The length of time of exposure to acetaldehyde is far less with mouth rinse than with alcoholic beverages.^1–3 A mouth rinse is used for a short period before being spat out, for instance for 30 seconds twice daily in the case of LISTERINE^®.

Exposure to salivary acetaldehyde from mouth rinses and alcoholic beverages

Even when mouth rinses are used twice every day, the total lifetime exposure to acetaldehyde is negligible compared with the level of exposure derived from consuming naturally occurring foods and alcoholic beverages.

Why is acetaldehyde exposure significantly less with alcohol-containing mouth rinses than alcoholic beverages? Acetaldehyde levels found in saliva are the sum total of acetaldehyde delivered directly from the ethanol in mouth rinse or alcoholic drink, which is fairly transient, and acetaldehyde produced by the liver from ethanol that has been ingested, which returns via the bloodstream to saliva, where levels are sustained for hours. Unlike with alcoholic drinks, minimal ethanol is ingested during mouth rinse use, so very little acetaldehyde returns to saliva from the liver. This helps explain the very significant difference between mouth rinses and alcoholic beverages in terms of acetaldehyde exposure and hence carcinogenic risk.

Additionally, the German Federal Institute of Risk Assessment concluded: “The contribution of mouth rinses to acetaldehyde exposure…is 0.25 μg/kg and vanishingly low compared to foods and alcoholic beverages.”^4*

*Translated from German