Drunk Driving: Even a Trace of Alcohol Is Dangerous on the Road, Says Study

Study shows drivers dangerous at 1/8 legal drinking level.

June 21, 2011, 5:56 PM

— -- Everybody knows drunk drivers are killers. But here's a startling finding by researchers at the University of California, San Diego:

Even a trace of alcohol, just enough to give a driver a "buzz," greatly increases the chances that the driver will be involved in an accident causing serious injuries and fatalities.

So how much is a trace? Anyone driving in the United States with a blood alcohol concentration of .08 percent is violating the law and considered drunk enough to be dangerous. But this study of nearly 1.5 million fatal accidents indicates that even .01 percent blood alcohol concentration is enough to increase the odds of a deadly accident. For many adults, that's less than half a beer.

"Accident severity increases significantly even when the driver is merely 'buzzed,'" according to the study, published in the current issue of the journal Addiction. The research, conducted by sociologists David Phillips and Kimberly M. Brewer, is based on federal statistics for fatal automotive accidents from 1994 through 2008.

The researchers were "initially startled" by their own findings, Phillips said during a telephone interview, "but then we discovered that people with such a low level of alcohol were behaving differently from sober drivers."

The authors said they believe this is the first study to use more than a decade of evidence from all U.S. counties and for all times of the day and all days of the week. They also believe their results are so conclusive that the legal limit should be lowered.

The U.S. limit of .08 percent is much more permissive than many countries. Some, including Brazil and Russia, have zero tolerance, so a driver in those countries is violating the law if he or she has even sipped a small glass of beer. Sweden, China, and Puerto Rico set the limit at .02 percent, and Japan outlaws drivers with .03 percent. Most countries fall between the United States and Brazil, setting the limit at around .05 percent.

The devastation caused by drunk drivers is well known in this country, and need not be repeated here, but the finding that even a small amount of alcohol increases the chances of a fatal accident is indeed sobering.

"Accidents are 36.6 percent more severe even when alcohol was barely detectable in a driver's blood," Phillips said in releasing the study. That begins at the .01 level, which is so low it would be difficult to detect short of a blood test, and increases steadily as the percentage rises.

Why would that little alcohol have such a deadly effect? The study, based on federal statistics collected after fatal accidents, reveals that "buzzed" drivers, as Phillips puts it, are more likely to speed, more likely to hit another vehicle, and less likely to be wearing a seat belt.

The findings are indeed startling, and in contrast with laboratory studies indicating that lack of coordination and impaired judgment begin to set in at two to three times the level required for a "buzz." But those studies are based on controlled experiments, not extensive records of real accidents.

Among the findings:

What it all adds up to, according to the researchers, is that alcohol, in any amount, is unsafe for drivers.

Drunk Driving: Alcohol Dangerous Even in Trace Amounts, Says Study

My guess is most people already know that, but also figure they can get away with a sip or two of wine or beer or even hard liquor. This study strongly suggests they are wrong.

"This is government data on an enormous number of cases," Phillips said. "We didn't invent any of this stuff."

Although he admits the findings were at first startling, he said he only had to look at his own past to believe them.

"When I was in college I used to play pool," he said. "My opponent, who was not as good a pool player as I was, would say to me wouldn't you like half a glass of beer. And I noticed that even with half a glass of beer inside of me, I was a less good pool player.

"Half a glass of beer would probably be even less than .01 concentration, but when you are playing pool a very, very tiny difference at one end can result in quite a big difference in your score."

Legal limits for alcohol and punishment for exceeding those limits vary from country to country, and even among adjacent communities. According to Phillips, they are "based on cultural and political and historical considerations, not just on data."

There is, however, much data on how to deal with drivers who have exceeded the legal limit.

A study at the University of Missouri-Columbia suggested that the risk of getting caught is probably a stronger deterrent than the perceived chance of getting in an accident. Participants in that study were much less likely to drive if they thought they might get arrested.

In the small town I live in, even first offenders spend a few nights in jail. But even worse, the local paper publishes their names, so all their neighbors know.

Researchers at the University of Florida took that a step further. They concluded that the "threat of immediate suspension of the driver's license is a larger deterrent than the threat of more severe penalties that may occur at a later date."

They compared the results to house-training a puppy.

"If you punish your dog two weeks after wetting the carpet, the behavior is not affected," the Florida researchers noted. "If you punish a drunk driver six to 10 months after the crime, the behavior is not changed. If you suspend the license immediately, the connection is made and the behavior is affected (at least in most cases.)"

And now, according to Phillips, it's unwise to wait until the driver is drunk. Maybe half a beer is all it takes to kill someone.

ABC News Live

ABC News Live

24/7 coverage of breaking news and live events