Even Small Amounts of Alcohol May Impair Driving

Study Shows a Link Between Car Accidents and Drivers With Less Than Legal Limit for Alcohol in Blood

Medically Reviewed by Laura J. Martin, MD on June 21, 2011
From the WebMD Archives

June 21 2011 -- Driving with a buzz can be as dangerous as driving when you are fully intoxicated, a new study suggests.

The blood-alcohol content (BAC) limit in the U.S. is set at 0.08%, but levels well below this legal limit are associated with car accidents that cause incapacitating injury and death. According to the CDC, close to 30 people in the U.S. die every day in motor vehicle crashes involving an alcohol-impaired driver. This is the equivalent of one death every 48 minutes.

"Buzz kills," says David Phillips, PhD a sociologist at University of California, San Diego. "No amount of alcohol seems to be safe for driving."

The new study appears in Addiction.

In the study, drivers who tested positive for blood alcohol at levels well-below the legal BAC limit were more likely to be in severe car accidents than sober drivers largely because they drove significantly faster, were less likely to be appropriately using a seatbelt, and were usually driving the striking vehicle.

The more alcohol the driver drank, the faster that they were likely to be driving, and the more severe the car accident was likely to be, the study shows.

Alcohol Blood Levels

Lowering the legal BAC limit may help, Phillips says. In Sweden, the BAC limit is 0.02%; in Japan, it is 0.03%.

Researchers looked at data from the Fatality Analysis Reporting System, which includes information on all 1,495,667 people in the U.S. who were involved in fatal car accidents from 1994 to 2008. This data included information on BAC in increments of 0.01.

Car accidents are 36.6% more severe even if alcohol was barely detectable in the driver's bloodstream, the study shows. The findings held even after researchers took into account the days and times of the week when car accidents are known to be more severe. Car accident severity is significantly higher on weekends, between 8 p.m. and 4 a.m., and in June through August.

"There is no safe level," Phillips says. "Why assume that just because you have been driving buzzed for years that it is safe?"

Designated Drivers

J.T. Griffin, the senior vice president of public policy at Mothers Against Drunk Driving (MADD), a nonprofit group aimed at putting an end to drunk driving, says drunk driving and related accidents are preventable.

"If you go out and drink, plan ahead and designate a driver," he says.

"I am not going to say that one drink is too many, but why would you want to risk it?" he says. "Even in rural areas, you can call somebody. Just don't get behind the wheel."

MADD is currently advocating for alcohol ignition interlocks, which would prevent a drunk person with a history of driving under the influence from operating the vehicle.

According to information posted on its web site, the Distilled Spirits Council, a national trade association representing distillers and distilled spirits brands, supports a 0.08% BAC limit along with strict penalties against repeat drunk drivers, license revocation, and other measures.

"While much has been done to reduce drunk driving, much more is still needed," the group states on its web site.

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J.T. Griffin, senior vice president of public policy, Mothers Against Drunk Driving, Washington, D.C.

David Phillips, PhD, sociologist, University of California, San Diego.

Phillips, D.P. Addiction, 2011.

CDC web site: "Impaired Driving."

Distilled Spirits Council web site.

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