log of all food and alcohol consumed on any 

drinking episode when they had two or more alcohol drinks, and to record breath-test readings after 

consuming alcohol. Subjects were encouraged to include whatever they felt noteworthy, but at a 

minimum, they were told the logs should contain the following: 

• The time at which a meal was consumed and whether the meal was considered to be 

a small snack or a small, medium, or large meal. 

• The time at which alcohol was consumed and the number of drinks consumed, 

where a drink equals one 12-ounce beer, one 4-ounce glass of wine, or a mixed drink 

containing one shot of liquor. Subjects were required to note when drinks consumed 

were larger or smaller than standard size (e.g., large beers or double shots of liquor) 

or stronger than usual (e.g., shots of 150-proof rum). 

• The time at which breath tests were taken and the reading. Subjects were instructed 

to take the first breath test 30 minutes after the first drink and once an hour 

afterward until their BACs reached .00 g/dL or until the subject went to bed for the 

night. 

Subjects were instructed to e-mail drink logs to project staff once a day. On drinking days, the logs 

would contain eating, drinking, and breath-test data. On non-drinking days, subjects were to send an 

e-mail stating that they had not had alcohol that day. In practice, subjects sometimes sent logs less 

frequently than once a day, but drinking logs were ultimately submitted for all but five of 249 selfdosed drinking events. The information about meal size was collected to help resolve any 

discrepancies between TAC and BAC levels. 

Device Acceptability 

In both the 4-week and the 2-week study phases, the procedures were identical. The longer duration 

study period satisfactorily answered the question about acceptability and wearability. For the most 

part, subjects easily complied with the requirements of the 4 weeks of wear, despite some initial 

discomfort. Following removal of the device, subjects were debriefed on discomfort issues and ways 

in which the devices interfered with everyday living. Wear-related issues are discussed in Results. 

Some subjects were more adversely affected than others, but no subjects dropped from the trial. 

Information about device acceptability for research purposes can be found in Appendices D and E 

that review focus group discussions with offenders. 

In addition to comfort/discomfort issues, another important aspect of the extended wear evaluation 

was accuracy and precision change over time, an aspect that has been reported upon previously. This 

topic is also reviewed in Results. 

Real World Emulation 

Because research subjects must be given a monetary incentive to participate and real world offenders 

are under some threat by the courts or corrections to participate, the compliance motivation of these 

two groups is different. More germane perhaps, research subjects were selected because they drink 

and are expected to drink during the evaluation, whereas offenders are explicitly told not to drink. 

This difference means that accuracy and precision findings in this study need to be qualified before 

13
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

attempting to generalize results as to how the devices would normally perform with subjects who 

were expected to remain abstinent. 

Coding Notes 

Having defined drinking episodes as having a peak BAC ≥ .02 g/dL, the next task was to determine 

if the transdermal devices could detect or follow a BAC elevation by registering a positive TAC 

value. For each subject, all BAC and TAC data were compiled into a spreadsheet, and a composite 

graph was created that included self-administered dosing, lab-dosing, SCRAMTM TACs, and 

WrisTASTM TACs. Converting this information into discrete categories is a judgment task. Two 

coders independently reviewed 41 episodes and achieved a high degree of agreement (>96%) on the 

definition of episodes, maximal BAC, maximal SCRAMTM TACs, maximal WrisTASTM TACs, and 

time of these maxima. Because there were no fundamental disagreements between the two coders, 

the subsequent judgments of a single coder were used. Using the spreadsheet, the following data 

were recorded for each drinking episode: 

• The time and level of the maximum BAC recorded. 

• The time of and maximum SCRAMTM TAC associated with the drinking episode 

following the maximal BAC occurrence. 

• The time of and maximum WrisTASTM TAC associated with the drinking episode 

following the maximal BAC occurrence. 

• The placement into categories of those TAC responses that were not clear truepositive hits but not easily coded as simple false negatives. The definitions for these 

“gray” categories are described below. 

When there were two or more maximum TAC or BAC readings of the same value for a drinking 

event, the earliest was used, but if a later reading exceeded an earlier one by as little as .001 g/dL, the 

later higher reading was taken as the maximum. The data were recorded for all drinking events 

noted by the subject, whether or not the maximum BAC reached .02 g/dL. In a few cases, a new 

drinking episode occurred so soon after a prior drinking episode that it was unclear whether a TAC 

was a late response to the first episode or a response to the second. When this occurred, the time of 

the first drink of the second episode was set as the end time of the first episode, and all other data 

coded accordingly. Occasionally, spikes in TAC readings would result in a reading significantly 

higher than surrounding readings. These were deemed to be “outliers,” and were not recorded as 

maximum TAC readings for an event. In a later section, we describe automated smoothing 

algorithms used to exclude outlier spikes from the data series. 

For each drinking episode and for each transdermal device, the coder categorized the TAC readings 

as one of the following: 

True Positives

• A hit - The drinking episode was clearly visible with a TAC of .02 g/dL or more. 

Subtypes of False Negatives

• < .02 g/dL - The drinking episode was evident but the TAC response was < .02 g/dL. 

• Low-confidence - A change in TAC was apparent, though it would have been difficult 

to identify it as reflecting a drinking episode without knowing that the BAC was 

14
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

elevated, mostly due to high variance in TAC before and after drinking episodes. 

• Too noisy - The TAC readings were patternless, too noisy, or too variable to clearly 

distinguish a drinking episode. 

• Missing data - There were no TAC data produced or retrieved during or after a 

drinking episode that could allow an estimation of sensor accuracy. 

• False negative with response failure - The transdermal device was on and recording, but 

based on TAC reading, it seems to have completely missed a positive BAC ≥.02 

g/dL. 

15
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Results 

A Priori Considerations 

The objective of this evaluation was primarily to acquire information on the accuracy and precision 

of two types of transdermal ethanol sensors. Accordingly, it is useful to review the concept of 

accuracy and precision. 

Accuracy, as used here, is an estimate of the extent to which a transdermal sensor evaluates a sample 

of ethanol vapor expired at the skin surface as equivalent to a known concentration of ethanol 

dissolved in body fluids and in general circulation. The standard (BAC) by which we evaluate the 

accuracy of transdermal sensors can be precisely known by estimating it from BAC. Although 

ethanol must move through several body water compartments to appear at the skin surface, the peak 

transdermal ethanol level (voltage or current signals that can be converted to equivalent units of 

ethanol concentration) can be set to represent the known BAC standards. The estimated amount of 

alcohol detected at the skin surface is referenced to BAC values typically associated with such levels 

of transdermal alcohol. Accuracy estimations are based on how the transdermal sensors’ voltage 

calibration (SCRAMTM) or oxidation current (WrisTASTM) can be stably referenced to a level of 

alcohol in the blood. When the mean of the transdermal signal is very close to the mean of the BAC, 

then the device will be considered highly accurate. 

The precision of transdermal sensors is estimated by the ability of the sensors to regularly detect the 

same levels of ethanol when confronted with the same degree of ethanol signal. Precision has to do 

with the replicability of a finding and is best estimated by the standard deviation of results if the 

mean ethanol signal it is attempting to estimate is constant. When the standard deviation is small, the 

device is precise. 

The precision criterion for transdermal sensors may be more difficult to estimate than accuracy. The 

time course of a BAC clearance curve is well known and described by the Widmark formula; 

however, the ethanol concentration estimated by transdermal sensors is just a small fraction (~ 1%) of 

the ethanol cleared from circulation. Passage through body water compartments and skin surfaces 

introduces complex kinetics into the problem of estimating the reduction in ethanol at the skin 

surface over time after a peak BAC level begins to decline. Accordingly, the BAC level at any point in 

time, other than the peak level, may not be a useful standard against which to estimate the precision 

of a transdermal device. If the devices are calibrated at the peak, their readings may diverge from 

BAC levels on both ascending and descending phases. If BAC and TAC were always the same, there 

would be less of a problem. 

The two devices under evaluation differ on several dimensions. Perhaps the most significant 

difference is that the AMS SCRAMTM is available for the criminal justice marketplace and is in service 

now, whereas WrisTASTM is a research prototype and Giner has no device on the market. 

Accordingly, these are not competitive products, and although both are electrochemical devices, they 

are not based on the same underlying technology. SCRAMTM is based on alcohol fuel-cell technology, 

whereas WrisTASTM is based on a hydrated proton exchange membrane. Each has certain strengths 

and weaknesses. This evaluation is not an effort to find a winner but rather to characterize their 

precision and accuracy under specifiable conditions. 

The AMS SCRAMTM device, available for use by courts or corrections, restricts the estimated BAC 

report to .08 g/dL, even when the actual estimated BAC exceeds that value. The flat peaks at .08 

16
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

g/dL, seen on AMS SCRAMTM specimen charts, is a convention the company has adopted to reduce 

unnecessary detail because any TAC of .08 g/dL is well above the “actionable” level. However, for 

this evaluation, AMS has made available the underlying raw data that is not usually available to its 

customers. The ability to track the full range of BAC information, including those extending higher 

than .08 g/dL, adds detail that has allowed PIRE to more fully characterize the behavior of the 

SCRAMTM sensors. 

Although the WrisTASTM device has a native output that writes a file in mg/dL, for reader 

convenience to maintain compatibility with forensic conventions of BAC, we converted all those 

values to g/dL. 

In addition, the y-axis on the output charts of Giner WrisTAS’s own data retrieval and display utility 

shows a zero point that may not always represent zero TAC. In most of the analyses reported here, 

we regard the zeros returned by the Giner data utility as true zero TACs and regard all positive 

values as positive TACs. In practice, however, the Giner head technician advised that he regards the 

true zero TAC on the WrisTASTM output to be more accurately defined by the baseline from which 

the sensor output departs when it detects alcohol and to which it returns when a TAC signal falls. 

Stated differently, the WrisTASTM baseline drifts, and although they are writing algorithms to correct 

for that drift, the version 5 that was made available for study does not have a native correction for 

baseline drift. Accordingly, in the sensitivity analyses later in this document and the Receiver 

Operating Characteristic (ROC) curves that are based on algorithmic reading of the data, we have 

included adjustments to the WrisTASTM data so a functional zero baseline is inferred from a series of 

points before an alcohol episode. Before that section much later in the “Results,” however, we 

interpret zero WrisTASTM TAC as representing zero alcohol. 

Categories of Findings Reported 

The following topics are reported in this “Results” section: 

• Definition of episodes of drinking 

 Laboratory drinking 

 Self-dosed drinking 

• Simple coded judgments of drinking detection 

 WrisTASTM transdermal sensor 

 SCRAMTM transdermal sensor 

 AMS alerts (SCRAMTM algorithm detected hit) 

 Graphical examples of data 

• Absolute deviation of the transdermal device peak from the BAC peak 

• Time difference between the transdermal device peak and the BAC peak 

• Percentage of deviation of the transdermal device peak from the BAC peak 

• SCRAMTM check valve replacement/removal (see text) 

 Before removal of faulty check valve 

 After removal of the check valve 

17
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

• Effects by subject sex 

• Accuracy of SCRAMTM ankle bracelet as a function of duration of wear 

• Definition of nonevents, smoothing algorithms, calculation of ROC curves, d prime 

(d’, a measure of accuracy), and sensitivity analysis 

• Effect of cold skin and sweating on TAC 

• Wearability issues for 4 weeks 

• Circumvention detection of SCRAMTM devices 

• Offender focus groups – views of SCRAMTM wearers (content on CD) 

• Provider (electronic monitoring providers) views of SCRAM 

Drinking Data for Analysis 

With a few known exceptions, each episode of alcohol consumption within each of the 30 distinct 

experimental trials when a subject wore the transdermal sensors in this study (i.e., the 22 unique 

subjects plus the 8 who served a second time) was marked by one or more PBT samples. During our 

evaluation, 309 episodes of drinking were logged either in the laboratory (n=60) or by the subjects 

conducting self-dosing (n=249). Of those 309 drinking episodes, 271 achieved a PBT-measured BAC 

value equal to or in excess of .02 g/dL. The range of BAC for these 271 episodes was from .020 g/dL 

to .230 g/dL with a mean of .078 g/dL. The data in Table 1 characterize the drinking episodes 

available for analysis. The two figures (3a and 3b) demonstrate the differences by type of dosing. In 

the laboratory setting (Figure 3a), the BAC results are symmetrical around .08 g/dL, the BAC level 

that we attempted to achieve with the dosing calculator based on the Widmark equation. All subjects 

were told to eat very lightly before coming to the laboratory to minimize differences in absorption 

time. 

Table 1. BAC Characteristics Lab-Dosing and Self-Dosing Episodes 

Type N Minimum Maximum Mean Std. Deviation 

Lab dosing BAC max 60 .041 .123 .08287 .015771 

Self dosing BAC max 211 .020 .230 .07675 .044295 

Total BAC max 271 .020 .230 .07811 .039835 

Figure 3b characterizes the BACs obtained from the self-dosing protocol. Self-dosing is simply 

normal drinking. Although evident from Table 1 that the means of the two types of dosing are 

similar, the self-dosing protocol provides some experience in evaluating the transdermal sensors 

when used by heavy drinkers. 

For the 38 self-dosed drinking episodes that were <.02 g/dL (not shown), the mean BAC was .011 

g/dL with a standard deviation of .005 g/dL. For all further analyses unless otherwise noted, these 

38 low-BAC drinking episodes were excluded; the 271 episodes of ≥.02 g/dL formed the basic data 

elements for this analysis. This convention of ignoring values lower than .02 g/dL is the same as is 

done by AMS SCRAMTM with their offender monitoring algorithms. 

18
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

.040 .060 .080 .100 .120 .140

BAC maximum

Frequency 14

12

10

8

6

4

2

0

Mean = .08287

Std. Dev. = .015771

N = 60

Figure 3a. BAC Maximum Levels Recorded with Laboratory Dosing 

.020 .040 .060 .080 .100 .120 .140 .160 .180 .200

BAC maximum

30

25

20

15

10

5

0

Mean = .07675

Std. Dev. = .044295

N = 211

Frequency Figure 3b. BAC Maximum Levels Recorded with Self-Dosing 

19
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

False Positives 

In addition to the episodes just described with known BAC tests, there were 14 occasions of selfdosed drinking when no BAC test information was provided by the subjects. We know from the 

drinking logs that these were not genuine false-positive transdermal responses; drinking did occur, 

but we do not have the corresponding BAC values. Rather than log these as false positives, it was 

more valid to exclude these from the sample. In the majority of these cases, there was drinking, but 

the subject did not use the PBT to evaluate the BAC level. Reasons included forgetting to bring the 

PBT, did not have a breath tube, or as per our instructions, claimed to have had only one drink (the 

instructions called for logging BAC anytime two or more drinks were consumed in temporal 

proximity). In a few of those cases, elevated SCRAMTM TACs were an artifact of the initialization 

process, where voltages may result in artificially high TAC readings until the SCRAMTM ankle 

bracelet establishes a baseline reading for a non-drinking subject. Actual false positives among the 

subjects we studied were rare, and when false positives did occur, it was attributable to an 

undetected external source of alcohol. The concept of false positives has two different meanings with 

transdermal detection: (1) we can say with some confidence that there are few or no events that the 

devices created that look like drinking but were really not drinking because with drinking logs of 

well-compensated subjects and BAC results we knew definitively when real drinking occurred, but 

(2) we also know that there are external sources of ethanol signal that are unrelated to drinking that 

can cause a transdermal response. We detected one clear TAC event related to shaving cream 

containing an ethanol product, and there was one event that may have been related to perfume in the 

environment but we could not definitively identify the source. The shaving cream example did not 

look like a drinking event since it decayed too rapidly, whereas the other did look like a drinking 

event and had no clear cause. 

External sources of alcohol are all around. Many personal hygiene, home, and automotive products 

contain ethanol, and people who use or are around these products may show positive for exposure 

to ethanol even though they consumed no alcohol. For example, aerosol Lysol has between 79 and 85 

percent ethanol, and dozens of body sprays, such as Avon Naturals, have between 60 and 98 percent 

ethanol. The National Library of Medicine has a searchable database with product ingredient 

information (http://householdproducts.nlm.nih.gov). Restricting a search to ethanol-containing 

ingredients yields 447 consumer products that fall into eight categories, but of these products, 265 

(59%) fall into one category: personal care products that are used on or near the skin. The issue of 

false positives is revisited in a later section dealing with the calculation of ROC curves. The recent 

paper by Sakai et al. (2006) reported no evidence of false positives in their SCRAMTM research. 

However, external sources of alcohol can and do result in positive transdermal responses because 

ethanol or ethanol-like ingredients are in many consumer products. It is important for vendors of this 

technology to adequately train their staff and customers to appreciate this. 

Simple Detection: Sensitivity When BAC ≥ .02 g/dL 

Each type of device had strong points and weak points. The following section reviews some of the 

evidence for simple detection by each type. The definition of a “hit” for the purposes of describing 

simple detection was the occurrence of any elevated transdermal alcohol equal to or higher than .02 

g/dL in proximity with a time when the BAC was also higher than .02 g/dL. Defining a transdermal 

response as a true-positive “hit” was made through observation of the data series and curves for both 

WrisTASTM and SCRAMTM; the coding criteria are shown in “Methods.” In addition, for SCRAMTM, a 

20
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

supplemental method for judging a positive transdermal was available through use of the SCRAMTM 

alcohol detection algorithm. This is the protocol used by AMS for alcohol monitoring of offenders. 

WrisTASTM Judged Performance Detecting BAC ≥.02 g/dL 

Comprehensive evaluation of the WrisTASTM alcohol sensors was impeded by an apparently 

unreliable chipset (as understood from communications with the biomedical research director of 

Giner Inc.) that is unique to WrisTASTM version 5. The chipset manages the storage and retrieval of 

data from the device version 5 that was under evaluation in this study. Of the 271 episodes of 

drinking with known maximal BAC ≥ .02 g/dL, only 64 or 23.6 percent were hits, correctly detected 

by WrisTASTM to be ≥ .02 g/dL. A more accurate way to state that is whether or not the BAC was 

correctly detected by the Giner sensor; on only 23.6 percent of those occasions could correct data be 

coaxed out of the device for display and evaluation. It should be noted that a similar data loss was 

reported at the 2005 meeting of the Research Society on Alcoholism (RSA) by Greenfield et al. (2005), 

who also evaluated the WrisTASTM version 5. They found that “of the 456 person-days of data 

collected, the WrisTASTM unit failed on 194 person-days (43%).” They further distinguished between 

“all-person days” (n=246) that could be studied and “high-quality person days” (n=89). Accordingly, 

the findings we present here concerning data loss are not unique. 

