In many jurisdictions, the use of chewing gum by a drunk driving subject is not allowed for at least 15 minutes prior to a breath alcohol test. Does chewing gum affect breath alcohol tests and, if it does, is 15 minutes sufficient to clear the potential effect? A recently published study examined the effect of 75 different types of sugar free gum on four different breath testing instruments. The study is:
Tremblay, H. and Nolin, G. “Lack of Response of Breath Alcohol Screening Devices to Sugar Alcohols Contained in Chewing Gum”, Canadian Society of Forensic Science Journal, 47(2): 46-54, 2014 (2 tables, 32 references) (WOA305U4)
This issue is sometimes raised in criminal court as chewing gum contains up to 75% “alcohol”. Scientifically, alcohol is the generic name for hydrocarbons in which one or more of the hydrogen atoms have been replaced by a hydroxyl (-OH) group. Alcohols are generally identified by the suffix –ol.
The sugar alcohols found in chewing gum are listed in the following table and compared to ethanol.
As seen in the table, the sugar alcohols have a different chemical structure and are much less volatile than the beverage alcohol (ethanol). As such, the sugar alcohols should not result in a positive breath alcohol result.
This is exactly what Tremblay and Nolin found, even under the extreme conditions used in their study. The alcohol-free subjects chewed 5 pieces of sugarless gum and at the time when the subjects detected the maximum taste in their mouth, blew into an Alco-Sensor IV DWF, Alco-Sensor FST, Alcotest 7410 GLC or an Intoxilyzer 400D. Of the 300 breath results, 298 gave a zero response after chewing gum. The only positive result occurred after chewing Trident Splash Strawberry and Kiwi, which actually did contain traces of ethanol (0.05% w/w). The results were all less than 0.01 g/100mL and were zero less than 1 minute later.
The authors concluded:
Chewing gum prior to providing a breath sample gives a null result on breath alcohol screening devices in the vast majority of cases. A positive result is not due to sugar alcohols found in sugar-free gums but rather to the small amount of ethanol present. The effect was only seen for one flavor and lasted for less than one minute. Chewing gum in realistic conditions prior to providing a breath sample in a breath alcohol screening instrument will not produce a false positive result, especially when administered by a peace officer in the field (gum removed, explanations given and breath provided more than one minute later). Although the study focused on breath alcohol screening devices, there is no reason to believe that different results would have been obtained if they had been carried out on approved instruments.
Beneficial Effects of Chewing Gum
Rather than causing a false positive breath alcohol test result, chewing gum can actually reduce the mouth alcohol effect. This was found in an earlier study, which is listed in my book:
Wigmore, JG, and Bugyra, IM, “Decreasing the Mouth Alcohol Effect by Increasing the Salivary Flow Rate”, Canadian Society of Forensic Science Journal, 36: 211-216, 2003 (2 tables, 1 figure, 12 references), (WOA30505)
In this study, 19 female and 11 male alcohol-free subjects rinsed their mouth with 20 mL of 20% v/v alcohol for 20 seconds and then expectorated. The subjects kept their mouths closed and provided breath samples 5 and 10 minutes later into an Intoxilyzer 5000, with or without chewing one piece of a sugar free gum. Since chewing gum increases the salivary flow rate by nearly 10X, it was found that the mouth alcohol effect was decreased dramatically as shown in the following table.
The authors concluded:
Another interesting aspect is that it has been argued in criminal courts in Ontario and other jurisdictions that the subject had food, candy, chewing tobacco or gum hidden in their mouth during the evidential breath alcohol test without the police being aware of it and that these substances would act like a sponge and soak up and retain the alcohol beyond the 15-20 minute deprivation period. These substances, however, when chewed promote the flow of saliva and, as shown in this study, the duration and magnitude of the mouth alcohol effect is actually decreased not increased.
For those of you who follow me on LinkedIn, LinkedIn now has a new feature called postings in which members can publish a posting, or mini article, in their profile. I have used this feature to publish several short articles over the past month including posts on “Remote Sampling of Alcohol Vapor in a Moving Car”, “Do Blood Alcohol Samples Need Constant Refrigeration?” and several others. I hope you’ll take the time to pop over to my LinkedIn account as there are several interesting comments posted by readers.