So you’re driving along and suddenly there are flashing red lights in your rear view mirror. You recall that glass of wine with dinner: not nearly enough to be over .08%, of course, but enough to cause an odor of alcohol on the breath. As you pull over, you grab the breath freshener and quickly spray it into your mouth. The officer asks you to step out of the car, holds out a portable breath testing device and asks you to blow into it. A moment later you are being handcuffed.
What happened? One of the many problems with breath machines is that they cannot tell the difference between alcohol coming from the lungs and alcohol which is already in the mouth or throat. This problem is referred to as mouth alcohol, and is particularly troublesome because, believing it to be alcohol from the lungs, the breath machines will incorrectly multiply the detected alcohol by 2100 times (see my earlier post, Breathalyzers — and Why They Don’t Work).
One common source of breath alcohol is breath spray, as well as mouthwash — both of which contain significant amounts of alcohol. Listerine, for example, contains 27% alcohol, Scope 19% and Astring-O-Sol 76%. Even a tiny amount of this on the breath or in the throat, if multiplied by the machine 2100 times, can result in high breathalyzer readings.
This was clearly illustrated in a study conducted with Listerine mouthwash on a breath machine and reported in an article entitled "Field Sobriety Testing: Intoxilyzers and Listerine Antiseptic", published in the July 1985 issue of The Police Chief . Seven alcohol-free individuals were tested at a police station, with readings of .00%. Each then rinsed his mouth with 20 milliliters of Listerine mouthwash for 30 seconds in accordance with directions on the label. All seven were then tested on the machine at intervals of one, three, five and ten minutes.
The results indicated an average reading of .43% blood-alcohol concentration — indicating a level that, if accurate, approached lethal proportions. After three minutes, the average level was still .20%, despite the absence of any alcohol in the system. Even after five minutes, the average level was .11% — well over the legal limit.
In another study, reported in 8(22) Drinking/Driving Law Letter 1, a scientist tested the effects of Binaca breath spray on an Intoxilyzer 5000. He performed 23 tests with subjects who sprayed their throats, and obtained readings as high as .81% — far beyond lethal levels. The scientist also noted that the effects of the spray did not fall below detectable levels until after 18 minutes.
Don’t spray and drive.