Using the protocol described in the “Coding” section, we determined that the problems with the 

WrisTASTM fell into the categories shown in Table 2. The most common false negative subtype 

(37.6%) was missing data (no data captured because the device shut down), followed by data that 

were too erratic or noisy to be associated with a BAC (16.2%), or data that could not be judged a 

positive hit due to the rater’s low confidence (13.3%) whether it could be coded as a hit. False 

negatives due to response failure occurred in 8.1 percent of cases. These negative findings could be 

due to any of the following reasons: 

• Recording of data would cease at some point between starting data collection and 

subsequent downloading. 

• No data could be found in the device at all (the data record was blank or an old data 

record was not overwritten). 

• Data record was erratic with no pattern such that there was little relationship 

between samples on successive 5-minute intervals. 

• The TAC baseline reading varied over time, rendering it difficult to tell changes in 

TAC from changes in baseline. This happened for different reasons, including a 

change in the devices’ TAC calculation formula that caused TAC measurements to 

vary as a function of skin temperature. A calculated correction for this category of 

errors is introduced in a subsequent section. 

21
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Table 2. WrisTASTM Judged Performance Detecting BAC ≥.02 g/dL 

64 23.6 23.6 23.6

3 1.1 1.1 24.7

36 13.3 13.3 38.0

44 16.2 16.2 54.2

102 37.6 37.6 91.9

22 8.1 8.1 100.0

271 100.0 100.0

hit

<.02

low-confidence

too noisy

missing data

non-response

Total

Valid

Frequency Percent Valid Percent

Cumulative

Percent

A notable aspect of the results in Table 2 is the relative rarity (1.1%) of WrisTASTM underdetecting a 

positive BAC (row <.02). This row contains only three cases, and in two of those cases, the maximal 

BAC attained was only .020 g/dL. This suggests that when the alcohol information is recorded 

properly, it appears to work well; however, the failure rate, as represented by version 5, is clearly 

unacceptable with over 75 percent of trials either not detected or not logged. 

SCRAMTM Judged Performance Detecting BAC ≥.02 g/dL 

Table 3 shows the SCRAMTM device correctly detected BACs equal to or higher than .02 g/dL in 155 

of the 271 positive BAC events, for a valid hit rate of 57.2 percent overall. The SCRAMTM devices did 

not have missing data problems. Sixty (22.1%) of the positive BAC events were detected as a positive 

TAC but less than .02 g/dL. False negatives in which no response was found occurred in 14.8 percent 

of the events. 

Table 3. SCRAMTM Performance Detecting BAC ≥.02 g/dL

155 57.2 57.2 57.2

60 22.1 22.1 79.3

7 2.6 2.6 81.9

8 3.0 3.0 84.9

1 .4 .4 85.2

40 14.8 14.8 100.0

271 100.0 100.0

hit

<.02

low-confidence

too noisy

missing data

non-response

Total

Valid

Frequency Percent Valid Percent

Cumulative

Percent

SCRAMTM Automated Alerts 

With SCRAMTM, there are two different methods to assess the detection rate, via coded rater 

judgments described in “Methods” as shown in Table 3 and through the “Alcohol Alerts” found on 

the AMS server. The PIRE-coded judgments and the AMS Alerts were independently scored; Table 4 

shows a cross-tabulation between them. The Alcohol Alert derives from an AMS proprietary 

algorithm that serves to call a finding to the attention of an offender monitor or supervisor. The 

agreement for true-positive detection by these two methods was 93.5 percent and the agreement for 

true negatives was 91.5 percent (kappa =.85, p=.000). The 155 coded hits (total row value) in Table 4 

are the same events as the 155 hits in Table 3. Each method agreed on 145 events and differed on 10 

events. Upon examination, all disputed events were near the thresholds for detection. 

22
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Table 4. Agreement of Two Methods for Estimating SCRAMTM Hits ≥.02 g/dL

Count

106 10 116

10 145 155

116 155 271

.00

1.00

Coded Hit

Total

no alert alert

AMS alc alert

Total

Because we have found no false positives of any note, the key question for a simple detection 

evaluation concerns the false-negative rate. The alerts provided by SCRAMTM can be used to portray 

how well SCRAMTM detects true positives in the range of BAC ≥.02 g/dL to BAC ≥.08 g/dL, the 

range in which SCRAMTM normally flags a TAC. The data in Figure 4 show the hit rates (truepositive rates) and misses (false-negative rates) at seven cutoff levels when subjects dosed 

themselves. Below the cutoff criterion on the x-axis is shown the number of drinking episodes 

represented by the plotted points. The data in Figure 5 show the same type of plot when subjects are 

dosed in the laboratory to a known BAC targeted at .08 g/dL (80 mg/dL). 

0.0

20.0

40.0

60.0

80.0

100.0

=.02 

n=211

=.03 

n=186

=.04 

n=163

=.05 

n=139

=.06 

n=124

=.07 

n=96

=.08 

n=83

BAC Level

% Detection

no alert

alert

Figure 4. SCRAMTM Alerts (True Positive Detection) and No Alerts (Misses) by BAC (g/dL) Cutoffs 

When Self-Dosed 

When subjects are dosed in the laboratory, the alert or true-positive detection rate is much lower. 

These findings are summarized in Figure 5. The possible reasons for this are discussed later. In 

Figure 5, the lines remain parallel through the first three categories because there is no difference in 

the underlying data (n=60). There is no difference because the laboratory dosing of the subjects to the 

target BAC level of .08 g/dL was fairly consistent (and this is represented by the central [lepto] 

kurtotic distribution of the lab BAC data of Figure 3a). However, the contrived dosing regimen we 

used in the lab made it more difficult for the SCRAMTM devices to register elevated BACs. When the 

doses were higher, and especially when the duration of elevated BAC was longer, then the 

SCRAMTM alert was more likely to occur. This is well represented by the difference between the selfdosing and the lab-dosing evidence in Figures 4 and 5 and the slight growth in detection of TAC at 

higher BAC for lab-dosing. 

23
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

0.0

20.0

40.0

60.0

80.0

100.0

=.02 

n=60

=.03 

n=60

=.04 

n=60

=.05 

n=58

=.06 

n=56

=.07 

n=49

=.08 

n=37

Maximum episode of BAC Recorded

% Detection

no alert

alert

Figure 5. . SCRAMTM Alerts (True Positive Detection) and No Alerts (Misses) by BAC (g/dL) Cutoffs 

When Dosed in the Laboratory 

Plotted Example Charts 

Appendix F shows a complete 4-week chart for one subject. In successive pages, the date is 

represented on the x-axis, and the charts show data from SCRAMTM TAC, WrisTASTM TAC, labmeasured BACs, and self-measured BACs. The y-axis scale varies from 0 to .3 g/dL (300 mg/dL). 

Appendix G shows an example of each coded judgment type for each device. The judgment types 

were hits, TAC <.02 g/dL, low confidence, too noisy, and false negative. The category “missing data” 

is not represented as there is nothing to show. 

Other Measures of Coded Hits and Misses: SCRAMTM and 

WrisTASTM 

Magnitude of Peak Differences 

There is a commonly reported 2-hour lag between a peak BAC and a peak TAC under normal 

circumstances. This lag has been described in the peer-reviewed research literature and in the 

materials from the private companies. The delay likely represents transit time of ethanol from body 

core out to the skin surface. On the descending limb of a BAC curve, the TAC curve usually lags 

behind the BAC curve more so, such that the absorption and elimination curves are asymmetrical. 

When subjects dosed themselves with ethanol, the majority of the drinking episodes that were 

judged to be “hits” had a mean peak SCRAMTM TAC lower by .014 g/dL than BAC in paired 

comparisons of mean peaks in BAC (.095 g/dL) and SCRAMTM TAC (.081 g/dL) during the same 

drinking episode (this represents a mean difference of less than 12%). By contrast, in the laboratory 

dosing studies where the TAC response was muted, paired comparisons within a drinking episode 

found the mean SCRAMTM TAC peak (.047 g/dL) to be 44 percent lower than mean peak BAC (.085 

g/dL). That is to say, the lab mean peak difference is three times lower than the self-dose peak 

difference for episodes of drinking that were detected as true positives, even when the BAC peak 

was approximately the same. 

24
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

TAC output from the WrisTASTM generally overestimates BAC levels in the self-dose situation if no 

correction is made for variable WrisTASTM baselines. A sensitivity analysis in which baseline 

adjustments are made will follow in a later section. However, when we regard a zero value as a zero 

TAC, we find the paired comparisons of BAC and TAC for WrisTASTM hits, estimated from mean 

peak levels to differ by .073 g/dL; this represents a WrisTASTM TAC higher than peak BACs by 86 

percent. By contrast in the laboratory situation, for true-positive hits, the WrisTASTM devices logged 

TAC peaks only .019 g/dL lower than mean peak BAC (TAC 21% lower than BAC). The difference 

of mean peak TAC from BAC broken by type of drinking event is large considering the mean peak 

BAC in both situations was in the .08-.09 g/dL range. The SCRAMTM and WrisTASTM devices appear 

to have different optimal BACs when accuracy is highest. SCRAMTM more accurately estimated selfdosing, and WrisTASTM more accurately estimated lab-dosing. Neither device accurately estimated 

both types of drinking. 

The Bland-Altman (1986) method was devised as a way to compare two types of measurement to 

examine similarities or differences, an approach used by Sakai et al. (2006) in their evaluation. When 

laid out for this method, deviations of the linear fit line from a horizontal line off the Y axis suggest 

there are underlying differences in two methods. For comparison purposes between BAC and TAC, 

data are from all results where TAC was judged a “hit.” The average of paired TAC and BAC 

maximum values are plotted on the x-axis and the difference between them on the y-axis. TAC 

results that are stable across all BAC values would line up with a slope of zero; when perfectly 

identical the mean difference would be zero on the y-axis. The charts in Figure 6 are plotted this way 

and show a fitted line along with 95 percent confidence intervals. The overall measured mean 

difference between BAC and TAC is represented by a lightly shaded dashed line from the y-axis. The 

left panel (Figure 6a) is for WrisTASTM and the right panel for SCRAMTM (Figure 6b), both y-axes 

have tick mark steps scaled at .10 g/dL. The evidence suggests that WrisTASTM TAC shows a very 

high systematic error such that higher TAC values linearly exceed BAC values. The SCRAMTM 

results capture zero within the 95 percent confidence intervals. 

.00 .10 .20 .30 .40

Avg of BAC and TAC

-.20

-.10

.00

.10

.20

.30

.40

WrisTAS BAC-TAC difference

R Sq Linear = .701

.00 .05 .10 .15 .20 .25

Avg of BAC and TAC

-.20

-.10

.00

.10

.20

.30

.40

SCRAM BAC-TAC difference

R Sq Linear = .149

Figure 6. Bland-Altman Type Data Layout to Compare BAC and TAC for WrisTASTM (6a left), and 

SCRAMTM (6b right) over a Range of Measured Values 

25
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

A correction for WrisTASTM baseline would reduce the upper end of its high levels, but if the 

adjustment were linear, it might also reduce detection at lower BAC levels. The difference in 

estimation may represent the different types of events each device is calibrated to detect (e.g., 

SCRAMTM self-dosed illicit drinking in an offender population and WrisTASTM laboratory-dosing 

situations as a treatment research device). Tables of data for SCRAMTM and WrisTASTM coded 

judgments are shown in Tables 5a and 5b. 

For both devices, Tables 5a and 5b show that the rapid rise and fall of laboratory-dosed BAC resulted 

in a lower peak transdermal signal than was found with the more protracted self-dosed drinking 

episodes. In the laboratory trials subjects were instructed to consume their dose within 30 minutes. 

The dose in all cases was sufficient to elevate BAC to the target range (as shown in Table 1 and Figure 

3a), and the form of ethanol used was distilled spirits diluted with some mixer (orange, cranberry, or 

tomato juices, or a soft drink). The rapid ascent and descent of BAC appears to prevent the 

transdermal alcohol concentration from following as closely as when individual subjects more 

typically self-dose with spaced, longer-duration drinking. It should be noted that there is little about 

the laboratory-dosing sessions that emulate real-world drinking (four to six drinks in 30 minutes and 

then no more). The time required for the ethanol to move across body water compartments appears 

to have the effect of flattening the overall transdermal curve for the SCRAMTM device, more so than 

for the WrisTASTM device. 

Time Delays in BAC to TAC Peaks 

When there were true-positive hits with WrisTASTM, the timeframe of the results was less variable 

than when there were true-positive hits with SCRAMTM. Estimating the performance of either device 

regarding the time lag is best done with the lab-dosed studies where we had control over the amount 

of alcohol under consideration. It can be seen in Table 5b that the mean time delay in a lab-dosed 

peak TAC was 2.40 ± 1.5 hours later than mean BAC for the WrisTASTM. This is within the expected 

range based on the published literature. In Table 5a, the SCRAMTM device had a mean peak delay of 

TAC in lab-dosing relative to BAC peaks of 4.5 ± 2.9 hours. This lengthier delay with SCRAMTM 

exceeds by about 2 hours the theoretically expected delay in TAC maximum. An explanation for this 

that appears consistent with our observations and our conversations with technical staff at AMS 

reflects a water management problem inside the SCRAMTM unit that may cause dilution and delay in 

recording TAC. 

In the initial series of studies (the first 11 subject trials of the 4-week wear studies), AMS determined 

that a safety check valve was impeding moisture exit from the SCRAMTM unit due to faulty materials 

provided by its supplier and subsequently used in construction of the valve (see AMS letter 

Appendix B). After the first 11 subject trials (22 dosing studies), newer AMS devices were provided 

to the evaluators with the check valve removed. It may be that the delayed peak responses between 

BAC and TAC reflected residual alcohol laden moisture inside the SCRAMTM unit, leading to a 

continuing positive alcohol signal and/or a dilution effect of any new alcohol-laden sweat vapor 

coming in from the skin. This might explain the time delay found with the SCRAMTM units. 

26
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Table 5a. Characteristics of BAC Maxima and SCRAMTM TAC Maxima for True Positives 

(SCRAMTM HITS) by Type of Dosing

Descriptive Statistics - SCRAMTM

31 .041 .123 .08519 .016125

31 .010 .130 .04639 .025566

31 -85.29 42.86 -44.7248 29.71988

31 -.08 .04 -.0388 .02701

31 .00 13.33 4.5108 2.91417

31 1.00 1.00 1.0000 .00000

31

124 .020 .230 .09474 .041914

124 .008 .271 .08086 .056369

124 -89.61 134.57 -12.3700 44.87133

124 -.11 .11 -.0139 .04502

123 -1.08 26.80 5.1355 4.17534

124 1.00 1.00 1.0000 .00000

123

BAC maximum

SCRAM max TAC

TAC/BAC % diff

TAC/BAC peak diff

TAC/BAC peak time diff (hr)

SCRAM HIT

Valid N (listwise)

BAC maximum

SCRAM max TAC

TAC/BAC % diff

TAC/BAC peak diff

TAC/BAC peak time diff (hr)

SCRAM HIT

Valid N (listwise)

TYPE

lab

self

N Minimum Maximum Mean

Std.

Deviation

Note: Zero or negative time differences in TAC/BAC peak reflect cases when future episodes of 

drinking overlapped with past episodes. For SCRAMTM, there were six such cases (four self-dosed, 

two lab-dosed). 

Table 5b. Characteristics of BAC Maxima and WrisTASTM Maxima for True Positives 

(Wrist HITS) by Type of Dosing

13

13

13

13

13

BAC max any event

wrist max TAC

% wrist dev

wrist peak diff

wrist peak time diff

TYPE Minimum Maximum Mean

Std.

Deviation

lab

N

Descriptive Statistics - WrisTASTM

27
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Note: Zero or negative time differences in TAC/BAC peak reflect cases when future episodes of 

drinking overlapped with past episodes. For WrisTASTM, there were three such cases (two selfdosed, one lab-dosed). 

Performance of SCRAMTM Before and After Check Valve Removal 

A materials problem with the check valve, which is supposed to prevent moisture from entering the 

device, may have also prevented moisture from exiting. When removed, it raised the SCRAMTM truepositive hit rate in the laboratory from 8 of 22 (36.4%) to 24 of 38 (63.2%), a chance probability of .07; 

similar levels of improvement were found for males and females. Overall for laboratory detection, 

the mean TAC peak before the check valve removal was 50 percent lower than BAC peak, and after 

check valve removal, the peak BAC to peak TAC difference was 41 percent. These findings suggest 

that the valve was an impediment to correctly detecting alcohol in the laboratory, and removal of the 

check valve appears to have improved the device’s detection capabilities. Although the gain in 

detection rate (i.e., hit rate) was large, the gain in accuracy (deviation between BAC and TAC) was 

small. Appendix B explains in more detail the nature of the check valve problem. 

The check valve does not appear to explain the time delay in the peak difference between BAC and 

TAC maxima. Before check valve removal, the time difference between peaks in BAC and TAC was 

3 hours, and after removal, it was 5 hours. We should caution, however, that these series may not be 

fully comparable as the hit rate was twice as high after removal of the faulty valve (difference values 

before valve removal are based on only 8 cases of lab dosing). The mean and standard deviation of 

peak time delay was similar before and after valve removal when looking at only the self-dosed 

events. 

Sex of Subject – SCRAMTM 

As noted in the “Methods” section, we have 10 female subject trials (7 first and 3 repeats) and 20 male 

subject trials (15 first and 5 repeats). Across both types of dosing conditions and detection outcomes, 

females registered peak TACs that were 30.5 percent lower than their peak BACs, whereas males had 

peak TACs that were 14.6 percent lower than peak BACs. 

Restricting the analysis to only those that were judged true-positive hits, the data in Figure 7 portray 

the percentage of difference between peak SCRAMTM TAC and peak BAC split by sex of subject. 

Figure 7 also portrays the percentage of difference before and after the check valve change. The sex 

differences are not statistically significant with the number of study cases reported here (hits only), 

but even when restricting to the true-positive hits, females trend toward a greater percentage of 

differences in peak TAC and peak BAC (the y-axis in Figure 7). It is well known that females have a 

lower percentage of body water than males, but whether this is related to the mean differences in 

Figure 7 is not known. This figure also suggests that among actual true positives, the check valve 

removal did not consistently influence the deviation of TAC from BAC; sex appears to be a more 

important influence on the percentage of deviation than was the check valve change. Across all 

episodes of drinking with BAC ≥ .02 g/dL, SCRAMTM had 51 percent true-positive hits with females 

and 60 percent with males. 

