UMEM Educational Pearls

Title: Officer, I'm not drunk. I just used a mouth wash!

Keywords: ethanol, breath analyzer, mouth wash (PubMed Search)

Posted: 9/12/2019 by Hong Kim, MD
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Breath analyzers are commonly used by law enforcment officers to test for alcohol intoxication. Breath analyzer uses ethanol partition ratio between blood:breath of 1:2100 = 1 gm of ethanol in 2100 mL of breath/air.

Mouth wash products are frequently used for oral hygiene, and at times, to "mask" odor of substances. These products are readily available in any grocery stores or pharmacy and contain upto 26.9% ethanol (e.g. Listerine) (18.9% - Scope; 14.0% - Cepacol).

Recently, a small study using healthy volunteers (n=11) was published to investigate the impact of limited ethanol exposure (mouth wash and ethanol vapor) on the breath-alcohol concentration (BrAC).

Method

Ethanol vapor exposure (856 mg/m3) for 15 minute.
Oral rinse (for 30 sec) using mouth wash containing 22% ethanol, 1 hour after the ethanol vapor exposure
Blood and breath samples were collected before, between and after exposure.

Results

Blood: No or very low levels of ethanol (0.002 mg/g) were detected in blood at all collection time for both exposures.

BrAC - first collection -- seconds after exposure

Ethanol vapor: 0.14 mg/L (0.014 mg/dL)
Mouth wash: 4.4 mg/L (0.44 mg/dL)

Mean time to negative BrAC level (Swedish statutory limit of 0.1 mg/L = 0.01 mg/dL in air) (FYI: US limit = 80 mg/dL)

Ethanol vapor: 0.5 min (0.06 - 0.7 min)
Mouth wash: 11 min (6 - 15 min)

Conclusion

Ethanol vapor did not affect the BrAC
Mouth wash use can transiently increase BrAC; however, their use does not sufficiently increase the BrAC to result in "false positive" based upon US limit.

References

Ernstgard L et al. Washout kinetics of ethanol from the airways following inhalation of ethnaol vapors and use of mouthwash. Clin Toxicol. 2019 Jun 19:1-7. doi: 10.1080/15563650.2019.1626868. [Epub ahead of print]