Case Study: Unreliable Results from SCRAM Transdermal Alcohol Device
Sweat, dirt, household chemicals and improper contact with the skin can cause erratic readings on transdermal alcohol devices like SCRAM.
I recently reviewed data from a SCRAM transdermal alcohol device where the subject was accused of violating parole by drinking alcohol. I found the readings from the device were almost certainly erroneous.
The device recorded the subject going from near zero alcohol to >0.400 within a few minutes and then rapidly dropping back down to <0.100.
Alcohol at concentrations >0.400 would typically cause a person to require medical attention.
In addition, a person wouldn’t be able to burn off enough alcohol to go from an alcohol reading of >0.400 to less than 0.100 within 30 minutes.
SCRAM TAC Devices
SCRAM (Secure Continuous Remote Alcohol Monitor) devices use a fuel cell to monitor alcohol concentrations from the skin at 30-minute intervals and are typically worn as a condition of parole violations
But the devices don’t always work as intended.
Typically, TAC shows a delayed absorption and elimination profile compared to breath or blood alcohol, as seen in the graph below (Wojcik, 2020; Zettl, 2002).
In the case I reviewed, the subject was accused of drinking alcohol and tampering with the device.
However, the readings showed nothing like the gradual increase and decrease in alcohol concentration in the above graph.
The transdermal alcohol (TAC) went from near zero to > 0.400 within a few minutes, stayed there for around 90 minutes, then went down to around 0.100 within a 30-minute time period.
The above readings were almost certainly erroneous. At the >0.400 level of alcohol concentration, the subject would have been in a coma or dead.
The most widely used chart for clinical indicators of alcohol impairment is the Dubowski Chart. Dubowski correlates alcohol concentrations above 0.350 with being in a coma and levels of 0.45+ with death (Dubowski, 2012).
It is physiologically impossible to go from a TAC of >0.400 to 0.100 within 30 minutes. Even the fastest-recorded burn-off rates could not account for this anomaly (Jones, 2007, 2010).
Tampering
Fluctuations in temperature and IR voltage were alleged to cause tampering. However, potential tamper indications can also occur when the device is improperly positioned on the skin (Zettl, 2004).
The subject's ankles were swollen from the long flight. As the swelling went down, the device may not have fit as snugly as necessary to obtain accurate temperature and IR voltage readings.
If the SCRAM device is moved on the skin and does not maintain proper contact with the skin, it may give erroneous tamper indications. Another possibility of a potential tamper alert is from a build-up of sweat and dirt on the sensors (Markel, H. 2008).
Conclusion
The alcohol readings obtained from the SCRAM device in this case were almost certainly erroneous. Many of the readings were so high that the subject would have died or required medical attention.
In addition, the rate of absorption and elimination from many of the readings is beyond normal physiological capacity.
The anomalous readings indicate that the device cannot be trusted to give accurate results, casting a shadow over its reliability, including the so-called “tamper alerts.”
The case ended with the state making a satisfactory offer to the subject.
If you’re facing a parol violation due to inaccurate SCRAM readings, please contact me so I can review the readings.
References
Dubowski, K. The Dubowski alcohol table. IACT Newsletter 7–8 (2012)
Fairbairn, C. E. & Kang, D. Temporal Dynamics of Transdermal Alcohol Concentration Measured via New-Generation Wrist-Worn Biosensor. Alcohol. Clin. Exp. Res. 43, 2060–2069 (2019)
Jones, A. W. Ultra-rapid rate of ethanol elimination from blood in drunken drivers with extremely high blood-alcohol concentrations. Int. J. Legal Med. 122, 129–134 (2008)
Jones, A. W. Evidence-based survey of the elimination rates of ethanol from blood with applications in forensic casework. Forensic Sci. Int. 200, 1–20 (2010)
Markel, H. M.D. Forcing Sobriety, However Imperfectly. New York Times https://www.nytimes.com/2008/05/06/health/views/06essa.html
Marques, P. R. & McKnight, A. S. Field and laboratory alcohol detection with 2 types of transdermal devices. Alcohol. Clin. Exp. Res. 33, 703–711 (2009)
van Egmond, K., J C Wright, C., Livingston, M. & Kuntsche, E. Wearable Transdermal Alcohol Monitors: A Systematic Review of Detection Validity, Relationship Between Transdermal and Breath Alcohol Concentration and Influencing Factors. Alcohol. Clin. Exp. Res. (2020) doi:10.1111/acer.14432
Zettl, R. Tamper Detection Utilizing the SCRAM Transdermal Alcohol Monitoring Device. (2004)
Zettl, R. The determination of blood alcohol concentration by transdermal measurement. (2002)
Wojcik, M. Continuous Transdermal Alcohol Monitoring. The Journal of Offender Monitoring (2020)
Yu, J., Fairbairn, C. E., Gurrieri, L. & Caumiant, E. P. Validating Transdermal Alcohol Biosensors: A Meta-Analysis of Associations between Blood/Breath-Based Measures and Transdermal Alcohol Sensor Output. Addiction (2022) doi:10.1111/add.15953