28
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Figure 7. Mean Percent Difference ± 1 Standard Error of TAC from BAC by 

Sex and Type of SCRAMTM Device 

N = 20 24 57 54

SEX

female male

Mean +- 1 SE

% diff S

C

R

AM T

A

C/B

A

C

0

-10

-20

-30

-40

-50

Type SCRAM

With check valve

No check valve

Sex of Subjects – WrisTASTM 

The potentially lower transdermal response found for females using SCRAMTM technology was also 

found with WrisTASTM technology. Although we know the true-positive hit rate of WrisTASTM was 

low, there is a disproportionately lower WrisTASTM hit rate for females than males. Of 185 drinking 

episodes with a BAC ≥.02 g/dL, WrisTASTM on males correctly detected 31 percent of these, whereas 

WrisTASTM on females detected only 8 percent of the 86 episodes with females. This difference is 

statistically significant (p<.001), as are measured differences in the peak values of WrisTASTM TAC 

and BAC, and the percentage of difference in peak TAC and peak BAC. For males, the peak TAC 

measured 77 percent higher than the peak BAC, and for females, 48 percent lower than the peak 

BAC. This is shown graphically in Figure 8. It should be cautioned, however, that this large 

difference may be an artifact of only 7 cases of female drinking having been detected as a true 

positive with WrisTAS.TM Also overall mean male BAC attained during true-positive events for 

WrisTASTM was higher. 

The consistency of the lower transdermal detection rates for female drinking may be more than an 

artifact; however, the available data do not allow us to speculate further about what may be causing 

these differences. There was no significant difference in the average BAC maxima for males and 

females (.080 ±.042 for males and .073 ± .033 for females). 

29
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

N = 7 60

SEX

female male

Mean +- 1 SE

% diff WrisT

A

S

T

A

C/B

A

C

120

80

40

0

-40

-80

Figure 8. Mean Percent Difference ± 1 Standard Error of TAC from BAC 

By Sex for WrisTASTM Device 

Within Subjects Change in Accuracy 

SCRAMTM Within Subjects 

When repeat wear episodes for the same subjects are compared, the first and second times wearing 

SCRAMTM bracelets permits an assessment of stability of performance across time. In the case of 

SCRAMTM, this repeat assessment coincides with removal of the check valve, so the first and second 

laboratory dosing should show improvement if the valve was impeding proper performance of the 

devices. The mean alerts detected (using the AMS algorithm) in the first series with these subjects 

was just 25 percent, and after the valve removal, the alerts detected 62.5 percent of the lab-dosed 

BACs . For males, this detection was 30 percent in the first series and 80 percent in the second series. 

With the coded judgments, there were also large first- and second-round detection differences for 

males, with first-round hits equaling 40 percent and second-round hits equaling 80 percent. There 

were fewer females in the sample, and their detection was 33 percent for in both conditions. 

WrisTASTM Within Subjects 

The WrisTASTM devices appear to have detected more accurately in the first round (4-week study) 

than in the second round (2-week study). Judged WrisTASTM hits were initially 50 percent for 

laboratory dosing, whereas with the same subjects, performance fell to an average of 12.5 percent in 

the second round. However, this likely reflects the large increase in missing data in the second round 

and should not be viewed as a change in accuracy separate from the growing problem with missing 

data (device non-response). As with SCRAMTM, the performance with males was superior to females 

(60% dropping to 20% for males; 33% dropping to 0% for females). It is not clear if these differences 

by sex (and other sex differences already reported) are an artifact of sample size or are real 

consequences of differences in body water or other sex-specific physiological differences. 

30
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

For example, Anderson and Hlastala (2006) modeled the kinetics of transdermal ethanol exchange 

and determined the stratum corneum, the outer skin layer, was the most determinative factor in 

ethanol concentration at the skin surface. Jacobi, Gautier, Sterry, and Lademann (2004) evaluated the 

stratum corneum of males and females and reported that females have a significantly higher skin pH 

than males but that other parameters (water loss, hydration, and sebum content) of this external layer 

do not differ by sex. 

SCRAMTM Accuracy over Time 

One of the hypotheses we formed while working with the SCRAMTM devices was the possibility that 

the longer subjects wore the devices, the less accurate the results. It seemed that the best trials were 

often the earliest ones. 

Working from the coded judgments and the AMS alcohol alerts to indicate true-positive hit rates and 

using the most unbiased measure of peak accuracy – the percentage of deviation of the SCRAMTM 

peak TAC from the peak BAC, we evaluated the relationship between the percentage of deviation in 

accuracy and the duration of bracelet wear. Because the AMS server provides good detail on ankle 

bracelet history for each subject, we could plot the duration of bracelet wear so that any drinking 

episode and detection of it (true hits and percentage of deviation from BAC) could be related to the 

days of continuous wear. 

Figure 9a has a time axis representing days of wear ranging from at least 2 through 16 or more, 

separated at 2-day intervals, until the final category labeled 16 days. At each point on the time axis, 

the chart shows the mean percentage of TAC relative to BAC ± 1 standard error. It should be 

cautioned that this chart represents a mix of both types of dosing (lab and self), both before and after 

the check valve change, and with both males and females (all are potential sources of variation). With 

the exception of the check valve change, the other variables should be spread fairly evenly within 

each category. The accuracy appears to drop off over the first 10 days and then settles into a period of 

higher variability, with a particularly large standard deviation at the 14-day category. 

Plotting days of wear allows the episodes of drinking per day to vary (see Figure 9a). If the days of 

continuous SCRAMTM wear are ordered into a series and ranked, and then those ranks are broken 

out into 10 deciles, it distributes the number of drinking episodes evenly across categories. The 

deciles are shown on the category axis in Figure 9b (n=27 or 28 per decile to represent the 271 

episodes of drinking). Plotted this way, it allows for a comparison of the mean true-positive hit rate 

with equivalent statistical power per decile. The real mean days in Figure 9b are shown below the 10 

deciles of wear duration and from the 1st to the 10th decile, respectively; these range from .5 to 21.7 

days. The figure shows the true-positive hits based on our coded judgments and the AMS alcohol 

alerts as overlapping lines that reference the y1-axis. On the right side (y2-axis), the mean percentage 

of deviation of the TAC from BAC is plotted (triangles). The percentage of deviation starts with 

decile 1 at zero on the y2-axis (a perfect match between BAC and TAC), and then TAC relative to 

BAC declines over time with increasing days of ankle bracelet wear. The hit rates (y1-axis) are based 

on a constant number of drinking episodes, but from decile 1 to decile 10, the number of episodes 

contributing to the deviation score on the y2-axis declines from 24 to 10 (this is because there is no 

TAC value to use in the calculation for false negatives). With fewer underlying cases, the variance 

increases, and this may contribute to the wide swing in the mean deviation score in decile 9. This is to 

a considerable extent reflecting the same data that caused the swing upward in Figure 9a at 14 days. 

We considered whether a drop in hit rates and accuracy had some relation to the water/sweat vapor 

accumulation inside the devices. The water management issue was a topic that the AMS discussed 

31
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

frankly with the evaluators during our periodic conversations. It should be noted that the trend 

toward lower true-positive hits over duration of wear did not appear to go away when selecting only 

those drinking episodes when subjects wore the SCRAMTM devices after the check valve removal. 

After check valve removal, the first 3 deciles combined achieved hit rates of .775 (.77 and .78 for the 

two methods for true-positive hits), whereas the last 4 deciles had hit rates of about .44 (.43 and .45). 

It is important to consider that, although there is a decline in accuracy over time, this may be an 

artifact of testing subjects who consume alcohol regularly—that is, our subjects were required to 

drink alcohol, whereas AMS offenders are required to not drink alcohol. The nature of this 

evaluation study did not allow for an inference into accuracy following many days of continuous 

wear when a subject was not drinking. This would be an easy question to investigate by requiring 

abstinence for 2 weeks or more and then initiating self-dosed drinking. But that question was not 

anticipated in the work plan for this study, and regrettably we do not have an answer for it. 

8642 10 12 14 16

Days of Continuous Wear

20.00

0.00

-20.00

-40.00

Mean +- 1 SE % SCRAM deviation

Figure 9a. SCRAMTM TAC Percentage of Deviation from BAC 

by Days Wear Time ± 1 Standard Error 

32
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

1 2 3 4 5 6 7 8 9 10

Deciles (wear days)

0

.1

.2

.3

.4

.5

.6

.7

.8

.9

-50

-40

-30

-20

-10

0

10

20

30

40

0.5 1.7 3.3 4.6 6.2 7.7 9.3 11.0 13.6 21.7

Mean actual days

True P

ositive

Hit Rate

Percent difference

TA

C/BA

C

Judged (Y1)

Alc Alerts (Y1)

% dev TAC/BAC (Y2)

Figure 9b. SCRAMTM Hit Rate (y1) by Judgment or Alcohol Alerts and Accuracy (y2) 

by Continuous Days of Wear 

Rule-Based Sensitivity Analysis 

Up to this point, the evaluation has focused on the identification of simple decision criteria for 

judging whether a TAC response from the SCRAMTM or WrisTASTM devices can be viewed as a hit 

or a miss based on all BAC episodes ≥.02 g/dL. In addition to those coded judgments of whether a 

TAC response has occurred, we have also described use of the AMS alcohol alert algorithm as the 

criterion. However, the raw data (from which those judgments were made) can also be analyzed to 

build an algorithm from our own logic rules. This has the advantage of removing subjective 

judgments from coding and the disadvantage of needing to statistically remove known artifacts (e.g., 

such as transient spikes and floating baselines) that are often more easily found by just looking at a 

data record. The human observer is the most efficient pattern detector but is subject to various types 

of unintentional bias. The automated algorithmic analysis considers all the raw TAC and BAC data. 

As was noted in the Results Section, the judgment-based analysis excluded from the dataset 38 selfdosed drinking episodes that were <.02 g/dL BAC as well as positive TACs when BAC was missing 

for known reasons. In the raw data, all those events are included; the automated analysis is a fresh 

run at the raw numbers. 

Setting up the Rules 

The approach we took defines four separate virtual experiments for identification of BAC episodes. 

These correspond to screening for detection at four levels of BAC: .02 g/dL, .04 g/dL, .06 g/dL, and 

.08 g/dL. We calculated sensitivity statistics for each of these levels using methods derived from 

Signal Detection Theory (SDT), in which the true alcohol condition of the subjects (e.g., lower than .02 

g/dL BAC vs. higher than .02 g/dL BAC) was predicted using a binary decision criterion based on 

the TAC reading, and then we noted the success of these predictions in the classical SDT 2x2 

structure of true positives, false positives, false negatives, and true negatives. As before, however, we 

do not consider as false positive measured TAC events that exceeded a BAC once the BAC was 

actually higher than .02 g/dL. But when a BAC was less than .02 g/dL and the TAC was ≥.02 g/dL, 

then that TAC is a false positive (in this way known episodes of missing BAC due to subject error 

will be flagged as false positives). If TAC exceeds BAC≥.02 g/dL, then it has correctly detected a 

positive BAC. For example, a TAC of .07 g/dL is not considered a false positive for a BAC of .04 

g/dL because the transdermal sensor would have done its forensic detection job and issued an alert 

33
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

or flagged the positive. Accordingly, with these criteria it means that once the false-positive rate is 

established, then at increasing BAC test levels, there can be an increase in sensitivity but no change in 

the false-positive rate (1-specificity). In the virtual experiments, for each level of “real” BAC that we 

try to detect, we varied the criterion (or “cutoff”) value of the TAC through a range of thresholds 

(from .005 to .12 g/dL) to plot ROC curves. 

To establish a false positive rate for TAC in the virtual experiments, it was necessary to have cases 

representing an actual negative condition for BAC—that is, occasions when there was a known zero 

BAC, which ideally should be recognized by the screening device as true negatives. We had a 

theoretical maximum of 60 such actual negative occasions when subjects came in for laboratory 

dosing. Our rules required that no one could be dosed unless their BAC was zero. So we calculated 

the false-positive rate upon those occasions. For SCRAMTM, we used 58 zero BACs (two were 

excluded: one because there was no TAC produced and one because a subject’s TAC was on an 

obvious tail end of a prior drinking episode). With WrisTASTM, we used 42 zero BACs (one excluded 

was the same subject that SCRAMTM detected who was still elevated, and 17 were excluded due to 

missing data). When applying the screening cutoff level of .02 g/dL on the devices, the calculated 

false-positive rate for SCRAMTM was 12.3 percent, and for WrisTASTM, it was 25.9 percent. These are 

conservative (high) false-positive rates, representing 2 hours before the BAC test and 1 hour after the 

BAC test. WrisTASTM responds more quickly to elevated alcohol than SCRAMTM, and it is likely that 

some of the apparent elevation in the false-positive rate is due to a rapid transdermal response to the 

actual dosing that followed within 30 minutes of the zero BAC test. In addition, some of the 

unexpectedly high false-positive rates for both devices likely reflect the detection of some real 

elevated BACs from a prior night of drinking. Simply stated, the high false positive rates are to some 

extent artifacts of the algorithm setup. 

The calculated rate of false positives therefore does not necessarily represent actual false-positive 

rates, as it was not possible to perfectly define and identify ideal instances of pure negative 

conditions. However, to automate the SDT analysis, there has to be some false-positive rate based on 

some known zero BAC value. The time intervals surrounding the laboratory dosing were the closest 

practical thing to “certain” zero BAC values that we had in the data set. Had we narrowed the 

window of observation, it not only would have reduced the false-positive rate, but also would have 

eliminated many of the data points available for making the estimate. 

With respect to the true-positive rate (sensitivity), whether or not the transdermal signal correctly 

detected the BAC would depend upon the TAC result obtained during that drinking episode. For this 

algorithm, the drinking episode was defined as continuing from the earliest elevated BAC measure 

to an 8-hour interval immediately after the maximal BAC elevation. We modeled these data in three 

ways (e.g., allowing an episode to extend until the next episode or cutting off the period after 8 or 12 

hours). The sensitivity results were generally higher when the interval was longer, but negligibly so, 

indicating that when successful, the devices would generally detect an elevated BAC early—within a 

few hours—if they were going to detect it at all. 

The method we used, although it probably overestimated false-positive rates, was based on 

measured BAC values and allowed sufficient time after a maximal BAC for the transdermal device to 

respond. True positives, not false positives, are the more relevant measure for real-world 

applications of this technology. False-positive errors as a category have salience for people who work 

with industrial solvents or other alcohol-related environmental signals, so false-positive events 

should not be regarded as unimportant. But as a matter of normal performance and as discussed in 

an earlier section, there were few actual false-positive events found in the data when examined by 

34
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

coded judgments. This is the same result reported by Sakai et al (2006) in their SCRAMTM evaluation 

of subjects who received no alcohol in one condition of their trial. 

Dealing with Spikes and Other Noise Parameters 

We evaluated these data unadjusted for noise and also with smoothing algorithms. Common time 

series smoothing algorithms (e.g., running medians) and other time-contingent logic rules of 

selection were used to reduce the influence of extreme spikes in the transdermal devices’ data series. 

Without this adjustment, the rules-based approach might detect spurious “water spikes,” transient 

interfering substances or non-alcohol-related positives to be true-positive events. 

Dealing with Shifting Baselines 

As noted earlier, the baseline that defines real zero on the WrisTASTM is more variable than the 

nominal zero values provided on the raw data file and the charting protocol that Giner supplies. That 

is to say, even though the output from the WrisTASTM may not read zero, we know from 

conversations with the Giner head technician that real zero drifts over time. Actual TAC values are 

more appropriately read as the difference from a stable low value to the high value during a drinking 

episode. To compensate for this drift, we calculated an algorithm that subtracts from the reported 

maximal TAC values a minimal “neo-baseline” level that we defined as based on the apparent low 

point observed in the 3 hours immediately before the drinking event began. For WrisTASTM, this 

represents 36 of the 5-minute samples (the device stores a result 12 times per hour). The 3-hour 

period preceding the rise caused by the alcohol signal was divided into three 1-hour intervals; the 

hours closest in time to the positive signal were weighted more strongly than the hour intervals 2 or 3 

hours earlier. These 3 hours of WrisTASTM signal then define the neo-baseline. These adjustments 

were made before determining the false-positive rates already described. 

Signal Detection Statistics: d’ and A’

For each of the four dichotomized levels of actual BAC, the TAC measures were also dichotomized at 

a level corresponding to .02 g/dL TAC, and then true-positive (TP) and false-positive (FP) rates were 

calculated, along with the SDT accuracy measure d’ that ranges from zero (chance performance) to an 

effective practical limit of ~4.0. A d’ of 4.0 would indicate a near-perfect ability to capture almost 

every actual positive without also mistakenly capturing any false negatives. This measure, d’, is 

calculated as the sum of the two z-scores corresponding to each of the sensitivity (TP) and specificity 

(1-FP) rates, and assumes that a sensitivity error has the same relative cost as a specificity error (an 

assumption which we realize is not true for those who would be mandated to use TAC devices). 

These accuracy measures: sensitivity (TP percent), specificity (100-FP percent), and accuracy (d’) are 

shown for each of four levels of BAC impairment in Table 6, all of which were calculated using the 

single-decision criterion of TAC ≥.02 g/dL as reflecting the practical cutoff value used in real life. 

That is to say, .02 g/dL is the level at which SCRAMTM units issue alerts, a BAC at which many 

interlocks lock out, and the lower end at which performance studies can begin to identify some 

impairment. It is the appropriate criterion. 

The tabled values and the figures shown are prepared from those cases where the device under 

evaluation produced data—that is, the missing data described earlier as a problem with the 

WrisTASTM are not represented here as false negatives. For both devices these sensitivity analyses 

evaluate the accuracy of the devices when they gave an alcohol output signal. 

35
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

The sensitivity or true-positive rate for SCRAMTM (when it sees an alcohol signal of .02 g/dL at the 

skin) increases as the alcohol BAC signal increases. The detected values for SCRAMTM are within 

range of the numbers shown in Figure 4 for SCRAMTM hits. In Table 6, TP rates continue to rise from 

.02 g/dL at 65.3 percent through to .08 g/dL at 86.5 percent. In both analyses, the definition of a “hit” 

or true positive represents BAC detection when the TAC signal is .02 g/dL or greater. 

