Isopropanol & Fuel Cell Breath Alcohol Testers

Examining issues with specificity & false positives

Counterpoint Volume 6: Issue 4 - Article 6 (December 2022)

An article for participants in the myCAMprogram

Jan Semenoff, BA, EMA
​Forensic Criminalist

Article information:

1700 words (approximately 8-10 minutes)
What is the reliability of breath alcohol readings obtained when they are conducted in a substandard environment contaminated by the fumes such as those found in the back of the ambulance?
​I have a case where the test subject, injured from a single vehicle off-road accident on a patch of icy road, was breath tested using the Intoximeter Alco-Sensor FST device with a reported FAIL reading, and after only a three-minute wait period, was tested on another FST device with a second FAIL reading. He was tested in the back of an ambulance while strapped to a spine board and while an intravenous line was being put in place.
​Remember, the Intoximeter Alco-Sensor FST is a hand-held fuel cell device that incorporates an electrochemical (fuel cell) sensor.
Our only indication of troubles with the breath tests is found in the paramedic’s report:
​"Police asked patient for a breathalyzer. Breathalyzer seemed to have issues, and police officer said it was picking up the alcohol swabs from the ambulance interior. Patient asked to blow twice. Both times the machine seemed to pick up the alcohol swabs. Police officer states patient failed the breath tests."
None of this was noted in the officers’ report. If the lawyer handling the case had not subpoenaed the paramedic’s notes, none of this would have been discovered. 
  • We do not know what indication lead the officer to remark that the alcohol swabs were causing problems with the Alco-Sensor FST. 
  • We do not know what, if any, error messages were displayed by the device. 
  • We do not know what corrective actions, if any, were taken prior to receiving the samples analyzed.
As a former Primary Care Paramedic, I can attest that the patient compartments of ambulances are kept as clean as possible:
  • Strong medical-grade antiseptic solutions are used routinely to clean and disinfectant all surfaces after every call, where possible. 
  • As a matter of routine, paramedics use isopropanol alcohol swabs to clean and disinfect an injection site before starting an intravenous or obtaining a blood glucose level (both were performed in this case).
  • Additionally, and increasing with the advent of COVID-19, hand sanitizers utilizing a 60-70% concentration of isopropanol are also frequently used. All of these contribute to an environment that is not conducive to accurate and reliable breath alcohol testing results.

Fuel cell devices and interferent chemicals

The fuel cell component of preliminary breath alcohol testing devices are not immune to the effects of the interferent chemicals on the readings obtained. They are designed to identify the presence and concentration of ethanol. To a certain extent, all alcohols, including isopropanol, appear as ethanol to fuel cell instruments, not just the Intoximeter Alco-Sensor FST used in this case, and can routinely report a falsely elevated BrAC reading. Isopropanol is an alcohol. Isopropanol does have an impact on fuel cell devices, producing a discernable reading.
Isopropanol, by the way, is commonly called "rubbing alcohol" and is found in hand sanitizer, aftershave, perfume and colognes, some deodorants, hair care products, etc. 
​The blood to air partition ratio for isopropanol has an accepted value of about 1370:1. The partition ratio for ethanol has been legislatively accepted at 2100:1. Therefore, any trace levels of isopropanol found in the breath sample would have an exaggerated effect on the readings obtained on a device calibrated at 2100:1. 
​It has been identified by various researchers that certain hydrocarbon compounds, including methanol, isopropanol, and acetone, cause inflated breath alcohol readings on various breath testing devices that are often not detected by the testing devices themselves (Laakso et al, 2004; Hak, 1995; Jones et al, 1996; Caldwell & Kim, 1997; Bell et al, 1992; Logan et al, 1994 and Memari, 1999). 
​I am left to reasonably conclude, as have other researchers, that a combination of substances in the fuels cell may falsely over-report the true BrAC level, even if that true value is zero. The Laakso study was specifically on the effects of interferent compounds on a fuel cell breath testing device (the Draeger 7110). They found that the presence of other alcohols, including isopropanol, had a significant false positive effect on the reported readings that was not identified by the evidentiary breath test device.
​It should be noted that none of the fuel cell devices currently available have the capability of incorporating an interferent detector algorithm or component to screen for interferent chemicals in their reported analysis for BrAC levels. It is simply beyond the capability of fuel cell technology.

