Just over 7 percent of American workers drink during the workday — mostly at lunch — and even more, 9 percent, have nursed a hangover in the workplace, according to a study.

Young, single men are tied most often to workplace-related drinking, especially managers, salespeople, restaurant workers and those in the media, according to the findings by the University at Buffalo's Research Institute on Addictions.

The results, culled from telephone interviews with 2,805 employed adults from January 2002 to June 2003, appear in the current issue of the Journal of Studies on Alcohol.

Principal investigator Michael Frone said the national study was meant to help managers develop workplace policy on alcohol use and to open the door to exploring the causes and effects of workplace alcohol use.

"Of all psychoactive substances with the potential to impair cognitive and behavioral performance, alcohol is the most widely used and misused substance in the general population and in the work force," said Frone, research associate professor in the university's Psychology Department.

"It slows down your reaction time, it impairs your decision-making," said Elena Carr, who coordinates a U.S. Labor Department program to combat workplace alcohol and drug use.

"In close to 19 percent of on-the-job fatalities, the person who dies tests positive for either alcohol or drugs or both," Carr said, noting toxicology tests are not required for every incident.

In the study, employees around the country were asked about workplace alcohol use during the previous 12 months. The sample was designed to reflect the demographics of the U.S. work force from ages 18 to 65, the researchers said. Participants were promised confidentiality.

Seven percent said they had drunk alcohol at least once during a workday. Lunch was the preferred time to drink, according to the study, which was funded by the National Institute on Alcohol Abuse and Alcoholism.

Overall, 15 percent of respondents reported being directly affected by alcohol at work — either by drinking on the job or shortly before heading to work or working with a hangover. Nearly one in five workers, 19 percent, made it a monthly habit and 11 percent reported weekly use or impairment.

The NIAAA estimates nearly 14 million people in the United States abuse alcohol or are alcoholics.