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Breath Alcohol Tests

Breath Alcohol Concentration (BrAC) and Breath Alcohol Test

About 5% of the consumed alcohol is excreted from the body through breathing [8]. From the breath alcohol concentration (BrAC) the blood alcohol concentration (BAC) can be calculated:

  • In the legal procedures in the U.S., Canada and Australia, estimated BAC [in milligrams alcohol per 100 milliliter blood] = 2,100 x BrAC [in milligrams alcohol per liter of air] [1].
  • In the legal procedures in the UK, estimated BAC is 2,300 x BrAC and in various European countries it ranges from 2,000 to 2,400 x BrAC.

BAC : BrAC ratios measured in various studies ranged from 832 to 7,289 [1].

Why is a breath alcohol test done?

They are usually traffic police officers who perform breath alcohol test to find out if a driver is under influence of alcohol (DUI – driving under influence, DWI – driving while intoxicated).

How to perform a breath alcohol test?

Breath alcohol test is done by exhaling into what was once called breathalyzer – a portable or stationary device that measures the amount of alcohol in the exhaled air. In a legal procedure you usually have to wait 15-20 minutes after stopping drinking or putting anything other into the mouth and 1 minute after stopping smoking and keep exhaling into the device until instructed [2].

How accurate is a breath alcohol test?

According to certain studies, breath alcohol test may not be very accurate estimation of the blood alcohol concentration, because [1]:

  • The blood-breath alcohol partition ratio may differ by more than ±30% among individuals, but, according to another study, by only 4%.
  • The alcohol’s effect on airway surface may affect breathing pattern and cause an error of as much as ±50%.

There are several other factors that can affect the results of breath alcohol test:

What can give a FALSE POSITIVE result of a breath alcohol test?

  • Within 15-20 minutes after the last drink, the alcohol evaporating from the mouth mucosa or alcohol trapped in dentures or tongue piercings may cause a false positive result [3].
  • An alcohol-based mouthwash, when used within 15 minutes prior the test, could positively affect the test [4,5].
  • Isopropyl alcohol produced in the body from acetone in individuals with ketoacidosis, mainly in poorly controlled diabetes 1, but possibly also in prolonged fasting or during a low-carbohydrate diet, may cause false positive result (especially in combination with ethanol consumption) when using certain breath alcohol devices [25].
  • Methanol in the exhaled air after drinking windshield washer fluid (antifreeze) can be falsely detected as ethanol by breath alcohol devices Alco Senzor IV and Intoxilyzer 5000EN [6].
  • Holding breath for 30 seconds before the test may increase the breath alcohol concentration for 16% [7] and could therefore, for example, result in incorrect calculation of the blood alcohol concentration 0.08 instead of 0.07 g alcohol/100 mL blood.
  • According to one study, in a mildly dehydrated person (with 3-4% loss of body weight), after drinking a certain amount of alcohol, the measured BrAC and the calculated BAC may be 75% higher than in the same person when well hydrated, for example 0.07 g alcohol per 100 mL of blood when dehydrated and 0.04 when well hydrated [29]. Such increase in BrAC in a dehydrated person incorrectly reflects the actual BAC, measured with a blood alcohol test, which increases for only about 35% [29].
  • The rise of body temperature by 1 °C may increase measured BrAC for 6.5%. For example, BAC calculated from BrAC in a person having 40 °C (3 °C above normal) could be therefore overestimated by 19.5%.
  • Variation of the normal blood hematocrit (red blood cells/blood ratio) may cause an error of ±14% or, according to another study, of only ±2.6%. Greater the hematocrit, the more false positive the result of breath alcohol test tend to be.
  • Variation in the environmental air temperature and humidity may  cause an error of ±1o%.
  • According to various sources, but with lack of evidence, inhaling compounds found in lacquers, paint removers, nail polish, celluloid or “new car smell” might cause a false positive breath alcohol test.

What may DECREASE the results of the breath alcohol test?

  • Deep breathing for 20 seconds before a breath alcohol test may reduce the breath alcohol concentration (BrAC) by up to 11% [7] and could therefore, for example, result in incorrect calculation of  the blood alcohol concentration 0.07 instead of 0.08 g alcohol/100 mL blood.
  • Teabags filled with charcoal and held in mouth could absorb some alcohol in the exhaled air and thus cause false negative result of a breath alcohol test. This method would probably not work during a legal procedure, though.

What does NOT LIKELY AFFECT the breath alcohol test?