For the WrisTASTM, the TP rates are nearly the same all the way across (from 84.4 and 82.3%) for BAC 

≥.02 g/dL. This suggests that the device is working at a near optimal level once it detects alcohol—

that is, the likelihood of this device detecting alcohol at .02 g/dL BAC is not very different from the 

likelihood of detection at .08 g/dL. By contrast, SCRAMTM sensitivity improves with higher BACs. 

The SCRAMTM and WrisTASTM sensitivity data are based on a varying number of drinking episodes 

at each BAC level and that number of events is shown in the row TPn in Table 6. As noted earlier, the 

false-positive rates are based on a fixed number of events and the FPn and FP rows do not vary with 

BAC level. Table 6 also shows area under the curve (A’ which can be up to 1.0) and d’ which reflects 

the degree of separation of the signal and noise distributions in standard deviation units. All the 

signal detection statistics shown are based on the smoothed and filtered data for which adjustments 

have been made for baseline drift and spurious spikes. The markers on each graph represent the 

point from which the d’ statistic is evaluated. The closer the marker point is to the upper left corner of 

the graph, the higher the d’ and therefore the more distinctly different the signal and noise 

distributions. 

Table 6. Algorithm-Based Signal Detection Statistics for SCRAMTM and WrisTAS 

SCRAMTM WrisTASTM

.02 BAC .04 BAC .06 BAC .08 BAC .02 BAC .04 BAC .06 BAC .08 BAC 

TPn 265 217 174 117 179 146 121 79 

TP 65.3% 73.3% 78.2% 86.5% 84.4% 82.9% 82.6% 82.3% 

FP 12.34% 12.34% 12.34% 12.34% 25.90% 25.90% 25.90% 25.90% 

FPn 58 58 58 58 42 42 42 42 

A' .821 .861 .890 .918 .840 .835 .836 .831 

d' 1.392 1.580 1.702 1.982 1.464 1.469 1.436 1.392 

ROC (Receiver Operating Characteristic) Curves 

The theoretic ROC curves corresponding to the variable accuracy of the continuous TAC measures 

are shown in Figure 10 (SCRAMTM) and Figure 11 (WrisTASTM). On the y-axes, perfect detection 

would have a true-positive rate of 1.0; on the x-axes, a detection protocol with no false positives 

would have a rate of zero. The position of each marker in Figure 10 is positioned at the intersection of 

false-positive rate and the true-positive rate for SCRAMTM (values from Table 6). The positions of the 

markers in Figure 11 overlay each other and are evidence that the WrisTASTM sensitivity is not 

dependent on the BAC level at the levels evaluated in this study. This finding is in accord with the 

evidence in Table 2 showing only three cases of low TAC signal when a BAC episode was ≥ .02 

g/dL. The overlap of the curves suggests that the sensitivity of the WrisTASTM devices has a ceiling 

effect at the BAC maxima evaluated and that its potential sensitivity is likely much lower than .02 

g/dL. 

36
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

smoothed, SCRAM (ankle)

False Positives

BAC

True Positives

0.0 .4.3.2.1 .5 .9.8.7.6 1.0

1.0

.9

.8

.7

.6

.5

.4

.3

.2

.1

0.0

.08

.06

.04

.02

Figure 10. Signal Detection SCRAMTM at Four BAC Values 

smoothed, WrisTAS

0.0 .4.3.2.1 .5 .9.8.7.6 1.0

False Positives

BAC

.08

.06

.04

.02

True 

P

ositi

v

es 1.0

.9

.8

.7

.6

.5

.4

.3

.2

.1

0.0

Figure 11. Signal Detection WrisTASTM at Four BAC Values 

These plots represent the inherent tradeoffs between sensitivity and specificity. We select .02 g/dL 

for reasons already cited. The results would be somewhat different if we were to use some other level 

of TAC as our dichotomizing decision cutoff. These curves are obtained by varying the TAC cutoff 

level (or, criterion) through a range of .005 to .120, producing a separate 2x2 table of “hits” and 

“errors,” for each cutoff value and then plotting the set of true-positive and false-positive rates from 

each 2x2 table. The bold plotted point shown on each graph is the presumptive decision criterion of 

TAC >= .02 g/dL, corresponding to the rates and accuracy measures for the curves as shown in 

Table 6. 

37
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Circumvention Detection 

All of the results provided and discussed to this point have concerned the alcohol sensors. Both the 

AMS SCRAMTM and Giner WrisTASTM devices also have sensors for skin temperature (either in 

direct contact or near the skin), and sensors to detect either skin conductivity (Giner) or infrared 

signal (AMS). The latter sensors are designed to determine if the unit is no longer in proximity to the 

skin surface, or whether some blocking agent has been inserted between the skin and the alcohol 

sensor. Skin temperature can also be used to infer that a device is working normally. A benefit of the 

skin temperature sensor is that when examining multiple days of wear, the temperature sensor gives 

a good estimate of sleep cycles because while core body temperature declines during normal sleep 

hours, skin temperature ordinarily rises as heat leaves through the skin. Sleep cycles are seen in 

Figure 12 as 13 upward excursions. 

Temperature

1\29 11:20 AM 1\31

50

60

70

80

90

100

110

120

12:54 AM 2\1 2:29 PM 2\3 4:03 AM 2\4 5:38 PM 2\6 7:13 AM 2\7 8:47 PM 2\9 10:22 AM 2\10 11:57 PM

Figure 12. AMS SCRAMTM Temperature Sensor Data Over 13 Days 

for Subject MS10a (1/29/05-2/10/05) (Source: AMS screen capture) 

To evaluate circumvention, PIRE staff wore SCRAMTM devices on both ankles for 2 days. On day 

one, our staff consumed alcohol and achieved a BAC near .08 g/dL. The purpose of this was to 

establish that both sensors responded in approximately the same way to the same alcohol signal, 

which they did. On day two, one of the sensors was blocked. We selected a thin but absorbent 

material (cotton) that was very close to the color of the skin and inserted it under the analog (fuelcell) side of the SCRAMTM unit. The blocker was inserted just after hearing the sensor take a sample 

of air, thus allowing at least 30 minutes before another sample would be taken. Inserting the material 

was no problem; the material was intended to absorb the alcohol, and due to skin color matching 

conjectured that it might prevent the infrared sensor from detecting the barrier. 

The result of this was that while the alcohol was absorbed, the infrared sensor issued an alert because 

the infrared (IR) voltage signal rose from 3 up to 5. The alcohol signal was attenuated on the blocked 

ankle (from .08 g/dL during the unblocked night to less than .02 g/dL the following night) but the 

infrared detector issued a tampering alert. The circumvention effort was detected. A variation on this 

study was tried with other materials (plastic, tape), but it appears that matching color of the blocking 

substance is not sufficient to fool the sensor. There is also the matter of reflectivity. The ideal 

substance will likely have to have a surface that reflects like skin but through which body heat can 

warm the temperature sensor. 

In another study, we took unfair advantage of our knowledge of the SCRAMTM bracelet to determine 

if an offender with equivalent knowledge could block the signal. We knew exactly where the 

infrared sensor was located and this time inserted blocking material (thin plasticized wallet card) 

between the skin surface and the SCRAMTM bracelet, but not so far up the bracelet as to cover the 

infrared sensor. In this case, we did have partial success in preventing the skin alcohol signal from 

38
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

reaching the fuel cell. The maximum BAC of .085 g/dL resulted in less than .02 g/dL TAC – there 

was no alcohol alert and no infrared alert (tamper alert) was issued. 

Two cautions apply. This type of intervention is probably impractical for any extended period since 

it was both uncomfortable and required special knowledge of sensor locations. Possibly a redesign of 

the SCRAMTM unit that positioned the infrared sensor in between the vapor sampling areas would 

make it considerably more difficult to implement something like this, even knowing where the 

infrared sensor was located. 

Although there are many materials or approaches that can probably prevent alcohol detection, the 

bigger challenge is to do so in a way that does not activate the infrared detector. A tamper is a 

tamper, so there is a whole series of circumvention efforts that do not need to be tested with alcohol. 

Our experience has shown that it is difficult to find absorbent or blocking barriers that do not lead to 

significant and noticeable changes in infrared readings. 

By hearsay, we were informed that liquid skin or liquid bandage type products might be able to 

block the alcohol. This product is a substance that can be sprayed or brushed on and secures a 

wound and serves the same purpose as a bandage. We examined the contents (available in 

pharmacies) and found that it was about 7 percent alcohol. So to test it, it was necessary to get the 

product on the skin (after the SCRAMTM bracelet was installed) and then dry the alcohol before the 

device takes a sample. We determined that the substance can be applied without causing an infrared 

alert but that it has no ability to block alcohol. The TAC recorded was normal, a result that is not 

surprising as this product is advertised as “breathable.” 

Environmental Challenges 

The protocol to investigate the effects of exercise-induced sweating and low temperature exposure 

was only adequate to make a qualitative estimate of the direction of effect of each intervention 

condition. We imposed the low temperature manipulation for 10 trials, and the treadmill exercise on 

10 trials. Our inability to more quantitatively investigate these variables was due to three factors: 

• Humane considerations (subjects cannot be made cold for very long or required to 

exercise for very long). 

• The surprisingly low TAC responses (relative to BAC), particularly for SCRAMTM, 

that were attained in the laboratory dosing. 

• The unexpectedly long delay in time to peak TAC following a BAC peak making it 

difficult to observe an effect on alcohol detection within the timeframe allotted for 

the lab-dosing studies. 

Procedurally, subjects usually consumed their alcohol dose by 10:30 a.m. The planned scheduling 

(drink in the morning and test in the afternoon) accommodated a delay of 2 to 3 hours following the 

BAC peak to evaluate the effect of the low-temperature protocol and the exercise-induced sweating 

protocol. 

Regarding the low ambient temperature protocol, we exposed alcohol-dosed subjects wearing shorts 

and a thin top to a cold room for 30 minutes. The room’s temperature was lowered with a special airconditioning unit, plus a high-output fan that blew air directly on the subjects, after passing through 

10 pounds of frozen blue ice. The temperature-lowering protocol was adequate to result in strong 

shivering and gooseflesh, and the data in Figure 13 show an exemplary plot of skin temperature 

39
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

decline for leg (~6 oC) and arm (~5o C) during the 30-minute period. Nearly all subjects responded 

with a similar degree of cold. 

22

24

26

28

30

32

34

0 2 4 6 8 10 12 14 15 17 19 21 23 25 27 29

minutes in cold

Degrees Celsius

Leg Temp (C)

Arm Temp (C)

Figure 13. Skin Temperature on Arm and Leg of Subject While in the Cold Room 

The qualitative effect of lowered skin temperature was small, but in about half the cases, there was a 

discernable but brief lowering of the alcohol signal by less than .02 g/dL. It would not have been 

apparent unless someone knew where to look for it in the data record. Other than alcohol, the effect 

of the environmental temperature manipulation could be seen on the SCRAMTM temperature sensor 

in which a drop of approximately 5o to 6o C was found. The alcohol response in the presence of this 

temperature drop was of three types: either there was no response because alcohol had not yet begun 

to be detected, there was a transient dip in the alcohol signal consistent with the temperature signal, 

or the temperature manipulation introduced some variability. One could infer from these results that 

if there is a TAC reduction due to the cold, it is temporary and small. It would be difficult to give a 

good test of the question of whether cold lowers SCRAMTM detection of alcohol within the 

constraints of human subjects’ protocols. 

The treadmill settings for evaluating the effect of elevated skin temperature and sweating involved 

30 minutes of exercise at a setting of 3 miles per hour but at a grade of 9. This was like a walk up a 

very steep hill at a normal walking pace. It was sufficient to induce sensible (liquid) sweating in all 

subjects. The skin thermistors could not be reliably affixed in a way to document the change in skin 

temperature over the 30 minutes due to equipment limitations; however, at the end of the 30-minute 

exercise period, 3 to 5 minutes of skin temperature data were gathered to document the rise in skin 

temperature at that time. Most subjects showed a 2oC (arms) to 5oC (legs) degree rise in skin 

temperature over a 4-minute period as excess heat escaped past the skin surface and sweating 

continued. With starting skin temperatures of approximately 33o C, there are only a few degrees on 

the upside that can be attained. Normal core temperature is 37o C. 

The treadmill sweating protocol affected the SCRAMTM infrared sensor reading, so this may mean 

that exercise could lead to tamper alerts. The general tendency was for the alcohol TAC signal to 

increase in the presence of sweating or due to heating of the skin surface, but as TAC was already 

elevated, no new alcohol alerts were possible. The limited duration of the exercise intervention and 

the slower-than-expected response of the sensors to alcohol made it difficult to offer more than these 

qualitative observations of the data. 

40
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Wearability and Acceptability 

Overall, subjects tolerated the alcohol-sensing devices reasonably well. There were individual 

differences in the ability of subjects to tolerate either the SCRAMTM or WrisTASTM devices, but none 

of the subjects found the problems to be great enough to warrant dropping out of the study. All 

subjects who began the study completed the study. Several commented that the bonus money for 

sticking with the study all the way through dispelled any idea of dropping out, even when they 

found the devices annoying. The largest complaints centered on the manner in which the device 

interfered with participation in exercise, particularly swimming, but also to a minor extent, soccer 

and running. Many subjects commented that they did not want to be seen as offenders and were a 

little embarrassed by the devices, often wearing long pants when they would have ordinarily worn 

shorts. 

Having summarized these comments from research subjects, we found it interesting that similar 

comments were offered by the actual offenders who participated in focus groups to help us better 

understand their experiences as SCRAMTM offenders. More commentary on wear and wear-related 

problems are summarized in Appendices D and E. 

Focus Groups of SCRAMTM Offenders 

Seven SCRAMTM offenders participated in a focus group to help us understand some of the 

experiences reported by end users of this technology. A more complete accounting of this 

information can be found in Appendix E. 

Users experienced both problems and benefits. Problems usually fell into the same categories 

mentioned by our experimental research subjects: some discomfort with wear; public embarrassment 

or embarrassment with close acquaintances; and some equipment-related problems, such as having 

to use landlines rather than mobile phones for the daily modem data transfers. In addition, the courtordered offenders reported difficulties with the cost of the SCRAMTM device (typically $12 to $15 per 

day), and there was a strong fear of having their freedom (from going to jail) dependent upon the 

potential whims of provider or probation department employees who sometimes did not 

understand the devices. They strongly believed the devices were largely foolproof, and the general 

opinion reflected the view that it would be very stupid to risk any drinking. 

In addition to problems, users also reported benefits. Chief among these was the enforcement of 

abstinence so that they experienced the benefits that derive from not drinking, such as a sharper 

mind, better sleep, better work performance, and better relations with family. In addition, the 

SCRAMTM providers also offered proof to the probation authority that the offenders’ claims of 

abstinence were genuine. There was a resigned sense of gratitude expressed by several people that 

the alternative to SCRAMTM, jail, was worse than having to endure the discomfort. 

When asked about circumvention strategies, focus group participants might have tried, but they 

strongly expressed beliefs that there was no way to beat it. They felt the consequences of being 

caught tampering were not worth it. These seven offenders may not be typical as there was no 

random selection possible, so their comments should not be viewed as representative of SCRAMTM 

users. 

41
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Interview and Contacts with SCRAMTM Providers 

Discussions with SCRAMTM providers who are installing devices on end users were conducted both 

in small groups at meetings and via e-mail and telephone. The general feeling among these providers 

(often private contractors who lease or purchase the equipment from AMS) was that the SCRAMTM 

system works well. In their view, about 20 percent of offenders violate the system and that, when 

violations occur, they are readily discernable. Among the violations discussed were cutting the strap 

and removing the device and various attempts to circumvent or block the signal, similar to those we 

tested. They claimed circumvention efforts were easily detected and, when the offenders learn they 

cannot successfully circumvent, most stop drinking and stop trying to beat the device. Of course, if 

someone devised a perfectly successful circumvention, the providers, by definition, would not know 

it. There was a strong feeling among the providers that the SCRAMTM devices are useful and that 

many of their offenders benefit from having to wear the bracelets. More detail from provider 

conversations can be found in Appendix H. 

42
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Discussion 

This research on transdermal alcohol sensing adds information to the sparse literature in this field. In 

so doing, it confirms some facts that are well known and uncovers some previously undocumented 

findings that bear on the nature of transdermal alcohol sensing. As noted earlier, this project was not 

conducted for the purposes of comparing two devices in order to pick a winner. SCRAMTM and 

WrisTASTM represent the universe of available technologies in the larger category of transdermal 

electrochemical alcohol detection. This technology, already in use in the United States, can only 

benefit from more active independent study of its strengths and weaknesses. 

Depending on the application intended, electrochemical alcohol-sensing units mounted on the skin 

surface can have advantages over other forms of protracted alcohol detection such as biomarkers or 

frequent regular breath, blood, or saliva tests. The devices collect and store data on their own, 

accumulate results over time, and can be combined with tamper protocols. These features reduce 

human monitoring time, and the time needed for results analysis. Blood, urine, saliva, or hair 

biomarkers all require chain of custody sample collection, a potentially long time for measurement 

and /or significant costs per sample. BAC monitoring by telephone must by law exclude large 

portions of a 24-hour period. Transdermal alcohol-sensing technology does not have these 

limitations. 

Of the electrochemical devices under evaluation, only the SCRAMTM unit is commercially available 

at present, but the technology underlying both devices is commercially viable. Both companies have 

cooperated fully with the project, combining the best of openness with their product information and 

an eagerness to acquire any new information that might help improve their products in future 

versions. 

Giner WrisTASTM 

When discussions began with Giner Inc. to acquire WrisTASTM units for evaluation, they were in a 

transition phase between their version 5 and version 6 devices. Giner Inc. is a small research and 

development company that manufactures sensors for environmental gases and other products, 

many unrelated to biomedical applications. The alcohol detection product built around their proton 

exchange membrane is not available for the commercial market. Their version 5 prototype has had 

known problems with data integrity, and it does not have a remote telemetry system built into it as 

does the newer version 6. We expressed a desire to evaluate version 6, but it was not yet available. 

We ultimately agreed to evaluate their older version since it had already been the subject of several 

research studies by Swift and others. The data retrieval interface with version 5 is via a DOS-based 

program that uploads data from the unit through a hard-wired serial port (a serial port on a port 

replicator will not work). The program will run under DOS or in the DOS emulation box of some, 

but not all, Windows versions. Unlike the sensor itself, this aspect of version 5 is surely not cuttingedge technology. 

