Citation

Buczek Y, Wigmore JG. J. Can. Soc. Forensic Sci. 2002; 35(4): 185-193.

Copyright

(Copyright © 2002, Canadian Society of Forensic Science, Publisher Informa - Taylor and Francis Group)

DOI

10.1080/00085030.2002.10757546

PMID

unavailable

Abstract

Retention of mouth alcohol may result in falsely high breath alcohol concentrations and is thus a concern in evidential breath alcohol testing. Frequent breath sampling used in the typical mouth alcohol experiment may underestimate the duration and magnitude of the mouth alcohol effect in comparison to the real-life forensic situation. On each of three separate trials, nineteen female, and eleven male, alcohol-free subjects rinsed their mouths with 20 mL of diluted vodka (20% alcohol v/v) for 20 seconds and then expectorated. On each of the trials, the subjects provided breath samples into an Intoxilyzer® 5000C either every two minutes, every four minutes, or every eight minutes, respectively. The subjects did not talk or open their mouths throughout the experiment except for providing the breath sample. The final breath result displayed, as well as whether or not the instrument detected mouth alcohol, was recorded. As expected, an increase in the frequency of breath sampling significantly decreased the magnitude and duration of the mouth alcohol effect. At eight minutes after rinsing the mouth with alcohol, the mean mouth alcohol concentration (MAC) (± SEM) was 0.072 (± 0.011) g/210 L, 0.057 (± 0.005) g/210 L and 0.041 (± 0.004) g/210 L for breath sampling every eight, four, and two minutes, respectively. At sixteen minutes after rinsing the mouth with the diluted vodka, a positive MAC was found in 47%, 33%, and 13% of the subjects for breath sampling every eight, four, and two minutes, respectively. The rate of detection of mouth alcohol by the Intoxilyzer® 5000C increased from 53% at MACs < 0.050 g/210 L to 100% at MACs > 0.199 g/210 L. Frequent breath sampling leads to a more rapid and greater decrease in the mouth alcohol effect. The ability of correctly detecting mouth alcohol with the Intoxilyzer® 5000C increases with increasing MAC.