The Effect of Isopropanol on fuel cell devices

​I conducted a series of breath tests with an Intoximeter Alco-Sensor FST using a test chamber contaminated with isopropanol fumes from a freshly opened alcohol swab. I placed a single alcohol swab into a sealed test chamber with an inlet and outlet tube, then provided a breath sample through the chamber directly into the device. I obtained the following readings on the Intoximeter Alco-Sensor FST:
Picture
Table 1 - Readings from an Intoximeter Alco-Sensor FST obtained from an environment contaminated by isopropanol.
At no time did the unit indicate an ambient failure of the device, nor did it indicate that the reading was obtained from isopropanol, and not ethanol (beverage alcohol). Note that the readings fluctuated and did not dissipate or lower over time.

The Effects of Alcohol-Based Hand Sanitizers on the Readings Obtained

We’ve examined this topic before. See the Counterpoint article Alcohol Based Hand Sanitizers & Breath Alcohol Testing (Counterpoint Volume 5; Issue 4 – Article 3 (September 2021).
Just like the alcohol swab pads, Alcohol Based Hand Sanitizers (ABHS) use isopropanol at a concentration of 60-70% as a disinfectant. It has long been believed that ABHS do NOT create the potential for false positive breath alcohol readings. The assertion is based on the low amount of dermal (skin) absorption of ethanol, given the brief amount of sanitizer, and time, that it is on the subject’s hands.
​Three separate studies over the last decade cast doubt on those assertions. If the breath sample is provided after hand disinfection using an ABHS, the potential for false positive breath results exists.
​In 2016, Yale University School of Medicine researchers aimed to investigate the effects of alcohol-based hand sanitizers (ABHS) on a fuel cell breath alcohol analyzer. 
​Under ALL experimental conditions, alcohol was detected in breath at 1 minute after use of ABHS. In fact, the breath alcohol readings were incredibly high when the foam or gel was applied with immediate breath alcohol testing. The initial readings one-minute following application averaged .155 g/dL – basically twice the legal limit, with readings as high as .620 g/dL – well beyond the accepted lethal dose of ethanol (LD50). 
​Then, the normal evaporation curve reduced the reported readings dramatically. After five minutes, the readings were negligible (about 0.01 grams). After ten minutes, basically zero, although two test subjects still showed positive breath alcohol readings at 11 and 16 minutes. 
​The researchers concluded that the use of ABHS by individuals administering breath alcohol tests may result in false-positive detection of alcohol. 
​In 2017, Missouri breath test program forensic criminalists published their findings in the Journal of Forensic Sciences.
​Overall, about 10% of the test subjects provided an initial false positive reading as high as 0.04 g/dL. About 30% of the test yielded an error or status message of some sort requiring a re-test. Their general conclusion was that the use of ABHS before breath testing could potentially lead to false-positive results. They recommend that ABHS are NOT kept in the breath test room, and that a minimum of 15 minutes pass between application and breath testing. Additionally, they raise a concern for jurisdictions who only do one breath test.
​In 2009, an article appeared in the Journal of Addiction Medicine that identified that the use of ABHS gel caused false positive readings in both Ethylglucuronide (EtG) and breath test results. You may remember that EtG is a biomarker for ethanol found in blood and urine samples.
See the Counterpoint article The Effect of Hand Sanitizers on Urinalysis (Counterpoint Volume 4; Issue 4 – Article 3 (August 2020; updated September 2021).
​In summary, 13 of 18 of the test subjects produced false-positive readings. Although the breath alcohol readings produced were minimal (0.010 – 0.020 g/dL) in the false-positive cases the readings persisted for as long as 60 minutes following exposure. 
The unit used in this study was not properly identified and was simply listed as “an Intoximeter Breathalyzer with lower level of detection at 0.001 g%”.
An Impossible Lower Level of Detection
That lower level of detection (LOD) – 0.001 g/dL – is virtually impossible to achieve in any breath testing unit. Typically, the lower level of detection is capped at 0.007 grams by most manufacturers. Anything below 0.007 grams is just considered zero.
See the section on Floating Zero Air Blanks in the Counterpoint article Best Practice in Breath Alcohol Testing: Part 1 (Counterpoint Volume 2; Issue 1 – Article 6 (December 2017).
​The researchers concluded:
​“This study demonstrated that the breathing of (ABHS) vapor caused positive EtG tests and elevation of breathalyzer levels for up to 60 minutes.” (Emphasis added)
​Proper breath testing protocols dictate that all possible sources of contaminate should be eliminated prior to beginning the observation and deprivation period to receive breath samples that are truly suitable for analysis. The false positive effect of the ABHS may be minor, but it can occur. The percentage of false positives ranged from 10-100%, depending upon the study parameter. 
​Practice Tip:
Again, the importance of getting the paramedic's notes cannot be over-stated. In addition to being a third party witness, the paramedic will have performed a thorough CNS (Central Nervous System) assessment as part of their patient care. They may be able to identify signs and symptoms of head injury or trauma that the police officer otherwise ascribes to indicators of alcohol impairment or intoxication.

