A blood alcohol content of as little as .01 can impair driving, reports a new large-scale study, which found drivers were nearly twice as likely to be at fault in an accident with a sober driver.
"We find no safe combination of drinking and driving — no point at which it is harmless to consume alcohol and get behind the wheel of a car," says lead researcher and University of San Diego sociologist David Phillips.
The researchers analysed 570,731 fatal collisions between 1994 and 2011 from the US Fatality Analysis Reporting System (FARS) database. Any drivers with alcohol present in the bloodstream were classed as 'buzzed'.
"Our data support both the National Highway Traffic Safety Administration's campaign that 'Buzzed driving is drunk driving' and the recommendation made by the National Transportation Safety Board, to reduce the legal limit to a blood alcohol limit (BAC) of 0.05 per cent," says Phillips. "In fact, our data provide support for yet greater reductions in the legal BAC."
In fact, the researchers found that drivers with a BAC of .01 — the equivalent of less than one standard drink, depending on weight and gender, and well below the US legal limit of .08 — are 46 per cent more likely to be "officially and solely blamed" by accident investigators than the other driver (if the other driver is sober).
The researchers also found no evidence that any certain level of BAC dramatically changes driving habits. Instead, they found a gradual upward trend starting at .01 BAC.
But in the United States, buzzed drivers are not usually blamed, Phillips says.
Instead, police, judges and the public view the legal limit of .08 percent as "a sharp, definitive, meaningful boundary."
More than 100 countries around the world, including Australia, have limits set at BAC 0.05 percent or below.