The Science Behind 'Mouth Alcohol'
Breathalyzer devices are designed to measure the alcohol concentration in your deep lung air, known as alveolar air, which correlates with your blood alcohol content (BAC). However, for a short period after using certain oral products, residual alcohol can remain in the mouth's mucosal lining and dental work. This unabsorbed alcohol can contaminate a breath sample, causing a device to register a higher-than-actual BAC reading.
This phenomenon is known as “mouth alcohol.” While breathalyzers are intended to differentiate between deep lung air and mouth air, the presence of residual alcohol can sometimes skew the results, especially on older or less sophisticated portable devices.
The Ingredients in Toothpaste that Affect Breathalyzers
Not all toothpastes pose a risk, and the impact is temporary. The two main culprits are:
- Sorbitol: This sugar alcohol is a common ingredient in many sugar-free and oral care products, including toothpaste, gum, and mints. While it is not the intoxicating ethyl alcohol, some fuel cell breathalyzers may not be able to distinguish it from ethanol, potentially registering a false positive. The temporary nature of this reading means it quickly vanishes as the residue is cleared from the mouth.
- Ethyl Alcohol: While much higher concentrations are found in mouthwash, some brands of toothpaste may contain small amounts of ethyl alcohol, which can cause a short-term spike in a breath test reading. The concentration is typically not enough to cause intoxication, but it is enough to temporarily affect a sensitive device.
Other Oral Products and Medications that Cause False Positives
Toothpaste is just one of many everyday products that can cause a false positive breath test. Other common sources of mouth alcohol or substances that interfere with a breathalyzer include:
- Mouthwash and Breath Sprays: Many of these products contain high concentrations of ethyl alcohol, far more than toothpaste, making them a significant cause of false positives if used just before a test.
- Cold and Flu Medications: Cough syrups like NyQuil or other cold remedies often contain alcohol and can lead to a false positive reading.
- Asthma Inhalers: Some inhalers use alcohol as a propellant, which can linger in the airways and affect a breath test.
- Oral Gels and Toothache Medications: These can also contain ingredients that can affect breath test results.
How to Prevent a False Positive from Oral Products
For law enforcement to administer an evidentiary breath test, specific protocols must be followed to avoid mouth alcohol contamination. The standard procedure involves a 15- to 20-minute observation period during which the officer ensures the subject does not consume anything, smoke, belch, or regurgitate. This waiting period allows any mouth alcohol to dissipate naturally.
- Rinse Your Mouth: Always rinse your mouth thoroughly with water before a breath test if you have recently used an oral product.
- Wait It Out: If you know you've used an alcohol-containing product, allow a sufficient amount of time to pass. The mouth alcohol from toothpaste or mouthwash typically dissipates within 15-20 minutes.
- Inform the Officer: If you are asked to take a breath test shortly after using an oral hygiene product, inform the officer. A professional officer will recognize the potential for a temporary, false reading and follow the correct protocol.
Mouth Alcohol vs. Deep Lung Alcohol: A Comparison
The fundamental difference lies in the source of the alcohol and its effect on the test. Mouth alcohol is transient and confined to the mouth, whereas deep lung alcohol is absorbed into the bloodstream and exhaled from the lungs.
| Feature | Mouth Alcohol | Deep Lung Alcohol (BAC) |
|---|---|---|
| Source | Residual alcohol from oral products, medications, or belching. | Alcohol absorbed into the bloodstream from the stomach and intestines. |
| Location | Confined to the oral cavity, mucosal lining, and dental work. | Distributed throughout the body via the bloodstream and released from the lungs. |
| Duration | Short-lived; dissipates within 15-20 minutes. | Longer duration; concentration depends on amount consumed and metabolism. |
| Effect on Test | Can cause a temporary, artificially high reading on a breathalyzer. | Provides an accurate reflection of the individual's intoxication level. |
| Mitigation | Can be eliminated by waiting and rinsing the mouth. | Cannot be eliminated by waiting or rinsing; requires metabolism by the liver. |
Medical Conditions that Can Cause False Positives
Beyond external sources, certain medical conditions can also lead to a false positive reading, often due to substances mimicking alcohol on a breathalyzer or causing residual mouth alcohol.
- Diabetes: Individuals with diabetes, especially those in ketosis (low-carb diets or fasting), produce acetone on their breath. Some breathalyzers, particularly older models, can mistake acetone for ethyl alcohol.
- Gastroesophageal Reflux Disease (GERD): Acid reflux can bring stomach contents, including alcohol vapors, back into the mouth and throat, leading to an artificially high reading. This is why officers are supposed to observe subjects for an extended period to prevent belching or regurgitation.
- Dental Issues: Dental work, such as bridges, dentures, or advanced periodontal disease, can create pockets where alcohol can be trapped, releasing it slowly and interfering with a test.
Conclusion
While toothpaste can cause a positive alcohol test, it is not a widespread or sustained threat to a valid breathalyzer result. The potential for a false reading is a result of mouth alcohol, which dissipates rapidly and is accounted for by the standard 15-20 minute observation period mandated in breath-testing protocols. The key takeaway for anyone facing an alcohol test is to be mindful of what goes into their mouth, including oral hygiene products and certain medications, in the minutes leading up to the test. By understanding the causes of mouth alcohol and proper testing procedures, it's possible to ensure accurate and fair results.
Further Reading
- Massachusetts Bar Association: Violating the “alcohol free” probation requirement
