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DUI Videos Mouth Alcohol Bias
This is a collection of videos of experiments conducted relating to experimentaion with the reliability of evidentiary and other breath testing instruments including the Inoxilyzer 5000 and the Intoxilyzer 8000. This group of videos deals with mouth alcohol bias. Notwithstanding automatic systems on evidentiary breath testers, those automatic systems may fail to detect mouth or stomach alcohol, if the presentation by the particular subject's body does not fit the design of the instrument. Preliminary breath testers (PBTs) or approved screening devices (ASDs) do not usually include mouth alcohol detection systems or interferent detection systems for foods that may contain a small amount of alcohol or an intereferent, and can easily result in a false positive . Radio frequency interference from a cell phone can mimic mouth alcohol in automatic systems designed to detect mouth alcohol. Operators and qualified technicians MUST strictly comply with a 15 to 20 minute observation deprivation protocol as a condition precedent to instrument or screening device (PBT or ASD) reliability.
Video 01
Mouth Alcohol Resulting in 303 mg/100mls Apparent BAC
Video taken during controlled alcohol testing. Subject with well-documented true blood alcohol concentration between 116 and 120 mgs/100mls blows 303 mgs/100 mls as a result of mouth alcohol bias. Mouth alcohol detection algorithm fails to flag phenomenon as "Invalid Sample". Instrument is an Intoxilyzer 5000C.
The mouth alcohol detection system is looking for a pattern in the blow, whereby the BAC concentration rises quickly and then falls. However, breathing patterns during a subject test on an approved instrument aren't always the same. There are occasions when the presentation of some alcohol in the blood combined with some alcohol in the mouth or stomach, with a long gentle blow is a presentation not contemplated by the design of the instrument. The instrument accepts the sample as a valid sample, notwithstanding the presence of mouth alcohol.
Mouth alcohol detection systems are far from foolproof. Protocols followed by legal systems and operators must therefore require:
1. 15 to 20 minute observation/deprivation period before each subject test to watch for alcohol or food placed in the mouth, burping, belching, vomit
2, two tests with good agreement 15 minutes apart
3. never use a screening device (PBT or ASD) to attempt to obtain a quantitative result (ASDs and PBTs usually don't have mouth alcohol detection systems)