As the research began, we learned to appreciate the distinction the Giner staff makes between 

WrisTASTM devices and “pre-qualified” WrisTASTM devices. When not pre-qualified, the devices 

have a higher rate of data loss. As our results demonstrate, we readily duplicated the data loss 

problem. We found that some WrisTASTM devices became erratic that were once completely stable 

and dependable. There are different types of data loss, any of which rendered large chunks of data 

unavailable and formed the basis for the judged category of “missing data.” Sometimes a device 

43
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

would be working well when it went out the door on the wrist of a research subject only to discover 

2 weeks later that it had stopped collecting data within an hour after leaving the office. 

We do not know where the WrisTASTM data go when lost, but we do know that 38 percent of the 

data was missing and another 16 percent was too noisy to be used. We often did not know if the data 

were collected in the device and then lost, never collected, “stuck” so numbers could not be 

downloaded to the computer, erased by some stray electromagnetic signal, hit by a physical injury, 

or some other factor. Sometimes data were retrieved, but they were meaningless and patternless. We 

have estimated that slightly less than 25 percent of the BACs that exceeded .02 g/dL was detected as 

a hit even though all subjects (with a one-week exception) wore WrisTASTM devices throughout the 

study program, and those devices were regularly serviced and downloaded at weekly or biweekly 

intervals. On the other hand, the signal detection analysis determined that when the WrisTASTM 

correctly detects an episode of drinking, it can detect low, medium, or high levels of drinking with 

approximately equal sensitivity. The 4-week charts of a single subject (Appendix F) demonstrate how 

well this device can work when it works properly. Also evident in this single subject’s data is the 

occasional problem with shifting baseline and occasionally erratic readings. With this subject’s data, 

however, the WrisTASTM device recovered nicely from noisy intervals, even though the baseline 

remained elevated. 

Among actual true-positive hits, we found that the mean WrisTASTM accuracy was quantitatively 

quite good in the laboratory, but when the WrisTASTM registers the long duration self-dosing events, 

the estimated level of TAC runs high. This conclusion is based on data as represented in Figure 6a 

wherein the linear fit line shows divergence of TAC and BAC at the upper end of the measurement. 

This is not a serious problem for most applications because the error level is systematic and therefore 

correctable by software or scoring adjustments. In addition, we also know that the functional zero 

point on the WrisTASTM record can vary widely. For the applications needed by most alcohol 

monitoring programs, high sensitivity even as low as .02 g/dL is highly desirable, but as currently 

implemented, the only method for determining a true TAC is to visually subtract a positive deviation 

from an effective zero baseline that can range as high as .10 g/dL (on the nominal y-axis). 

In addition to the sensitivity evidence that we report here and that Swift and colleagues reported on 

as was discussed in the Introduction of this report, University of Indiana alcohol clamping studies 

(personal communication with Dr. Robert Swift) further corroborated this effect. In that research, 

subjects were held to a near constant BAC for an hour or more through feedback to an alcohol 

infusion pump. Their results showed that WrisTASTM can precisely rise to stable levels consistent 

with BAC and fall in equally precise fashion once the alcohol signal decays. It is unfortunate that all 

the WrisTASTM devices reported on here cannot match this degree of performance or the 

performance even of the generally excellent device shown in Appendix F. 

The most plausible explanation for WrisTASTM data loss is the one offered by Giner itself—that is, the 

chipset that was designed to handle data I/O functions in version 5 is faulty. Giner believes the new 

version 6 has solved many of these problems because it is based on a new chipset. This explanation, 

together with the sensitivity data we have seen when the device is working well, suggests the sensor 

itself may not be the problem. 

Obviously, however, until the new WrisTASTM version 6 or subsequent versions can be evaluated 

and shown (a) to have overcome the data loss problems, (b) that they are designed with adequate 

circumvention detection protocols, (c) that they can be secured so removal is difficult, (d) that they 

can be made more affordable, and (e) that they have functioning telemetry features that can reliably 

transmit data, it will be premature to consider WrisTASTM devices as suited for use in offender 

44
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

monitoring. On the other hand, if the promise of this sensor can be harnessed, packaged, and made 

available for offender monitoring at an affordable cost, it could form the basis for new applications of 

transdermal alcohol detection. We know of nothing available like it that detects alcohol in such a 

sensitive manner and in such a compact package. If the small size could be retained, and the I/O 

problem overcome, as anti-circumvention and communication capabilities are added, it would show 

great promise. 

AMS SCRAMTM 

The SCRAMTM device is currently in use by courts and correction agencies and therefore more 

thorough discussion is warranted about its performance. SCRAMTM devices are reportedly in service 

around the United States; devices are leased or sold to direct service providers or government 

agencies. From their own promotional materials, AMS claims to have more than 800 courts and 

agencies using SCRAM. 

Accuracy and Sensitivity 

There were two significant problems with the SCRAMTM bracelets uncovered in this evaluation. 

These are a higher-than-expected false-negative rate and the possibility that sensitivity and accuracy 

of the devices decline over time. Because sensitivity declines over time, and because the laboratory 

studies were a poor emulation of real drinking it is not very meaningful to focus on an overall 

average performance. Nonetheless, overall, across laboratory and field evaluations, 57 percent of the 

BAC events were judged hits and another 43 percent were misses for various reasons. Half of the 

missed events were judged as evident TAC responses but less than the cutoff of .02 g/dL, and 

therefore, less than the level at which AMS’ own automated system would issue an alert to the 

program monitor. Unlike the WrisTAS, there were few TAC responses to BAC ≥ .02 g/dL that fell 

into the categories that we judged and labeled “missing” or “noisy.” Among the 43 percent non-hits, 

after accounting for all response conditions, 15 percent were judged non-response false negatives, 

meaning no evident response to the elevated BAC. The 43 percent (including pre and post valve 

change) categorized as not true-positive hit is unexpectedly high. 

The declining accuracy over time to a great extent accounts for the reduced SCRAMTM true-positive 

hit rate. As can be seen in Figures 9a and 9b, initially near-perfect true-positive hit rates and 

accuracies fall off with time in service. We have come to understand this reduction in sensitivity and 

accuracy may be associated with water accumulation in the sensor area. For devices that are often 

assigned for 3 or more months of wear, a halving of sensitivity during the first 2 weeks is 

troublesome. 

Concerns about both accuracy and sensitivity all come with the same caveat. SCRAMTM bracelets are 

mostly used with people who are supposed to not consume alcohol. All of our subjects were 

required to consume alcohol. We cannot know if the measured decline in sensitivity and accuracy 

over time (as shown in Figure 9b) is related to alcohol exposure or is a consequence of wear (and 

consequent exposure to vapor sweat) independent of alcohol. Does time itself and exposure to vapor 

sweat reduce sensitivity and accuracy, or is decline in accuracy and sensitivity over time a 

consequence of repeated alcohol exposure? Our experience of occasionally low accuracy with light 

drinkers makes us somewhat skeptical that repeated alcohol exposure is the cause of the decline, but 

it cannot be ruled out. If it is the former, then it raises the question as to whether SCRAMTM would be 

capable of detecting more than half the drinking after the first couple weeks of wear. If it is the latter, 

then it is probably less important as SCRAMTM users, with some exceptions, should not be drinking. 

45
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

When we designed this research study, we did not provide for exposure effect because it was 

unanticipated. It would be a straightforward study to conduct and could be addressed by waiting for 

2 or more weeks of wear before testing the devices for sensitivity to alcohol. Alternatively, it could be 

evaluated by simultaneous BAC or alcohol biomarker assessments of offenders, or by promptly 

evaluating the sensitivity and accuracy differences of devices going out or coming back from 

offenders. AMS staffers have mentioned a “water management” issue with their devices, and we 

know that some research subjects were more prone than others to cause “water spikes” or transient 

elevations in the alcohol sensor readings that are clearly unrelated to drinking. Accuracy problems 

over time may reflect moisture accumulation in the sensor area that dilutes the alcohol signal and 

leads to extended periods of low amplitude signals long after we might expect the actual transdermal 

alcohol to have declined. 

As we initiated a plan to evaluate SCRAMTM, it seemed sensible enough to control conditions in a 

laboratory setting so that paid research subjects could consume known quantities of alcohol and the 

response of SCRAMTM monitored. At the outset, we also decided to propose a field research element 

using handheld fuel-cell PBT devices. Self-dosing and self-BAC measurement served to significantly 

increase the positive BAC episodes available for evaluation. The biggest risk with this study element 

was entrusting each subject with the two transdermal devices and the PBTs (about $3,500 worth of 

equipment); fortunately this proved not to be a problem. As is evident now, we found that the fieldcollected data provided a better evaluation of SCRAMTM sensor accuracy relative to maximum BAC 

level. It was surprising how poorly the laboratory testing served as a proxy for normal drinking and 

detection of that drinking. In reality, people do not drink that way, so the laboratory model was a 

poor emulation of “normal drinking,” and proved to be a suboptimal method for evaluating the 

SCRAMTM devices. 

The laboratory non-response false-negative rate for SCRAMTM was no worse than self-dosed (both 

around 15%), but the most striking difference was the accuracy as measured by the percentage of 

deviation of SCRAMTM TAC from the maximal BAC within an episode of drinking. SCRAMTM TAC 

was 45 percent less than maximal BAC in the laboratory testing but only 12 percent lower than the 

maximal BAC in field testing. This relative discrepancy was less a problem in the laboratory for the 

WrisTASTM TAC (21% less than lab BAC maximum versus 86% more than field BAC maximum). It 

may be that there is something about the laboratory protocol of rapid consumption that does not 

allow sufficient time for movement of the alcohol across the various dermal membranes before the 

enzymes convert it. If, as the Widmark equation suggests, the average rate of metabolism is .017 

g/dL/hour, then even a 2-hour delay in peak TAC means that .034 g/dL of detectable signal would 

have been diminished (approximately a 45% reduction). It may be that a transdermal device’s 

accuracy has to be tuned either for rapid consumption or protracted consumption. Most of the 

WrisTASTM trials have been laboratory-based studies, whereas the SCRAMTM devices are calibrated 

against stable wet bath alcohol concentrations before they are released for detection of field selfinitiated drinking. This might explain why each device has its own domain of accuracy with different 

types of alcohol administration. 

Communications 

A unique feature of the SCRAMTM product is the Scramnetwork server and the fairly seamless way 

that it communicates and uplinks data from the ankle bracelet. The server authorization process 

allows for varying levels of security and access that is granted based on the security clearance of the 

person who wants to see the data. From the company’s own top-level access, multiple call center 

supervisors might monitor several agencies, agents nest within agencies, and clients within agents. 

46
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

For each new client introduced into the Scramnetwork server, the equipment is initialized and a 

specific bracelet is linked to a specific modem. 

During initialization, when a new client begins a period of wear, the modem and bracelet 

communicate first with each other, then the modem calls into the server and initializes the process. 

Equipment is “checked out” so that dates of service initiation are clearly logged, and when service 

ceases, the equipment is checked in. This is done remotely without the need for anyone at AMS to 

intercede. Because the modem is typically set to call into the network every 24 hours during the sleep 

hours, the local manager/supervisor can examine new data daily after uploading. Between 

successive clients, the local installation center uses a disinfecting kit for the surfaces that come in 

contact with skin. 

The problems we encountered with the communication system were minimal. The biggest problem 

that we found is the current requirement that it be used only with landline (wired) telephones. This 

has become a problem as many people now use mobile phones exclusively for communication. 

Occasionally other problems, even with landline telephones, have occurred that may be associated 

with DSL lines or other competing sources of signal that may interfere with transmission. However, 

if call-in is prevented for 24 hours, the server flags this and issues an alert to inform the agent (in this 

case, our research staff), who then communicate by voice with the individual and resolve the 

problem. Overall, the data aggregation and reporting system is well designed and works well. 

Other Considerations 

Finding a doubling of SCRAMTM detection rates (from 36 to 63%) with males after the check valve 

problem was resolved may partially explain problems with the earlier equipment. We do not 

understand why the improved valve did not also result in improved results with females or why the 

overall percentage of accuracy improvement relative to BAC was only marginally better than it was 

before the valve change. The female difference might be related to sample size (although there were 

an overall 86 test trials with females, 20 in the lab and 66 in the field). The mere marginal 

improvement after check valve removal may be a consequence of allowing some of the water out of 

the SCRAMTM device, but not enough of it. With the check valve removed, there is an escape path for 

water vapor, but it does not mean that all the water is in a vapor form, and the sensor area could still 

be partially saturated. 

But as we puzzle over why female TAC accuracy was low, it should be noted that the problem was 

not restricted to SCRAMTM. Both SCRAMTM and WrisTASTM performed more poorly with female 

subjects. Relative to males, females had a greater percentage deviation of TAC from BAC for both 

types of devices in both lab-dosing and self-dosing situations. This may be worthy of focused study, 

and it would be interesting to know whether skin pH or the higher subcutaneous adiposity of 

females accounts for flattening of the TAC peaks. We are not aware of other transdermal studies 

commenting on sex differences in detection. 

As to wear and comfort, more females reported discomfort with the wearing of the SCRAMTM device 

than did men. Some suggested the size of SCRAMTM was more suited to men than women. Women 

in the study, and in focus groups, were more likely to complain about the tightness of SCRAMTM 

bracelets and of SCRAMTM limiting clothing options. Women also found it annoying to have to work 

around the bracelet when shaving their legs, and in one case, a clear false-positive was found during 

use of “Skintimate” shave cream, a product that contains triethanolamine. These spikes following 

brief external exposure to alcohols are easily distinguished from elevated BAC (and are not flagged 

by the automated alert system due to the rapid rise and fall), but there is the larger problem of 

47
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

detecting exposure to various alcohols or industrial chemicals on a regular basis if such substances 

are in someone’s work environment. AMS is aware of these problems and handles them on a caseby-case basis when they occur. 

Signal Detection Analysis 

Writing an automated algorithm for classifying transdermal events in a 2x2 table of true or false 

positives and negatives poses several challenges. There are transient spikes to exclude and 

fluctuating baselines to accommodate, but one big problem was not having BAC test logs recorded 

during times when subjects were not drinking. That would have provided a larger database from 

which to find more true negatives rather than relying solely on the first BAC samples on laboratory 

test days. To calculate the signal detection analysis (SDT) analysis with the ROC curves, all four cells 

need data. Our only solidly zero (0 g/dL) BAC data were those obtained before those morning 

laboratory-dosing events. Accordingly, the false-positive rates are unnaturally high for both devices 

because we took a wide 3-hour interval around those zero BACs (to get 3 TAC data points on 

SCRAMTM) and any positive TACs that were not sufficiently filtered out by the algorithm would 

have registered as a false positive. Nonetheless, the ROC curves have allowed us to determine that 

SCRAMTM and WrisTASTM differ on low-end sensitivity. WrisTASTM had similar sensitivity at all test 

BAC levels and, as is shown in Figure 11, with overlapping ROC curves (at fixed false positive rates). 

In Figure 10, SCRAMTM sensitivity was much improved as the test BAC level increased. The pattern 

of sensitivity detected in the automated SDT analysis is very similar to the pattern from AMS alcohol 

alerts found in Figure 4, which shows the plotted results of the AMS algorithm for detection. In both 

of these very different types of detection exercises, the true-positive rates increased from the low to 

mid 60s for all BACs of .02 g/dL or greater and ranged up through the mid to high 80s for BACs of 

.08 g/dL and higher. 

Circumvention Detection 

It is possible for a motivated and knowledgeable offender to engage in at least some degree of 

drinking without detection, but this is not likely to be a serious problem, especially among offenders 

who will typically be required to wear SCRAMTM transdermal devices for months. Theoretical 

circumvention and practical circumvention are not the same. Other technologies that detect alcohol, 

such as alcohol ignition interlock devices, can also be circumvented with adequate motivation, but in 

both cases, the proportion of offenders who could regularly circumvent with success is likely to be 

very small. 

Due to the poorer low-end sensitivity, a concern with SCRAMTM could be detection of low-level 

consumption because two drinks spread out over a few hours at typical metabolism rates would 

keep BAC and TAC below the detection level. That degree of drinking is not the type of drinking that 

led the offender to the attention of authorities in the first place. However, if there were an abstinence 

order in effect, such drinking would nonetheless represent an undetected violation. 

Also in our environmental conditions, we showed that temperature and sweat probably do affect the 

detection of skin alcohol for reasons that make physical sense (i.e., alcohol volatility and skin blood 

flow are both dependent on local temperature). However, the amount that we could detect in a 

laboratory evaluation of temperature factors was small. It is conceivable that someone drinking 

outside in the cold with an ankle bracelet fully exposed to the low air temperatures could reduce the 

alcohol signal. 

48
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Perceptions: Offenders and Vendors 

A focus group with seven post-SCRAMTM offenders opined that it would be foolish to try to 

circumvent the device, and none offered methods or admitted to attempts to do so as their freedom 

from jail was a strong motivating factor in compliance. These participants were selected only on the 

basis of their availability and willingness and therefore cannot be thought of as representing average 

users. Despite discomfort complaints by most, the bracelet was generally regarded as a net good by 

those who thought there was no way to “beat it” and who subsequently reported no longer drinking. 

Their commentary suggested a clear parallel to the bogus pipeline paradigm well-known among 

behavioral researchers as a method for improving the accuracy of self-disclosure. People will be 

more truthful and more compliant when they fear the consequences if they are caught lying. With 

that as a context, SCRAMTM can likely still serve its intended purpose even though the version we 

studied is imperfectly accurate and relatively insensitive to low-end alcohol after a couple weeks of 

service. 

Service providers we spoke with were all supportive of SCRAMTM and its ability to detect 

noncompliant offenders. Unlike the offenders in our focus group, service providers deal with the full 

range of offender types. Of course, as providers, they may have some personal stake in the product, 

so their views are not objective. Although they will have become aware of unsuccessful 

circumvention efforts, if there are offenders who found a way around SCRAMTM, they would 

probably not know about it. 

In informal conversations, AMS has said that about 20 percent of all who are forced onto SCRAMTM 

have to be removed from the program and confined to jail because they cannot find the selfdiscipline to not to drink. This is not a surprisingly high proportion considering that only about a 

third of those who enter alcohol treatment successfully sustain abstinence for 6 to 12 months after 

initiation. 

