A .05 blood-alcohol content equates to about one drink for a woman weighing less than 120 pounds, and two drinks for a 160-pound man. The NTSB said the safest thing for people who have only one or two drinks is not to drive at all.
In most studies a drink was defined as 12 ounces of beer, 4 ounces of wine or 1 ounce of 80-proof alcohol.
The NTSB recommendation noted that more than 100 countries have the .05 or lower blood-alcohol content standard. After the standard was dropped to .05 in Europe, the share of traffic deaths from drunken driving dropped by more than half within 10 years.
About 10,000 people die from drunken-driving-related vehicle incidents every year. About 30,000 people in total die each year on U.S. highways, the NTSB study said. Those numbers have remained consistent for 15 years, said the NTSB.
An Insurance Institute for Highway Safety study estimates 7,082 deaths would have been prevented in 2010 if all drivers on the road had blood-alcohol content below .08 percent.
More than 4 million people drive intoxicated every year in the U.S., studies show. The NTSB said about half of intoxicated drivers stopped by police officers escape detection.
In the 1980s and '90s, the minimum drinking age was raised to 21 and the legal limit of blood-alcohol content was lowered to .08. In 1982, about 21,000 people were killed in drunken driving accidents, and alcohol-related deaths made up 48 percent of highway deaths.
"Our goal is to get to zero deaths because each alcohol-impaired death is preventable," NTSB Chairman Deborah Hersman said. "Alcohol-impaired deaths are not accidents, they are crimes. They can and should be prevented. The tools exist. What is needed is the will."
States and the restaurant/bar industry were not expected to embrace the NTSB recommendation. Mothers Against Drunk Driving and the Auto Club did not endorse lowering the level. Nor did the National Highway Traffic Safety Administration.
The board recommended NHTSA established "incentive grants" designed to encourage states to adopt the lower threshold.
An alcohol concentration threshold of .05 is likely to meet strong resistance from states, said Jonathan Adkins, an official with the Governors Highway Safety Association, which represents state highway safety offices.
"It was very difficult to get .08 in most states so lowering it again won't be popular," Adkins said. "The focus in the states is on high (blood alcohol content) offenders as well as repeat offenders. We expect industry will also be very vocal about keeping the limit at .08."
The lower threshold was one of nearly 20 recommendations made by the board, including that states adopt measures to ensure more widespread use of use of alcohol ignition interlock devices. Those require a driver to breathe into a tube, much like the breathalyzers police ask suspected drunken drivers to use.
The Associated Press contributed to this report.
