The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 01-15-2010, 04:32 PM
UncleFred UncleFred is offline
Guest
 
Join Date: Jan 2008
Can mouthwash make you flunk a breathalyzer test?

Here in Boston we're all a doo-dah about a state senator who got put on a house-arrest no-drinking probation after a hit-n-run incident. Not one week into his house arrest he flunked one of several daily breathalyzer tests.

He claimed he hadn't been drinking and that it was a false positive caused by his toothpaste. The judge didn't buy it and now the senator's in the slammer.

But wait - doesn't mouthwash have a high alcohol content? Something like 15%? You don't drink it, but it lingers in your mouth and on your breath.

Could using mouthwash right before taking the test result in a failure?

Or maybe its the 'wrong' type of alcohol?

Last edited by UncleFred; 01-15-2010 at 04:33 PM..
Reply With Quote
Advertisements  
  #2  
Old 01-15-2010, 04:37 PM
beowulff beowulff is online now
Member
 
Join Date: May 2001
Location: Scottsdale, more-or-less
Posts: 10,191
Didn't you say toothpaste?
That doesn't have any significant alcohol in it, AFAIK.

Mouthwash - maybe.
Reply With Quote
  #3  
Old 01-15-2010, 04:41 PM
UncleFred UncleFred is offline
Guest
 
Join Date: Jan 2008
Quote:
Originally Posted by beowulff View Post
Didn't you say toothpaste?
That doesn't have any significant alcohol in it, AFAIK.

Mouthwash - maybe.
Like I said...the judge didn't buy it.
Reply With Quote
  #4  
Old 01-15-2010, 04:50 PM
pravnik pravnik is offline
Charter Member
 
Join Date: Apr 2002
Location: TX
Posts: 13,335
The breathalyzer is designed to measure deep lung alcohol. Mouth alcohol can cause a false positive if the alcohol is ingested (or swished around) immediately before taking the sample, as can stomach alcohol if the subject burps or regurgitates. To avoid false positives due to mouth or stomach alcohol the subject is observed for a minimum of 15 minutes prior to taking the sample. Some breathalyzers also have a feature that measures a very sharp dropoff in alcohol in the first part of the breath and the last part - if the subject is blowing much higher during the first part of the blow the last part, there could be mouth alcohol contamination and the instrument will read the test as invalid.
Reply With Quote
  #5  
Old 01-15-2010, 04:53 PM
Shagnasty Shagnasty is offline
Charter Member
 
Join Date: May 2000
Posts: 21,829
The academic answer is that it can under the right circumstances. Mouthwash like Listerine is 54 proof alcohol for example. You can swish some in your mouth and take a breathalyzer immediately and flunk it. You wouldn't flunk a blood test however from that unless you actually drank a lot of it (which some people do if they are desperate).

The answer to the larger question is that he was lying or the equipment was faulty (less likely for the latter). I am a recovering alcoholic with a lab grade breathalyzer and have done these experiments on myself. You can 'trick' them into a high reading pretty easily with alcohol containing products but that will go away in a few minutes if you wash your mouth with water. Toothpaste won't cause a failure reading at all.
Reply With Quote
  #6  
Old 01-15-2010, 06:17 PM
BigT BigT is offline
Guest
 
Join Date: Aug 2008
OP reminded me of a reverse version of this urban myth.
Reply With Quote
  #7  
Old 01-15-2010, 11:08 PM
Fear Itself Fear Itself is offline
Charter Member
 
Join Date: Apr 1999
Location: 847 mi. from Cecil
Posts: 28,298
Quote:
Originally Posted by beowulff View Post
Didn't you say toothpaste?
That doesn't have any significant alcohol in it, AFAIK.
Most toothpaste has a significant amount of sorbitol (up to 30%). Sorbitol is a sugar alcohol, but i don't know how it would affect a breathalyzer.
Reply With Quote
  #8  
Old 01-16-2010, 01:40 PM
muldoonthief muldoonthief is online now
Member
 
Join Date: Jul 2003
Location: North of Boston
Posts: 6,956
Quote:
Originally Posted by Fear Itself View Post
Most toothpaste has a significant amount of sorbitol (up to 30%). Sorbitol is a sugar alcohol, but i don't know how it would affect a breathalyzer.
The manufacturer of the breathalyzer that nailed Gallucci claimed it wouldn't affect it at all. And at his hearing, Gallucci dropped the toothpaste defense, and instead, brought in an outside expert who testified, using a testing method of his own that has not been approved by anyone, that Gallucci hadn't had a drink in the past 4 weeks. This worked flawlessly, in that a dangerous drunken driver who couldn't even remain sober for a week after his suspended sentence has been placed in jail.
Reply With Quote
  #9  
Old 01-16-2010, 07:40 PM
TurboNuke TurboNuke is offline
Guest
 
Join Date: Jun 2009
I was just on a jury for a DWI case. We heard a lot of testimony about breathalyzers. The breathalyzer in NY is a fairly foolproof device. Can "mouth alcohol" affect the test? Yes. But the tester also knows when this happens and it will invalidate the test.

