5 things your teen needs to know that may cause an L or P plater to fail a breathalyzer even if they haven't been drinking alcohol

No matter your age, your driving experience or how sober you are, that feeling of being flagged over by a police officer for a random breath test (RBT) is never pleasant. You may not have had a drink for days but as you're blowing or talking into that little machine, for many people there's still that fear that something could go wrong … Speaking to young drivers across the country, that first time that they're pulled over and asked to do the test can even be more scary. They may have watched the TV show RBT many times or been sitting in the car when one of their parents has been tested and know how the process works, but experiencing it for themselves for the first time can be quite confronting. What is so important for L and P platers (who must have a blood alcohol concentration (BAC) of 0.00) to know is that there are so many things that could cause them to fail a breathalyzer even if they haven't been drinking alcohol …

Over the years I've been contacted by many young drivers who have failed a preliminary test, some saying that they had never drank alcohol in their lives. In the vast majority of these cases, police give the driver the benefit of the doubt, wait a couple of minutes and then test them again, usually resulting in them passing with flying colours. When they ask police why they could have failed in the first place, sometimes they're offered a possible explanation (some truly bizarre, e.g., chewing gum, toothpastes, cough lollies, Cherry Ripes) but for most of them they're just left wondering. It's important that teens are aware that because they have to have a BAC of 0.00, even if they haven't had a drink of alcohol there are things that may cause them to fail an RBT. They also need to know that there are a couple of simple things they can do to reduce the risk of this happening ...

Here are five things that teens need to know may cause a young driver to fail a breathalyzer:

• mouthwash
• 'ambient air'
• foods containing alcohol
• lemon, lime and bitters
• products containing vanilla essence 

Firstly, it is important to acknowledge that these products are only really going to cause an issue as far as the 'preliminary test' is concerned, i.e., the hand-held breathalyzer administered by a police officer (the 'blowing' machine used in all states and/or the 'talking' machine, currently only used in NSW and the ACT). None of these products should cause problems with the 'evidentiary test', i.e., the more accurate test that counts, with those results being used in court. Apart from 'ambient air', it is 'alcohol debris' that is likely to be the issue and because the second test is conducted some time after the first (there should be at least a 15 minute wait between the two), natural saliva production should have washed that debris away and won't be picked up.

Also, failing an RBT as a result of any of these is not the norm. A young driver would have to be pretty unlucky for it to happen (particularly the last one which is a bit strange and quite 'out-there') - but being aware of the risk is important. So let's take a look at them ...

Mouthwash: This seemed to be the one most likely to get young men into trouble, possibly because there was the belief that gargling with mouthwash could actually prevent you from failing an RBT if you had been drinking. In reality, some brands contain very high levels of alcohol (some over 25% alcohol content) and keeping a bottle in your car to swig back should you be pulled over is just plain dumb. You can now buy 'alcohol-free' mouthwash and I certainly recommend all young drivers use this whenever they can. The problem with mouthwash is that if you do have good dental hygiene practices and gargle, it is more likely that you do so just before you go out (few people gargle and sit and watch TV). If you do gargle, get into your car and then get pulled over by police and breathalyzed in the minutes after leaving your home there is a chance that you could get a positive reading due to 'debris' of alcohol in your mouth.

'Ambient air': This is a really interesting one and most probably the most likely reason given to young people by police as to why they may have failed a test. Ambient air basically means the smell of alcohol in the car and can cause a problem if the driver has had alcohol spilt over them (particularly their right shoulder near where the test is conducted) or have had a bottle smash or spill in the car (a number of young people have told me that they have had bottles or cans of alcohol explode in their vehicle and subsequently fail an RBT). Now I would imagine the smell would have to be pretty out there and obvious but it's a possibility. But it's not alcohol that you drink that is most likely to cause problems here, it's the alcohol that you wear - perfume and after-shave. I've spoken to many police who say that this is often the reason why they believe a young driver blows over 0.00, with the smell being pretty overpowering as the window is wound down. Interestingly, I met a teacher last year who blew over 0.05 on her way to school on the day of my visit, apparently due to the fact that when she was pulled over and waiting for the officer she sprayed perfume on herself. After assuring him that she hadn't been drinking, she was tested again a couple of minutes later and blew 0.00!