In our interviews, we learned that judges differ in their reaction to drinking while on SCRAM. Some 

send offenders to jail right away, others do little. The biggest fear among the offenders we 

interviewed seemed to be a result of encounters with capricious or uninformed monitoring staff who 

did not understand the difference between external interfering substances spikes and real drinking, 

and who had the authority to send them back to jail. 

49
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Final Note and Recommendations 

In general, the sensitivity and accuracy of these devices were poorer than we expected. But if they are 

not yet perfected, further product improvement is likely to get them closer. It may be impossible to 

ever expect the alcohol signal at the skin surface to be a precise estimate of BAC if Anderson and 

Hlastala (2006) are correct. Their model suggests that the stratum corneum, the outer most layer of 

skin, and other systemic factors importantly affect the measurable ethanol gas concentration near the 

skin. Individual differences or state differences within individuals in hydration, temperature, and 

other factors theoretically affect the transdermal alcohol signal strength greatly. 

On the other hand, the monitoring of alcohol consumption does not depend on precise measurement 

of BAC; it depends on the ability of a technology to detect abstinence violations as measured by a 

signal in excess of some minimal amount, such as .02 g/dL. As a monitoring device for offenders, the 

transdermal concept is valid and the benefit appears evident despite the limitations of the actual 

equipment with false-negatives rates that are too high. Nonetheless, these devices warrant further 

development and further study. 

AMS has reportedly redesigned the interior of its SCRAMTM devices to solve the water problem by 

reducing the potential spaces where water can accumulate inside the housing. It is likely that the 

accuracy problem, like the sensitivity problem, is due to the water accumulation. The problem of 

declining accuracy over time in this regard is a very significant concern. AMS needs to demonstrate 

that equipment in service beyond 2 weeks has adequate sensitivity. 

It is likely that female complaints about size and fit of the bracelet are valid and worthy of attention 

by AMS staff. Miniaturization and improved accuracy will only happen if the industry achieves the 

kind of success that warrants further investment in research and engineering. 

On that point, the communication of the SCRAMTM bracelet with its remote server, along with data 

retrieval and reporting technology, is exceptionally innovative. The sensor technology that is at the 

heart of the Giner device also appears to be exceptional. 

This report, or any like it, that concludes transdermal alcohol sensing has many more benefits than 

problems is unlikely to spark a rush to transdermal sensing as a monitoring remedy for alcohol 

abusive offenders; average daily cost is still a barrier, particularly with DWI offenders. The typical 

daily cost of leasing SCRAMTM is around $12. This compares very well with regular house arrest, 

which runs about $12/day, but quite poorly with alcohol ignition interlock devices that usually cost 

about $2.50/day. Accordingly, the use of transdermal sensing is probably going to be less used with 

routine DWI offenders than for multi-problem alcohol abusers; people who need to be entirely 

prevented from drinking, not just drinking-and-driving, are the natural market for SCRAMTM. 

Transdermal technology could make a very important contribution to the societal problem of low 

penetration of alcohol ignition interlocks among DWI offenders if it were an alternative to the 

interlock rather than simple license suspension, as is now most typical. 

50
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

References 

Anderson, J. C., & Hlastala, M.P. (2006). The kinetics of transdermal ethanol exchange. Journal of 

Applied Physiology, 100(2), 649-655. 

Bjerre, L. (2003). An evaluation of the Swedish alcohol ignition interlock program. Traffic Injury 

Prevention 4(2), 98-104. 

Bland, J.M., & Altman, D.G. (1986). Statistical methods for assessing agreement between two 

methods of clinical measurement. The Lancet, February 8, 1986, 307-310. 

Bock, S. (2003). Michigan DOC runs BETA test of new remote transdermal alcohol monitoring 

system. The Journal of Offender Monitoring, 16(1), 9-10, and 13, 19-20. 

Brown, C.D., & Ridder, T.D. (2005). Framework for multivariate selectivity analysis, Part I: 

Theoretical and practical merits. Applied Spectroscopy, 59(6), 787–813. 

Gilg, T., Buchholtz, U., & Huth, O. (2000). CDT (carbohydrate deficient transferrin) and other 

alcohol markers in the MPA (medical and psychological assessment) of alcohol offenders 

regranting driving licenses – Results of an empirical study in Germany. In H. Laurell & F. 

Schlyter (Eds.). Proceedings of the 15th International Conference on Alcohol, Drugs and Traffic Safety 

(Vol. 4, pp. 1183-1184). Stockholm, Sweden: ICADTS. 

Gjerde, H., & Morland, J. (1987). Concentrations of carbohydrate-deficient transferrin in 

dialysed plasma from drunken drivers. Alcohol and Alcoholism, 22(3), 271-276. 

Gjerde, H., Sakshaug, J., & Morland, J. (1986). Heavy drinking among Norwegian male drunken 

drivers: A study of gamma- glutamyltransferase. Alcoholism: Clinical and Experimental Research, 

10(2), 209-212. 

Greenfield, T.K., Tujague, J., Bond, J., & Kerr, W. ( 2005). A pilot study of self-report alcohol 

consumption: Diary versus transdermal alcohol sensor accuracy. Paper presented at the Research 

Society of Alcoholism Meeting, Research Society of Alcoholism, Santa Barbara, CA. 

Jacobi, U., Gautier, J., Sterry, W., & Lademann, J. (2005). Gender-related differences in the 

physiology of the stratum corneum. Dermatology, 211(4), 312-317. 

McCartt, A.T., Geary, L.L., & Nissen, W.J. (2002, September 2002). Observational study of the 

extent of driving while suspended for alcohol-impaired driving (DOT HS 809 491). Washington, DC: 

U.S. Department of Transportation, National Highway Safety Administration. 

Marques, P., Bjerre, B., Dussault, C., Voas, R.B., Beirness, D.J., Marples, I.R., & Rauch, W.R. 

(2001). Alcohol ignition interlock devices. I: Position paper. Oosterhout, Netherlands (Online: 

http://www.icadts.org/reports/AlcoholInterlock Report.pdf. Accessed Nov. 16, 2004): 

International Council on Alcohol, Drugs and Traffic Safety (ICADTS). 

Phillips, M., Greenberg, J., & Andrzejewski, J. (1995). Evaluation of the Alcopatch, a transdermal 

dosimeter for monitoring alcohol consumption. Alcoholism: Clinical and Experimental Research, 

19(6), 1547-1549. 

Ridder, T.D., Brown, C.D., & Ver Steeg, B.J. (2005). Framework for multivariate selectivity 

analysis, Part II: Experimental applications. Applied Spectroscopy, 59(6), 804–815. 

51
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Ridder, T.D., Hendee, S.P., & Brown, C.D. (2005). Noninvasive alcohol testing using diffuse 

reflectance near-infrared spectroscopy. Applied Spectroscopy, 59(2), 181–189. 

Roizen, J., Lichtor, L., & Lane, B. (1990). A “band-aid” to detect alcohol levels in blood. 

Anesthesiology, 73, A510. 

Sakai, J.T., Mikulich-Gilbertson, S.K., Long, R.J., & Crowley, T.J. (2006). Validity of transdermal 

alcohol monitoring: Fixed and self-regulated dosing. Alcoholism: Clinical and Experimental 

Research, 30(1), 26–33. 

Swift, R. (2000). Transdermal alcohol measurement for estimation of blood alcohol 

concentration. Alcoholism, Clinical and Experimental Research, 24(4), 422-423. 

Swift, R.M., Martin, C.S., Swette, L., LaConti, A., & Kackley, N. (1992). Studies on a wearable, 

electronic, transdermal alcohol sensor. Alcoholism: Clinical and Experimental Research, 16(4), 721-

725. 

Swift, R.M. (2003). Direct measurement of alcohol and its metabolites. Addiction, 98(Suppl 2), 73-

80. 

Widmark, E.M.P. (1932). Principles and applications of mediolegal alcohol determination. 

Berlin: Urban & Schwartzenberg. 

Zettl, J.R. (2002). The determination of blood alcohol concentration by transdermal measurement: A 

white paper. Alcohol Monitoring Systems, Inc. Retrieved August 16, 2004 online: 

http://www.alcoholmonitoring.com/pdf/TransdermalWhitePaper.pdf

52
APPENDICES 

53
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix A – Literature Search Sources 

Scientific Literature 

At a minimum, the following Dialog databases will be examined: 

• Law enforcement databases: 

Criminal Justice Periodicals Index [Dialog file #171] 

Gale Group Business A.R.T.S. SM [Dialog file #88] 

Gale Group Legal Resource IndexTM [Dialog file #150] 

NCJRS [Dialog file #21] 

PAIS International [Dialog file #49] 

Periodical Abstracts PlusTextTM [Dialog file #484] 

• Social science, psych, and medicine databases: 

American Medical Association Journals [Dialog file #442] 

Dissertation Abstracts Online [Dialog file #35] 

ERIC [Dialog file #1] 

Gale Group Health & Wellness DatabaseSM [Dialog file #149] 

General Science Abstracts/Fulltext [Dialog file #98] 

MEDLINE® (1966-present) [Dialog file #155] 

MEDLINE® (1990-present) [Dialog file #154] 

NCJRS [Dialog file #21] 

NTIS - National Technical Information Service [Dialog file #6] 

New England Journal of Medicine [Dialog file #444] 

NewsweekTM [Dialog file #482] 

PAIS International [Dialog file #49] 

PsycINFO® [Dialog file #11] 

Social SciSearch® [Dialog file #7] 

Wilson Humanities Abstracts Full Text [Dialog file #436] 

• Transportation and safety databases 

Occupational Safety and Health (NIOSHTIC®) [Dialog file #161] 

Wilson Social Sciences Abstracts [Dialog file #142] 

Wilson Applied Science & Technology Abstracts [Dialog file #99] 

54
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

• Government agencies 

National Institute on Alcohol Abuse and Alcoholism 

National Highway Traffic Safety Administration 

National Institute of Justice 

55
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix B – AMS Letter Regarding Check Valve 

56
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

57
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix C – Participant Agreements and 

Instructions 

1. Informed Consent Form 

2. Participant Agreement Form 

3. Subject Do’s and Don’ts Checklist 

58
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

INFORMED CONSENT FORM 

FOR EVALUATION OF TRANSDERMAL ALCOHOL DEVICES 

The Pacific Institute for Research and Evaluation (PIRE) is conducting an evaluation 

of the effectiveness of 2 devices for measuring alcohol levels from the skin’s surface. 

This research study is funded by the National Highway Traffic Safety Administration. 

The purpose of the study is to determine the accuracy levels of the two different 

devices. If you meet all the qualifications for participation, you are invited to take part 

in this study. 

You are invited to participate only if you: are at least 21 years of age but under 35, 

drink alcohol on a regular basis, have never had an alcohol or drug related health or 

criminal problem, are not taking medication of any kind, are not pregnant, and are in 

good health. You will be asked to complete two short questionnaires regarding 

alcohol use before qualifying for the study. You will also be asked to provide a urine 

sample to screen for drug use. Females will be asked to take an early pregnancy test. 

Participation in the research project is voluntary. If you are eligible to be in the study, 

you may receive up to $800 for your time. Note that the IRS requires us to send you a 

1099 tax form for any payment over $600, so you will receive a 1099 form for tax 

reporting purposes if you complete the entire study and receive $800. 

You will be asked to wear two transdermal devices (one on your ankle and the other 

on your wrist) 24 hours a day for 28 consecutive days. During that four-week period, 

you will be asked to keep a daily diary or log of your drinking, and home breath tests. 

You will also need to come to the PIRE offices and spend up to 20 hours total across 5 

occasions. Some of that time will be used to install and remove the devices as well as 

discuss the study tasks with you. 

On 2 occasions when you come to the PIRE offices, you will participate in alcohol 

dosing lab studies that will involve your drinking vodka and juice in a brief period. 

During this time, your blood alcohol concentration (BAC) will be regularly monitored 

with breath tests so that your BAC does not exceed .08. To test the effect of different 

temperatures and conditions on the transdermal devices, you will also be exposed to a 

cold room (60 degrees F) and a hot room (90 degrees F) and asked to walk on a 

treadmill for approximately 10-15 minutes. Transportation from and to your home 

will be provided. You will not be allowed to leave the PIRE offices until your BAC 

level has decreased to at least .02, after which time you will be given a ride directly to 

your home. A certified paramedic will be monitoring your status throughout the 

study. 

To protect your confidentiality, your data will be coded with a unique ID number. The 

key linking your name and ID number (along with the consent form) will be kept 

secure in a locked file cabinet separate from the data collection forms. Only senior 

staff will have the key. Your name will not be used when reporting the results of the 

study. No information traceable to you will be released to anyone. 

There are some risks to you by participating in this research. You could be 

embarrassed by your behavior while under the influence of alcohol, although you 

59
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

may stop participating at any point in the study. You may become sick as a result of 

drinking alcohol, although a paramedic will be on hand to assist and provide medical 

attention if needed. You will benefit by receiving $100 for each of 4 weeks in the study 

and an additional $400 upon final completion of the study for your participation. You 

will be contributing to understanding the results of using alcohol sensing transdermal 

devices. 

If you have any questions about the research study, you can contact Dr. Paul Marques 

who is in charge of the study at the Pacific Institute for Research and Evaluation, 

11710 Beltsville Drive, Suite 300, Calverton, MD 20705, Phone (301) 755-2700. If you 

have questions about your rights as a research subject, you can contact Elysia 

Oudemans, Manager of Research Integrity Compliance, at the same address and 

phone number. 

I have read the consent form and agree to participate in the evaluation of transdermal 

devices. 

____________________________ ________________________ 

Participant Date 

____________________________ ________________________ 

Witness Date 

60
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

PIRE TRANSDERMAL ALCOHOL STUDY 

PARTICIPANT AGREEMENT FORM 

Participant Name _____________________________ Date______________ 

I, ________________, am participating in a study of transdermal technology for the Pacific Institute 

for Research and Evaluation (PIRE). I understand that for participating in this research study, I will 

be paid at a rate of $100 per week plus and additional $300 upon satisfactory completion of the full 28 

days of the study, for a maximum payment of $700. I agree to comply with all study requirements set 

forth in this Agreement and to strictly follow the instructions of PIRE research staff. I understand that 

any failure by me to comply with this Agreement or the instructions of PIRE research staff will be 

considered a violation of this agreement and may constitute grounds to be dropped from the study 

prior to becoming eligible for the full $700 payment. 

SCRAMTM EQUIPMENT 

As a condition of my participation in the study, I agree to properly use the Secure Continuous 

Remote Alcohol Monitoring TM (“SCRAMTM”) equipment provided to me by PIRE research staff. In 

that regard, I will wear the SCRAMTM Bracelet on my ankle for the duration of the Program and will 

allow the SCRAMTM Modem to be connected to my home or office telephone or as agreed with 

research staff. I understand that the SCRAMTM Bracelet will, at pre-programmed intervals, test me for 

the presence of a positive blood alcohol concentration by the measurement of ethanol, which is being 

emitted as vapors through my skin. When the SCRAMTM Bracelet detects the presence of ethanol, it 

will record a positive reading and will later transmit a reading to the SCRAMTM Modem. The 

SCRAMTM Bracelet also contains systems designed to detect interference or tampering and will also 

transmit a tampering alert to the SCRAMTM Modem in the event of a tampering attempt. 

I understand that I have a responsibility to do everything reasonable, within my power to protect the 

SCRAMTM equipment from damage. I understand that if PIRE does not return the equipment in 

good working condition, they will be charged for the repair or the replacement of the equipment as 

follows: 

Full replacement of the SCRAMTM Bracelet - $1,400.00 

Full replacement of the SCRAMTM Modem - $ 700.00 

Front strap replacement - $ 75.00 

Back strap replacement - $ 175.00 

Back comfort strap replacement - $ 75.00 

Clip and battery replacement - $25.00 

I agree to allow authorized personnel to inspect and maintain the SCRAMTM Bracelet and SCRAMTM 

Modem. 

While participating in the study, I agree to wear a non-removable SCRAMTM Bracelet that will be 

attached by PIRE research staff. I agree not to remove the device during the course of the study. I 

agree not to tamper with the SCRAMTM bracelet, or place any obstruction material between the 

SCRAMTM bracelet and my leg, except where directed to do so as part of PIRE’s investigation of 

circumvention of the SCRAMTM device. Under no circumstances will an attempt to circumvent the 

device involve acts that might damage the SCRAMTM equipment Only in a life-threatening 

61
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

emergency or with the prior permission of PIRE research staff will I remove the SCRAMTM Bracelet 

by cutting the front strap where indicated by the words ‘Cut Here’. 

I agree to maintain an analog telephone line and electrical service in my residence at my own 

expense, unless some other arrangement has been agreed to by PIRE staff. 

I understand that PIRE staff and I will agree on a time everyday when I will be in range of the 

SCRAMTM modem. I agree to be physically in range of my SCRAMTM Modem for 15 minutes prior to 

the designated reporting time. I will not leave SCRAMTM Modem range while the green light is 

blinking. SCRAMTM Modem range is within the same room as the SCRAMTM Modem or within 30 

feet of the SCRAMTM Modem. 

If I experience problems with the SCRAMTM Bracelet or SCRAMTM Modem, or if I lose electrical 

power at my residence, I agree to call PIRE research staff immediately. 

If I am unable to reach PIRE staff immediately, I agree to call and leave a message on their answering 

machine including my name, the date, the time, and the nature of my problem. If there has been a 

power problem, I agree that I will call and leave another message when the power is restored. I also 

agree to notify PIRE research staff of any problems with my telephone service as soon as I am able to 

do so. 

I understand that as a participant in the study, I am to refrain 

from the following practices which are potentially harmful to the 

SCRAMTM equipment: 

Tampering – I understand that attempts to tamper with SCRAMTM 

devices or alter their readings will be considered a violation of this 

Agreement. 

Swimming & Bathing – I understand that I am not to submerge 

the SCRAMTM Bracelet in water. Showers are the only permitted 

bathing method. 

Personal Hygiene - I agree, that when bathing, I will thoroughly 

rinse with clean water and dry underneath the SCRAMTM Bracelet. 

I understand that failure to rinse away all soap may result in a 

mild skin rash. 

I agree to return all SCRAMTM-related equipment in my possession, including the SCRAMTM bracelet 

and SCRAMTM modem, to PIRE promptly upon completion of my role in the study. 

