The concentration-time profiles of ethanol in saliva and
whole blood followed a similar but not identical time course, as
expected from the different amounts of water in these body
fluids. Because saliva contains more water than whole blood,
there must be a higher concentration of alcohol in salivary
secretions. Moreover, the concentration of alcohol in saliva
should run closer to the concentration in arterial blood compared
with the venous blood (8); this might account for the
somewhat different time profiles, namely arteriovenous differences
in the pharmacokinetics of ethanol. Concentrations of
ethanol in end-expired breath are closer to concentrations in
arterial blood, which might explain the narrower 95% limits of
agreement when comparing QED tests with Datamaster
breath-instrument readings (Table II).