  • copper penny under the tongue does not affect the breath alcohol test [20].
  • Mints, alcohol-free mouthwash, garlic and onion may disguise the smell of alcohol, but they do not affect the breath alcohol test.
  • Small amounts of ethanol occasionally found in soft drinks, energy drinks and bread, do not likely produce a positive breath test result [9,10].
  • Burping and regurgitating alcohol from the stomach (in gastroesophageal reflux or GERD) into the mouth does not likely affect the breath alcohol test [11].
  • Asthma inhalers (triamcinolone, salbutamol, albuterol, epinephrine, beclomethasone, budesonide), nasal decongestants (oxymetazoline, desoxyephedrine), volatile anesthetics and nitrous oxide (N2O), dimethyl sulfoxide or DMSO (a medicine for interstitial cystitis) do not affect breath alcohol test, if the test is performed after the 5-minutes waiting period [12,13].
  • Acetone in breath of individuals who are fasting or are on a low-carbohydrate (Atkins) diet and those who have hypoglycemia or untreated diabetes 1 with ketoacidosis does not likely affect breath alcohol devices currently in use in the U.S. [14,15].
  • Acetaldehyde in breath of individuals with ALDH2 deficiency who experience Asian flush reaction does not affect breath alcohol test [16].
  • Benzene, cough syrup in a regular dose, diethylether, gasoline, glue fumes, isoprene, methane, methanol, methyl-ethyl ketone (MEK), methyltert-butyl ether or MTBE (a gasoline additive), mineral spirits, paint fumes, tetrachloroethylene, toluene, trichloroethane, trichloroethylene, xylene, substances in contact cement or paint thinners do not likely significantly affect the breath alcohol device Alco-Sensor IV (electrochemical or fuel cell) or Intoxilyzer 8000C (infrared) [14,15,17,18,19,20,21].

Types of Breath Alcohol Devices

  1. Breathalyzers (semiconductor)
  2. Alcosensors (fuel cell, electrochemical or EC): Alco Sensor IV, Alcotest 7410, Alcometer Pocket Model (false+: acetaldehyde, methanol, isopropanol and n-propanol, formaldehyde and ether [21]. NOT false+: acetone.
  3. Intoxilyzers (IR): Alcotest 8510, DataMaster, Ethylometer, Intoxilyzer 8000C (false+: methyl (CH3) groups, such as methane, ethane, propane, butane). NOT false+: acetone, acetaldehyde [21].
  4. Intoximeters (gas chromatography)
  5. Combination IR+EC: Alcotest 7110, Intoxilyzer 6000, Intoximeter EC-IR)

Alcohol and Ignition Interlock Device

What is ignition interlock device and how it works?

An ignition interlock device (IID) is an alcohol-detecting device installed in the motor vehicles of individuals on probation after driving under influence (DUI) or from other reasons. A driver exhales into the tube connected to the IID and if this detects the amount of alcohol in his or her breath that, after analyzing, exceeds a pre-programmed blood alcohol concentration, which is 0.02 g alcohol/100 mL blood in the U.S, the device will block the engine’s ignition [22,23].

  • 0.02 g alcohol/100 mL blood may result from one single alcoholic drink or, in persons with low body weight, after half of the drink (6 oz 5% beer, 2.5 oz 12% wine, 0.75 oz 40% spirit) [24]. A 160 lbs (73 kg) person would need to drink about 7 12 oz cans of non-alcoholic beer (containing up to 0.5% alcohol) to reach BAC 0.02 [24].
  • About 1 drink per hour is eliminated from the body, so a person who has had 3 drinks can expect to have blood alcohol concentration below 0.02 in about 3 hours after the last drink.

What else could affect ignition interlock device?

Modern IIDs use an alcohol-specific, but not ethanol-specific fuel cell as a sensor, which means they cannot distinguish between ethanol and other alcohols, such as methanol, n-propanol or isopropyl alcohol (isopropanol) [25].

  • Isopropyl alcohol, produced from acetone and exhaled in the breath of individuals during fasting, very low-calorie or low-carbohydrate diet (ketogenic diet), or in those with poorly controlled diabetes 1 can be detected [25]. Acetone in the breath of the same individuals is not detected, though.
  • Alcohol-containing foods, such as certain ice creams, overripe fruits, hot pizza dough, donuts, cinnamon rolls and other yeast-leavened carbohydrate foods [25]mouthwash and medicines, such as cough, multivitamin or iron syrups, may react with the device, if used within 15 minutes before the test [25,26,27].
  • Methanol, isopropanol or n-propanol inhaled from the fumes of windshield washer fluid or de-icer and exhaled into a device could theoretically react with the device, but there is a lack of studies about this [25].

