Alcohol has long been known to play a role in suicides, but there have been little data regarding which victims use it and how often. Now the federal Centers for Disease Control and Prevention reports that in a large sample of suicide victims whose blood alcohol levels were measured post mortem, one in four had been legally drunk, with a blood alcohol content at or above the federal standard of 0.08, or 8 milligrams of alcohol per 100 milliliters of blood.

The study’s findings were limited because it examined data from only 17 states and because blood alcohol measurements were available for only 70 percent of those who committed suicide in those states. Still, about one-third of those tested had some level of alcohol in their bloodstream at death, the researchers found.

“Alcohol is a component of suicidal behavior,” said Dr. Alex Crosby, author of the report published on Thursday in the C.D.C.’s Morbidity and Mortality Weekly Report. “It leads to disinhibition, and it can enhance feelings of hopelessness and depression. Alcohol impairs judgment and can lead to much more impulsive behavior."

“Any suicide prevention efforts must take that into account and address alcohol and substance abuse as well,” he added.