A new study of designated drivers finds 35 percent of them drink. Many imbibing designated drivers have blood-alcohol levels high enough to impair their driving, researchers from the University of Florida report.
They conducted breath tests on more than 1,000 people, including 165 who said they were designated drivers, as they left bars.
They found 65 percent had no blood alcohol content, while 17 percent had levels between 0.02 and 0.049, and 18 percent had levels measuring 0.05 or higher, according to The New York Times.
In the United States, it is illegal to drive with a blood-alcohol level of 0.08 or higher.
Last month, the National Transportation Safety Board (NTSB) recommended states lower allowable blood-alcohol levels for drivers, from 0.08 percent to 0.05 percent. The NTSB said thousands of people are killed or injured each year by drivers who are not legally drunk, but who are still impaired. Currently about 10,000 people die in alcohol-related car crashes each year.
A person with a blood-alcohol level of 0.05 percent is 38 percent more likely to be involved in a crash, compared with someone who has not been drinking, according to the NTSB. A person with a 0.08 blood-alcohol level is 169 percent more likely to be involved in an accident.
The new study appears in the Journal of Studies on Alcohol and Drugs.
"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," lead author Adam E. Barry said in a news release.