Note that the QED measures and reports the concentration
of ethanol in mixed whole salivary fluid, and the response is not
converted or reported as a presumed coexisting BAC. Measuring
the concentration of alcohol in breath and saliva is
equally as valid as measuring the blood-alcohol concentration
for the purpose of demonstrating that a person has been
drinking and has alcohol in the body (25). Whenever the concentrations
of alcohol in plasma (PAC), breath (BrAe), saliva
(SAC), or urine (UAC) are converted into the presumed BAC,
the uncertainty in the result is always much greater than the
uncertainty when PAC, BrAe, SAC, or UAC are measured and
reported directly.