Adam Barry, an assistant professor of health education and behavior at the University of Florida, and his team recruited patrons as they left bars in a restaurant and bar district of a major university town in the Southeast between 10 p.m. and 2:30 a.m. across six Friday nights before home football games in fall 2011.
The mean age of the 1,071 people who agreed to be tested was 28. Most were white male college students, while 10 percent were Hispanic, 6 percent were Asian and 4 percent were African-American, the researchers said.
After completing a 3- to 5-minute interview asking demographic data and alcohol-related behaviors, participants had their blood-alcohol content tested with a hand-held, breath-testing instrument.
The study, scheduled to be published in the July issue of the Journal of Studies on Alcohol and Drugs, found of the designated drivers who had consumed alcohol, half recorded a blood-alcohol level higher than .05 percent -- a recently recommended new threshold for drunken driving.
"If you look at how people choose their designated drivers, oftentimes they're chosen by who is least drunk or who has successfully driven intoxicated in the past -- successful meaning got home in one piece ... that's disconcerting," Barry said in a statement.