IMO, there is really no way to fool or cause the breathalyzer to read spuriously.

Last edited by TurboNuke; 01-16-2010 at 07:40 PM..
Reply With Quote
  #10  
Old 01-17-2010, 08:30 AM
UncleFred UncleFred is offline
Guest
 
Join Date: Jan 2008
Quote:
Originally Posted by muldoonthief View Post
The manufacturer of the breathalyzer that nailed Gallucci claimed it wouldn't affect it at all. And at his hearing, Gallucci dropped the toothpaste defense, and instead, brought in an outside expert who testified, using a testing method of his own that has not been approved by anyone, that Gallucci hadn't had a drink in the past 4 weeks. This worked flawlessly, in that a dangerous drunken driver who couldn't even remain sober for a week after his suspended sentence has been placed in jail.
A friend just informed me that the senator failed the breathalyzer not once but three times on that one day. That probably helped kill the toothpaste defense.
Reply With Quote
  #11  
Old 01-17-2010, 09:28 AM
Fear Itself Fear Itself is offline
Charter Member
 
Join Date: Apr 1999
Location: 847 mi. from Cecil
Posts: 28,298
Quote:
Originally Posted by TurboNuke View Post
Can "mouth alcohol" affect the test? Yes. But the tester also knows when this happens and it will invalidate the test.
In Gallucio's case, he was being tested remotely by a device in his home. If there was an operator, he would have no knowledge of the conditions surrounding the test.
Reply With Quote
  #12  
Old 01-17-2010, 09:33 AM
muldoonthief muldoonthief is online now
Member
 
Join Date: Jul 2003
Location: North of Boston
Posts: 6,956
Quote:
Originally Posted by Fear Itself View Post
In Gallucio's case, he was being tested remotely by a device in his home. If there was an operator, he would have no knowledge of the conditions surrounding the test.
No - it was the day the device was being installed. The installer had him do a test right then and there, which he failed. He did say something like he thought it would be a few weeks before the device was ready - which I interpret as "I wouldn't have breakfasted on bourbon if I knew you were coming today."
Reply With Quote
  #13  
Old 01-17-2010, 10:27 AM
RickJay RickJay is offline
Charter Jays Fan
Moderator
 
Join Date: Jun 2000
Location: Burlington, Ontario
Posts: 31,255
My wife once failed a breathalyzer test because she'd used a Listerine mouthwash strip immediately before being tested. She got out of being arrested by asking the police officer to try one and test himself - which he did, and failed the test himself. (They were perceptive enough to notice she wasn't acting drunk and so were willing to try out her explanation.) Absolutely true story, happened in 2001 in Mississauga, Ontario.

So yes, it can happen. I suspect, however, that the use of mouthwash must be immediately before the test.
Reply With Quote
  #14  
Old 01-17-2010, 10:45 AM
billfish678 billfish678 is offline
Guest
 
Join Date: Jun 2006
Quote:
Originally Posted by RickJay View Post
My wife once failed a breathalyzer test because she'd used a Listerine mouthwash strip immediately before being tested. She got out of being arrested by asking the police officer to try one and test himself - which he did, and failed the test himself. (They were perceptive enough to notice she wasn't acting drunk and so were willing to try out her explanation.) Absolutely true story, happened in 2001 in Mississauga, Ontario.

So yes, it can happen. I suspect, however, that the use of mouthwash must be immediately before the test.
So, I guess the moral of the story is if you are gonna swish, make sure to bring some wash with you in the car to convince the local cops?

Great, yet another highly unlikely but plausible thing to have to worry about.
Reply With Quote
  #15  
Old 01-17-2010, 01:26 PM
EdwardLost EdwardLost is offline
Guest
 
Join Date: Apr 2009
Also, don't brush your teeth with at bottle of Jack.
Reply With Quote
  #16  
Old 01-17-2010, 01:42 PM
Chessic Sense Chessic Sense is offline
Guest
 
Join Date: Apr 2007
Quote:
Originally Posted by EdwardLost View Post
Also, don't brush your teeth with at bottle of Jack.
"Cuz when I leave for the night, I'm...going to jail."
Reply With Quote
  #17  
Old 01-17-2010, 02:46 PM
GilaB GilaB is offline
Charter Member
 
Join Date: Mar 2001
Location: New York, New York!
Posts: 2,456
My college chemistry teacher actually did this as an in-class demonstration of a chemically-based breathalyzer test - she had a student swish with mouthwash, then take the test, which she failed.
Reply With Quote
  #18  
Old 01-17-2010, 09:37 PM
needscoffee needscoffee is offline
Guest
 
Join Date: Oct 2009
I don't know of any alcoholic who isn't well aware of the alcohol content of mouthwashes. Or Nyquil (does it still come with its own shotglass?).
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:16 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.