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The Science Behnd .05

Studies back up the National Transportation Safety Board’s call
for a reduced blood alcohol limit.

You’re at a wedding and you toast the bride and groom with a couple of glasses of champagne, or you’re at the ballgame and have a large cup of beer with your buddies. Is it safe for you to drive home?



Technically, impairment begins with the first drink. Legally, for drivers in the United States at least, it begins at a blood alcohol concentration (BAC) of .08. Scientifically, however, alcohol’s tragic effects seem to become truly magnified at a BAC of .05.

When the National Transportation Safety Board (NTSB) released a safety report called “Reaching Zero: Actions to Eliminate Alcohol-Impaired Driving” in May 2013, it included a list of 19 recommendations that, if enacted, could make considerable progress toward the project’s ambitious goal.

One bullet point, however, received the most attention by far: the NTSB’s call to reduce the legal BAC limit from .08 to .05 for all drivers.

In a presentation to Public Affairs delegates at the 2014 AAA annual meeting, former NTSB member Mark Rosekind made clear that the .05 figure wasn’t “just pulled out of a hat” and that there was plenty of science behind it. More than 70 countries already have a .05 limit or lower, including most of Europe, South America, and Australia.

“The U.S. is behind,” Rosekind said in a recent follow-up interview. “As bold as everybody likes to think this is, the reality is that 70 countries around the world have already gone to .05 or lower. While we pride ourselves in the United States on being on the cutting edge of transportation safety, we are woefully behind.”

Indeed, the science is consistently clear:

• Studies in 2002 and 2005 showed that at a BAC level of .05, drivers are 1.38 times more likely to be in a crash than sober drivers. At .08, the risk jumps to 2.69 times higher.

• Since .05 BAC limits were instituted in Australia, Japan, and many European nations, studies have shown that fatal crashes have decreased and injuries have been reduced in those countries. Fatal crashes among males ages 18 to 49 in Europe have markedly decreased and overall fatal crashes in Australia were reduced up to 18 percent.

• A 2014 study showed that in two-vehicle accidents between drivers with BAC levels of .05 to .07 and drivers with BAC levels of .08, the drivers with the lower BAC levels were found solely at blame for the crash just as often as the .08 drivers.

The effort to reduce the BAC threshold from .10 to .08 in the U.S. took two decades, so when it released its 2013 report, the NTSB realized it was just a starting point.

In the two years since, legislation to lower BAC limits has been introduced in five states–Kentucky, New York, South Carolina, Vermont, and Washington–and a hearing on the topic has been held in Utah. None of these initiatives achieved serious traction.

A number of organizations support the NTSB’s call for a lower limit, including the American Trucking Association, the American Society of Safety Engineers, the American Medical Association, and the World Health Organization. AAA agrees that the science is clear on impairment below .08 BAC. And while AAA is not currently pushing for changes in state laws, it has begun to educate its members and the public about the risks of driving while impaired at lower BAC levels–an integral first step to changing public opinion on this safety issue.

A 2014 poll of AAA members in Missouri, southern Illinois, southern Indiana, and eastern Kansas showed mixed feelings about lowering BAC levels. Thirty-three percent of members polled strongly supported .05 BAC levels, while 32 percent strongly opposed the change. The remaining third of respondents were equally divided among somewhat supporting, neither supporting nor opposing, and somewhat opposing the change.

“The biggest barrier is education,” Rosekind said. “Impairment starts with the first drink. People will say, ‘You mean I can’t have one drink?’ No, this is about saving lives, about saying this is what science shows, and here’s how you manage it.

“It’s not about drinking,” he added. “It’s about separating the drinking from the driving.”

Kevin Adams is a freelance writer based in Orlando, Fla., and writes for multiple AAA publications. AAA Missouri added information to this article.

July/August 2015 Issue

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