The potential of alcohol absorbed inside the mouth to affect
the accuracy of a breath alcohol test has been known since the
advent of breath alcohol testing. Although large concentrations
of mouth alcohol are normally due to the oral consumption of
an alcoholic beverage, ethanol can also be absorbed in the oral
cavity from a number of other sources, such as alcohol-containing
mouthwashes, breath sprays, and aerosol medications
(1,2). Mouth alcohol has been shown to normally disappear
within 15–20min on a non-drinking subject, and it drops to insignificant
levels in a shorter period on drinking subjects (3–5).
For this reason, an observation period is usually mandated to
allow for the dispersion of alcohol in the oral cavity prior to a
breath alcohol test being performed. Although there has been
speculation on the ability of significant alcohol concentrations
to be retained for even longer timeframes in the oral cavity due
to the presence of foreign objects such as oral piercings, chewing
tobacco, and gum, these claims have been proven false