Drinking & Driving – Breath analyzer myths

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Drinking & Driving – Breath analyzer myths

There are a number of substances or techniques that can supposedly “fool” a breath analyzer (i.e., generate a lower blood alcohol content – BAC).

A 2003 episode of the popular science television show MythBusters tested a number of methods that supposedly allow a person to fool a breath analyzer test. The methods tested included breath mints, onions, denture cream, mouthwash, pennies and batteries; all of these methods proved ineffective. The show noted that using items such as breath mints, onions, denture cream and mouthwash to cover the smell of alcohol may fool a person, but, since they will not actually reduce a person’s BAC, there will be no effect on a breath analyzer test regardless of the quantity used, if any, it appeared that using mouthwash only raised the BAC. Pennies supposedly produce a chemical reaction, while batteries supposedly create an electrical charge, yet neither of these methods affected the breath analyzer results.

The Mythbusters episode also pointed out another complication: It would be necessary to insert the item into one’s mouth (e.g. eat an onion, rinse with mouthwash, conceal a battery), take the breath test, and then possibly remove the item – all of which would have to be accomplished discreetly enough to avoid alerting the police officers administering the test (who would obviously become very suspicious if they noticed that a person was inserting items into their mouth prior to taking a breath test). It would likely be very difficult, especially for someone in an intoxicated state, to be able to accomplish such a feat.

In addition, the show noted that breath tests are often verified with blood tests (which are more accurate) and that even if a person somehow managed to fool a breath test, a blood test would certainly confirm a person’s guilt. However, it is not clear why a negative breath test would be verified by a subsequent blood test.

Other substances that might reduce the BAC reading include a bag of activated charcoal concealed in the mouth (to absorb alcohol vapor), an oxidizing gas (such as N2O, Cl2, O3, etc.) that would fool a fuel cell type detector, or an organic interferent to fool an infrared absorption detector. The infrared absorption detector is more vulnerable to interference than a laboratory instrument measuring a continuous absorption spectrum since it only makes measurements at particular discrete wavelengths. However, due to the fact that any interference can only cause higher absorption, not lower, the estimated blood alcohol content will be overestimated. Additionally, Cl2 is rather toxic and corrosive.

A 2007 episode of the Spike network’s show Manswers showed some of the more common and not-so-common ways of attempts to beat the breath analyzer, none of which work. Test 1 was to suck on a copper-coated coin such as a penny. Test 2 was to hold a battery on the tongue. Test 3 was to chew gum. None of these tests showed a “pass” reading if the subject had consumed alcohol.

Products that interfere with testing

On the other hand, products such as mouthwash or breath spray can “fool” breath machines by significantly raising test results. Listerine mouthwash, for example, contains 27% alcohol. The breath machine is calibrated with the assumption that the alcohol is coming from alcohol in the blood diffusing into the lung rather than directly from the mouth, so it applies a partition ratio of 2100:1 in computing blood alcohol concentration—resulting in a false high test reading. To counter this, officers are not supposed to administer a PBT for 15 minutes after the subject eats, vomits, or puts anything in their mouth. In addition, most instruments require that the individual be tested twice at least two minutes apart. Mouthwash or other mouth alcohol will have somewhat dissipated after two minutes and cause the second reading to disagree with the first, requiring a retest. (Also see the discussion of the “slope parameter” of the Intoxilyzer 5000 in the “Mouth Alcohol” section above.)

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 (p. 70). Seven individuals were tested at a police station, with readings of 0.00%. 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 0.43 blood-alcohol concentration, indicating a level that, if accurate, approaches lethal proportions. After three minutes, the average level was still 0.020, despite the absence of any alcohol in the system. Even after five minutes, the average level was 0.011.

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 0.81-far beyond lethal levels. The scientist also noted that the effects of the spray did not fall below detectable levels until after 18 minutes.

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Author: AllOntario Team

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