What does NOT affect ignition interlock device?

  • Acetone in breath of individuals who are fasting or are on a low-carbohydrate diet (ketogenic or Atkins diet) and those who have hypoglycemia or untreated diabetes 1 is not detected by ignition interlock device [25]. Isopropyl alcohol in the breath of the same individuals is detected by the device, though [25].
  • Spicy foods without alcohol do not affect the device [25].
  • Cigarette smoke does not interfere with the device [27].
  • Ethanol from perfumes, after-shave cologne, deodorants, hairspray, hand sanitizers and other substances applied on the skin do not likely affect the device [27]. The same may be true for methanol, ethylene glycol, n-propanol and isopropyl alcohol (rubbing alcohol from from disinfecting pads, gasoline drier, whiteboard cleaner, laptop cleansers, stain removers, preservative for biological specimens) evaporating from the hands after handling with these alcohols.
  • Normal gas refueling on a gas station should not affect the device [27].

  1. Hlastala MP, 1985, Physiological errors associated with alcohol breath testing  Mphlastala.com
  2. Breath alcohol test  MedlinePlus
  3. Logan BK et al, 1998, Lack of effect of tongue piercing on an evidential breath alcohol test  PubMed
  4. Modell JG et al, 193, Breath alcohol values following mouthwash use  PubMed
  5. DuPont R et al, 2005, GUIDE TO RESPONSIBLE FAMILY DRUG AND ALCOHOL TESTING  Institute for Behavior and Health
  6. Caravati M et al, 2010, Breath alcohol analyzer mistakes methanol poisoning for alcohol intoxication   PubMed
  7. Hlastala MP, 1985, The alcohol breath test–a review  PubMed
  8. Information about alcohol  NIH Curriculum Supplement Series
  9. Lutmer B et al, 2009, Potential effect of alcohol content in energy drinks on breath alcohol testing  PubMed
  10. Logan BK et al, 1998, Ethanol content of various foods and soft drinks and their potential for interference with a breath-alcohol test  PubMed
  11. Kechagias S et al, 1999, Reliability of breath-alcohol analysis in individuals with gastroesophageal reflux disease  PubMed
  12. Gomm PJ et al, 1991, The effect of salbutamol on breath alcohol testing in asthmatics  PubMed
  13. Gehring H et al, 1996, Measurement of expired alcohol concentrations with a new electrochemical sensor. A model investigation to determine interference with volatile anesthetics and clinical application  PubMed
  14. Watterson JH, 2009, Assessment of response of the Intoxilyzer 8000C to volatiles of forensic relevance in vitro, part I: acetone, isopropanol, and methanol  PubMed
  15. 2012, Breath alcohol operator manual  State of Missouri Website
  16. Jones AW, 1986, Drug-alcohol flush reaction and breath acetaldehyde concentration: no interference with an infrared breath alcohol analyzer  PubMed
  17. Buckley TJ et al, 2001, Evaluation of methyl tert-butyl ether (MTBE) as an interference on commercial breath-alcohol analyzers  PubMed
  18. Gill R et al, 1991, The response of evidential breath alcohol testing instruments with subjects exposed to organic solvents and gases. I. Toluene, 1,1,1-trichloroethane and butane  PubMed
  19. Cooper S, 1981, Infrared breath alcohol analysis following inhalation of gasoline fumes  PubMed
  20. 2014, Controlled Substances and Toxicology Laboratory  Departemnt of Emergency Services and Public Protection
  21. Williams PM, Analytical and Physiological Specificity Issues in Breath Alcohol Analysis  University of Adelaide
  22. Aderjan R et al, 1992, Glue solvent as the cause of a “breath alcohol value” of “1.96 promille” PubMed
  23. Ignition Interlock Program  Ontario Ministry of Transportation
  24. 2003, Alcohol Problems in Intimate Relationships: Identification and Intervention  National Institute on Alcohol Abuse and Alcoholism
  25. Jones AW et al, 2007, False-positive breath-alcohol test after a ketogenic diet  PubMed
  26. Guide to alcohol-free products  & Incidental exposure index & products containing alcohol  Board of Occupational Therapy
  27. Ignition Interlock Truths and Myths  Smart Start of California
  28. 2004, Breath testing for prosecutors  National District Attorney Association
  29. Alcohol and dehydration  Frostburg State University

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