Residual Mouth Alcohol

Last updated: June 21, 2018

What Does Residual Mouth Alcohol Mean?

Residual mouth alcohol refers to any alcohol left in a person's mouth after ingestion of a product that contains alcohol. In alcohol breath tests, residual alcohol can return a false reading because the testing device is picking up the alcohol left in the mouth instead of measuring the alcohol in the lungs. Employees may sometimes attempt to deliberately use mouthwash or other innocuous products that contain alcohol to explain their breath alcohol level and cover up alcohol abuse.


WorkplaceTesting Explains Residual Mouth Alcohol

Residual mouth alcohol is a term used in breath alcohol testing that refers to any left over alcohol in the mouth from ingestion of a substance that contained alcohol.

A person's blood alcohol content (BAC) is indirectly estimated by measuring the breath alcohol content (BrAC) . In order for the results of the breath test to be accurate, the breath needs to come from deep within the lungs and not be contaminated by recent alcohol in the mouth.

Residual mouth alcohol can come from a variety of sources including recent alcohol consumption, or the use of breath fresheners or mouthwashes that contain alcohol. Belching, vomiting, or experiencing acid reflux after the consumption of alcohol can also lead to residual mouth alcohol. To ensure a positive breath alcohol result is not caused by residual mouth alcohol, a confirmation test is performed after a supervised waiting period to ensure that enough time is given for the residual mouth alcohol to dissipate, and ensure that the donor does not ingest anything that may cause further contamination of the mouth to cause further residual mouth alcohol.


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