Alcohol and oral cancer research breakthrough

http://www.oralcancerfoundation.org/news/story.asp?newsId=2114

After reading this article one of my nagging questions comes back.

The article states "During alcohol ingestion acetaldehyde appears to react with proteins in the mouth to form rigid bonds with amino acids".

So does ingestion actually mean drinking or simply having alcohol present in one's mouth?
This is where I am going with this: I am perfectly comfortable with heavy drinkers and this study, but what about non-drinkers. Specifically I know that many of the mouthwashes contain alcohol (ex. Listerine alcohol is 26.9%, thats over 50 Proof. The directions call for one to rinse full strength for 30 seconds. What effect may this have?

Thoughts, questions, observations??

Kevin

18 YEAR SURVIVOR
SCC Tongue (T3N0M0) diag 06/2006.
No evidence of disease 2010
Another PET 12-2014 pre-HBO, still N.E.D.

�Remember to look up at the stars and not down at your feet. It matters that you don't just give up.�
Stephen Hawking