Foods containing alcohol: It's more likely to be cakes and desserts that cause problems here, foods with alcohol 'soaked' into them, e.g., tiramasu, sherry trifle and one of the worst offenders, Christmas pudding. If you're an L or a P plater and you get a small amount of the brandy-soaked dessert stuck between your teeth, it is possible to fail that preliminary test (apparently an episode of RBT highlighted this problem with a young driver failing her preliminary test due to having just eaten tiramisu). Some young people ask whether pastas in wine sauces and the like can cause a similar problem and the answer is most probably 'no'. According to people I have spoken to, when the alcohol is used in cooking and heated, you get the taste of alcohol but you lose the alcohol content - it's the soaking that could cause a problem.

Lemon, lime and bitters (LLB): Although many people believe that LLB is a non-alcoholic option, aromatic bitters (the product that makes this drink unique) has in fact a very high alcohol content. It's just that you don't use much of it (or at least you're not meant to!) and so over the years it has become the drink of choice for many non-drinkers. It doesn't contain much alcohol (tests have found that a glass is the equivalent of about one-tenth of a standard drink) but it is alcoholic. If an L or P plater has this as their last drink of the night, skols it down (remembering that the bitters is likely to settle to the bottom of the glass if left sitting for a time) and gets breathalysed shortly afterwards, they can fail a preliminary test due to 'alcohol debris'. Most importantly, lemon, lime and bitters is likely to be far more alcoholic today than in the past with some bar staff not just using a 'shot' of bitters at the bottom of the glass (it was once almost an art watching a bartender make a LLB!), but also sprinkling a whole pile more over the top, potentially increasing its alcohol content …

Products containing vanilla essence: Now this is where it gets a little weird … There are two stories about the products 'Up & Go' and a 'Bubble 'O' Bill' ice cream that many young people have raised with me that made little sense but, if true, it is possible that both had to do with the presence of vanilla essence. From what I can gather (and I can't guarantee that this is absolutely true) the 'Up and Go' story seems to have come from a Channel 7 News item that ran in December 2010. Apparently a man who had a breathalyser interlock on his car drank a vanilla 'Up & Go' and got a positive reading for alcohol and was subsequently unable to drive. He went to the media and the story has rolled on ever since… Another story that got extensive media coverage a number of years before was about a 'Bubble 'O' Bill' ice cream that caused a similar problem for a driver with the same device. This man appeared in court and wanted his lock removed because of the false reading caused by the ice cream. The magistrate found his claim difficult to believe and got him to purchase and eat the product in court. A breath test was then carried out and he blew a reading of 0.018! It is important to note that both cases involve interlock devices on cars and that both men most probably consumed the product and then blew into the device straight away. It would be unlikely that this would happen with an RBT. As already said, the presence of vanilla essence (a product that contains high levels of alcohol) are believed to have caused the positive tests but, once again, this is certainly not the norm. Realistically, a young driver would have to be extremely unlucky to get a positive test from a product containing vanilla essence. That said, I was recently contacted by a mother of an L plater who failed a preliminary test and was told by the officer once her son had passed the second test that the likely reason for the result was the biscuit (containing vanilla essence) he had just finished eating in the car. I find that difficult to believe but I'm just putting it out there …

So can a young driver ensure they don't get caught out on any of these? Well, it's pretty simple really - here are the two tips I give to students:

• to prevent ambient air issues, wind the windows down for a few minutes as you're driving
• to avoid 'alcohol debris' being picked up, always rinse your mouth before getting behind the wheel

Although no-one usually tells young drivers that this can happen, the strong smell of alcohol in the car or on their person could possibly cause a positive test. It's important to note that this is much more likely when the 'talking' machine is used, where the breathalyzer could potentially 'scoop up' the ambient air. If you're driving and you can smell alcohol in your vehicle or on your passengers, or there is an overpowering stench of perfume and/or after shave wafting around, all you have to do is wind the windows down for a few minutes. get that smell moving - it won't take long at all to clear the air.

Young drivers should also be aware that there are some foods and liquids that can cause an elevated reading in the minutes after they are consumed, but that is why there is a break between the preliminary and evidentiary tests. The best way for an L or P plater to avoid an embarrassing moment and failing an RBT due to something they've eaten is to ensure they always rinse out their mouth before driving. Have a bottle of water in the car and before you put the key into the ignition, take a mouthful, swill it around and then spit it out - do this and that'll most likely remove any debris that may be there and prevent an unpleasant and unnecessary visit to the 'booze bus' or the local police station.