WARNING: The SCRAMTM Bracelet contains caustic liquid and a lithium battery. Should the plastic 

casing become cracked or otherwise visibly damaged or there is a burning sensation on my skin or 

other apparent health risk, I will remove the SCRAMTM Bracelet immediately by cutting the front 

bracelet strap where it says “Cut Here.” If this occurs, I will immediately notify PIRE staff of this 

problem. 

I acknowledge receipt of SCRAMTM Bracelet number _______ and SCRAMTM Modem number 

_______. 

62
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

WrisTASTM EQUIPMENT 

The WrisTASTM (wrist-worn transdermal alcohol sensor) has different care requirements than the 

SCRAMTM bracelet. Unlike SCRAMTM, the WrisTASTM should not get wet. 

I understand that I am to wear the WrisTASTM sensor for the duration of the study, except that I will 

remove it for the time it takes to take a shower. I will put it back on when I finish showering. I 

understand that the WrisTASTM device is sensitive to moisture and physical shocks. While I am 

wearing the WriTASTM I will completely refrain from activities that that would cause the device to be 

submerged (e.g., swimming and bathing) and avoid activities that would subject the device to 

dampness. I will avoid activities that subject the device to shocks (e.g., contact sports, heavy 

manufacturing and construction work). If for some reason I am forced to remove the device for a 

period of more than 30 minutes I will put it into an airtight zip-lock bag. I will not allow anyone else 

to wear the WrisTASTM. I understand that the WrisTASTM device is extremely expensive ($2,500) and 

will endeavor to protect it from damage and theft while it is in my possession. I will return the 

WrisTASTM device to PIRE when my participation in the study is over. 

I acknowledge receipt of WrisTASTM Bracelet number _______. 

INTOXILYZER BREATH TESTER 

I understand that I am to keep the Intoxilyzer 400 with me when I will be drinking and use it when I 

have two or more drinks to take breath measurements. I will start taking breath measurements 

approximately a half hour after I have my first drink and continue taking measurements at least once 

an hour until my BAC returns to .000, or until I go to bed for the night (whichever comes first). I will 

record BAC measurements and enter them into my drinking log. It is important to obtain accurate 

measurements that do not include the effects of alcohol in the mouth. In order to do this I will rinse 

my mouth with water and/or wait 15 minutes after drinking alcohol before taking a breath 

measurement. 

I will bring the Intoxilyzer with me when I come in for dosing studies so that the data can be 

downloaded from the Intoxilyzer. These data will be used as confirmation of the breath 

measurements in your log. To prevent creating confusing breath data files, I will refrain from using 

the breath testers to test anyone but myself. 

If I believe that the Intoxilyzer 400 is not functioning properly I will contact PIRE to discuss whether 

it is malfunctioning and how to address the problem. I understand that the Intoxilyzer 400 is quite 

expensive ($700) and will endeavor to protect it from damage and theft while it is in my possession. 

[NOTE: PIRE experience with use of breath testers in the field has shown that breath testers are often 

the targets of theft attempts.] I will return the Intoxilyzer 400 to PIRE when my participation in the 

study is over. 

I acknowledge receipt of Intoxilyzer 400 number _______. 

DRINKING LOG 

During my participation in the study I will keep a log of my eating and drinking activity and BAC 

readings for days when I drink alcohol. I will send a report to PIRE everyday by e-mail. If I am 

reporting on a drinking day the report will contain my drinking log for that day. If I am reporting on 

a non-drinking day the report will simply state that I did not drink that day. I will include the day 

and date to which the drinking log applies. I will send each drinking log as a separate e-mail 

message. 

63
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Entries for eating will contain: 

• The time at which the food was consumed 

• A brief description of the type of food consumed (e.g., “hamburger and fries,” or 

“bowl of cereal”) 

• Whether you consider it a “snack,” a “small meal,” a “medium meal” or “large 

meal” 

Entries for drinking alcoholic beverages will contain: 

• The time during which drinking took place (e.g., 4 p.m. – 7 p.m.) 

• The number of drinks consumed, where a “drink” is one 12 oz. beer, one 4 oz. glass 

of wine or a liquor drink containing one shot of liquor. Larger amounts of beer 

should be counted based on their size (e.g., 16 oz. pints of beer would be counted as 

1.3 drinks, 22 oz. “schooners” of beer would count as 2 beers). Liquor served as 

“doubles” would count as 2 drinks. 

Entries for breath tester readings would contain: 

• The time at which the reading was taken; and 

• The breath test reading. 

A sample drinking log is attached as an Appendix to this agreement form. 

You will need to keep a note pad to record your breath test readings – it is highly unlikely that you 

will be able to remember your readings until you fill out the daily log. As long as you are recording 

your breath test readings you will probably want to record eating and alcoholic drinks on the same 

note pad. As soon as possible, at the end of the day or the next morning, transfer your drinking log 

information to an e-mail and mail it to ____________@pire.org. 

NATURE OF DRINKING 

When study participants are at PIRE for the dosing portion of this study, PIRE will control the 

amount of alcohol being consumed by participants. As mentioned in the consent for signed by 

participants, subjects may discontinue drinking during the dosing study if they feel that drinking 

will make them sick or feel uncomfortable. 

When study participants are not participating in the dosing study, but are drinking as they normally 

would in the course of their normal lives, participants will drink only as much as they decide they 

want to drink. Participation in this study should not be considered encouragement by PIRE to drink 

any more than a participant would normally choose to drink. PIRE will not be held liable for adverse 

consequences resulting from a participant’s decision to drink. 

PIRE will provide a letter to participants that can be used to help explain the nature of the devices to 

officials needing information about them. An example would be security personnel in airports. This 

letter can not be construed by participants as permission to drink, or have alcohol in their system, 

under circumstances where drinking or having alcohol in their system is unlawful. For example, a 

study participant who is stopped under suspicion of driving under the influence can not use the 

letter to avoid possible legal consequences. 

Participants must understand that using the breath test equipment to check whether they are under 

the “legal limit” (i.e., the illegal-per-se level of .08 g/dL) for driving under the influence is not a 

64
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

guarantee that they can drive safely or be free from possible charges of driving under the influence. 

First, these devices are not guaranteed to be accurate for measuring blood alcohol levels for 

determining who is subject to prosecution for drinking driving. Secondly, drivers with BACs below 

the State’s “legal limit” can nevertheless be convicted of driving under the influence if it can be 

shown that the alcohol in their system has impaired their driving. Lastly, research shows that driving 

ability is negatively affected at blood alcohol levels below .04 g/dL BAC. 

I acknowledge that I have received a copy of this Agreement and that it has been explained to me 

before signing. 

______________________________ _______________ 

(PARTICIPANT) (DATE) 

______________________________ _______________ 

(PIRE AGENT) (DATE) 

65
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Sample Drinking Log

7:00AM - Bowl of cereal – small meal 

12:30 PM - 3 pieces of pizza – medium meal 

12:30 PM - one 12 oz beer with lunch 

4:00PM - 7:00PM – four 12 oz beers 

4:32 PM - BAC = .030 

5:29 PM - BAC = .061 

6:31 PM – BAC = .045 

7:30 PM – BAC = .032 

7:30 PM – Steak, salad, baked potato – large meal 

8:30 PM – BAC = .000 

11:00 PM – two shots of tequila 

11:30 PM – BAC = .036 

12:30 AM – BAC = .012 

12:45 AM - bed 

66
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Do’s and Don’ts Checklist

Do: 

• Take proper care to protect all equipment from damage and theft 

• Record a drinking log and email it to alcoholstudy@pire.org 

everyday 

• Record breath tests every hour when drinking 

• Rinse mouth and/or wait 15 minutes before taking a breath test 

• Take off the WrisTASTM before showering and keep WrisTASTM in 

ziplock bag when not wearing it 

• Be near the SCRAMTM modem at the designated download time 

Don’t: 

• Get WrisTASTM wet 

• Tamper with equipment 

• Drink more than you normally would 

• Make drinking-driving decisions based on breath test results 

• Use the breath tester to test other people 

• Put WrisTASTM on other people. 

• Eat heavy meals before dosing 

• Drive to dosing appointments 

In case of problems or questions call: 

Scott McKnight – 301-755-2735 

Paul Marques – 301-755-2723 

Eileen Taylor – 301-755-2719 

67
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix D – Wearability of the SCRAMTM and 

WrisTASTM Devices 

One of the evaluation tasks in this transdermal alcohol device study was an informal debriefing of 

subjects on the question of wearability. That is, with four continuous weeks of wearing the devices 

how did they interfere with daily activities? The questions posed addressed issues of comfort, 

limitations, as well as expected and unexpected difficulties in complying with the conditions of the 

research agreement. Wear issues were very different for the two devices and answers to these 

questions are summarized separately. Because the debriefing was informal with no particular 

structure, so too this summary will be mostly unstructured. 

SCRAMTM Ankle Bracelet 

As part of the orientation we informed subjects that according to the manufacturer most people find 

wearing the bracelet to be most difficult during the first 2 to 3 days. And whether through this 

suggestion or their own experience, this is very much what the subjects reported back to us at 

debriefing. The following is from a sequence of debriefing reports of some male subjects: 

• It seemed too tight for 2 days then seemed to loosen 

• Agreed with our comment that the first 3 days were the hardest but then he accepted 

it and found it to be relatively non-problematic 

• Commented that the first week was tough with SCRAMTM but then more acceptable 

• For 48 hours he found it terribly annoying and then almost overnight it seemed to 

become virtually unnoticeable 

• First three days were annoying while trying to sleep. 

• First four days were uncomfortable but after that it was no big deal. 

Overall it seems that more females reported wear problems than men. Many thought that the 

physical size of it was more suited to a male than female and there may have been some additional 

interaction between the device and changes in body water retention. The following is a selection of 

commentary from female subjects: 

• She found the first two weeks to be very uncomfortable particularly because she is 

physically very active and she discovered the tendon on the back of her ankle 

throbbed quite a lot when she exercised with the device on. 

• Biggest issues were showering and shaving legs and was unable to play soccer since 

when kicking the ball there was discomfort at device contact with leg. 

• Running was a pain but not a stopper. Found that depending on where she was on 

the puffy/not-puffy continuum the ankle bracelet would slide around somewhat 

and the more it slid around, the more uncomfortable it was. 

• Subject reported bruising on her ankle and device left a clear impression of the 

SCRAMTM faceplate that lasted for months after the study ended. 

68
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

WrisTASTM Wrist Device 

The WrisTASTM device is a prototype and not available for the criminal justice market so accordingly 

the version tested (version 5) is not designed with anti-circumvention features. Accordingly, subjects 

would have to remove the wrist device prior to showering and then reattach it after the shower. 

Since the removal and reattachment of the device is completely under control of the research subject, 

tightness was not a problem. However several subjects did report rash and itch related problems in 

long term wear of the WrisTASTM. The following is sampling of characteristic comments... 

• WristTAS led to chafing and found comfort in switching it from wrist to wrist on 

occasion. He also had the need to change pads regularly due to sweating. 

• WrisTASTM pad became sticky and stuck to his skin. 

• The wrist device took a long time to become accustomed to since he did not 

regularly wear wrist watches. 

• He reported that the wrist device got stinky after a while despite a swap out of wrist 

devices at one point. 

• WrisTASTM gave him skin rashes. He would move it from arm to arm and to 

different places on his arm. This resulted in a number of pink dots the size of the pad 

on his arms. 

• Comfort was no problem. 

• No skin problems. He left it on his left arm the whole time. 

The general experience of subjects seemed to depend somewhat on individual differences in skin 

sensitivity. We found that it was a good idea both hygienically and pragmatically to change the pads 

regularly so that they do not sweat out or distort in a way that blocks the vapor flow from skin to 

sensor. Probably it is best to charge them at least weekly or as needed. 

In summary, there are individual differences in the ability of subjects to tolerate either the SCRAMTM 

or WrisTASTM devices but no subjects found the problems to be great enough to warrant dropping 

out of the study. All subjects who began the study completed the study. Several commented that the 

bonus money for sticking with the study all the way through dispelled any idea of dropping out 

even though when they found the devices annoying. The largest complaints centered on the manner 

in which it interfered with participation in exercise, particularly swimming, but also to a minor extent 

soccer and running. Many subjects commented that they did not want to be seen as offenders and 

were a little embarrassed by the devices, often wearing long pants when they would have ordinarily 

worn shorts. 

69
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix E – SCRAMTM Focus Group 

and Users Feedback 

This appendix is a report on a Focus Group (FG) conducted with people who had worn the 

SCRAMTM device as ordered by courts in response to various alcohol offenses. The following caveats 

apply to this and other focus groups. FGs are intended to give insight into beliefs and experiences of 

participants, they constitute a small sample of the overall population of interest, and the results do 

not provide information that can be generalized to the larger population. Participants are encouraged 

to talk honestly and openly, but there is no guarantee that comments are not filtered to please the 

facilitator. A primary purpose of this FG was to learn about problems the offender participants had 

with the SCRAMTM system. Participants may have taken this opportunity to complain to someone 

who they believe will have the ear of someone in authority. Results of such a discussion will 

necessarily be somewhat negative. 

Focus Group 

A Focus Group (FG) meeting was held in Dallas, Texas, with seven people who had completed 

sentences to wear the SCRAMTM device. Following Federal human subjects protections guidelines, 

FG subjects were recruited by PIRE with contacts provided by the Dallas-area SCRAMTM provider. 

All subjects volunteered freely and were given a $100 money order each to participate. Subjects were 

both male and female. The ages ranged from 21 to 45. Most of the subjects were at the younger end of 

that age range. Most, but not all, were sentenced to SCRAMTM as a result of an alcohol-related 

driving offense. Subjects had worn their bracelets for periods ranging from 2.5 months to almost a 

year. The meeting was held in a hotel meeting room and lasted about 2 hours. 

Subjects spoke about problems that they had with the SCRAMTM system, benefits of SCRAMTM, and 

other issues. 

Problems 

Physical Discomfort 

Discomfort caused by the bracelet was a common complaint. All subjects reported problems sleeping 

with the bracelet on during the first few days of wear, and about half said that they had problems 

sleeping during the entire time they wore it. Subjects also complained of skin irritation and a few 

reported severe bruising. One offender complained of being cut by the bracelet so that he was 

bleeding, and that the bracelet prevented the cut from healing. The problem was eventually solved 

by having the bracelet switched to the other leg. In some cases the bracelet would loosen and bounce 

on the ankle bone. This was solved by wearing socks or a head band around the leg, though this was 

done at the risk of potential tamper alerts should the bracelet work its way down over the cloth. 

Another common complaint was related to being overheated due to wearing long pants in hot 

conditions, rather than wearing shorts that showed the bracelet. 

Embarrassment 

Most subjects preferred that others not know that they were wearing the bracelet. Situations in which 

the bracelet was visible or audible caused them embarrassment. Offenders reported being 

embarrassed when others heard sounds coming from the bracelet at work, in school, in church and 

70
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

during a wedding ceremony. Offenders reported a range of sounds from the bracelet that may have 

been interpreted by others as a mobile phone vibrating, someone moaning or passing gas. Offenders 

discussed embarrassment as part of what was called the “shame factor.” In general, offenders 

accepted the notion that “shame” was an intended part of the punishment and that this was not 

particularly unfair. Offenders accepted that, while they were not particularly happy at being 

sentenced to SCRAMTM, it was something that happened due to their bad behavior. 

Equipment-Related Problems 

Occasionally there would be equipment failures that affected offenders. This resulted in frequent 

phone calls to the offenders in an attempt to determine what was going on, and frequent orders to 

come into the provider’s office to have the bracelet checked. Offenders objected to being called into 

the office to address equipment issues as often as once every week or two at inconvenient times. In 

some cases, SCRAMTM provider staff members traveled to the offender to perform maintenance. The 

most commonly reported equipment problem was related to batteries that failed prematurely. 

However, most batteries last for a month or more. One subject reported having two bracelets fail 

completely, however this seemed to be due primarily to abuse while participating in sports (e.g., 

sliding feet-first into base while wearing the bracelet). One subject reported having long pants torn at 

the bottom by the bracelet. 

There were also complaints of modems malfunctioning. This was most often a function of the phone 

system, not the modem. Sometimes modems would pick up during the day (not at the scheduled 

communication time) and interrupt phone calls and Internet connections. Internet problems mostly 

involved dial-up connection but included offenders with DSL connections using micro-filters as 

required. One subject dealt with this problem by leaving the modem unplugged and forcing a 

download once a day by powering up the modem. The fact that the modem requires a land line 

caused inconvenience to some offenders who had only mobile phones. One made arrangements to 

download daily at a neighbor’s house. Others went to the provider’s office to download data. 

Costs 

Offenders reported having problems paying to use SCRAMTM. One had opted to use SCRAMTM 

rather than an interlock before understanding the difference in price. By the time he realized the cost 

of SCRAMTM it was too late to go back to the interlock option. One person used funds from a student 

loan to pay for SCRAMTM. Others felt fortunate that they could afford SCRAMTM with the help of 

their families. In addition to the problems caused by the total cost, there were problems related to 

inflexibility in payment – when payments were due the client needed to be able to pay or drop out of 

the program and go to jail. Offenders pointed out that, while they managed to pay for SCRAMTM, 

many people could not, therefore the benefits of SCRAMTM to society (e.g., getting non-violent 

offenders out of jail) might be increased if SCRAMTM could be made more affordable. 

Possible Misinterpretation of Data 

A few subjects said that they had problems when they were forced to defend themselves against 

people who weren’t able to correctly interpret SCRAMTM data. In one case an offender reported 

being called into the office by a provider staff member and accused of drinking based on a 

misinterpretation of an interferrant spike. A supervisor was eventually contacted who correctly read 

the chart, but the offender said that it was extremely distressing, in the meantime, feeling that he may 

be sent back to jail when innocent of drinking. FG participants reported that the provider was 

sending charts of SCRAMTM data to parole officers who were not trained to read them. Parole officers 

71
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

72

were said to have been questioning offenders in an accusing manner about TAC data that did not 

represent confirmed drinking events. For this reason the provider eventually stopped sending charts 

with reports. 

The SCRAMTM system provides alerts when data indicate that offenders may have attempted to 

tamper with the bracelet. Not all of these are actual tamper attempts. These are generally investigated 

by the provider and judged to be confirmed or unconfirmed tampers. Offenders reported that for a 

while all potential tampers, including unconfirmed tampers, were being reported to parole officers as 

“tampers.” This caused problems when offenders were forced to explain that they had not actually 

attempted to tamper with the device. 