Final thoughts:

So, what conclusions can we reasonably draw?
Well, isopropanol can cause false-positive readings on a fuel cell based breath alcohol testing device.
  • The reading may be considerable, with false-positive median results of .150 grams, and transitive outliers as high as .600 g/dL or more than one study.
  • Another study reported ranges from 0.01– 0.06 g/dL.
  • Simple fuel cell devices are more prone to false positives, as they have no means to identify contaminated ambient air issues, and invalid samples due to false positive alcohol bias.
​So, breath sample results obtained in cases where atmospheric contamination occurs by isopropanol, whether from alcohol swabs, hand sanitizers, or cleaning agents, may not be reliable. The readings I obtained from a contaminated environment with an Intoximeter Alco-Sensor FST and the studies on alcohol based hand sanitizers support the conclusion that a contaminated testing environment can lead to false-positive results.

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For further study:

  1. Caldwell, J, and Kim, N., The Response of the Intoxilyzer 5000® to Five Potential Interfering Substances, J. Forensic Science 1997;42(6) pages 1080-1087.
  2. Dubowski, K.M., The Technology of Breath-Alcohol Analysis, U.S. Department of Health and Human Services, Prepared for The National Institute on Alcohol Abuse and Alcoholism, 1991.
  3. Emerson, B. L., Whitfill, T., Baum, C. R., Garlin-Kane, K., Santucci, K., Effects of Alcohol-Based Hand Hygiene Solutions on Breath Alcohol Detection in the Emergency Department. Am. J. Infect. Control. 2016 Dec 1;44(12):1672-1674. doi: 10.1016/j.ajic.2016.05.036. Epub 2016 Sep 7. PMID: 27614708.
  4. Gullberg, R. G., Breath Alcohol Measurement Variability Associated with Different Instrumentation and Protocols, Forensic Science International 131 (2003) 30-35.
  5. Hak, E.A., The Effects of Volatile Substances on the Intoxilyzer 5000C Breath Testing Instrument, Royal Canadian Mounted Police Forensic Laboratory, Peer-Reviewed Paper for the Traffic Safety 1995 Conference, 1995.
  6. Jones, A. W., Concerning Accuracy and Precision of Breath-Alcohol Measurements, Clinical Chemistry, 33/10, 1701-1706 (1987).
  7. Jones, A.W., Interfering Substances Identified in the Breath of Drinking Drivers with Intoxilyzer 5000S, Journal of Analytical Toxicology, Vol. 20, November/December 1996, Pages 522-527.
  8. Jones, A.W., Observation on the Specificity of Breath Alcohol Analyzers Used for Clinical and Medicolegal Purposes, Journal of Forensic Sciences, JFSCA, Vol. 34, No. 4, July 1989, Pages 842-847.
  9. Laasko, O., Pennanem, T., et al, Effect of Eight Solvents on Ethanol Analysis by Draeger 7110 Evidential Breath Analyzer, Journal of Forensic Science, Sept 2004, Vol 49, No. 5.
  10. Logan, B, Gullberg, R. and Elenbaas, J., Isopropanol Interference with Breath Alcohol Analysis: A Case Report, J. Forensic Science 1994 Jul:39(4), pages 1107-1111. 
  11. Memari, B., Variables Affecting the Precision and Accuracy of the Intoxilyzer 5000, Florida International University, Thesis for Master of Science in Chemistry, academically reviewed and approved, 1999.
  12. Norfold, G. & Quartly, C., Volatile Substances and their Potential to Interfere with Breath Alcohol Reading Instruments, Journal of Clinical Forensic Medicine (1997) 4, Pages 21-23.
  13. Semenoff, Jan, Alcohol Based Hand Sanitizers & Breath Alcohol Testing: Exploring the Potential for False Positive Readings, Counterpoint, Volume 5; Issue 4 – Article 3, September 2021.
  14. Simpson, G., Accuracy and Precision of Breath Alcohol Measurements for Subjects in the Absorptive State, Clinical Chemistry, 33/6, 753-756 (1987).
  15. Skipper, G. E., Wurst, F., Weinmann, W., and Liepman, M., Ethanol-Based Hand Sanitizing Gel Vapor Causes Positive Alcohol Marker, Ethylglucuronide, and Positive Breathalyzer, J. Addict. Med, Volume 3, Number 2, June 2009.
  16. Strawsine, E. and Lutmer, B., The Effect of Alcohol-Based Hand Sanitizer Vapors on Evidential Breath Alcohol Test Results, J. Forensic Sci., 2017 doi: 10.1111/1556-4029.13691.