Patch May Tell Drinkers When to Stop

NEW YORK —  Hey, bartender. A shot and a patch, please.

A patch stuck to the skin can estimate how much alcohol is in a person’s blood, and it may someday be able to tell imbibers when they’ve had enough, a preliminary study suggests.

The penny-sized white patch starts turning green within about a minute of being stuck on the back of a drinker’s hand, study co-author James Zacny said.

Experiments with seven men found that the more alcohol they drank, and the higher their blood-alcohol levels rose, the darker the patch turned.

If further research bears out its promise, such a patch might be handed out by bartenders or dispensed with six-packs to warn people when they are nearing intoxication, said Zacny, a psychologist and assistant professor in the department of anesthesia and critical care at the University of Chicago.

Speaking in a telephone interview, he said the patch would not replace breath-analyzing devices for police work.

In the study, each participant drank a tonic-and-lime drink on four occasions with a different alcohol dose each time. The doses ranged from zero to one that produced blood-alcohol levels just below legal intoxication, Zacny said.

The patch was applied 15 minutes after the drink. Within about 20 minutes of application, the hue of its pea-sized color zone could reveal what dose of alcohol each man had consumed, Zacny said. The hue also was related to each man’s blood alcohol concentrations, which were measured by breath tests.

Altering the size of the color zone may cut the 20-minute delay, he said.

The patch detects alcohol vapor that escapes through the skin, he said.

Psychologist Elsie Shore of Wichita State University, who studies alcohol use, said that if the patch proves reliable and inexpensive enough, it might help bartenders persuade patrons that they are too drunk to drive.

But she noted that people’s ability to drive can be impaired below the legal blood-alcohol limit. “You can be legal and still be dangerous,” she said.

She also cautioned that the patch might promote drinking games to see who could turn the patch the darkest.