Offenders were very bothered at the prospect of having their fate decided by people who might 

misinterpret the SCRAMTM data, and by the fact that they had no recourse if they were pronounced 

guilty of drinking or tampering. No participants were aware of anyone who had been taken off the 

program due to misinterpreted data. 

Security Checkpoints 

There was some question as to whether it would be difficult for SCRAMTM clients to get through 

security checkpoints wearing the metal bracelets on their leg. Most offenders did have experience 

with checkpoints, primarily when entering court buildings. Offenders reported little inconvenience 

from going through checkpoints, including those who went through security in airports. Aside from 

determining that the bracelet contained no explosives, security personnel had little interest in the 

bracelet aside from some curiosity as to what it was. 

Benefits 

Enforcement of Abstinence 

All focus group members had been through alcohol treatment, claimed to be abstinent and expressed 

a desire to remain so. Several had stories of how much they had been drinking and using drugs, and 

saw this as a problem that needed to end. Offenders also recognized that abstinence prevented 

impaired driving, which helped keep them safe and out of the legal system. Simply being sentenced 

to SCRAMTM was beneficial because it meant quitting, rather than managing drinking. Several 

expressed the feeling that SCRAMTM helped them to quit drinking by “keeping them honest” – any 

attempts to cheat would be detected. Another benefit was that complying with SCRAMTM required a 

definite end to drinking on a certain date rather than allowing them to put off quitting, or trying to 

cut down slowly, which may not have worked. 
EVALUATING TRANSDERMAL ALC

Appendix F – One Subject’s Four-Week Chart 

ZL29 Trial, pg 1

0.0000.0500.1000.1500.2000.2500.300

DATE

1/28/2005 15:15

1/28/2005 19:04

1/28/2005 22:39

1/29/2005 2:15

1/29/2005 5:59

1/29/2005 9:54

1/29/2005 13:49

1/29/2005 17:44

1/29/2005 21:54

1/30/2005 1:39

1/30/2005 5:24

1/30/2005 9:29

1/30/2005 13:29

1/30/2005 17:24

1/30/2005 21:34

1/31/2005 1:44

1/31/2005 5:49

1/31/2005 9:59

1/31/2005 14:09

1/31/2005 18:09

1/31/2005 22:14

2/1/2005 1:49

2/1/2005 5:44

2/1/2005 9:39

2/1/2005 13:49

2/1/2005 17:54

2/1/2005 22:04

2/2/2005 1:59

2/2/2005 5:59

2/2/2005 10:14

2/2/2005 14:29

SCRAM TAC Lab BAC Self BAC Wrist TAC

73
EVALUATING TRANSDERMAL ALC

ZL29 Trial, pg 2

0.0000.0500.1000.1500.2000.2500.300

DATE

2/3/2005 22:24

2/4/2005 2:44

2/4/2005 6:59

2/4/2005 11:25

2/4/2005 15:35

2/4/2005 19:34

2/4/2005 23:30

2/5/2005 3:35

2/5/2005 7:45

2/5/2005 11:55

2/5/2005 16:01

2/5/2005 20:20

2/6/2005 0:35

2/6/2005 4:30

2/6/2005 8:40

2/6/2005 12:50

2/6/2005 17:05

2/6/2005 21:25

2/7/2005 1:40

2/7/2005 6:00

2/7/2005 10:17

2/7/2005 14:35

2/7/2005 18:50

2/7/2005 23:05

2/8/2005 3:12

2/8/2005 7:15

2/8/2005 11:30

2/8/2005 15:55

2/8/2005 20:10

2/9/2005 0:30

SCRAM TAC Lab BAC Self BAC Wrist TAC

74
EVALUATING TRANSDERMAL ALC

ZL29 Trial, pg 3

0.0000.0500.1000.1500.2000.2500.300

DATE

2/10/2005 7:20

2/10/2005 11:30

2/10/2005 15:40

2/10/2005 19:50

2/10/2005 23:55

2/11/2005 3:50

2/11/2005 8:00

2/11/2005 12:05

2/11/2005 16:15

2/11/2005 20:20

2/12/2005 0:20

2/12/2005 4:10

2/12/2005 8:05

2/12/2005 11:57

2/12/2005 15:50

2/12/2005 19:55

2/12/2005 23:45

2/13/2005 3:45

2/13/2005 7:22

2/13/2005 11:15

2/13/2005 15:15

2/13/2005 19:10

2/13/2005 23:05

2/14/2005 2:55

2/14/2005 7:00

2/14/2005 11:10

2/14/2005 15:20

2/14/2005 19:20

2/14/2005 23:35

2/15/2005 3:45

2/15/2005 7:50

SCRAM TAC Lab BAC Self BAC Wrist TAC

75
EVALUATING TRANSDERMAL ALC

ZL29 Trial, pg 4

0.0000.0500.1000.1500.2000.2500.300

DATE

2/16/2005 16:05

2/16/2005 20:30

2/17/2005 0:50

2/17/2005 5:13

2/17/2005 9:35

2/17/2005 14:00

2/17/2005 18:15

2/17/2005 22:40

2/18/2005 3:00

2/18/2005 7:05

2/18/2005 11:20

2/18/2005 15:03

2/18/2005 19:05

2/18/2005 23:20

2/19/2005 3:30

2/19/2005 7:35

2/19/2005 11:50

2/19/2005 16:15

2/19/2005 20:35

2/20/2005 1:00

2/20/2005 5:15

2/20/2005 9:25

2/20/2005 13:35

2/20/2005 18:00

2/20/2005 22:20

2/21/2005 2:35

2/21/2005 6:55

2/21/2005 11:16

2/21/2005 15:35

2/21/2005 1955

SCRAM TAC Lab BAC Self BAC Wrist TAC

76
EVALUATING TRANSDERMAL ALC

ZL29 Trial, pg 5

0.0000.0500.1000.1500.2000.2500.300

DATE

2/23/2005 1:08

2/23/2005 5:20

2/23/2005 9:40

2/23/2005 13:55

2/23/2005 18:10

2/23/2005 22:35

2/24/2005 2:45

2/24/2005 6:55

2/24/2005 11:00

2/24/2005 15:05

2/24/2005 19:15

2/24/2005 23:20

2/25/2005 3:13

2/25/2005 7:10

2/25/2005 11:15

SCRAM TAC Lab BAC Self BAC Wrist TAC

77
EVALUATING TRANSDERMAL ALC

78
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix G – Coded Judgment Examples 

SCRAMTM Examples 

SCRAM Hit 

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

3/8/2005 10:063/8/2005 12:103/8/2005 14:153/8/2005 16:253/8/2005 18:303/8/2005 20:353/8/2005 22:40

3/9/2005 0:403/9/2005 2:403/9/2005 4:403/9/2005 6:343/9/2005 8:35

3/9/2005 10:353/9/2005 12:403/9/2005 14:473/9/2005 16:503/9/2005 19:053/9/2005 21:103/9/2005 23:153/10/2005 1:303/10/2005 3:353/10/2005 5:403/10/2005 7:453/10/2005 9:50

3/10/2005 12:003/10/2005 14:05

SCRAM TAC Self Dose BAC

SCRAM <.02

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

3/9/2005 10:183/9/2005 11:483/9/2005 13:163/9/2005 14:483/9/2005 16:183/9/2005 17:433/9/2005 19:133/9/2005 20:363/9/2005 22:033/9/2005 23:253/10/2005 0:483/10/2005 2:183/10/2005 3:483/10/2005 5:183/10/2005 6:433/10/2005 8:133/10/2005 9:43

3/10/2005 11:133/10/2005 12:383/10/2005 14:083/10/2005 15:383/10/2005 17:08

SCRAM TAC Self Dose BAC

79
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

SCRAM Low Confidence

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

3/28/2005 22:05

3/29/2005 0:303/29/2005 2:503/29/2005 5:013/29/2005 7:203/29/2005 9:45

3/29/2005 12:053/29/2005 14:253/29/2005 16:453/29/2005 19:053/29/2005 21:203/29/2005 23:30

3/30/2005 1:553/30/2005 4:153/30/2005 6:353/30/2005 8:55

3/30/2005 11:153/30/2005 13:303/30/2005 15:503/30/2005 18:103/30/2005 20:253/30/2005 22:45

3/31/2005 1:103/31/2005 3:303/31/2005 5:50

SCRAM TAC Self Dose BAC

SCRAM Too Noisy

0

.02

.04

.06

.08

.1

.12

.14

.16

.18

.2

2/4/2005 13:02

2/4/2005 14:22

2/4/2005 15:422/4/2005 16:582/4/2005 18:172/4/2005 19:37

2/4/2005 20:572/4/2005 22:172/4/2005 23:37

2/5/2005 0:57

2/5/2005 2:07

2/5/2005 3:17

2/5/2005 4:322/5/2005 5:522/5/2005 7:072/5/2005 8:282/5/2005 9:52

2/5/2005 11:122/5/2005 12:322/5/2005 13:522/5/2005 15:122/5/2005 16:272/5/2005 17:472/5/2005 19:07

2/5/2005 20:27

SCRAM TAC Self Dose BAC

SCRAM Too Noisy

0

.02

.04

.06

.08

.1

.12

.14

.16

.18

.2

2/4/2005 13:02

2/4/2005 14:22

2/4/2005 15:422/4/2005 16:582/4/2005 18:172/4/2005 19:37

2/4/2005 20:572/4/2005 22:172/4/2005 23:37

2/5/2005 0:57

2/5/2005 2:07

2/5/2005 3:17

2/5/2005 4:322/5/2005 5:522/5/2005 7:072/5/2005 8:282/5/2005 9:52

2/5/2005 11:122/5/2005 12:322/5/2005 13:522/5/2005 15:122/5/2005 16:272/5/2005 17:472/5/2005 19:07

2/5/2005 20:27

SCRAM TAC Self Dose BAC

80
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

SCRAM False Negative

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

0.050

3/31/2005 16:053/31/2005 17:103/31/2005 18:103/31/2005 19:103/31/2005 20:053/31/2005 21:003/31/2005 21:553/31/2005 22:553/31/2005 23:55

4/1/2005 0:554/1/2005 1:554/1/2005 2:554/1/2005 3:554/1/2005 5:004/1/2005 6:004/1/2005 7:004/1/2005 8:004/1/2005 9:00

4/1/2005 10:054/1/2005 11:10

SCRAM TAC Self Dose BAC

81
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

WrisTASTM Examples 

WrisTAS Hit

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.450

1/28/2005 17:001/28/2005 18:191/28/2005 19:391/28/2005 20:591/28/2005 22:241/28/2005 23:44

1/29/2005 1:041/29/2005 2:091/29/2005 3:191/29/2005 4:391/29/2005 5:541/29/2005 7:041/29/2005 8:241/29/2005 9:39

1/29/2005 10:491/29/2005 12:041/29/2005 13:181/29/2005 14:341/29/2005 15:491/29/2005 17:091/29/2005 18:241/29/2005 19:391/29/2005 20:591/29/2005 22:14

WrisTAS TAC Self Dose BAC

WrisTAS <.02

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

0.080

0.090

3/31/05 22:51

4/1/05 1:164/1/05 3:414/1/05 6:064/1/05 8:36

4/1/05 10:454/1/05 12:454/1/05 14:564/1/05 17:214/1/05 19:414/1/05 22:06

4/2/05 0:314/2/05 2:564/2/05 5:214/2/05 7:46

4/2/05 10:114/2/05 12:464/2/05 15:214/2/05 17:564/2/05 20:314/2/05 23:06

4/3/05 1:41

WrisTAS TAC Lab Dose BAC

82
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

WrisTAS Low Confidence

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

2/17/2005 12:232/17/2005 13:082/17/2005 13:532/17/2005 14:382/17/2005 15:212/17/2005 16:032/17/2005 16:532/17/2005 17:332/17/2005 18:182/17/2005 18:582/17/2005 19:482/17/2005 20:282/17/2005 21:052/17/2005 21:482/17/2005 22:332/17/2005 23:18

2/18/2005 0:032/18/2005 0:482/18/2005 1:332/18/2005 2:132/18/2005 3:002/18/2005 3:432/18/2005 4:33

WrisTAS TAC Self Dose BAC

WrisTAS Too Noisy

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

2/19/2005 12:332/19/2005 13:182/19/2005 13:582/19/2005 14:432/19/2005 15:282/19/2005 16:082/19/2005 16:482/19/2005 17:332/19/2005 18:082/19/2005 18:482/19/2005 19:342/19/2005 20:132/19/2005 20:532/19/2005 21:382/19/2005 22:182/19/2005 22:582/19/2005 23:38

2/20/2005 0:232/20/2005 1:032/20/2005 1:432/20/2005 2:24

WrisTAS TAC Self Dose BAC

83
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

WrisTAS False Negative

0.000

0.010

0.020

0.030

0.040

0.050

0.060

0.070

3/9/2005 6:333/9/2005 8:133/9/2005 9:53

3/9/2005 11:283/9/2005 13:083/9/2005 14:483/9/2005 16:233/9/2005 18:033/9/2005 19:333/9/2005 21:133/9/2005 22:433/10/2005 0:183/10/2005 1:533/10/2005 3:333/10/2005 5:133/10/2005 6:483/10/2005 8:28

3/10/2005 10:083/10/2005 11:433/10/2005 13:183/10/2005 14:583/10/2005 16:383/10/2005 18:183/10/2005 19:53

WrisTAS TAC Self Dose TAC

84
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Appendix H – SCRAMTM Vendor Feedback 

Several SCRAMTM Providers were interviewed regarding their experiences with the 

SCRAMTM system and offenders sentenced to SCRAMTM. Interviewees included private 

providers, officials from parole offices and judges. 

None of the people interviewed had exact numbers on the percentage of offenders who had 

violated the terms of SCRAMTM by drinking. Estimates from both vendors and AMS were 

somewhere around 20 percent. This includes people who would be identified as drinking 

small amounts of alcohol and/or people who violated early but stopped later. Reasons for 

improvement may have been: (1) realizing that the device would in fact detect their drinking, 

and (2) getting their drinking more under control over time. Offenders who drink tend to 

start out denying that they did so, until confronted with the data and an explanation of how 

the devices works, at which point they will admit to drinking. Most of the time when 

offenders attempt to get away with drinking, they will try to drink small amounts and 

obstruct the device. Providers say they can identify these situations relatively easily. They 

will call the offender as soon as possible and tell them they can see the drinking and/or the 

obstruction and tell them to stop drinking. Once offenders understand that they will get 

caught they improve. There are some offenders who simply decide that they are going to 

drink as much as ever. They tend to cut the device off. Often these offenders will also leave 

home and hide to avoid being arrested for violating parole. Sometimes these offenders are 

identified not by receiving data indicating the bracelet has been removed, but because the 

modem is disconnected and never calls in. 

Providers discussed ways in which offenders have tried to circumvent the system. Most 

involve obstructing the bracelet input. Common substances used include plastic wrap and 

socks. Also mentioned were cardboard, Vaseline, aluminum foil, and large band-aids. 

Multiple providers mentioned offenders who thought they could avoid detection by using 

antiperspirant to prevent alcohol from exiting the body with sweat. Some of the more 

amusing obstruction stories involved slices of bologna and a plastic bag full of raw meat. A 

few offenders had managed to remove the bracelet for a while, though it was obvious from 

the data that it had been off if it was not shifted to someone else. There was a report of one 

offender who came into the office with the device obviously damaged from removal, and 

reinstalled upside down and on the wrong leg. There was a report of someone managing to 

get the bracelet off and putting it on someone else. In this case, a change in infrared distance 

suggested tampering and the offender eventually admitted what had happened. Providers 

allowed that offenders might get away with drinking if they drank only a little, spaced 

drinking out over time, and/or drank after eating. Providers suggested, though, that this 

wasn’t the kind of behavior they were most concerned about, that the offenders with the 

most problems would not be able to limit drinking in such a way, and that drinking 

offenders would be identified eventually, if not immediately. 

Providers felt that they were able to understand the graphs provided on the SCRAMNet site. 

They stressed that it was important to know the offenders and their lifestyles so that they 

could interpret the data properly. In particular, offenders’ work situations had much to do 

with the likelihood of seeing interferent spikes and distance anomalies at certain times of the 

day. 

85
EVALUATING TRANSDERMAL ALCOHOL MEASURING DEVICES 

Providers did not believe that false positives were a problem. Most potential false positives 

are in the form of interferent spikes. These are generally easy to distinguish from actual 

drinking. They are usually caused by exposure to substances that offenders have been 

warned to avoid. When offenders experienced these spikes they were further warned to 

avoid the substances. Those offenders who experienced negative consequences as a result of 

spikes seemed to do better at avoiding them afterward. Where spikes were not predictable 

(e.g., offender experienced a new substance and was not aware that it contained an 

interferent) or where interferents were unavoidable (e.g., occasional exposure at work), 

providers could interpret them appropriately by talking to the offenders and knowing the 

offenders’ personal stories. 

Providers were positive about their experiences working with AMS support staff, whom they 

found to be knowledgeable and helpful. There have been problems with some of the 

equipment which required them to bring offenders in for maintenance and equipment 

swapping. This was more the case in the early days of SCRAMTM than recently. One 

frequently mentioned problem was a bad bunch of batteries that had been sent out into the 

field. This problem was identified and addressed relatively swiftly. 

Providers sometimes had problems working with offenders. A primary problem involved 

trying to get paid by offenders on a timely basis. Providers were displeased with the large 

and generally unpredicted amount of time they spent being “bill collectors.” Other problems 

included getting data from offenders when they were supposed to. Some referred to a 

phenomenon which one referred to as the “80/20 rule” in which 20 percent of offenders 

accounted for 80 percent of their problems. It was suggested that the problem offenders 

tended to behave as they did out of a number of inter-correlated factors which included 

alcoholism, unstable work and home lives, lack of education, difficulties understanding what 

is being required of them and lack of honesty. It was reported that most problem clients 

either dropped out of the program or improved as they became more familiar with 

SCRAMTM and as they “got their act together” following cessation of drinking. 

Providers reported that SCRAMTM was a beneficial experience for many of the offenders. As 

with the offenders who participated in the focus groups, SCRAMTM helped to quit drinking 

by providing a specific date after which they were not allowed to drink, and a system for 

“keeping them honest.” Some offenders reportedly credited SCRAMTM with saving their life 

by facilitating drinking cessation. 

86

DOT HS 810 875

November 2007